PARTICIPATORY ASSESSMENT OF MANGROVES IN · reported five species of mangroves and several species...

IUCN Eastern Africa Programme

Mnazi Bay Ruvuma Estuary Marine Park

Assessment of Marine Biodiversity, Ecosystem Health, and Resource Status in

Mangrove Forests in Mnazi Bay Ruvuma Estuary Marine Park

G.M. Wagner, F.D. Akwilapo, S. Mrosso, S. Ulomi and R. Masinde

December 2004

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Assessment of Marine Biodiversity, Ecosystem Health, and Resource Status in

Mangrove Forests in Mnazi Bay Ruvuma Estuary Marine Park

G.M. Wagner, F.D. Akwilapo, S. Mrosso, S. Ulomi and R. Masinde

For the UNDP/GEF Development of Mnazi Bay Ruvuma Estuary Marine Park (MBREMP) Project

December 2004

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The designation of geographical entities in this book, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of IUCN, MPRU, GEF or UNDP concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The views expressed in this publication do not necessarily reflect those of IUCN, MPRU, GEF or UNDP. This publication has been made possible in part by funding from UNDP/GEF and FFEM. Published by: Reproduction of this publication for educational or other non-commercial

purposes is authorized without prior written permission from the copyright holder provided the source is fully acknowledged.

Reproduction of this publication for resale or other commercial purposes is

prohibited without prior written permission of the copyright holder. Citation: G.M. Wagner, F.D. Akwilapo, S. Mrosso, S. Ulomi and R. Masinde (2004):

Assessment of Marine Biodiversity, Ecosystem Health, and Resource Status in Mangrove Forests in Mnazi Bay Ruvuma Estuary Marine Park, viii +106pp

Cover photo: Anthony King Available from: IUCN EARO Publications Service Unit P. O. Box 68200 - 00200, Nairobi, Kenya Tel: + 254 20 890605 - 12, Fax: +254 20 890615 E-mail: [email protected]

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TABLE OF CONTENTS

ACKNOWLEDGEMENTS .............................................................................................................. iv

EXECUTIVE SUMMARY ................................................................................................................ v

INTRODUCTION......................................................................................................................... v

METHODOLOGY........................................................................................................................ v

GENERAL RESULTS, DISCUSSION AND CONCLUSIONS – AN OVERVIEW OF MANGROVE ECOSYSTEM ASSESSMENTS, ISSUES AND OPPORTUNITIES........................ vi

RECOMMENDATIONS ..............................................................................................................vii General Recommendations........................................................................................................vii

SECTION ONE: INTRODUCTION .................................................................................................. 1

1.1 Importance of Mangroves ...................................................................................................... 1

1.2 Factors Affecting the Distribution of Mangroves/Mangrove Ecology ...................................... 1

1.3 Mangrove Forests of Tanzania .............................................................................................. 2

1.4 Mangroves of Mnazi Bay and Ruvuma Estuary Marine Park: Previous Studies..................... 2

1.5 Mnazi Bay-Ruvuma Estuary Marine Park (MBREMP) ........................................................... 2

1.6 Objectives of the study .......................................................................................................... 2

SECTION 2: METHODS ................................................................................................................. 3

2.1 Study Sites ............................................................................................................................ 3

2.2 Quasi-quantitative, Rapid Assessment with Wide Coverage.................................................. 7

2.3 Quantitative Assessment of Selected Sites............................................................................ 7

2.3.1 Mangrove vegetation....................................................................................................... 7

2.3.2 Benthic macrofauna ........................................................................................................ 8

2.4 Tapping Indigenous Knowledge Through Discussions with Residents................................... 8

2.5 The Data Collection Team, Their Training and Supervision ................................................... 8

2.6 Production of Maps................................................................................................................ 9

SECTION 3: GENERAL RESULTS AND DISCUSSION – AN OVERVIEW OFMANGROVE ECOSYSTEM ASSESSMENTS, ISSUES AND OPPORTUNITIES....................... 10

3.1 Assessment of Current Status of Mangroves and their Resources ...................................... 10

3.2 Resource Use Patterns, Issues and Threats: Past, Present and Potential ........................... 21

3.3 Solutions to Issues and New Opportunities ......................................................................... 24

SECTION 4: CONCLUSIONS....................................................................................................... 29

SECTION 5: RECOMMENDATIONS ............................................................................................ 30

5.1 General Recommendations ................................................................................................. 30

5.2 Recommendations for a Long-term Monitoring Program...................................................... 31

REFERENCES ........................................................................................................................ 33

APPENDICES ........................................................................................................................ 35

Appendix A: Species Inventory.................................................................................................. 35

Appendix B: Site-Specific Results and Discussion..................................................................... 36 Appendix C: Tables showing GPS readings for all sites ............................................................ 96 Appendix D: Data Collection Sheets.......................................................................................... 98 Appendix E: List of Field Team Members ................................................................................ 100 Appendix F: Certificate for attendance in the training and participation

in mangrove assessment .................................................................................... 101 Appendix G: List of tables and figures (main text).................................................................... 102 Appendix H. List of tables, figures and photographs (Appendices) .......................................... 103

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ACKNOWLEDGEMENTS

We express our sincere gratitude to the management and staff of Mnazi Bay-Ruvuma Estuary Marine Park (MBREMP) for their kind cooperation and great efforts in facilitating the fieldwork. We also express our appreciation to Els van Walsum, a GIS expert working at the Agricultural Research Institute in Naliendele, Mtwara, for producing the maps presented in this report. We are greatly indebted to Dr. Matthew D. Richmond for his suggestions, information and ideas, which helped to improve the final report. Moreover, we would like to express our gratitude to The World Conservation Union, Eastern Africa Regional Office (IUCN-EARO), for initiating and overseeing this important study. Lastly, we express our warm thanks to the members of the community residing in the MBREMP area who were very kind and assisted us in a multitude of ways.

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EXECUTIVE SUMMARY

INTRODUCTION Mangrove forests are considered critical habitats with great ecological and socio-economic value. In Mtwara Region, as in most parts of Tanzania, mangroves are a source of firewood, charcoal, building poles and materials of boat construction. They are also a great tourist attraction. There are presently 9,458 ha of mangroves in Mtwara Region, most of which are in Mnazi Bay-Ruvuma Estuary Marine Park (MBREMP). Very few studies have been carried out on the mangroves in MBREMP. One brief study was conducted by Frontier-Tanzania in 1997 in Mnazi Bay and the offshore islands, but it did not cover the main mangrove area in Ruvuma Estuary. The study reported five species of mangroves and several species of macrofauna. Objectives of the Study The main objectives of this study were:

1. To assess the marine biodiversity, ecosystem health and resource status of mangrove forests in MBREMP,

2. To make preliminary assessments of threats affecting biodiversity in these mangrove forests, and

3. To provide recommendations for long term monitoring of the MBREMP mangrove forests. METHODOLOGY Quasi-quantitative, Rapid Assessment with Wide Coverage

Rapid assessments were conducted by moving through the study area and random sites selected to record data. At each site, quasi-quantitative observations were made with respect to mangrove density, height, health, seedlings, stumps, aesthetics and erosion, recording data on an arbitrary 5-point scale. Using this method, 40 sites were examined in Ruvuma Estuary, 7 in Mnazi Bay and 3 around the two offshore islands.

Quantitative Assessment of Mangrove Vegetation and Benthic Macrofauna in Selected Sites

The transect line permanent plots method (English et al., 1994) was applied to assess mangroves quantitatively. Along transects across vegetation types, 5 m x 5 m plots were examined and permanently marked. In each plot, all mangroves were identified to species level and counted according to their maturity categories. The girth at breast height (GBH) of saplings and trees was measured and stumps were counted by species. Using this method, 10 sites were examined in Ruvuma Estuary, 6 in Mnazi Bay and 2 on the offshore islands. In total 274 plots were examined. Benthic epi-macrofauna were assessed by placing a quadrat (0.25 x 0.25 m) in 4 random locations on the substratum in each permanent plot and counting fauna by species. Tapping Indigenous Knowledge Through Discussions with Residents

While carrying out both the rapid assessment method and the plot method, informal discussions were held with the villagers who assisted us in the survey work. In addition, discussions were held with other people whom we met on site regarding past and on-going threats, trends and other relevant information. The Data Collection Team, Their Training and Supervision

A total of 5 scientists, 7 MBREMP staff members and 8 villagers participated in the field data collection. All members of the team were trained thoroughly in the methodology and there was close supervision throughout the study.

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GENERAL RESULTS, DISCUSSION AND CONCLUSIONS – AN OVERVIEW OF MANGROVE ECOSYSTEM ASSESSMENTS, ISSUES AND OPPORTUNITIES

Assessment of Current Status of Mangroves and their Resources

The assessment of the mangrove ecosystems and their biodiversity, based on both methods used, are summarized in 9 maps of the entire MBREMP area, each showing a different parameter, i.e., mangrove basal area, density, number of species, height, health and aesthetics, as well as number of macrofauna species and stump density. In general, most of the parameters mentioned were noticeably higher or better in Ruvuma Estuary than in Mnazi Bay or the offshore Islands. Moreover, within Ruvuma Estuary, the best mangroves were in the southern part, while mangroves in the north tended to be only in moderate condition. This excellent status of mangroves in the southern part of the Estuary is likely due to the influx of nutrients from Ruvuma River, particularly when it floods during the heavy rainy season (March to May). The mangroves of Ruvuma Estuary appear to be amongst the best mangrove forests in Tanzania. Basal area in some sites of the Estuary reached as high as 1015 cm2/25m2 plot, which is comparable to that found in sites in the well-developed mangrove forest of Rufiji Delta (1261 cm2/25m2 plot). Thus, the MBREMP mangroves provide a rich natural resource base and are potentially a major tourist attraction. Resource Use Patterns, Issues and Threats: Past, Present and Potential

Though for centuries, people inhabiting the area have used mangrove resources sustainably, the rise in human populations has created significant pressure on these resources. Thus, presently, there are several issues or problems that threaten biodiversity in the MBREMP mangroves, in particular, mangrove harvesting, clear-cutting, unsustainable fishing methods, harvesting of macrofauna, particularly edible shellfish, and erosion (Fig. 4.10). Fortunately, mangrove harvesting still appears to be sustainable in most areas. However, there were a few sites found in Ruvuma Estuary and others in Ruvula Peninsula in Mnazi Bay, where there was a significant density of stumps found. At the same time, the species Bruguiera gymnorrhiza has been preferentially cut and its abundance has decreased substantially in most MBREMP mangrove areas. Although fishing practices in the mangroves appeared to be sustainable, since dynamite fishing has been controlled, shellfish (mollusc) harvesting in parts of Mnazi Bay and the offshore islands appeared to be carried out at an unsustainable rate. Erosion on the seaward half of Ruvuma Estuary and along Ruvuma River appears to be occurring at a faster rate than accretion. Thus, although erosion is a natural process, there is a possibility that it may be exacerbated by human activities such as deforestation, construction and bad agricultural practices in the Ruvuma River watershed area. In addition, it is unknown whether global climate change and sea level rise may be contributing factors. Site-specific results and discussion are given in Appendix B. Information obtained from every quasi-quantitative, rapid assessment site is displayed in graphs, showing the parameters mentioned in the methodology above. The data obtained from the quantitative plot method were used to calculate basal area by species, density of each mangrove species by maturity category, stump density by species and density of macrofauna by species, all of which were shown in graphs and tables. This appendix contains a total of 54 graphs and 2 tables.

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Solutions to Issues and New Opportunities

There are several cross-cutting solutions, e.g. enhancement of environmental awareness, that can address most of the identified issues simultaneously. In addition, there are a number of solutions to specific issues as well as new opportunities that can be developed. All of these are discussed in this report and given as recommendations in the final section (summarized below). RECOMMENDATIONS General Recommendations A number of recommendations can be made as follows (Fig. 4.10):

• Several cross-cutting solutions should be applied, including enhancement of environmental awareness, a participatory approach to management, zoning, surveillance and enforcement, participatory monitoring and the establishment of alternative/supplementary income-generating activities.

• Three core zones should be designated, i.e., in the southern part of Ruvuma Estuary, the northern part of Ruvula Peninsula and the southeast half of Membelwa Island. Specific-use zones should be designated for ecotourism, sustainable shellfish harvesting, etc. The remainder of the MBREMP mangrove areas should be multiple-use zones.

• Proper control of harvesting of mangroves should be implemented, in collaboration with communities in Mozambique. Harvesting of Bruguiera gymnorrhiza and Heritiera littoralis should not be permitted.

• No new developments should be allowed without proper EIAs.

• Community-based rehabilitation efforts should be conducted in various hot spots in MBREMP where mangrove cutting has been excessive or species specific (e.g., Bruguiera gymnorrhiza).

• A scheme for mangrove plots to be managed and “owned” by villagers could be pilot tested.

• Non-mangrove trees should be planted in surrounding areas in order to relieve future pressure on mangroves for building poles and firewood.

• There should be constant vigilance for unsustainable fishing practices.

• Sustainable harvesting of molluscs should be promoted.

• Ecotourism is a new opportunity that has great potential and should be exploited, but the local communities should be fully involved.

• Beekeeping is another opportunity that should be developed as an economic activity.

• Reforestation as well as regulation of construction and agriculture practices should be carried out in the Ruvuma River watershed area.

• Further assessments and issue-specific research should be conducted on ecotourism development, shellfish harvesting, other alternative/ supplementary income-generating activities, alternative sources of energy and building materials, the status of Heritiera littoralis, erosion and accretion in Ruvuma Estuary, infauna and nutrient levels.

Recommendations for a Long-term Monitoring Program

In future monitoring, the same transect line permanent plots method that was used in this study should be applied. In fact, some of the same plots examined in this study should be re-examined throughout the monitoring program. Monitoring should be done either every six months or once per year. Villagers should be involved in monitoring since it enhances their environmental awareness and motivates them to protect the mangroves. Financial sustainability in long-term monitoring can be achieved; firstly, by the involvement of villagers, which reduces cost; secondly, by convincing the district council that environmental monitoring should be a routine part of government business; and thirdly, by involving the private sector.

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SECTION ONE: INTRODUCTION

1.1 Importance of Mangroves Mangrove forests are considered as critical habitats with great ecologic and socio-economic value. They are keystone ecosystems since they provide important ecological services that extend far beyond their area of coverage. They have high productivity, producing large quantities of organic matter that serves as food for many organisms, not only living within the forest, but also outside it, since much of the organic matter produced is exported to other areas of the marine environment. Mangroves also serve as feeding, breeding and nursery grounds for a great variety of invertebrates and fish, many of which move out into the ocean during their adult stages. In addition, mangroves filter river water and facilitate the settlement of sediments, which would otherwise be detrimental to surrounding seagrass beds and coral reefs. Mangroves also play an important role in stabilizing the coastline, thus preventing shoreline erosion. Economically, mangroves are a source of firewood, charcoal, building poles, materials of boat construction, tannin and traditional medicines. Moreover, mangrove forests serve as great tourist attractions and have important scientific value. 1.2 Factors Affecting the Distribution of Mangroves/Mangrove Ecology Various environmental factors affect the structure and function of mangrove plants as well as species composition and distribution. These include coastal physiography, climate, tides, waves, currents, river flow, salinity, dissolved oxygen, soil and nutrients. Mangroves thrive in sheltered bays, estuaries, inlets, leeward sides of islands and areas of the coast sheltered by coral reefs. Climatically, mangroves require ample solar radiation, adequate rainfall and warm temperatures. Mangroves rarely occur outside the range delimited by the winter position of the 20oC isotherm. Normally mangroves thrive with 1,500 – 3,000 mm of rainfall annually. Optimal range of light intensity for mangroves is 3,000-3,800 kcal/m2/day (Aksornkoae, 1993). Wind is required for the pollination of some mangroves, e.g., Rhizophora spp., but high winds cause strong wave action, which is detrimental to mangroves. Tides influence mangroves in several ways. Tides affect salinity and temperature, which in turn affect mangrove species distribution. Tidal frequency and range have a great effect on mangrove zonation. Waves, currents and river flow have a complex effect on erosion and accretion as well as sedimentation and the re-suspension of sediments. Waves and currents also help in the dispersion of mangrove species and fauna. Optimum salinity is 28-35 ppt and below 28 ppt, growth of many species will decline (Aksornkoae, 1993). Dissolved oxygen is extremely important for animal and plant life in mangrove ecosystems, particularly respiration and photosynthesis. It also influences for decomposition. Since different species of mangroves have developed different adaptations to stress, salinity and dissolved oxygen levels affect species distribution and have a strong influence on mangrove zonation. There are two sources of mangrove soils, firstly, accumulation of sediment from coastal or riverbank erosion, which provides mainly sand, and sediments transported from inland areas along rivers and canals, which provide mainly fine mud. Degradation of organic matter over time also contributes significantly to mangrove soil formation. Soil particle size affects the distribution of species. For example, Avicennia spp. prefer sandy conditions, while Rhizophora spp. prefer muddy or sandy/muddy conditions and Sonneratia spp. prefer fine mud.

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1.3 Mangrove Forests of Tanzania There are eight species of mangroves found in mainland Tanzania and a ninth species found in Zanzibar. According to remote-sensing data, the total area covered by mangroves in mainland Tanzania dropped only slightly from 109,593 ha in 1990 to 108,138 ha in 2000 (Wang et al., 2003 in Wagner et al., 2003). By far the greatest mangrove forest in Tanzania occurs in the Rufiji delta, where area coverage dropped slightly from 49, 799 ha in 1990 to 48,030 ha in 2000. Mtwara is the district with the third largest area coverage of mangroves, constituting almost 10% of the mangroves in mainland Tanzania. In Mtwara, mangrove area coverage rose slightly from 9, 226 ha in 1990 to 9,458 ha in 2000. 1.4 Mangroves of Mnazi Bay and Ruvuma Estuary Marine Park: Previous Studies There is little information about mangroves in Mnazi Bay and Ruvuma Estuary. Semesi (1991) conducted a study based on aerial photographs (taken in 1989) and limited ground truthing. There has been a lack of ground studies in the Ruvuma Estuary region of the Marine Park, where by far the greatest area coverage occurs, i.e., over 7,000 ha (Wagner et al., 2003). Frontier-Tanzania conducted a brief study in 1997, which covered only mangroves in Mnazi Bay and the offshore islands (Muller et al., 1997). They found five mangrove species. Rhizophora mucronata dominated the offshore islands, Membelwa Island and Namponda Island. Mnazi Bay had more complex zonation, with Sonneratia alba dominating the lower (seaward) zone, while there were mixed stands of R. mucronata, Bruguiera gymnorrhiza and Ceriops tagal in the middle zone and C. tagal and Avicennia marina in the upper (landward) zone. Regeneration was relatively high throughout all stands. Muller et al. (1997) also qualitatively investigated macrofauna present in the mangroves. Several taxa of crabs were found, though not identified to species level. The gastropod Terebralia palustris was found in high abundance. The gastropod Cerithidium anticipata and the periwinkle Littorina spp. were found in low abundance. Oysters were found on the trunks and roots of mangroves. 1.5 Mnazi Bay-Ruvuma Estuary Marine Park (MBREMP) MBREMP is the second marine park in Tanzania, established in 2000. It covers 650 km2, of which, 200 km2 is marine, including islands, coral reefs and mangrove forests. The project has four components: participatory planning and protected area conservation and management, sustainable resource use and livelihoods, capacity building, and project monitoring and evaluation (United Republic of Tanzania, 2003). Biodiversity assessments have recently been carried out in all types of habitats as a pre-requisite for developing a detailed management plan. This study is an assessment of the mangrove forests in the Park area. 1.6 Objectives of the study The main objectives of this study were:

1. To assess the marine biodiversity, ecosystem health and resource status of mangrove forests in MBREMP,

2. To make preliminary assessments of threats affecting biodiversity in these mangrove forests, and

3. To provide recommendations for long term monitoring of the MBREMP mangrove forests.

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SECTION 2: METHODS

The mangrove assessment was carried out over a 15-day period, which included training MBREMP staff and villagers residing in the area to assist with the collection of scientific data. Two main methods that were intended to complement each other. One was a quasi-quantitative, rapid assessment technique, which allowed wide coverage of many sites, 50 in total (Table 2.1). The second was a quantitative plot method, carried out at selected sites, which gave accurate data, but was much more time consuming and covered a smaller area. Nevertheless, since MBREMP staff and villagers residing around the mangrove forests were trained to collect data using the plot method, quite a large amount of data was collected from 18 sites during the study period with this method. Various other types of observations were recorded in additional sites, 9 of which are indicated in Table 2.1 and shown in Figs. 2.1 and 2.2 In addition to these two methods, indigenous knowledge was tapped through informal discussions with the villagers and resource users whom we met other people during the course of the assessment. Moreover, general observations about the characteristics of the forests were recorded throughout the fieldtrip. Photographs were taken to record the condition of the forest or to depict important issues or opportunities. 2.1 Study Sites In the Ruvuma estuary mangrove area, a total of 40 sites were examined by the rapid assessment method and 10 sites by the plots method (Fig. 2.1, Table 2.1). Two of these sites were examined using both methods. In Mnazi Bay and the offshore islands, 10 sites were examined with the rapid assessment method and 8 sites with the plots method (Fig. 2.2, Table 2.1). GPS readings for all sites and many of the plots examined are given in Appendix A.

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Table 2.1: List of study sites grouped by rivers (and sections within rivers) or by islands.

Sites Marine Park area

River/ Island Section of river

Rapid assessment

method

Plot method

Other observa-

tions

Lower 1C, 1D, 1E 2D

Nachika tributary into the lower part

1F

Upper, northern branch

X, Y, Z, 1A, 1B

Nganje

Upper, southern branch

V,1G 1U

Lugue N-west, N-east, O, P, Q, R, S, T, U

N-west, N-east, L

K

Lower B, 1Q, 1R 1V

Upper, northern branch

1S, 1T A C

Middle, southern branch

1K, 1L, 1M

Kingumi

Upper, southern branch

1H, 1I, 1J M

Lidengo 1N, 1O

Nkurukala 1X E, F

Lower (Litokoto) D

Upper, northern branch (Chikomolela)

1Y, 1Z

Chikomolela/ Litokoto

Upper, southern branch (Kitope)

2A-west, 2A-east, 2B, 2C

Ruvuma Estuary

Ruvuma G, J H, I

Total for Ruvuma Estuary 40 10 7

Membelwa Island

C, D, E A B Offshore islands

Namponda Island

F G

Mnazi Bay

I, J, K, L, M, N, O

H, P, Q, S, T, U

Total for Mnazi Bay and offshore islands 10 8 2

GRAND TOTAL 50 18 9

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2.2 Quasi-quantitative, Rapid Assessment with Wide Coverage The rapid assessment technique involved moving through the study area and stopping at representative sites to record observations. In most cases, observations were made from the boat, but where necessary, we walked a short distance into the forest to examine it better. At each site, quasi-quantitative observations were made with respect to mangrove density, height, health, presence of seedlings, presence of stumps (as an indication of cutting pressure), overall aesthetics (an important factor when considering the potential for tourism) and erosion. All data were recorded on an ordinal scale of 0-5, where 0 = nil, 1 = very low (or very poor), 2 = low (or poor), 3 = moderate, 4 = high and 5 = very high. It is understood; however, that for some of the variables, such as health, 0 does not apply. Ratings were based not only on comparisons among sites within the MREMP area, but also on comparisons with mangrove forests in many other parts of Tanzania, such as Tanga, Bagamoyo, Dar es Salaam, Rufiji and Kilwa, which have been visited by the same research team. A number of photographs were also taken at each site and between sites in order to provide additional information and subsequent verification of observations. Similar methodology has previously been applied by the same research team in Kilwa (Ngoile et al., 2002). Limitations of this method are that it is somewhat subjective and there is thus the possibility of observer error. Moreover, data recorded are based on only what can be seen near the edge of the river or channel from which observations are made, i.e., it cannot determine the condition of mangroves in zones away from the channels. Nevertheless, this rapid assessment technique made it possible to get a broad picture of the MBREMP mangrove areas, which would not have been possible otherwise. 2.3 Quantitative Assessment of Selected Sites

2.3.1 Mangrove vegetation The transect line permanent plots method (English et al., 1994) was applied as a quantitative method. This method was used to assess mangrove abundance, species diversity, and regeneration capacity. An additional parameter that was recorded was the density of stumps, by species, as an indication of cutting pressure. In each site, transects were taken perpendicular to vertical tidal zones dominated by particular forest types. Within each zone, replicate plots were placed randomly for sampling. Plots (each 5 m x 5 m) were permanently marked with spray paint and GPS readings were recorded, so that the same plots can be re-examined during future monitoring sessions. Where vegetation was too dense to allow GPS readings to be taken for each plot, readings were taken at the edge of the forest and compass readings were recorded for the direction of the transect. In total, 181 plots were examined in Ruvuma Estuary and 93 plots in Mnazi Bay and the offshore islands. Within each plot, all mangroves were identified to species level and counted according to three maturity categories: seedling (< 1 m in height), sapling (height > 1 m, girth < 4 cm) and tree (girth > 4 cm). The girth at breast height (GBH, standardized at 1.3 m above ground) was measured for all trees and saplings. Stumps were also counted and the girth of each at 15 cm above ground was measured, as an indication of cutting pressure. In most cases, the species of the stump could also be discerned. Data on mangrove vegetation for each plot was recorded using the data sheet shown in Appendix B, Table B.1. The GBH measurements were used to calculate basal area of mangroves, which is one of the best measures of mangrove abundance and is generally proportional to canopy cover. It is also one of the best indicators of ecosystem health and maturity. Moreover, when calculated by species, basal area indicates the importance or dominance of each species in a given site.

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2.3.2 Benthic macrofauna A quadrat method was used to record data on benthic epi-macrofauna. Within some of the permanent plots, quadrats (each 0.25 x 0.25 m), were place in 4 random locations on the substratum. However, before placing the quadrats, crabs were counted at some distance, in an estimated quadrat area. Other organisms were counted within the quadrat. As much as possible, macrofauna were identified to species level. Data on macrofauna were recorded using the data sheet shown in Appendix B, Table B.2. 2.4 Tapping Indigenous Knowledge Through Discussions with Residents While carrying out both the rapid assessment method and the plot method, informal discussions were held, at each site, with the villagers who assisted, particularly elderly members of the group, as well as other people whom we met along the way. Questions were asked at every site. Through these discussions, ample information was obtained concerning past trends in mangrove abundance and species composition, threats to mangroves, both natural and human, as well as present ways in which the mangroves are being utilized and the on-going threats. 2.5 The Data Collection Team, Their Training and Supervision A total of 5 scientists, 7 MBREMP staff members and 8 villagers participated in the field data collection (Photograph 2.1, see list of team members in Appendix C). The scientists trained the others in scientific mangrove assessment methodologies, while at the same time gaining substantial indigenous knowledge from the villagers. For part of the fieldwork, the larger group split into two groups, each group having some scientists, MBREMP staff and villagers, in order to implement the main two field data collection methods described above. All worked together very efficiently and maintained a good team spirit. On the last day, a get-together dinner was arranged and certificates (Appendix D) were awarded to the villagers having gone through the training and participated in the mangrove assessment. Though data collection was carried out with the assistance of MBREMP staff and villagers, it involved thorough training as well as very close and constant supervision of the participants by scientists. Therefore, the data collected in this study can be considered accurate. MBREMP staff were also trained in data entry and analysis. After being trained on every step of the process, they actually processed some of the data themselves so as to get enough practice to be able to repeat the process later on their own.

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Photograph 2.1: Data collection team composed of scientists, MBREMP staff and villagers (a few were missing from the photograph).

2.6 Production of Maps During the fieldwork, the mangrove maps produced by Semesi (1991) (based on aerial photographs taken in 1989) were used as a guide and as a basis for comparison with respect to the present status of rivers, mangrove coverage, etc. Data obtained through all the methods mentioned above were brought together to make GIS maps, making use of all the GPS readings recorded. These maps were produced by Els van Walsum at the Agricultural Research Institute at Naliendele, Mtwara.

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SECTION 3: GENERAL RESULTS AND DISCUSSION – AN OVERVIEW OFMANGROVE ECOSYSTEM ASSESSMENTS, ISSUES AND OPPORTUNITIES

3.1 Assessment of Current Status of Mangroves and their Resources In general, based on the quantitatively sampled sites, the southeast side of the Marine Park mangrove area of Ruvuma Estuary had higher basal area, ranging from moderate to very high (>801 cm2/25m2), than the northwest side of the estuary where it ranged from low to very low(<600 cm2/25m2, Fig. 3.1). In Mnazi Bay and the offshore Islands, basal area was primarily very low, though at one site it was very high. Density (based on quasi-quantitative, rapid assessment) was moderate to high in most of the sites in the Estuary, the Bay and offshore islands (Fig. 3.2). Mangrove species richness (number of species) was higher in the southern part of Ruvuma Estuary than in the northern part of the Estuary, Mnazi Bay or the offshore islands (Fig. 3.3). Avicennia marina, Bruguiera gymnorrhiza, Ceriops tagal, Rhizophora mucronata and Sonneratia alba were found in Mnazi Bay and the offshore Islands (Appendix A, Table A.1). In Ruvuma Estuary, in addition to these five species, Heritiera littoralis and Xylocarpus granatum were also found. The height of mangrove trees was moderate to very high in most sites in the southern part of the Estuary, while it was moderate to low in most sites in the northern part of the Estuary as well as the Bay and offshore Islands (Fig. 3.4). Health ranged from moderate to very good in most sites in the southern Estuary, while it ranged widely from very good to very poor in the north (Fig. 3.5). In Mnazi Bay and the offshore Islands, health was either moderate or good. Aesthetics ranged from moderate to very good in most sites in the southern part of the Estuary, but ranged from good to very poor in the northern part and from poor to good in Mnazi Bay and the offshore islands (Fig. 3.6). Macrofauna species richness, i.e., the number of species per site was high (5 species) to very high (6-7 species) in most of the sites in the Estuary (Fig. 3.7), while most sites in Mnazi Bay and the offshore islands had moderate species richness (4 species), except for one site where it was very low (1-2 species) (Appendix A, Table A.2).

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In all rapid assessment sites, stump density was either very low or low throughout all sites in MBREMP (Fig. 3.8). In most of the quantitatively assessed sites, stump density was also very low or low throughout the area, except for two sites in the Estuary (one along Kingumi River and one on the northern side of the Estuary near Msimbati Village) and two sites in Mnazi Bay (both near Msimbati Village) (Fig. 3.9). Particularly the site along Kingumi River (Site 1V) had very high cutting pressure (>12 stumps/25m2 plot). This site is a hot spot that deserves special attention since the forest is very well developed there, as indicated by its very high basal area (1015 cm2/25m2 plot), but it is likely to become seriously degraded at the present cutting rate. In general, most of the parameters recorded were noticeably higher or better in Ruvuma Estuary than in Mnazi Bay or the offshore Islands. Moreover, within Ruvuma Estuary, the best mangroves were in the southern part, while mangroves in the north tended to be only in moderate condition. This excellent status of mangroves in the southern part of the Estuary is likely to be natural and due to the influx of nutrients from Ruvuma River, particularly during the heavy rainy season (March to May). The mangroves of Ruvuma Estuary appear to be amongst the best mangrove forests in Tanzania. Basal area in some sites of the Estuary (up to 1015 cm2/25m2 plot) was very similar to that found in parts of the most well-developed mangrove ecosystem in Tanzania, the Rufiji Delta, such as at Kifuma where basal area was 1261 cm2/25m2 plot (Wagner, 2004). By comparison, basal area ranged from 631 to 753 cm2/25m2 plot at sites in Ruvu Estuary, Bagamoyo and was 85 and 64 cm2/25m2 in Mbweni and Kunduchi near Dar es Salaam (Wagner, 2004), where cutting pressure is very high (Akwilapo, 2001). All these studies were done using the same methods. The present condition of mangroves in the MBREMP, in terms of overall coverage, is very similar to that reported by Semesi (1991) who used aerial photographs taken in 1989. Decrease or increase in mangrove coverage in certain areas could be explained by the villagers in terms of erosion or accretion, respectively. However, in a number of areas there were differences in species composition. These differences may either be due to actual changes in species composition that have taken place since 1989 or may be due to the fact that Semesi (1991) mapped species composition by general forest types, which did not necessarily reflect the exact species composition found in each area since ground truthing was limited.

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3.2 Resource Use Patterns, Issues and Threats: Past, Present and Potential For centuries, people inhabiting the MBREMP mangrove area have used mangroves for firewood and building materials. Since human populations were low in the past and migration was limited, it is likely that most human uses of these mangrove resources were sustainable. However, according to villagers and MBREMP staff, in recent decades, some types of resource use patterns, i.e., heavier harvesting of mangroves for firewood, charcoal, building materials and boat making, have been a threat to the health of the mangrove forest. Moreover, human populations in the MBREMP area have increased over the past decade and there is greater influence of human populations from other areas; thus, the pressure on mangrove resources has been increasing. According to information provided by community members, Bruguiera gymnorrhiza, Ceriops tagal and Rhizophora mucronata are particularly used as building poles as well as firewood. Avicennia marina, Sonneratia alba and Xylocarpus granatum are also used for firewood. Besides mangrove harvesting, there are several other issues which have the potential to threaten biodiversity in the MBREMP mangroves. These include clear-cutting (which has sometimes occurred in the past, such as the solar salt pans on the northeast side of Ruvuma Estuary), the harvesting of macrofauna, particularly edible shellfish (which were observed to be gathered in large number in Mnazi Bay and the offshore islands) as well as erosion, if it is exacerbated by human activities (Fig. 3.10). While there was evidence of mangrove harvesting in many sites, so far, it still appeared to be more or less sustainable in most areas. This is due to the large number of seedlings seen in most sites, which far exceeded the density of cut stumps. Moreover, in most places the harvesting has not left areas open to the extent that the conditions of the forest environment and soil properties could have changed significantly. However, according to a combination of our own field observations as well as indigenous knowledge, there are some areas of Ruvuma Estuary, such as along the lower Kingumi River, Lidengo River, the northern edge of the Estuary, adjacent to Msimbati Village and one site in upper Nganje, southern branch, where harvesting seems to have exceeded the natural regeneration rate. In Mnazi Bay, high cutting pressure was observed at two sites near Msimbati Village. Even in such sites however, cutting is patchy. For example, in Site 1V (lower Kingumi River), which has the highest cutting pressure of more than 12 stumps/25m2 plot (primarily Ceriops tagal), the mean density of seedlings is more than 60/25m2 plot (again primarily C. tagal). Thus the potential for recovery is quite high if further cutting pressure is controlled. Nevertheless, considering the rapid growth of Mtwara’s population and the dynamics of human movement, mangrove harvesting is potentially a significant threat, so steps should be taken to deal with this issue. While harvesting appears to be sustainable in most places, it appears that preferential cutting may have caused a shift in species composition in some areas. In particular, the abundance of Bruguiera gymnorrhiza has been greatly reduced in most parts of Ruvuma Estuary (according to traditional knowledge) due to its great popularity for the production of building poles. Thus, this species is in danger of being depleted.

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Clear-cutting mangroves to make space for construction, saltpans or other purposes took place in some areas in past years. For example, the saltpans on the northwest side of Ruvuma Estuary were made more than 10 years ago. However, clear-cutting for such purposes does not seem to be on-going. One of the most destructive fishing methods is dynamite fishing, which has been commonly practice in Ruvuma Estuary in past decades, according to indigenous knowledge. This practice not only indiscriminately killed fish, invertebrates and plankton, but also destroyed the mangrove habitat and accelerated erosion. It seems to be well controlled now, but constant vigilance is still needed. Most other types of fishing that are practiced in the mangroves seem to have minimal impact. Fence traps are used across narrow channels. Though this method could, potentially, deplete fish stocks if widely used, we did not see more than 4 or 5 fence traps throughout Ruvuma Estuary. Thus, it is unlikely to be occurring at unsustainable levels. Basket traps were also observed, but again the number observed was very low, so it is unlikely that their use has any detrimental impacts. One of the issues of concern related to macrofauna is the harvesting of gastropod and bivalve shells, which is particularly evident on the offshore islands and some parts of Mnazi Bay. Several edible species where observed in abundance in many of the sites, in particular, Cerithidea decollata (Nyambua in Kiswahili) and Terebralia palustris (Mangrove Whelk or Suka in Kiswahili). These species are harvested for food and fish bait and, in some areas, numerous piles of shells harvested for these purposes were observed. It appears that the present harvesting rate may not be sustainable over a long period of time, particularly since gastropods showed low density in these sites. However, since shells may exist for a long time without being degraded, just the appearance of piles of shells does not mean that they are being overharvested. Nevertheless, since, in some areas, the shells are being taken away and burnt to make lime, the harvest rate cannot be determined by just observing new piles of shells. It was also reported by people living in the area that the crab Scylla serrata is collected and sold in Mtwara and Dar es Salaam, but the extent of this trade could not be ascertained. Thus, further research into this issue is required. Potentially, this threat to shellfish may become a much greater problem in the near future due to growing populations in the area, the increase in tourists and the influx of investors wishing to establish export businesses. Erosion is another issue observed in the Ruvuma Estuary. Erosion, which is brought about by four types of water movement (i.e., wave action, tidal movement, ocean currents and river flow, particularly during flooding), is largely a natural process that is often dynamically balanced with accretion of sediments in other places or at different times. However, if erosion becomes exacerbated by human activities, such that it exceeds accretion, it becomes an issue of concern. Erosion particularly affects the seaward half of Ruvuma Estuary and the Ruvuma River bank itself. This is due to the huge volume of water that must move from the upper reaches of the estuary to the ocean within 6 hours, especially during spring tides. In several channels (Nganje River, Lugue River, Kingumi River) as well as along the Ruvuma River itself, several meters of riverbank have been swept away in recent years. In, addition some new channels have been opened up, such as one site in the Lugue River and on in upper Kingumi River, northern branch. However, there is very little erosion occurring in the landward half of the estuary. The accretion of sediments and development of new mangrove stands (e.g., two sites along Lugue River and three sites along Kingumi River) in Ruvuma Estuary to some extent offset the impacts of erosion. In such newly formed growths of mangroves, Sonneratia alba is invariably the first colonizer. However, according to indigenous knowledge and on-site observations, it appears that the rate of erosion in the past few of decades has exceeded accretion. This observation matches trends shown in an overlay of remote sensing maps produced in 1990 and 2000, indicating

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observable loss of mangroves along the channels in Ruvuma Estuary and Ruvuma River itself, with only minor additions of mangrove area in other parts of the Estuary (Makota, 2002). It is very likely that various human activities have caused an intensification of erosion. In particular, it is possible that deforestation, construction and poor agricultural practices upcountry within the Ruvuma watershed area have altered rainfall patterns, severity of flooding and sediment loads. Erosion may increase as global warming and sea level rise gain momentum. Pernetta (1993) predicts that in alluvial and tidal plains, the recession of the seaward Sonneratia zone, is likely to occur at a faster rate than the landward migration of Rhizophora and Bruguiera zones. Thus, the overall extent of the mangrove forest as well as the relative extent of different zones could change significantly and, as a result, dramatically alter the productivity of fish and prawns. Inundation from sea level rise would result in increased salinity (Mgaya, 2004). Some mangrove stands may adjust to changing conditions fast enough to survive, while other stands may not. Although we do not know whether global warming and sea level rise have, as yet, had any impact on the MBREMP mangroves, this is a phenomenon that we should be aware of. While some of the main issues directly impacting mangroves and their resources have been discussed above, the underlying socio-economic root causes that have created these issues should also be considered (Fig. 3.10). It is obvious that in Mtwara, like most coastal areas of Tanzania, poverty is a major root cause that necessitates villagers to use the natural resources to their maximum. Other root causes are inadequate environmental awareness, inadequate general education, demographic change (including rising populations in coastal areas and increasing movement of transient resource users and temporary dwellers, particularly from Mozambique), lack of alternative sources of livelihood, lack of alternative sources of building materials and energy (other than mangroves) and difficulties with surveillance and enforcement in such a large area as the Ruvuma Estuary, 3.3 Solutions to Issues and New Opportunities There are a number of general solutions and approaches that a Marine Park can apply to solve the identified management issues (Salm et al., 2000). They are crosscutting, i.e., they address most of the issues simultaneously (Fig. 3.10). They are as follows:

• Enhancement of environmental awareness

• Participatory approach in all planning and implementation

• Zoning

• Teamwork amongst community members, MBREMP staff and invited scientists/resource persons

• Surveillance and enforcement

• Regular, participatory monitoring

• Further assessments

• Facilitation of the establishment of alternative/supplementary income-generating activities Although marine parks are designed to protect and conserve marine biodiversity, in an area such as Mtwara, like most coastal areas of Tanzania where people depend very much on coastal and marine natural resources for their survival, the most appropriate approach to management is to allow communities to benefit as much as possible from these resources as long as their utilization is sustainable. In management plans for Marine Protected Areas, zoning is a common strategy (Francis et al., 2002). A good approach to zoning would be to have three types of zones in a similar manner to Mafia Island Marine Park (MIMP). These types of zones could be as follows:

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• Multi-user zones where activities or uses of the zones would be carried out with the full agreement of all stakeholders or users involved,

• Zones of specified use, e.g., ecotourism, shellfish collection, etc., and

• A few core, fully-protected zones that would be closed to human activities in order to allow the perpetuation of stable ecosystems of high biodiversity and the maintenance of seed populations.

While the process of zoning should be done through full consultation and agreement of the villagers and other stakeholders, a few recommendations on zoning can be made based purely on scientific assessments made in this study. Core zones should be selected such that they are habitats with high conservation values, are vulnerable to disturbances and have low tolerance to human uses (Salm et al., 2000). Therefore, it is recommended that the southern part of Ruvuma Estuary, i.e., the whole area south of the southern branch of Upper Kingumi River (from the upper reaches of the river at Site 1J the mouth of the river at Site B) (Fig. 2.1), could initially be protected as a core zone. One of the design features of a protected area is that it should be as large as possible in order to preserve not only species diversity, but also ecosystem diversity and functioning (Hunter, 1996). The reasons for the selection of this particular area, in line with the mentioned criteria, are as follows:

• It is an area of high ecosystem complexity and biodiversity

• It is the only area where the mangrove species Heritiera littoralis is found in abundance and this species is vulnerable here, since it is subjected to erosion on the Ruvuma River side and seasonal drying farther away from the river. Thus, it could potentially become locally endangered.

• Since the area is subjected to seasonal flooding, even minor cutting pressure would make it prone to erosion brought about by vigorous river and tidal flow during that period.

In establishing this area, however, villagers should be allowed access to Ruvuma River, which is an important area for fishing activities. Perhaps they could be allowed to pass through Kingumi River, Nkurukala Channel and Litokoto River in order to reach Ruvuma River. Another core zone could be Ruvula Peninsula, north of Site J (Fig. 2.2), since the mangroves of this area form well-developed forests, with all common vegetation zones of a mangrove forest represented and there is high biodiversity. A third core zone could be established on the southeast half of Membelwa Island (Fig. 2.2). This is recommended due to the uniqueness of the island environment, the well-developed mangrove ecosystems and the presence of interesting biodiversity, including bird life. Buffer zones around the core zones, though recommended by Salm et al. (2000), should not be necessary since the area surrounding core zones would be multiple-use zones that are managed in any case. An important type of specific-use zone would be areas designated for ecotourism. These would necessarily be areas that have well-developed, mature mangrove ecosystems with high biodiversity and that are attractive and exciting for tourists. Therefore, within the three core zones, which have these characteristics, smaller zones could be selected for ecotourism. For example a very attractive tour route could be established from Litembe village, down the Kingumi River, and then into the core zone, passing through Nkurukala Channel, up Litokoto River, through Kitope River and finally to Ruvuma River. At certain sites, the tourists could get off the boat and walk through the forest. Then, when the tide is high, the tour could make its way back from the mouth of Ruvuma, upstream along the Litokoto River, back to Nkurukala Channel, etc.

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Likewise, selected routes for ecotourism could be established through the core zones on Ruvula Peninsula and Membelwa Island. In these places there are other things of interest in the vicinity besides mangroves, such as sandy beaches, birds, etc. Other zones for specified use could be established for harvesting shellfish used for human food and fish bait. Areas should be selected where there is a high abundance of such shellfish, e.g., more that 50 individuals/m2. Such zones could include the northern side of Ruvuma Estuary (around Site 2D) (for harvesting Cerithidea decollata) and Sites A (upper Kingumi River, northern branch) and J along Ruvuma River (for harvesting Terebralia palustris). None of the sites visited in Mnazi Bay or the offshore islands qualify. However, prior to establishing shell harvesting in these sites, further research is required and constant monitoring of shellfish populations is necessary. The remainder of the MBREMP mangrove areas would be multiple-user zones, which could be utilized for controlled harvesting of mangroves, ecotourism, beekeeping and various types of fishing. Certain channels should be designated for the use of fence traps. These should be selected such that they are not the only channels for tidal movement over a large area. In addition to the crosscutting solutions mentioned above, there are several strategies/actions that can be implemented to solve the specific issues identified and new opportunities that can be pursued in order to improve the livelihood of the villagers. These include proper control of harvesting and clear cutting, rehabilitation, pilot testing of a scheme for community-“owned” mangrove plots, planting non-mangrove trees (as an alternative to building materials and fuel) in the area surrounding the Estuary, development of ecotourism, control of unsustainable fishing practices, sustainable harvesting of shellfish, beekeeping, reforestation and control of construction and bad agricultural practices in the Ruvuma watershed area (to mitigate erosion) as well as conducting issue-specific research (Fig. 3.10). Mangrove harvesting must be controlled and regulated through a tight permit system. Moreover, those that are given permits to harvest should be instructed to cut trees in a widely scattered fashion, which has minimal impact on the soil and forest environment. Cutting many trees in one spot has major negative impacts. Cutting of Bruguiera gymnorrhiza and Heritiera littoralis should not be permitted. Since there appears to be a lot of transient mangrove cutters from Mozambique, this issue should be examined in collaboration with communities in Mozambique. Also, since there are only a few channels through which mangrove poles can be transported to Zanzibar or elsewhere, patrol staff should be stationed at these outlets to the ocean. There should be constant patrol of the edges of the mangrove forests where villagers or private investors are eager to clear-cut mangrove areas in order to establish farms (particularly rice farms), solar saltpans, hotels or settlements. No new developments should be allowed without proper Environmental Impact Assessments (EIAs) being conducted. Rehabilitation efforts, through planting propagules or transplanting seedlings, should be promoted. Locations particularly requiring rehabilitation include the areas around Sites 1V and 1G and between Sites 1N and 1O in Ruvuma Estuary and around Sites Q, T and P in Mnazi Bay. Any such activities should involve the villagers, who are the mangrove resource users. Involvement of the villagers has the advantage that it enhances their awareness of the environment and they will be the first to make efforts to protect the mangroves they have planted from unauthorized harvesting (Wagner et al., 1999, 2001). Rehabilitation should be supervised such that a similar species composition is planted as has existed in the past. Moreover, there should be concentrated effort to transplant Bruguiera gymorrhiza in various parts of Ruvuma Estuary and Mnazi Bay where it existed in abundance in the past. In addition, Heritiera littoralis should be transplanted in some part of the southern side of the Estuary where it is facing disturbance from seasonal drying or erosion.

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An idea that could be considered by MBREMP is to pilot test a scheme for mangrove plots to be managed and “owned” by villagers. The plots could be allocated, through a screening process, to selected individuals, families or small groups, not to be owned by them, of course, but to be under their care, almost like a lease. It would be their responsibility to protect the plot and replant mangroves trees where needed. In return, these “owners” could be allowed to harvest some of the trees for firewood or building poles on a sustainable basis, under certain guidelines. This would entail their being trained to monitor their own plots in order to know the sustainable yield and to maintain species composition. Another benefit they could gain is that, during ecotours, the best plots could be visited by the tourists and the “owners” could receive a certain fee as a reward. A similar idea was recommended to Kinondoni Integrated Coastal Area Management Programme (KICAMP) in Dar es Salaam (Wagner, 2002), though it has not yet been implemented. Since, in general, the only affordable building materials and energy sources for villagers in the MBREMP area come from forest products, there should be vigorous campaigns for planting non-mangrove trees in the surrounding area in order to relieve future pressure on mangroves There should be constant vigilance for unsustainable fishing practices. Though dynamite fishing in the mangroves appears, at present, to be eliminated, it is on the upsurge in many other parts of Tanzania, so there is no guarantee that the problem will not recur in the MBREMP mangroves. There should also be regular patrols to check the mesh size of nets used in fence traps as well as the number and position of the traps. The harvesting of shellfish found in the mangroves, particularly gastropods is both an issue, since these organisms seem to be presently overharvested in some parts of Mnazi Bay and the offshore islands, and a potentially, new opportunity in Ruvuma Estuary. However, it is an aspect that first requires issue-specific research in both areas. Research is required on both the present rate of harvesting of these organisms and the rate of multiplication need to be investigated. These rates will vary, of course, from one area to the other and from one species to the other. Moreover, the possible negative impacts of harvesting on these shellfish populations in some areas should be investigated. Two edible gastropod species, in particular, should be targeted for this research, i.e., Cerithidea decollata and Terebralia palustris. Ecotourism is a new opportunity that should be exploited, but it needs prior research and planning. The mangroves of the MBREMP area, particularly some parts of Ruvuma Estuary, are potentially a very important tourist attraction. The maturity of some of the stands (as indicated by high basal area), their very good health, biodiversity and aesthetics, all make them very interesting sites for tourists. MBREMP should ensure that, to the greatest extent possible, the type of tourism operating in the marine park area should be ecotourism or sustainable tourism. Contrary to the conventional type of tourism, in which profit for the tour operators and pleasure for the tourists are the only driving forces, ecotourism has several beneficial aspects. Although ecotourism is a catchword that has been misused, real ecotourism has certain essential components. First of all, it aims at actively improving the ecosystems visited, either through fees paid or through actively participating in rehabilitation efforts, such as is done in Mbweni, Dar es Salaam (Wagner et al., 2001). Secondly, the people living in the area visited are considered as part of the environment, i.e., the social environment, so there should be an aspect of cultural tourism, in which their culture is appreciated, but not disturbed (Dimanche and Smith, 1996). In addition, the people involved should benefit in some way, usually economically. In any case, the tidal regime in Ruvuma Estuary is very complicated and it is the villagers who best know the appropriate time to go through some of the narrow channels and what size of vessel to use. To give an example of how a one-day ecotour could be arranged in Ruvuma Estuary, tourists could start their tour at Litembe village, where they are greeted by the villagers, offered a meal and be entertained with traditional dancing, perhaps even joining in. Alternatively, these cultural aspects could be after the trip through the mangroves. The tourists should then be accompanied through

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the mangroves by a group of villagers as guides, with arrangements for translation. If possible villagers boats could be used. They could be taken through the channels down to Kitope River, visiting some of the best sites in the Estuary, then follow the Ruvuma River to its mouth and then return to the village through a different route. Along the way, the village guides should give some history of the area or describe certain site of interest. They should stop in some degraded sites and transplant mangroves. Or, the rehabilitation could be done on a second day, if time is insufficient. The villagers should be paid adequately for their time, their indigenous knowledge and the use of their boat. MBREMP could contract certain investors to establish such ecotours, but these should be arranged under the guidance and agreement of MBREMP. While this is just an example of how ecotourism could be carried out, there should be issue-specific research conducted on this activity as well, as training of community members, before it is established. Ecotourism should be developed as an alternative/supplementary source income for the villagers in order to reduce resource extraction. Beekeeping is another opportunity which could be investigated through a feasibility study. This activity could be very beneficial, economically, for the community. In addition, issue-specific research should be conducted to investigate other viable alternative/supplementary income-generating projects so as to take pressure off the MBREMP mangrove resources. The occurrence of erosion requires issue-specific research by a physical oceanographer that also understands river dynamics, in order to obtain proper recommendations. As stated earlier, erosion/accretion in such areas is largely a dynamic, natural process. Nevertheless, research is required to determine whether various human activities in the area and upcountry may be exacerbating the rate of erosion. If the rate of erosion appears to be increased by human activities, mitigative measures that could be considered include reforestation along the Ruvuma watershed area, including far inland. In addition, there should be proper planning and management of agricultural practices, construction and development projects in the watershed.

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SECTION 4: CONCLUSIONS

Conclusions that can be made based on this study include the following:

• In general, MBREMP mangroves are healthy ecosystems, rich in biodiversity and natural resources.

• Within the MBREMP areas, mangroves in Ruvuma Estuary, particularly those in the southern part of the estuary near Ruvuma River, are better developed than those of Mnazi Bay and the offshore islands. This is likely due to the influx of nutrients from Ruvuma River during the rainy season as well as the input of freshwater, which is beneficial to some species such as Heritiera littoralis.

• Mangroves in parts of Ruvuma estuary are amongst the best mangroves in Tanzania in terms of mangrove basal area, density, species diversity and ecosystem health. Some parts are even comparable to well-developed, mature forest areas of the Rufiji Delta.

• Mangroves in the MBREMP area have great potential as a tourist attraction.

• Both offshore islands as well as Ruvula Peninsula are also very attractive to tourists.

• The present rate of utilization of mangroves in many parts of the MBREMP area is still sustainable, but in a few areas harvesting seems to be exceeding the natural regeneration rate.

• The establishment of MBREMP has come just at the right time to save the mangrove forests. Presently, most mangrove areas are in good condition, but considering the rising population and projected trends, unless strong management is initiated, serious degradation could occur in the near future.

• Harvesting of mangroves has already caused certain changes in species composition. Particularly, Bruguiera gymnorrhiza, which is very popular in the species for building poles, has been depleted.

• The collection of shellfish, particularly the gastropods Terebralia palustris and Cerithidea decollata, as well as the bivalves Pinna muricata and Anadara antiquata, for human food and fish bait, is widespread, particularly in the Mnazi Bay area and the offshore islands. These species may be in danger of depletion.

• The rate of erosion appeared to be quite high in some areas such as the seaward area of Ruvuma Estuary and the banks of the Ruvuma River. Although new mangrove stands are being established in some areas due to the accretion of sediments, according to information obtained from villagers, the overall the rate of erosion of mangroves may be greater than the rate of establishment of new stands, although this needs to be determined by further research.

• Although erosion and accretion are largely dynamic, natural processes, which cannot be controlled by man, it is likely that some of man’s activities in the Ruvuma river watershed area, e.g., deforestation, construction and bad agricultural practices, have been exacerbating the occurrence of erosion.

• The people in the local communities in the MBREMP area are very cooperative and most of them seem to have a very positive attitude about environmental issues.

30 30

SECTION 5: RECOMMENDATIONS

5.1 General Recommendations Based on the findings of this study, a number of recommendations can be made for solutions to the identified problems and issues as well as new opportunities to be pursued (Fig. 3.10). Details of these recommendations and discussion about their implementation have been given in Section 3.3. They are as follows:

• A number of general, cross-cutting solutions and approaches should be applied, e.g., enhancement of environmental awareness, a participatory approach, zoning, surveillance and enforcement, participatory monitoring and the establishment of alternative/supplementary income-generating activities.

• Three core zones should be designated, i.e., in the southern part of Ruvuma Estuary, the northern part of Ruvula Peninsula and the southeast half of Membelwa Island.

• Specific-use zones should be designated for ecotourism, particularly routes through the core zones.

• Specific-use zones should also be established for sustainable shellfish harvesting.

• The remainder of the MBREMP mangrove areas should be multiple-use zones for activities such as controlled mangrove harvesting, beekeeping and various types of fishing.

• Now that MBREMP has been established, proper control of harvesting of mangroves should be implemented, in collaboration with communities in Mozambique. Moreover, patrol staff should be stationed permanently at the outlets to the ocean to check all boats going to Zanzibar and elsewhere. When harvesting is done, trees should not be cut close together, but in a widely scattered fashion. Harvesting of Bruguiera gymnorrhiza and Heritiera littoralis should not be permitted.

• Constant patrol of the edges of the mangrove forests for evidence of the initiation of clear-cutting for the establishment of farms, solar saltpans, hotels or settlements. No new developments should be allowed without proper EIAs being conducted.

• Community-based rehabilitation efforts should be conducted in various hot spots in MBREMP where mangrove cutting has been excessive or species specific.

o Site 1V in Ruvuma Estuary is one such hot spot. Particularly Ceriops tagal should be replanted since it has been greatly harvested there.

o Lidengo River between Sites 1N and 1O in the Estuary.

o Site D on the northern side of the Estuary

o The area around Sites Q, T and P in Mnazi Bay.

o The species Bruguiera gymnorrhiza needs special attention since it has largely been depleted in the MBREMP area. A campaign should be launched for replanting this species in many parts of the Park where, according to indigenous knowledge, it was once abundant or at least present.

o Heritiera littoralis should also be planted since adverse conditions appear to be affecting it in some areas.

• A scheme for mangrove plots to be managed and “owned” by villagers could be pilot tested. The “owners” would be responsible for protection, rehabilitation and monitoring of the mangroves and would be allowed to harvest them on a sustainable basis.

• Non-mangrove trees should be planted in surrounding areas in order to relieve future pressure on mangroves for building poles and firewood.

• There should be constant vigilance for unsustainable fishing practices. There should be regular patrols to check the mesh size of nets used in fence traps as well as the number and position of the traps.

31 31

• Sustainable harvesting of molluscs should be promoted. The issue of whether the present harvest rate of shellfish in parts of Mnazi Bay and the offshore islands should be assessed. In areas of Ruvuma Estuary where there are large numbers of molluscs, harvesting could be carried out after doing research to determine the sustainable rate of collection.

• Ecotourism is a new opportunity that has great potential and should be exploited, but it needs prior research and planning. It should be conducted in such a way that the environment is improved, e.g., by undertaking mangrove replanting as part of the tour, or at least not negatively impacted and that the local communities benefit by being fully involved as guides, boatmen, etc.

• One-day tours through the mangroves could be established. For example, a tour may start at Litembe village, go down the Kingumi River, through Nkurukala Channel, up Litokoto River, through Kitope River to Ruvuma River. Then, when the tide is high, the tour could make its way back from the mouth of Ruvuma. Moreover, mangrove planting in degraded areas could be an integral part of every tour.

• Beekeeping is another opportunity that should be developed as an economic activity, but it needs issue-specific research and training.

• Reforestation as well as regulation of construction and agriculture practices should be carried out in the Ruvuma River watershed area.

• Further assessments and issue-specific research should be conducted on the following (in some cases an expert in the field is recommended in brackets):

o Ecotourism development.

o Shellfish harvesting – potential economic species, present harvest rate, reproduction rate, recommended sustainable harvest rate. (Flora Akwilapo of NEMC is recommended.)

o Other alternative/supplementary income-generating activities. (Dr. S. Bidanda of NEMC is recommended.)

o Alternative sources of energy and building materials.

o Heritiera littoralis – present health status, stress, projected trends in abundance and distribution.

o Unusual abundance of lichens growing on dead mangrove trees on Membelwa Island.

o Erosion and accretion in Ruvuma Estuary. (Dr. Julius Francis of WIOMSA and FAST is recommended.)

o Infauna, including meiofauna. Since it was beyond the scope of this study infauna and they are very important in nutrient dynamics, additional studies should be conducted on these organisms. (Flora Akwilapo of NEMC is recommended for macrofauna and Dr. Simon Ndaro of FAST is recommended for meiofauna.)

o Collection of baseline data on nutrient levels in Ruvuma Estuary and Mnazi Bay. (Dr. John Machiwa of FAST is recommended.)

5.2 Recommendations for a Long-term Monitoring Program As part of this study, it was required that specific recommendations be given for establishing a long-term monitoring program. The program can be set up as follows:

• Long-term monitoring should be established using the same transect line permanent plots method (English et al., 1994) that was applied in this study (details given in Section 2.3.1).

• The same transects and plots examined in this study should be re-examined in future monitoring sessions. Since all plots were permanently marked and their GPS readings recorded, it should be possible to find most of them again.

32 32

• Thus, the data recorded in this study can actually serve as a baseline for future monitoring.

• Since it may be difficult to regularly monitor all the plots covered in this study, some of the transects and plots could be strategically selected from amongst those covered in this study.

• Monitoring every six months would be most suitable. This would allow for description of seasonality in mangrove health and aesthetics and in macrofuana abundance and diversity. If this is financially or logistically impossible, monitoring could be done once per year.

• In any such monitoring, members of the local communities should be involved. Even many of the same villagers who participated in this study could be involved in future monitoring, since they are already trained and experienced and have demonstrated their competence. Involvement of the villagers in monitoring has several advantages. In particular, it enhances their environmental awareness and gives them a feeling of responsibility for protecting the mangroves. In addition, large amounts of data can be collected at relatively low cost (Wagner, 2004).

• Financial sustainability in long-term monitoring can be achieved; firstly, by the involvement of villagers, which makes it possible for many plots to be covered at reduced cost; secondly, by convincing the district council that environmental monitoring should be a routine part of government business; and thirdly, by involving the private sector, particularly tour operators, such that they may sponsor monitoring and rehabilitation in order to protect and improve their investments.

33 33

REFERENCES

Aksornkoae, S. 1993. Ecology and management of mangroves. IUCN, Bangkok. 176 pp.

Akwilapo, F.D. 2001. Distribution and abundance of mangrove benthic macrofauna in mangrove ecosystems showing different levels of anthropogenic degradation. M.Sc. Thesis, University of Dar es Salaam. 111 pp.

Dimanche, F. and Smith, G. 1996. Is ecotourism an appropriate answer to tourism’s environmental concerns? Journal of Hospitality and Leisure Marketing 3(4): 67-76.

English, S., Wilkinson, C. and Baker, V. (eds.) 1994. Survey Manual For Tropical Marine Resources. ASEAN-Australian Marine Science Project: Living Coastal Resources. Australian Institute of Marine Science, Townsville. 368 pp.

Francis, J., Nilsson, A and Waruinge, D. 2002. Marine protected areas in the Eastern African Region: How successful are they? Ambio 31 (7-8): 503-511.

Hunter, M.L. 1996. Fundamentals of Conservation Biology. Blackwell Science, Oxford. 482 pp.

Makota, V. 2002. Geographical Information for Sustainable Development (GISD): The role of GIS and remote sensing in monitoring. Presentation made at an Awareness and Planning Workshop for Community-Based Monitoring in Bagamoyo, Tanzania, December 2002.

Mgaya, Y.D. 2004. The vulnerability of mangrove and adjacent coral reefs to climate change in Rufiji Delta. Literature review submitted to WWF Tanzania (the Eastern African Marine Ecoregion), Dar es Salaam. 30 pp.

Muller, C., Guard, M. and Cavers, S. 1997. Marine Biological and Marine Resource Use Surveys in the Mtwara District, Tanzania. Report No. 3, Study of the biodiversity and vegetation composition of mangrove forests within Mnazi Bay, a preliminary report. Frontier-Tanzania Marine Research Programme. The Society for Environmental Exploration and the University of Dar es Salaam, Dar es Salaam, Tanzania. 28 pp.

Ngoile, M.A.K., Wagner, G.M., Akwilapo, F.A., Mbije, N.E., Mwichande, B. 2002. Rapid assessment of Kilwa for the suitability of establishing a conservation area. A report submitted to Pew Fellowship.

Pernatta, J.C. 1993. Mangrove forests, climate change and sea level rise: Hydrological influences on community structure and survival, with examples from the Indo-West Pacific. A Marine Conservation Development Report. IUCN, Gland, Switzerland. 46 pp.

Salm, R.V., Clark, J.R. and Siirila, E. 2000. Marine and coastal protected areas: A guide for planners and managers. IUCN, Washington DC. 371 pp.

Semesi, A.K. 1991. Management Plan for the Mangrove Ecosystem of Mainland Tanzania. Volume 11: Mangrove Management Plan for All Coastal Districts. Ministries of Tourism, Natural Resources and Environment, Forest and Beekeeping Division, Catchment Forest Project, Dar es salaam.

United Republic of Tanzania. (2003b) Development of Mnazi Bay-Ruvuma Estuary Marine Park: Inception Report. UNDP/MPRU/IUCN. 34 pp.

Wagner, G.M. 2002. Synthesis of information on the marine environment of Kunduchi and Mbweni. Kinondoni Integrated Coastal Area Management Program (KICAMP), Dar es Salaam. 38 pp.

Wagner, G.M. 2004. Participatory monitoring of changes in coastal and marine biodiversity. Indian Journal of Marine Sciences (in press).

Wagner, G.M., Makota, V. and Sallema, R. 2003. Mangrove forests. In: Tanzania State of the Coast Report 2003: The National ICM Strategy and Prospects for Poverty Reduction. Tanzania Coastal Management Partnership (TCMP), Dar es Salaam: 5-11.

Wagner, G.M., Mallya, U., Juma, S., Mgaya, Y.D., Wahure, O., Mahika, G., and Wagner, S.M. 1999. A preliminary investigation for an integrated, community-based approach to conservation and restoration on marine ecosystems along the Dar es Salaam coast. African Development Foundation, Dar es Salaam. 124 pp.

34 34

Wagner, G.M., Mgaya, Y.D., Akwilapo, F.D., Ngowo, R.G., Sekadende, B.C., Allen, A., Price, N., Zollet, E.A., and Mackentley, N. 2001. Restoration of coral reef and mangrove ecosystems at Kunduchi and Mbweni, Dar es Salaam, with community participation. In Richmond, M.D. and Francis, J. (Editors), Marine Science Development in Tanzania and Eastern Africa. Proceedings of the 20th Anniversary Conference on Advances in Marine Sciences in Tanzania, 28 June - 1 July 1999, Zanzibar, Tanzania. Institute of Marine Sciences (IMS) and Western Indian Ocean Marine Science Association (WIOMSA), Zanzibar: 467-488.

35 35

APPENDICES

Appendix A: Species Inventory

Table A.1: List of mangrove species (with Kiswahili and common English names, where applicable).

Species name Kiswahili name Common English name

Avicennia marina Mchu White mangrove

Bruguiera gymnorrhiza Mzinzi Black mangrove

Ceriops tagal Mkandaa Tagal mangrove

Heritiera littoralis Msikundazi Silver-leafed mangrove

Rhizophora mucronata Mkoko Red mangrove

Sonneratia alba Mlilana Evening bloom mangrove

Xylocarpus granatum Mkomafi Ribbon-root mangrove

Table A.2: List of invertebrate species (with Kiswahili and common English names, where applicable).

Species name Kiswahili name Common English name

Dottilla fenestrata Soldier crab

Neosarmatium meinerti Marsh crabs

Scylla serrata Kaa koko Mangrove crab

Sesarma guttatum Marsh crabs

Uca lactea annulipes Fiddler crabs

U. tetragonon Fiddler crabs

U. vocans Fiddler crabs

Uca sp. (Unidentified) Fiddler crabs

Cerithidea decollata Nyambua Cut-off Swamp Cerith

Littoraria scabra Koamikoko Periwinkles

Terebralia palustris Suka Mangrove Whelk

Saccostrea cucullata Chaza Hooded Oysters

36 36

Appendix B: Site-Specific Results and Discussion B.1 Ruvuma Estuary B.1.1 Hydrography Based on in-site observations as well as traditional knowledge, it is apparent that the southern part of the Ruvuma Estuary (i.e., south of Site F, Fig. 2.1) is influenced by fresh water from the Ruvuma River, especially during the rainy seasons, when it floods a considerable area in the southern part of the estuary. However, there is very little influence of freshwater in the middle and northern parts of the estuary, though there is some runoff flowing into the estuary from the surrounding terrestrial environment during rains. In these areas, the main source of water for the mangroves is tidal movement from the Indian Ocean. Thus, the so-called “rivers” within the estuary (which meet the ocean at Sites 1E, O and B) are primarily inlets from the ocean and are, thus, channels for tidal flow. Though most of the channels do not appear to dry up during low tides, inadequate information could be obtained about the levels reached during low and high tides. B.1.2 Nganje River Nganje River (which flows into the ocean between Sites 1D and 1E) is the main water inlet in the northern part of the Ruvuma Estuary. Along most of the lower part of this inlet, the mangroves had moderately high density, height, health and aesthetics, with low cutting pressure, such as was the case at Site 1C (Figs. 2.1, B.1). At this site, Sonneratia alba dominated a narrow zone along the river, while the area further from the river was dominated by Rhizophora mucronata, mixed with Ceriops tagal and Avicennia marina. Site 1D was dominated by R. mucronata, followed by C. tagal, Bruguiera gymnorrhiza, Xylocarpus granatum and S. alba, while S. alba, R. mucronata and C. tagal dominated Site 1E. The mangroves at Site 1F (Fig. B.1), which is up Nachika River, a small tributary off Nganje River, and which is adjacent to non-mangrove vegetation on Lihongo Island, had only moderate density, height and aesthetics, with R. mucronata being the dominant species, followed by C. tagal. Although the occurrence of seedlings at Sites 1C, 1D and 1F was rated low, this level is probably sufficient to maintain the forest since density, height and health were adequate. Erosion was observed along Lower Nganje River. At the mouth of the river, there was heavy erosion caused by strong wave action at high tide, particularly on the southern side of the mouth at Site 1D (Fig. B.1). There was also considerable erosion at Site 1E on the northern side of the river mouth. Along the northern branch of upper Nganje River, mangroves rated high with respect to density, height, health and aesthetics at Sites Z and 1B, while Sites X, Y and 1A had a moderate to low rating with respect to these characteristics (Figs. 2.1, B.2). At all sites, erosion was negligible and cutting pressure (in terms of sighting stumps) was quite low, though a few piles of logs were observed (Photograph B.1). Near Site Y people were observed hauling bags of salt (Photograph B.2) produced in solar saltpans a few meters to the northwest. These saltpans had been constructed about 15 years ago in a saline area on the upper side of the mangrove forest. Some mangroves had also been cleared to create enough area for the saltpans. Along the southern branch of upper Nganje River, Sites V and 1G had only a moderate rating with respect to density, height, health and aesthetics (Figs. 2.1, B.3). At both sites, erosion was negligible. Oysters of the species Saccostrea cucullata were commonly observed on Rhizophora mucronata prop roots (Photograph B.3).

37 37

Fig. B.1: Rapid assessment of condition of mangroves at

sites 1C, 1D and 1F along the lower Nganje River.

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

1C

1D

1F

Dn = density Hg = height S = seedlings Hl = health St = stumps A = aesthetics E = erosion


sites X, Y, Z, 1A and 1B along the upper Nganje River

(northern branch). (Abbreviations explained in Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

X

Y

Z

1A

1B


38 38


sites V and 1G along the upper Nganje River (southern

branch). (Abbreviations explained in Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

V

1G


Photograph B.1: Sonneratia alba logs observed at Site X (Ruvuma Estuary).

39 39

Photograph B.2: Bags of salt (near Site Y, Ruvuma Esturary) produced in solar saltpans, which had been constructed about 15 years previous. Some mangroves had

been cleared to create enough area.

Photograph B.3: Oysters of the species Saccostrea cucullata were commonly observed growing on Rhizophora mucronata prop roots in the area,

such as here at Site V (Ruvuma Estuary).

Site 1G (known as Kikwaju) showed significant degradation due to cutting pressure, indicated by the presence of stumps. We also found about 1000 poles of C. tagal (Photograph B.4), which had been recently cut without a permit and hidden in the forest, ready to be transported out at night.

40 40

The only sites along the Nganje River area where the quantitative plot method was conducted were Site 2D, located on the upper landward side of the mangroves, and Site 1U, located in a small tributary south of the river (Fig. 2.1). Only two species were found at Site 2D, Rhizophora mucronata with a low basal area (55 cm2/25m2 plot) and Ceriops tagal, with an almost negligible basal area, making a total or stand basal area of 56 cm2/25m2 plot (Fig. B.4). Site 1U had a high basal area of C. tagal and a low basal area of R. mucronata (421 and 121 cm2/25m2 plot, respectively), making a stand basal area of 542 cm2/25m2 plot. Both sites thus showed very low species diversity and the areas visited consisted of only one uniform vegetation zone (Table B.1). Rhizophora mucronata had the highest density in Site 2D, especially seedlings (Fig. B.5), while Ceriops tagal had the highest density in Site 1U, particularly trees (Fig. B.6).

Photograph B.4: In Site 1G (Ruvuma Estuary), there was high cutting pressure on mature Ceriops tagal trees,

commonly used for building poles. Mangrove harvesting was a major issue in Site 2D, where there were more than 10 stumps/25m2 plot (Fig. B.7). Cutting pressure at Site 1U was low. Site 2D was rich in macrofauna, with 4 species of crabs being present and 2 species of gastropods (Fig. B.8). The crab Neosarmatium meinerti and the edible gastropod Cerithidea decollota were the most abundant, being 116 and 81 individuals/m2, respectively. At Site 1U, 2 crab species and 2 gastropod species were present, but at lower abundance.

41 41

B.1.3 Lugue River Sites N and P in lower Lugue River rated moderate to low with respect to density, height, health and aesthetics, while Site O (at the mouth of the river) rated low to very low (Figs. 2.1, B.9). Erosion rated moderate to high in these sites.

Fig. B.4: Basal area (mean + standard error) of various

mangrove species at Sites L, N, 1U and 2D in the northern

part of Ruvuma Estuary.

0

50

100

150

200

250

300

350

400

450

500

Avi

cenn

iam

arin

a

Bru

guie

ragy

mno

rrhiz

a

Cer

iops

taga

l

Her

itier

alit

tora

lis

Rhi

zoph

ora

muc

rona

ta

Son

nera

tiaal

ba

Xyl

ocar

pus

gran

atum

Basal are

a (

cm

2/2

5m

2 p

lot) L

N

1U

2D

Fig. B.5: Density (mean + standard error) of various

mangrove species at Site 2D in Ruvuma Estuary.

0

5

10

15

20

25

30

35

40

45

Ceriopa tagal Rhizophora mucronata

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

42 42


mangrove species at Site IU in Ruvuma Estuary.

0

2

4

6

8

10

12

14

16


Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

Fig. B.7: Density of stumps (mean + standard error) of

various mangrove species at Sites L, N (east side of

channel),1U and 2D in the northern part of Ruvuma Estuary.

0

2

4

6

8

10

12

14

16

Bruguieragymnorrhiza

Ceriops tagal Heritiera littoralis Rhizophoramucronata

Stu

mp d

ensity (

no./

25m

2 p

lot)

L

N (east)

1U

2D

43 43

Table B.1: Mean basal area (cm2/25m2 plot) of mangrove species and sample size (i.e., number of plots examined) in various zones at sites in Ruvuma Estuary.

Site Species Zone Overall

A

Middle Upper Middle

Avicennia 2 10 43 26

Ceriops 261 19 428 259

Rhizophora 36 0 244 129

Xylocarpus 146 0 0 18

All species 443 30 715 433

Sample size 4 12 17 33

G

Lower Middle Lower Overall

Bruguiera 0 62 0 20

Ceriops 0 8 0 2

Heritiera 0 0 182 80

Rhizophora 0 1012 1128 810

Sonneratia 0.3 99 161 101

All species 0.3 1182 1471 1013


J

Upper Middle - Overall

Avicennia 220 137 - 178

Bruguiera 16 92 - 56

Heritiera 124 92 - 108

Rhizophora 0 82 - 41

Xylocarpus 44 631 - 338

All species 404 1034 - 720

Sample size 12 14 - 26

L

Lower Middle Upper Overall

Avicennia 254 1 77 111

Ceriops 133 270 537 313

Heritiera 0 52 65 39


Sonneratia 154 0 0 51


All species 615 421 679 572


M

Lower Middle Upper Overall

Avicennia 378 254 228 293

Bruguiera 99 99 0 57

Ceriops 46 5 8 23



All species 758 732 254 549


N

Middle-West Middle-East - Overall

Avicennia 163 0 - 119

Ceriops 114 662 - 263

Rhizophora 449 240 - 392

All species 726 902 - 774


44 44

1U

Middle - - Overall

Ceriops 421 - - 421

Rhizophora 121 - - 121

All species 542 - - 542

Sample size 16 - - 16

1V

Upper-middle

Middle -

Overall

Ceriops 580 816 - 698

Rhizophora 1 0 - 1

Sonneratia 0 125 - 63

Xylocarpus 30 478 - 254

All species 611 1419 - 1015


2D

Upper-middle

Overall

Ceriops 2 - - 2

Rhizophora 198 - - 198

All species 201 - - 201

Sample size 8 - - 8

Erosion was particularly high at Sites O and P. These sites are on the outer side of a curve in the Lugue River, which is quite wide at this point, and thus are subjected to heavy forces during the spring tidal flow. According to villagers, approximately 50 m of mangroves have been eroded away at Site P over the past 20 years. At the seaward side of Site O, erosion was very marked due to the additional factor of being exposed to the open ocean waves, particularly at high tide (Photograph B.5). At Site N, on the western side of the channel, there were a few Sonneratia alba trees along the waters edge, with Rhizophora mucronata, Ceriops tagal and Avicennnia marina dominating the zone away from the channel. The eastern side of the channel was dominated by R. mucronata, followed by Ceriops tagal and Xylocarpus granatum. A common phenomenon in the tidal channels in the estuary is that, where there is a bend, such as at Site N, there is erosion on the outer side of the bend (Photograph B.6) and accretion of sediments on the opposite inner side of the bend (Photograph B.7). However, the erosion was often appeared to be greater than the accretion. The substantial erosion at Site N is due to tidal movement during spring tides, which is greatest during the heavy rainy season. According to the villagers, dynamite fishing in the past also had contributed to erosion.

45

45

Fig

. B

.8: D

ensity

of m

acro

fauna (

mean +

sta

ndard

err

or)

at S

ites N

(east sid

e o

f channel),1

U

and 2

D in

the n

ort

hern

part

of R

uvum

a E

stu

ary

.

0

20

40

60

80

100

120

140

160

180

Scylla serrata

Sesarmaguttatum

Neosarmatiummeinerti

Uca lacteaannulipes

Uca tetragonon

Uca sp.

Cerithideadecollata

Littoraria scabra

Terebraliapalustris

Density (no./m2)

N (

east)

1U

2D

46 46


sites N (east side of river), N (west side of river), O and P

along the lower Lugue River. (Abbreviations explained in Fig.

B.1).

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl A E

Rating o

n 5

-poin

t scale

N (east)

N (west)

O

P

Photograph B.5: Erosion is very high on the seaward side of Site O (Ruvuma Estuary), since it is exposed to the open ocean waves, particularly at high tide.

47 47

Photograph B.6: Erosion commonly occurs on the outer side of bends in the tidal channels, such as is shown here on the eastern side of Site N (Ruvuma Estuary).

Photograph B.7: Accretion of sediments occurs on the inner side of bends in the tidal channels, such as is shown here on the western side of Site N (Ruvuma Estuary).

48 48

In middle Lugue River, around Sites Q and R (Fig. 2.1), interesting trends in erosion and accretion have been occurring. Site Q is a small islet where the mangroves showed high density, but rated low with respect to height, health and aesthetics (Fig. B.10). It was dominated by Rhizophora mucronata, followed by Ceriops tagal and Sonneratia alba. The low aesthetic rating was due to substantial erosion and poor health. According to the participating villagers, about 25 years ago, Site Q was joined to the non-mangrove forest on the opposite side of the channel by a continuous growth of mangroves. In other words, the present channel was not there (Photograph B.8). However, in the mangrove maps produced by Semesi (1991), which were based on aerial photographs taken in 1989, the channel between Site Q and the non-mangrove forest appears much as it does today. At the same time, just north of the eroding islet at Site Q is a new islet of mangroves (about 70 m long and 10 m wide) at Site R, which started forming about 7 years ago due to accretion of sediments (Photograph B.9). It does not, therefore, appear in the mangrove maps produced by Semesi (1991). The mangroves at Site R were very healthy and had good aesthetic value, but were still of moderate density and height. In such a situation, of course, erosion does not exist. The only species found there was Sonneratia alba, which is a common first colonizer in such a situation. Site S was in moderate condition, with a low rate of erosion (Figs. 2.1, B.10). Ceriops tagal was the dominant species, followed by Rhizophora mucronata. On the opposite (north) side of the channel, R. mucronata was dominant, followed by C. tagal and Avicennia marina. In upper Lugue River, a similar combination of accretion and erosion is occurring. Site T (Fig. 2.1) is a small new Islet, somewhat larger than Site R, where the mangroves have already attained moderate density and height and rate high for health and aesthetics (Fig. B.11). Again, the only species found was Sonneratia alba (Photograph B.10). Just a few hundred meters to the west of Site T was another small island, which has been eroding. Site U (Fig. 2.1) is located in an area known as Nakolachi at a bend in the channel where Lugue River actually joins Nganje River. The mangroves there rated high for most characteristics, but some stumps occurred due to harvesting (Fig. B.11). Species richness is high, with Avicennia marina being dominant, followed by Sonneratia alba, Rhizophora mucronata, Ceriops tagal and Xylocarpus granatum.

49 49


sites Q, R and S along the middle Lugue River.

(Abbreviations explained in Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl A E

Rating o

n 5

-poin

t scale

Q

R

S


sites T and U along the upper Lugue River. (Abbreviations

explained in Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

T

U

50 50

Photograph B.8: This channel in the Ruvuma Estuary, from Site Q (where the photograph was taken) to the non-mangrove forest in the distance, had previously been a

continuous stand of mangroves, which was eroded away about 25 years ago.

Photograph B.9: A new islet of mangroves (Site R, Ruvuma Estuary), consisting only of Sonneratia alba, which started forming about 7 years ago due to accretion of sediments.

51 51

Photograph B.10: A recently formed mono-specific stand of Sonneratia alba (Site T, Ruvuma Estuary), which is continuing to expand outwards, through the establishment of new seedlings.

Along Lugue River, the quantitative plot method was conducted at Site N (in the lower part of the river, which was also examined quasi-quantitatively) and Site L (in the upper part of the river) (Fig. 2.1). Site N had a stand basal area of 774 cm2/25m2 plot consisting of only three species, with Rhizophora mucronata dominating, followed by Ceriops tagal and Avicennia marina (Fig. B.4). Though Sonneratia alba had been observed in the quasi-quantitative sampling (mentioned above), this species was not recorded in the quantitative sampling since plots were not taken immediately at the waters edge, which is the only position where this species was found. At Site L, the stand basal area was 572 cm2/25m2 plot and species richness was high, with a total of seven species being present (Fig. B.4). C. tagal was dominant, followed by Avicennia marina, with minor representation from S. alba, R. mucronata, Heritiera littoralis and Xylocarpus granatum and an almost negligible abundance of Bruguiera gymnorrhiza. There was obvious zonation at Site L, with Ceriops tagal dominating (in terms of basal area) the upper and middle zones and Avicennia marina and Sonneratia alba dominating the lower zone (Table B.1). Site N consisted basically of one vegetation zone on both sides of the channel. In terms of density, Rhizophora mucronata, particularly trees, was dominant on the west side of the channel at Site N (Fig. B.12), while Ceriops tagal, particularly seedlings, was dominant on the east side (Fig. B.13). C. tagal, particularly seedlings had the highest density at Site L (Fig. B.14). Cutting pressure in the quantitative sites (Sites L and N) was very low (2 stumps/25m2 plot or less) (Fig. B.7). At Site L, there was a very high density of Uca sp., but only minor representation of four other species of crabs (Fig. B.8). There were no gastropods observed. Near this site, an open saline area was observed (Site K).

52 52

B.1.4 Kingumi River Site B, located on the northern side of the mouth of Kingumi River (Fig. 2.1), had moderate density, height, health and aesthetics (Fig. B.15). Though the site was near the mouth of the river where there is strong wave action, it was protected by a sand bank; thus there was no erosion. The dominant species was Sonneratia alba, followed by Avicennia marina and Rhizophora mucronata.


mangrove species at Site N (west side of channel) in

Ruvuma Estuary.

0

2

4

6

8

10

12

Avicennia marina Ceriopa tagal Rhizophoramucronata

Density(n

o./

25m

2 p

lot)

Seedling

Sapling

Tree


mangrove species at Site N (east side of channel) in Ruvuma

Estuary.

0

5

10

15

20

25


Density (

no./

25m

2 p

lot)

Seedling

Tree

53 53

Fig. B.14:Density (mean + standard error) of various

mangrove species at Site L in Ruvuma Estuary.

0

10

20

30

40

50

60

70

Avi

cenn

iam

arin

a

Bru

guie

ragy

mno

rrhiz

a

Cer

iopa

taga

l

Her

itier

alit

tora

lis

Rhi

zoph

ora

muc

rona

ta

Xyl

ocar

pus

gran

atum

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree


sites B, 1Q and 1R along the lower Kingumi River.


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

B

1Q

1R

Site 1Q is a new mangrove stand which does not appear on the mangrove maps produced by Semesi (1991). According to villagers, this stand just began about 7 years ago. This stand is several hundred meters across and the trees have already attained moderate density, height and aesthetic rating (Fig. B.15). Sonneratia alba is dominant, the occurrence of a few Avicennia marina and Ceriops tagal.

54 54

Site 1R, located where Lidengo River enters Kingumi River, is another new mangrove stand that does not appear on the Semesi (1991) mangrove maps, though it is located a few hundred meters west of another new stand, which is slightly older and does appear on Semesi’s map. The characteristics of Site are very similar to those of Site 1Q (Fig. B.15) and is also dominated by Sonneratia alba. Along upper Kingumi River (northern branch), also known as Jinguo River, Site 1S (north side) (Fig. 2.1) showed a moderate to low rating for density, height, health and aesthetics (Fig. B.16). It was dominated by Rhizophora mucronata and Ceriops tagal, with a low abundance of Xylocarpus granatum. Site 1S (south side) had a moderate to high rating for these characteristics and was dominated by Avicennia marina, R. mucronata and C. tagal. The northern side had no stumps, because the trees were too small to be of interest, while there were some stumps on the southern side indicating low cutting pressure. Neither side showed erosion. Site 1T (located at Nawiya) is a new pure stand of young Sonneratia alba trees (Fig. B.16). Site C on the northern branch of upper Kingumi River was actually not a mangrove site, but a newly formed channel formed by erosion, which has left a small island to the south of Site C (Fig. 2.1). The eroded area is from 10o 26.68’ S, 40o 22.98’ E to 10o 26.59’ S, 40o 22.98 E, a distance of 166 m. At Site 1K along middle Kingumi River (southern branch) (Fig. 2.1), there is a vast difference between mangroves on the two sides of the river. On the northern side, density, height, health and aesthetics are very low (Fig. B.17), with Ceriops tagal being dominant along with only a few representatives of Rhizophora mucronata and Avicennia marina. The poor condition of the mangroves could have been due to the high sand content of the soil found on the northern side. The condition of the mangroves on the southern side rated moderate to good and species diversity was higher. Along the water was a narrow zone of A. marina, beyond which was a mixture of R. mucronata (dominant), A. marina, Xylocarpus granatum and C. tagal. At Site 1L, located on the southeast side of middle Kingumi River (southern branch) (Fig. 2.1), mangrove condition was moderate to high, with low cutting pressure (Fig. B.17). Avicennia marina was dominant, with the presence of some Rhizophora mucronata, Ceriops tagal and Xylocarpus granatum trees. On the northwest side of the river, there was a large area of non-mangrove forest, which is not indicated on the map produced by Semesi (1991).

55 55


sites 1S (Jinguo, south side), 1S (Jinguo, north side) and 1T

along Kingumi River (northern branch). (Abbreviations


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

1S(north)

1S(south)

1T


sites 1K (north side of river), 1K (south side of river), 1L and

1M along the middle Kingumi River (southern branch).


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Ra

tin

g o

n 5

-po

int

sca

le

1K(north)

1K(south)

1L

1M

At Site 1M (in an area known as Misuaki), located just north of Site 1L, but on the opposite side of the river (western side) (Fig. 2.1), mangrove condition rated moderate to low, with a low level of erosion (Fig. B.17). The dominant species was Rhizophora mucronata, with the presence of a few Xylocarpus granatum and Ceriops tagal trees.

56 56

At Site 1J (in an area known as Lilundunda) on upper Kingumi River (southern branch) (Fig. 2.1), mangroves on both sides of the river were assessed as being in moderate to good condition and cutting pressure was low (Fig. B.18). Erosion was low on the western side and nil on the eastern side. On both sides, Avicennia marina dominated, with some representation of Xylocarpus granatum, Rhizophora mucronata and Ceriops tagal on the western side and R. mucronata and Sonneratia alba on the eastern side.

Further up the southern branch of Kingumi River, mangroves at Sites 1H (northeast), 1H (southwest), 1I (northwest) and 1I (southeast) all had a moderate rating for density, height, health and aesthetics (Fig. B.19). Cutting pressure was very low. A low level of erosion occurred only at Sites 1H (northeast) and 1I (northwest). Site 1H is known as Makupa, while Site 1I is known as Namakupa.

Along Kingumi River, quantitative plot sampling was done at Site 1V in the lower river, Site A along the northern branch of the upper river and Site M along the southern branch of the upper river (Fig. 2.1). At Site 1V (known as Kingumi Cha Mnengela), there was very high stand basal area of 1015 cm2/25m2 plot, with Ceriops tagal being dominant, followed by Xylocarpus granatum and Sonneratia alba (Fig. B.20). Stand basal area at Site A was 492 cm2/25m2 plot, with C. tagal being dominant, followed by R. mucronata, with only a few representatives of Avicennia marina and Xylocarpus granatum. Total or stands basal area at Site M was 549 cm2/25m2 plot, with A. marina dominating, followed by Rhizophora mucronata, X. granatum, Bruguiera gymnorrhiza and C. tagal.

Only two zones were discerned at Site 1V, the upper-middle zone at the river bank, which was almost a pure stand of Ceriops tagal, which went slightly downwards away from the river into middle zone vegetation, where three species were well represented, but C. tagal was still dominant (Table B.1). Site A had typical middle zone vegetation at the river bank, then there was a rise in elevation to an upper zone, where only C. tagal was found and finally, there was a slope down to a middle Rhizophora-Ceriops zone. At Site M, there were lower and middle zones, with 5 species represented in each and an upper zone with only 2 species.

The species with the highest densities were Ceriops tagal, in Site A (Fig. B.21), Avicennia marina and C. tagal in Sites M (Fig. B.22) and C. tagal in Site 1V (Fig. B.23).


sites 1J (west side of river) and 1J (east side of river) along

the upper Kingumi River (southern branch). (Abbreviations


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Ra

tin

g o

n 5

-po

int

sca

le

1J(west)

1J(east)

57 57


sites 1H (northeast side of river), 1H (southwest side), 1I

(northwest side) and 1I (souteast side) along the upper

Kingumi River (southern branch). (Abbreviations explained in

Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

1H(NE)

1H(SW)

1I(NW)

1I(SE)


mangrove species at Sites A, M, and 1V in the central part of

Ruvuma Estuary.

0

100

200

300

400

500

600

700

800

Avi

cenn

iam

arin

a

Bru

guie

ragy

mno

rrhiz

a

Cer

iops

taga

l

Rhi

zoph

ora

muc

rona

ta

Son

nera

tiaal

ba

Xyl

ocar

pus

gran

atum

Basal are

a (

cm

2/2

5m

2 p

lot)

A

M

1V

58 58


mangrove species at Site A in Ruvuma Estuary.

0

2

4

6

8

10

12

14

Avicenniamarina

Ceriopa tagal Rhizophoramucronata

Xylocarpusgranatum

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree


mangrove species at Site M in Ruvuma Estuary.

0

2

4

6

8

10

12

14

16

Avicenniamarina



Xylocarpusgranatum

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

59 59


mangrove species at Site IV in Ruvuma Estuary.

0

10

20

30

40

50

60

70

80


Xylocarpusgranatum

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

The outstanding issues at Site 1V are erosion and cutting pressure. According to the villagers, the riverbank at this site has eroded about 25 m over the past 10 years (Photograph B.11). Although Site 1V had very high basal area, it appeared to have the highest cutting pressure of any site visited, as indicated by the large number of stumps in almost every plot. This means that basal area would have been even higher if it were not for the cutting pressure. Ceriops tagal and Xylocarps granatum were the most popular (Photograph B.12). C. tagal, in fact, had the highest cutting pressure at all three quantitative sites (Sites A, M and 1V, Fig. B.24). Six crab species and 2 gastropod species were observed in the Sites A, M and 1V (Fig. B.25). The edible gastropod Terebralia palustris was found in very high abundance in Site A (200 individuals/m2), while other species were in low abundance.

60 60

Photograph B.11: Eroded riverbank at Site 1V (Ruvuma Estuary).

Photograph B.12: Numerous stumps of Ceriops tagal at Site 1V (Ruvuma Estuary), indicating the very high cutting pressure there.

61 61


various mangrove species at Sites A, M and 1V in the central


0

2

4

6

8

10

12

14

16

18

Avicenniamarina


Ceriops tagal Heritieralittoralis

Rhizophoramucronata

Xylocarpusgranatum

Stu

mp

de

nsity (

no

./2

5m

2 p

lot)

A

M

1V

62

62

Fig

. B

.25: D

ensity

of m

acro

fauna (

mean +

sta

ndard

err

or)

at S

ites A

, M

and 1

V in

the c

entr

al

part

of R

uvum

a E

stu

ary

.

0

50

10

0

15

0

20

0

25

0

30

0

Scylla serrata

Sesarmaguttatum

Neosarmatiummeinerti

Uca lacteaannulipes

Uca tetragonon

Uca sp.

Cerithideadecollata

Terebraliapalustris

Density (no./m2)

A M 1V

63 63

B.1.5 Lidengo River Along Lidengo River, which flows into Kingumi River, two sites were observed. Site 1N (near the mouth of Lidengo River) showed moderate mangrove condition, while Site 1O (at the upper reaches of the river) showed high condition (Figs. 2.1, B.26). At Site 1N (northern side) Rhizophora mucronata was dominant, followed by Avicennia marina, Ceriops tagal and Xylocarpus granatum. At Site 1N (southern side), C. tagal was dominant, followed by R. mucronata, X. granatum, and A. marina. According to the villagers, Lidengo River was another very popular area for cutting mangroves, though in the particular sites visited, Sites 1N and 1O, the occurrence of stumps only rated very low and low, respectively. According to the villagers, Bruguiera gymnorrhiza, used for building poles, has been the most commonly cut mangrove in the area, to such an extent that this species in now becoming rare in the area. Now, Ceriops tagal is commonly targeted (Photograph B.13). B.1.6 Nkurukala Channel With the rapid assessment method, one site (Site 1X) was examined in the narrow Nkurukala Channel, which joins Kingumi River at Site E and Litokoto River at Site F (Fig. 2.1). On both sides of the channel, although height and aesthetics rated moderate, density and health were very high (Fig. B.27, Photograph B.14). Cutting pressure was low and erosion was nil. Rhizophora mucronata was the dominant species, followed by Avicennia marina, Ceriops tagal and Xylocarpus granatum. B.1.7 Chikomolela/Litokoto River Mangroves at Site 1Y, located at the extreme upper end of Chikomolela River (Fig. 2.1) rated moderate to low with respect to density, height, health and aesthetics (Fig. B.28). Cutting pressure was very low and erosion was nil. Species diversity was high, with the dominant species being Heritiera littoralis, followed by Rhizophora mucronata, Xylocarpus granatum, Ceriops tagal, Bruguiera gymnorrhiza and Avicennia marina. The villagers said that monkeys were often observed at this site, but the species could not be determined. At Site 1Z (Fig. 2.1), the mangroves on the northern side rated high for condition, while those on the southern side rated low to very low (Fig. B.28). This is primarily because the southern side was dominated by Heritiera littoralis, with only a few Xylocarpus granatum and Bruguiera gymnorrhiza trees. During our visit, which was during the dry season, H. littoralis trees appeared to be very unhealthy with wilted, whitish leaves (Photograph B.15). According to the participating villagers, water only reaches the southern side of the river during extreme spring tides. Moreover, H. littoralis only appears to be healthy following the rainy season.

64 64


sites 1N (north side of river), 1N (south side of river) and 1O

(east side of river) along Lidengo River. (Abbreviations


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

1N(north)

1N(south)

1O(east)


sites 1X (northeast side) and 1X (southwest side) along

Nkurukala Channel between Kingumi and Litokoto rivers.


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

1X(NE)

1X(SW)

65 65


sites 1Y, 1Z (north side of river) and 1Z (south side of river)

along upper Chikomolela River. (Abbreviations explained in

Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

1Y

1Z(north)

1Z(south)

Photograph B.13: Cut stumps of Ceriops tagal a short distance away from Site 1N (Ruvuma Estuary).

66 66

Photograph B.14: Luxurious growth of mangroves at Site 1X (Ruvuma Estuary).

The northern side of this river, on other hand, is dominated by Avicennia marina, followed by Rhizophora mucronata and Sonneratia alba and the tides reach this side every two weeks during spring tides. It should be noted that, downstream from the point where the Kitope River joins the Chikomolela River at Site 2A, this river is known as Litokoto River, which flows into Ruvuma River at Site D. Therefore, on the map produced by Semesi (1991) it has been incorrectly labelled at Chikomolela River, rather than Litokoto River (Fig. 2.1).

67 67

Photograph B.15: Heritiera littoralis trees at Site 1Z (Ruvuma Estuary), photographed during the dry season. They are apparently only healthy during the rainy season.

B.1.8 Kitope River Sites 2A (west), 2A (east) and 2B rated high with respect to mangrove density, height, health and aesthetics (Figs. 2.1, B.29). Cutting pressure rated low to very low and erosion was nil. At Site 2A, on both sides, Rhizophora mucronata was dominant, with the occurrence of Xylocarpus granatum, Ceriops tagal and Avicennia marina. Site 2B had high species diversity, with an almost even mixture of X. granatum, R. mucronata, Bruguiera gymnorrhiza, C. tagal and A. marina.

68 68


sites 2A (west side of rive), 2A (east side of river), 2B and 2C

along Kitope River. (Abbreviations explained in Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

2A(west)

2A(east)

2B

2C

The boat trip through the narrow channel between Sites 2B and 2C, passing under huge, overhanging branches was quite an adventure. Site 2C (Fig. 2.1) was probably the most attractive, scenic and interesting sites in the entire MBREMP area—a well-developed, mature ecosystem (Photograph B.16). It rated very high with respect to mangrove density, height, health and aesthetics (Fig. B.29). Though there was some cutting pressure, the forest was so healthy that was unnoticeable. There was high species diversity with Xylocarpus granatum, Rhizophora mucronata, Ceriops tagal, Bruguiera gymnorrhiza and Avicennia marina being present. Going through this area is a very exciting experience for tourists, scientists and nature lovers in general. B.1.9 Ruvuma River Along the edge of Ruvuma River, which forms the southern border of the mangrove forest and the boundary between Tanzania and Mozambique, Sites G and J (Fig. 2.1) were examined using the quantitative plot method. Site G had a stand area of 1010 cm2/25m2 plot (Fig. B.30) and was dominated by Rhizophora mucronata, with minor representation of Sonneratia alba and Heritiera littoralis. Thus, this site was a well-developed, mature forest, almost impenetrable to light (Photograph B.17). Site J had a stand basal area of 720 cm2/25m2 plot. Species diversity was high since there was almost even representation of five species, namely, Xylocarpus granatum, A. marina, H. littoralis, Bruguiera gymnorrhiza and R. mucronata.

69 69

Photograph B.16: Site 2C (Ruvuma Estuary), probably the most attractive and interesting sites in the entire MBREMP area. The canopy was so dense that

light penetration was minimal and thus getting a proper photograph was difficult. At Site G, there was a lower Sonneratia alba zone, which consisted mainly of dead stumps and logs, followed by a middle zone, consisting of an almost pure stand of Rhizophora mucronata, which sloped down to another lower zone with good representation of three species (Table B.1). Site J consisted of an upper zone dominated by Avicennia marina, followed by a middle zone dominated by Xylocarpus granatum. In Site G, Rhizophora mucronata had by far the highest density (particularly seedlings), though three other species were represented (Fig. B.31). At Site J, there was good representation of 7 species (Fig. B.32).

70 70

Photograph B.17: A well-developed, mature and diverse mangrove ecosystem occurs at Site G (Ruvuma Estuary).


mangrove species at Sites G and J in the southern part of

Ruvuma Estuary.

0

100

200

300

400

500

600

700

800

900

1000

Avi

cenn

iam

arin

a

Bru

guie

ragy

mno

rrhiz

a

Cer

iops

taga

l

Her

itier

alit

tora

lis

Rhi

zoph

ora

muc

rona

ta

Son

nera

tiaal

ba

Xyl

ocar

pus

gran

atum

Basal are

a (

cm

2/2

5m

2 p

lot)

G

J

71 71


mangrove species at Site G in Ruvuma Estuary.

0

10

20

30

40

50

60


Ceriopa tagal Heritieralittoralis

Rhizophoramucronata

Sonneratiaalba

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

Fig. B.32: Density (mean + standard error) of of various

mangrove species at Site J in Ruvuma Estuary.

0

0.5

1

1.5

2

2.5

3

3.5

Avi

cenn

iam

arin

a

Bru

guie

ragy

mno

rrhiz

a

Cer

iopa

taga

l

Her

itier

alit

tora

lis

Rhi

zoph

ora

muc

rona

ta

Son

nera

tiaal

ba

Xyl

ocar

pus

gran

atum

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

Sites H and I are Bahasha and Biteulumbwa Islands, respectively, located in Ruvuma River. Both of these islands have fishing villages.

72 72

The effects of erosion were quite noticeable along the Ruvuma River. At Site G, almost 2 m (vertical distance) of earth have been eroded away in recent times (Photograph B.18). This has resulted in many meters being eroded away horizontally and has caused many trees to fall over and die (Photograph 3.19). Thus, the Sonneratia alba zone indicated on the map by Semesi (1991) has virtually been eroded away. Moreover, Bahasha Island in the River has been split into two parts by erosion (Photograph B.20). Stumps density was significant (Fig. B.33). Another issue is that there are various types of fishing for both finfish and prawns carried out along the Ruvuma River and the islands within it. Some of the techniques used are environmentally friendly, such as the fence trap used for catching finfish and prawns (Photograph B.21). There was good diversity of macrofauna in Site G, but only 2 species in Site J (Fig. B.34). However, Terebralia palustris was found in very high abundance in the latter site.

Photograph B.18: One of the investigators, Flora Akwilapo, standing beside a Bruguiera gymnorrhiza tree (Site G, Ruvuma Estuary), in order to demonstrate that

almost 2 m of earth (vertical distance) have been eroded by Ruvuma River in recent times.

73 73

Photograph B.19: At Site G (Ruvuma Estuary), many meters have been eroded away (horizontal distance), causing many mangrove trees to fall over and die.

Photograph B.20: This channel has been eroded away such that it separates two parts of Bahasha Island in Ruvuma River, which was formerly one.

74 74

Photograph B.21: A fence trap, an environmentally friendly fishing device, fixed across Mipapaya channel, which flows into Ruvuma River.


various mangrove species at Sites G and J in the southern


0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Avi

cenn

iam

arin

a

Bru

guie

ragy

mno

rrhiz

a

Her

itier

alit

tora

lis

Rhi

zoph

ora

muc

rona

ta

Son

nera

tiaal

ba

Xyl

ocar

pus

gran

atum

Stu

mp d

ensity (

no./

25m

2 p

lot) G

J

75 75


sites C, D and E on Membelwa Island off Mnazi Bay.


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Ra

tin

g o

n 5

-po

int

sca

leC

D

E

B.2 Islands Off Mnazi Bay At Sites C, D and E at Membelwa Island (Fig. 2.2), mangrove condition rated moderate to low (Fig. B.35). At Site A, which was examined using the plot method, stand basal area was 131 cm2/25m2 plot, with the dominant species being Rhizophora mucronata (in both the lower and lower-middle zones, Table B.2), followed by Bruguiera gymnorrhiza, C. tagal and Sonneratia alba (Fig. B.36). This site was adjacent to the village of Membelwa (Site B). At Site F on Namponda Island (Fig. 2.2), stand basal area was 139 cm2/25m2 plot, with good representation from Rhizophora mucronata (which dominated in both the lower and lower middle zones, Table 3.2), Sonneratia alba, Bruguiera gymnorrhiza and Ceriops tagal (Fig. B.36). This site was adjacent to Namponda Village (Site G). In terms of density, Rhizophora mucronata dominated at both sites A (Fig. B.37) and F (Fig. B.38), followed by Ceriops tagal. Seedlings were numerous. Cutting pressure was very low (< 1 stump/25m2 plot) at both quantitative sites (Fig. B.39). Only stumps of Rhizophora mucronata and Ceriops tagal were observed.

76 76

Table B.2: Mean basal area (cm2/25m2 plot) of mangrove species in various zones at sites in Mnazi Bay and the offshore islands.

Zone Site Species Lower Lower-

middle Upper-middle

Upper Overall

A Bruguiera 0 150 - - 75

Ceriops 0 11 - - 6

Rhizophora 320 540 - - 430

Sonneratia 23 0 - - 12

All species 343 701 - - 522

Sample size 8 8 - - 16

F Bruguiera 57 4 - - 30

Ceriops 102 162 - - 132

Rhizophora 454 421 - - 438

Sonneratia 57 62 - - 59

All species 669 648 - - 659

Sample size 8 8 - - 16

H Avicennia - 39* - - 39

Bruguiera - 101* - - 101

Ceriops - 60* - - 60

Rhizophora - 38* - - 38

All species - 238* - - 238

Sample size - 9 - - 9

P Avicennia 0 0 6 - 2

Bruguiera 0 0 50 - 20

Ceriops 0 0 261 - 104

Rhizophora 506 1221 227 - 537

Sonneratia 861 0 0 - 344

All species 1367 1221 544 - 1009

Sample size 8 4 8 - 20

Q Bruguiera - - - 84 84

Ceriops - - - 211 211

All species - - - 295 295

Sample size - - - 8 8

S Avicennia - 28* - - 28

Ceriops - 67* - - 67


All species - 381* - - 381


T Avicennia - - - 423 423

Bruguiera - - - 11 11

Ceriops - - - 70 70

Rhizophora - - - 11 11

All species - - - 515 515

Sample size - - - 8 8

U Ceriops - 278* - - 278


All species - 947* - - 947


* Middle zone

77 77


sites C, D and E on Membelwa Island off Mnazi Bay.


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Ra

tin

g o

n 5

-po

int

sca

leC

D

E


mangrove species at Sites A and F on Membelwa and

Namponda Islands, respectively, off Mnazi Bay.

0

100

200

300

400

500

600

Bruguiera gymnorrhiza Ceriops tagal Rhizophora mucronata

Basal are

a (

cm

2/2

5m

2 p

lot)

A

F

78 78


mangrove species at Site A on Membelwa Island in Mnazi

Bay.

0

5

10

15

20

25

30

35



Sonneratia alba

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree


mangrove species at Site F on Namponda Island in Mnazi

Bay.

0

5

10

15

20

25

Avicenniamarina



Sonneratiaalba

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

79 79


various mangrove species at Sites A and F on Membelwa and

Namponda Islands, respectively, off Mnazi Bay.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Ceriops tagal Rhizophora mucronata

Stu

mp d

ensity (

no./

25m

2 p

lot)

A

F

The macrofauna found in the highest density at both sites were Uca craps of the species U. lacteal annulipes, U. tetragonon and U. vocans (Fig. B.40). At Site A, interesting fauna were observed. At the lowermost zone, large areas of mud were covered with extensive mats of a colonial sea anemone (Order Zoanthidea) (Photograph B.22). Large crabs of the species Scylla serrata were seen in the area, though they did not occur in any of the plots. One of the important issues on the offshore islands is that, around both the villages of Membelwa and Namponda, were large heaps of shells, including those of Cerithidea decollata (Photograph B.23), Pinna muricata (Photograph 3.24) and Anadara antiquata (Photograph B.25), which are used as both human food and fish bait. Only the first species mentioned, however, is harvested from mangrove mud. Another issue that should be reported, although it may be quite minor, is that there some areas at Membelwa Island, particularly Sites C and E, where a noticeable number of mangrove trees were dead and overgrown with lichens (Photograph B.26). This issue should be investigated further to assess the cause, the extent of the problem and possible solutions. Both islands are very attractive to tourists, due to their extensive mangrove stands, white sandy beaches and peaceful setting. An additional attraction is the presence of numerous birds, such as the Yellow-billed storks observed on Membelwa Island (Photograph B.27).

80

80

Fig

. B

.40: D

ensity

of m

acro

fauna (

mean +

sta

ndard

err

or)

at S

ites A

and F

on M

ongo a

nd

Nam

ponda Is

lands, re

spectively

, off M

nazi B

ay.

0

20

40

60

80

100

120

Dot

tilla

fene

stra

taS

esar

ma

gutta

tum

Neo

sarm

atiu

mm

eine

rtiU

ca la

ctea

annu

lipes

Uca

tetra

gono

nU

ca v

ocan

sLi

ttora

riasc

abra

Density (no./m2)

A F

81 81

Photograph B.22: Large areas of mud in the lowermost zone at Site A (Membelwa Island) were covered with mats of a colonial sea anemone (Order Zoanthidea).

Photograph B.23: A large heap of Cerithidea decollata shells seen near Membelwa Village. This species is used as human food and fish bait.

82 82

Photograph B.24: A heap of shells of Pinna muricata (seen on Namponda Island), which is used as human food and fish bait.

Photograph B.25: A heap of shells of Anadara antiquata (seen on Namponda Island), which is used as human food and fish bait.

83 83

Photograph B.26: A noticeable number of mangroves were observed dead and overgrown with lichens at Sites C and E on Membelwa Island.

Photograph B.27: Numerous Yellow-billed Storks were present at Membelwa Island.

84 84

B.3 Mnazi Bay Mangroves in the quasi-quantitative sites in Mnazi Bay, Sites I, J and K (Fig. 2.2) rated moderate to low with respect to condition (Fig. B.41). Cutting pressure was generally low. In these sites, Sonneratia alba dominated the lower zone, while Rhizophora mucronata dominated the next zone. Sites L, M, N and O (Fig. 2.2) were in very similar condition (Fig. B.42). Again, Sonneratia alba dominated the lower zone, while Rhizophora mucronata, Avicennia marina and Ceriops tagal were found in the next zone. Stand basal area at Sites H, P, Q, S, T and U (Fig. 2.2) were 134, 451, 125, 70, 60 and 213 cm2/25m2 plot, respectively (Figs. B.43, B.44). In most of these sites, Sonneratia alba dominated the lower zone, Rhizophora mucronata the middle zone and Ceriops tagal the upper zone (Table B.2). In Site T, the upper zone was dominated by Avicennia marina. Ceriops tagal was the species with the highest density at Sites H (Fig. B.45), P (Fig. B.46), Q (Fig. B.47), S (Fig. B.48) and T (Fig. B.49). Particularly C. tagal seedlings were found in vast numbers, with a mean of almost 2500 seedlings/25m2 plot. Rhizophora mucronata had the highest density in Site U (Fig. B.50). Crabs were the most abundant macrofauna in Sites P and Q (Fig. B.51). The crab Uca tetragonon was the most abundant species in Site T, while the gastropod Terebralia palustris was most abundant in Site U (Fig. B.52). The most well-developed mangrove forest was found at Site P where there was high density as well as very good health and aesthetics (Photograph B.28). In the lower zone, Rhizophora mucronata trees have developed massive prop roots that are overgrown with oysters (Photograph B.29). Mangrove cutting is an issue in some parts of Mnazi Bay. The density of stumps was particularly high at Sites Q (Fig. B.53) and T (Fig. B.54), where there were more than 8 and 10 stumps/25m2 plot, respectively. The species that was subjected to the highest cutting pressure in all sites (except Site S) was Ceriops tagal. Although the overall density of stumps at Site P was not very high (Fig. B.53), there were some patches where heavy cutting was observed (Photograph 3.30). Although the site had very numerous seedlings (also shown in the photograph), if the cutting is not controlled in time, the regeneration rate may give way to the harvesting rate. Another issue is the harvesting of mollusc shells, particularly Cerithidea decollata and Pinna muricata, as on the offshore islands. Many piles of these shells were observed, especially at Site P. In relation to that, kilns were observed, for example, in Site N (Photograph B.31), in which a mixture of mollusc shells and hard coral were set up for burning. This issue should be further investigated to determine its seriousness in terms of the rate of collection of shells and corals, the number of areas where kilns are made and the volume and frequency of burning. A solution to the problem of mangrove cutting, which has already been initiated, is mangrove replanting. This was observed near Site Q (Photograph B.32), where students and the village environmental committee were involved in planting mangrove seedlings in degraded areas.

85 85


sites I (Kaya River mount), J (north side of Kiwale River), J

(south side of Kiwale River) and K (Chiwale) along Ruvula

peninsula in Mnazi Bay. (Abbreviations explained in Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

I

J(north)

J(south)

K


sites L (Mnamba River), M (Kipwa), N (Nkurusara River) and

O (Mnete) in Mnazi Bay. (Abbreviations explained in Fig. B.1.)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Dn Hg S Hl St A E

Rating o

n 5

-poin

t scale

L

M

N

O

86 86


mangrove species at Sites H, P and Q in Mnazi Bay.

0

100

200

300

400

500

600

Avicenniamarina


Ceriopstagal

Rhizophoramucronata

Sonneratiaalba

Basal are

a (

cm

2/2

5m

2 p

lot)

H

P

Q


mangrove species at Sites S, T and U in Mnazi Bay.

0

100

200

300

400

500

600

700

800

900

Avicenniamarina


Ceriops tagal Rhizophoramucronata

Basal are

a (

cm

2/2

5m

2 p

lot)

S

T

U

87 87


mangrove species at Site H in Mnazi Bay.

0

5

10

15

20

25

30

35

40

Avicennia marina Bruguieragymnorrhiza


Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

Fig. B.46 : Density (mean + standard error) of various

mangrove species at Site P in Mnazi Bay.

0

20

40

60

80

100

120

140

160

180

Avicenniamarina



Sonneratiaalba

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

88 88


mangrove species at Site Q in Mnazi Bay.

0

500

1000

1500

2000

2500

3000

3500

4000



Density(

no./

25m

2 p

lot)

Seedling

Sapling

Tree

Fig. B.48: Density ( mean + standard error) of various

mangrove species at Site S in Mnazi Bay.

0

10

20

30

40

50

60

70

80

90

Avicennia marina Ceriopa tagal Rhizophoramucronata

Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

89 89

Fig. B.49: Density ( mean + standard error) of various

mangrove species at Site T in Mnazi Bay.

0

2

4

6

8

10

12

14

16

18

20

Avicenniamarina



Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree


mangrove species at Site U in Mnazi Bay.

0

10

20

30

40

50

60


Density (

no./

25m

2 p

lot)

Seedling

Sapling

Tree

90 90


various mangrove species at Sites H, P and Q in Mnazi Bay.

0

2

4

6

8

10

12


Ceriops tagal Rhizophoramucronata

Sonneratia alba

Stu

mp d

ensity (

no./

25m

2 p

lot)

H

P

Q


various mangrove species at Sites S, T and U in Mnazi Bay.

0

2

4

6

8

10

12

14

16

18

Bruguiera gymnorrhiza Ceriops tagal Rhizophora mucronata

Stu

mp d

ensity (

no./

25m

2 p

lot)

S

T

U

91

91

Fig

. B

.53: D

ensity

of m

acro

fauna (

mean +

sta

ndard

err

or)

at S

ites P

and Q

in M

nazi B

ay.

0

10

20

30

40

50

60

Dot

tilla

fene

stra

taU

ca la

ctea

ann

ulip

esU

ca te

trago

non

Uca

voc

ans

Tere

bral

ia p

alus

tris

Density (no./m2)

P Q

92

92

Fig

. B

.54: D

ensity

of m

acro

fauna (

mean +

sta

ndard

err

or)

at S

ites S

and T

in M

nazi B

ay.

0

20

40

60

80

100

120

Dot

tilla

fene

stra

taU

ca la

ctea

ann

ulip

esU

ca te

trago

non

Uca

sp.

Tere

bral

ia p

alus

tris

Density (no./m2)

S T

93 93

Photograph B.28: A luxurious growth of dense, healthy mangrove trees at Site P (Mnazi Bay).

94 94

Photograph B.29: Rhizophora mucronata trees, observed in the lower zone at Site P (Mnazi Bay), have developed massive prop roots that are overgrown with oysters.

Photograph B.30: Heavy cutting was observed at Site P (Mnazi Bay) and, at the same time, the regeneration potential was very high, as indicated by this vast number of seedlings.

95 95

Photograph B.31: A kiln observed at Site N (Mnazi Bay), with a mixture of mollusc shells and hard corals, prepared for burning.

Photograph B.32: A degraded area near Site Q (Mnazi Bay) where seedlings had been transplanted by students and the village environmental committee.

96 96

Appendix C: Tables showing GPS readings for all sites

Table C.1: GPS readings of the entry point into each site in the

Ruvuma Estuary where plot sampling was conducted.

Site Name of locality Latitude (South) Longitude (East)

A Nyati 10o 26.19’ 40o 23.39’

G Mitimikavu 10o 28.67’ 40o 25.39’

J Mtungayomba 10o 29.62’ 40o 24.57’

L Makanye 10o 25.60’ 40o 22.88’

M Namakupa 10o 28.11’ 40o 21.75’

N-W Kingumi 10o 26.02’ 40o 24.79’

N-E Kingumi 10o 26.01’ 40o 24.83’

IU Kikwajuni - -

IV Kingumi 10o 27.13’ 40o 24.20’

2D Kipondo 10o 22.17’ 40o 25.24’

Table C.2: GPS readings taken at each rapid assessment site and other sites of interest in Ruvuma Estuary.


B Mouth of Kingumi River 10o 26.82’ 40o 25.13’

C North side of eroded channel 10o 26.59’ 40o 22.98’

C South side of eroded channel 10o 26.68’ 40o 22.98’

D Mouth of Chikomolela River 10o 28.28’ 40o 25.69’

E Northwest end of Nkurukara channel 10o 27.28’ 40o 24.55’

F Southeast end of Nkurukara channel 10o 27.71’ 40o 25.15’

H Bahasha Island 10o 29.18’ 40o 25.21’

I Mapapaya River 10o 29.38’ 40o 24.88’

K Saline area at Makanya 10o 25.61’ 40o 22.85’

O Kingumi cha Luave 10o 25.14’ 40o 25.24’

P Site in Lugue River 10o 25.27’ 40o 24.83’

Q Site in Lugue River 10o 25.72’ 40o 24.16’

R Site in Lugue River 10o 25.57’ 40o 24.25’

S Malungu 10o 25.43’ 40o 23.89’

T Near Site L 10o 25.78’ 40o 23.12’

U Nakolachi 10o 25.66’ 40o 22.27’

V Site in southern branch of upper Nganje River

10o 25.02’ 40o 22.27’

X Nahake 10o 24.25’ 40o 22.64’

Y Chui-village Mgoji 10o 24.26’ 40o 21.35’

Z Mabomwe 10o 25.34’ 40o 21.71’

1A Chui 10o 24.22’ 40o 21.70’

1B Nahake 10o 23.95’ 40o 22.14’

1C North side of Nganje River 10o 22.96’ 40o 24.69’

1D South side of Nganje River 10o 23.21’ 40o 25.13’

1E Northern side of mouth of Nganje 10o 22.28’ 40o 25.83’

1F Lihongo Island 10o 24.26’ 40o 23.99’

1G Kikwajuni 10o 24.82’ 40o 23.57’

1H Makupa 10o 24.78’ 40o 23.56’

1I Namakupa 10o 28.15’ 40o 21.76’

1J Lilundunda 10o 28.26’ 40o 22.10’

1K Nyati 2 10o 27.95’ 40o 22.25’

97 97

1L Nyati 3 10o 27.76’ 40o 22.62’

1M Misuaki 10o 27.32’ 40o 23.83’

1N Lidengo 10o 27.48’ 40o 24.16’

1O Misuaki 10o 28.40’ 40o 23.55’

1Q Lower Kingumi River 10o 26.63’ 40o 24.64’

1R Lower Kingumi River 10o 27.25’ 40o 24.20’

1S Jinguo River 10o 26.97’ 40o 23.12’

1T Nawiya 10o 26.65’ 40o 22.48’

1X Nkurukala channel 10o 27.42’ 40o 24.69’

1Y Chikomolelo 10o 28.65’ 40o 24.17’

1Z Chikomolelo stream 10o 28.79’ 40o 24.31’

2A Kitope River joins Chikomolelo River 10o 27.95’ 40o 24.99’

2B Kitope River 10o 29.04’ 40o 24.61’

2C Near junction of Kitope and Ruvuma rivers

10o 29.16’ 40o 24.76’

Table C.3: GPS readings of the entry point into each site in Mnazi Bay and

the offshore islands where plot sampling was conducted.


A Membelwa 10o 14.82’ 40o 19.44’

F Namponda 10o 17.16’ 40o 22.31’

H Ruvula 10o 19.56’ 40o 22.93’

P Ruins 10o 19.27’ 40o 23.67’

Q Ruvula river 10o 18.76’ 40o 24.10’

S Lianje 10o 21.92’ 40o 22.18’

T Ikita 10o 20.48’ 40o 25.52’

U Chitumbulu 10o 20.57’ 40o 25.52’

Table C.4: GPS readings taken at each rapid assessment site and

other sites of interest in Mnazi Bay and the offshore islands.


B Village of Membelwa 10o 14.65’ 40o 19.25’

C Membelwa Island 10o 15.33’ 40o 20.45’

D Mpata 10o 15.89’ 40o 20.88’

E Kiyape 10o 14.96’ 40o 19.60’

G Namponda Village 10o 17.36’ 40o 22.29’

I Kaya River 10o 19.12’ 40o 23.84’

J Kiwale River 10o 19.70’ 40o 24.97’

K Chiwale 10o 20.14’ 40o 24.59’

L Mnamba River 10o 20.66’ 40o 24.87’

M Kipwa 10o 21.36’ 40o 24.36’

N Nkurusara River 10o 21.47’ 40o 21.25’

O Mnete 10o 18.21’ 40o 18.51’

98 98

Appendix D: Data Collection Sheets

MANGROVE DATA SHEET (FOMU YA MIKOKO)

Date (Tarehe): ______________ Village (Kijiji): ______________________________________ Site (Eneo la msitu): _______________ Zone (Kanda): __________ Plot (Shamba): _________ GPS reading: Long.__________________________ Lat. ______________________________ Compass direction of transect: _________

Species (Aina ya mikoko)

Maturity category (Kiwango cha ukuaji)

GBH (Mzunguko)

No. (Idadi)

Avicennia marina Seedling (mche)

(Mchu) Sapling (mti mdogo)

Tree (mti mkubwa)

Stump (kisiki)

Rhizophora mucronata Seedling (mche) N

(Mkoko) Seedling (mche) T

Sapling (mti mdogo) N

Sapling (mti mdogo) T

Tree (mti mkubwa)

Stump (Kisiki)

Ceriops tagal Seedling (mche)

(Mkandaa) Sapling (mti mdogo)

Tree (mti mkubwa)

Stump (kisiki)

Bruguiera gymnorrhiza Seedling (mche)

(Msinzi) Sapling (mti mdogo)

Tree (mti mkubwa)

Stump (kisiki)

Sonneratia alba Seedling (mche)

(Mliana/Mpira) Sapling (mti mdogo)

Tree (mti mkubwa)

Stump (kisiki)

Xylocarpus granatum Seedling (mche)

(Mkomafi) Sapling (mti mdogo)

Tree (mti mkubwa)

Stump (kisiki)

Heritiera littoralis Seedling (mche)

(Mkungu/ Msikundazi) Sapling (mti mdogo)

Tree (mti mkubwa)

Stump (kisiki)

Lumnitzera racemosa Seedling (mche)

(Mkandaa dume /mjazi) Sapling (mti mdogo)

Tree (mti mkubwa)

Stump (kisiki)

OTHER MANGROVES TRANSPLANTED (MIKOKO MENGINE ILIYOPANDWA)

Seedling (mche) < 1 m N = natural

Sapling (mti mdogo) > 1 m, GBH ≤ 4 cm T = transplanted Tree (mti mkubwa) > 1 m, GBH > 4 cm

99 99

MANGROVE SOIL MACROFAUNA DATA SHEET (FOMU YA WADUDU WANOPATIKANA KWENYE MIKOKO)

Date (Tarehe): ______________ Village (Kijiji): ______________________________________ Site (Eneo la msitu): _______________ Zone (Kanda): __________ Plot (Shamba): _________ GPS reading: Long.__________________________ Lat. ______________________________ Compass direction of transect : _________

Plot (Shamba)

Quadrat (Ubao)

Macrofauna (Wadudu)

Tally marks (Namna ya kuhesabu)

No. (Idadi)

100 100

Appendix E: List of Field Team Members

Dr. G.M. Wagner – team leader

F.D. Akwilapo – scientist

S. Mrosso – scientist

S. Ulomi – scientist

R. Masinde – technician

R. Ngowo – MBREMP

J. Mahenge – MBREMP

B. Chiwinga – MBREMP

Mwesaka – MBREMP

Uwesu Saidi Kibaya – resident of Litembe Juu

Rashid Hamisi Kampande - resident of Litembe Chini

Isa Ismail Chidole – resident of Tangazo

Salum Isa Lipwida – resident of Kilambo

Shufaa Mpoja - resident of Litembe Juu

Abas Issa – resident of Kilambo

Saidi Salum Chenge - resident of Litembe Juu

Salum Masood Mengi - resident of Kilambo

101 101

Appendix F: Certificate for attendance in the training and participation in mangrove assessment

CHETI CHA KUHUDHURIA MAFUNZO NA KUSHIRIKI KATIKA

UTAFITI WA MIKOKO

MTAJWA BW./BI. _____________________________

AMEHUDHURIA MAFUNZO PAMOJA NA KUSHIRIKI KATIKA UTAFITI WA MIKOKO KATIKA ENEO LA HIFADHI YA

BAHARI YA GHUBA YA MNAZI NA MAINGILIO YA MTO RUVUMA,

KUANZIA TAREHE 15 HADI 30 MWEZI SEPTEMBA 2003.

MHIFADHI MFAWIDHI CHUO KIKUU CHA MBREMP DAR ES SALAAM BW. M.E. MACHUMU DK. GREG M. WAGNER __________________ ________________

102 102

Appendix G: List of tables and figures (main text)

Table Page 2.1 List of study sites grouped by rivers (and sections within rivers) or by islands. 4 Figure 2.1 Location of Mangrove survey sites in Ruvuma Estuary. 5 2.2 Location of Mangrove survey sites in Mnazi Bay and the offshore Islands. 6 3.1 Basal area (cm2/25m2) in mangrove sites assessed quantitatively. 11 3.2 Mangrove density in quasi-quantitative, rapid assessment sites. 12 3.3 Number of mangrove species in mangrove sites assessed quantitatively. 13 3.4 Mangrove height in quasi-quantitative, rapid assessment sites. 14 3.5 Mangrove health in quasi-quantitative, rapid assessment sites. 15 3.6 Mangrove aesthetics in quasi-quantitative, rapid assessment sites. 16 3.7 Number of species of macrofauna in mangrove sites assessed quantitatively. 17 3.8 Density of mangrove stumps in quasi-quantitative, rapid assessment sites. 19 3.9 Stump density in mangrove sites assessed quantitatively. 20 3.10 Diagram showing identified issues, cross-cutting solutions, specific solutions

and opportunities 22

103 103

Appendix H. List of tables, figures and photographs (Appendices)

Table Page A.1 List of mangrove species (with Kiswahili and common English names, where

applicable). 35.

A.2 List of invertebrate species (with Kiswahili and common English names, where applicable).

35

B.1 Mean basal area of mangrove species and sample size (i.e., number of plots examined) in various zones at sites in Ruvuma Estuary.

43

B.2 Mean basal area of mangrove species in various zones at sites in Mnazi Bay and the offshore islands.

76

Figure B.1 Rapid assessment of condition of mangroves at sites 1C, 1D and 1F along

the lower Nganje River 37

B.2 Rapid assessment of condition of mangroves at sites X, Y, Z, 1A and 1B along the upper Nganje River (northern branch)

37

B.3 Rapid assessment of condition of mangroves at sites V and 1G along the upper Nganje River (southern branch)

38

B.4 Basal area (mean + standard error) of various mangrove species at Sites L, N, 1U and 2D in the northern part of Ruvuma Estuary

41

B.5 Density (mean + standard error) of various mangrove species at Site 2D in Ruvuma Estuary

41

B.6 Density (mean + standard error) of various mangrove species at Site IU in Ruvuma Estuary

42

B.7 Density of stumps (mean + standard error) of various mangrove species at Sites L, N (east side of channel),1U and 2D in the northern part of Ruvuma Estuary

42

B.8 Density of macrofauna (mean + standard error) at Sites N (east side of channel), 1U and 2D in the northern part of Ruvuma Estuary

45

B.9 Rapid assessment of condition of mangroves at sites N (east side of river), N (west side of river), O and P along the lower Lugue River

46

B.10 Rapid assessment of condition of mangroves at sites Q, R and S along the middle Lugue River

49

B.11 Rapid assessment of condition of mangroves at sites T and U along the upper Lugue River

49

B.12 Density (mean + standard error) of various mangrove species at Site N (west side of channel) in Ruvuma Estuary

52

B.13 Density (mean + standard error) of various mangrove species at Site N (east side of channel) in Ruvuma Estuary

52

B.14 Density (mean + standard error) of various mangrove species at Site L in Ruvuma Estuary

53

B.15 Rapid assessment of condition of mangroves at sites B, 1Q and 1R along the lower Kingumi River

53

B.16 Rapid assessment of condition of mangroves at sites 1S (Jinguo, south side), 1S (Jinguo, north side) and 1T along Kingumi River (northern branch)

55

B.17 Rapid assessment of condition of mangroves at sites 1K (north side of river), 1K (south side of river), 1L and 1M along the middle Kingumi River (southern branch)

55

B.18 Rapid assessment of condition of mangroves at sites 1J (west side of river) and 1J (east side of river) along the upper Kingumi River (southern branch)

56

B.19 Rapid assessment of condition of mangroves at sites 1H (northeast side of river), 1H (southwest side of river), 1I (northwest side of river) and 1I (� outheast side of river) along the upper Kingumi River (southern branch)

57

B.20 Basal area (mean + standard error) of various mangrove species at Sites A, M, and 1V in the central part of Ruvuma Estuary

57

104 104

B.21 Density (mean + standard error) of various mangrove species at Site A in Ruvuma Estuary

58

B.22 Density (mean + standard error) of various mangrove species at Site M in Ruvuma Estuary

58

B.23 Density (mean + standard error) of various mangrove species at Site IV in Ruvuma Estuary

59

B.24 Density of stumps (mean + standard error) of various mangrove species at Sites A, M and 1V in the central part of Ruvuma Estuary

61

B.25 Density of macrofauna (mean + standard error) at Sites A, M and 1V in the central part of Ruvuma Estuary.

62

B.26 Rapid assessment of condition of mangroves at sites 1N (north side of river), 1N (south side of river) and 1O (east side of river) along Lidengo River

64

B.27 Rapid assessment of condition of mangroves at sites 1X (northeast side) and 1X (southwest side) along Nkurukala Channel between Kingumi and Litokoto rivers

64

B.28 Rapid assessment of condition of mangroves at sites 1Y, 1Z (north side of river) and 1Z (south side of river) along upper Chikomolela River

65

B.29 Rapid assessment of condition of mangroves at sites 2A (west side of rive), 2A (east side of river), 2B and 2C along Kitope River

68

B.30 Basal area (mean + standard error) of various mangrove species at Sites G and J in the southern part of Ruvuma Estuary

70

B.31 Density (mean + standard error) of various mangrove species at Site G in Ruvuma Estuary

71

B.32 Density (mean + standard error) of of various mangrove species at Site J in Ruvuma Estuary

71

B.33 Density of stumps (mean + standard error) of various mangrove species at Sites G and J in the southern part of Ruvuma Estuary

74

B.34 Density of macrofauna (mean + standard error) at Sites G and J in the southern part of Ruvuma Estuary.

75

B.35 Rapid assessment of condition of mangroves at sites C, D and E on Membelwa Island off Mnazi Bay

77

B.36 Basal area (mean + standard error) of various mangrove species at Sites A and F on Membelwa and Namponda Islands, respectively, off Mnazi Bay

77

B.37 Density (mean + standard error) of various mangrove species at Site A on Membelwa Island in Mnazi Bay

78

B.38 Density of stumps (mean + standard error) of various mangrove species at Sites A and F on Membelwa and Namponda Islands, respectively, off Mnazi Bay

78

B.39 Density of macrofauna (mean + standard error) at Sites A and F on Membelwa and Namponda Islands, respectively, off Mnazi Bay

79

B.40 Density (mean + standard error) of various mangrove species at Site F on Namponda Island in Mnazi Bay

80

B.41 Rapid assessment of condition of mangroves at sites I (Kaya River mount), J (north side of Kiwale River), J (south side of Kiwale River) and K (Chiwale) along Ruvula peninsula in Mnazi Bay

85

B.42 Rapid assessment of condition of mangroves at sites L (Mnamba River), M (Kipwa), N (Nkurusara River) and O (Mnete) in Mnazi Bay

85

B.43 Basal area (mean + standard error) of various mangrove species at Sites H, P and Q in Mnazi Bay

86

B.44 Basal area (mean + standard error) of various mangrove species at Sites S, T and U in Mnazi Bay

86

B.45 Density (mean + standard error) of various mangrove species at Site H in Mnazi Bay

87

B.46 Density (mean + standard error) of various mangrove species at Site P in Mnazi Bay

87

105 105

B.47 Density (mean + standard error) of various mangrove species at Site Q in Mnazi Bay

88

B.48 Density (mean + standard error) of various mangrove species at Site S in Mnazi Bay

88

B.49 Density (mean + standard error) of various mangrove species at Site T in Mnazi Bay

89

B.50 Density (mean + standard error) of various mangrove species at Site U in Mnazi Bay

89

B.51 Density of stumps (mean + standard error) of various mangrove species at Sites H, P and Q in Mnazi Bay

90

B.52 Density of stumps (mean + standard error) of various mangrove species at Sites S, T and U in Mnazi Bay

90

B.53 Density of macrofauna (mean + standard error) at Sites P and Q in Mnazi Bay

91

B.54 Density of macrofauna (mean + standard error) at Sites S and T in Mnazi Bay

92

Photo 2.1 Data collection team composed of scientists, MBREMP staff and villagers (a

few were missing from the photograph). 9

B.1 Sonneratia alba logs observed at Site X (Ruvuma Estuary). 38 B.2 Bags of salt (near Site Y, Ruvuma Esturary) produced in solar saltpans,

which had been constructed about 15 years previous. Some mangroves had been cleared to create enough area

39

B.3 Oysters of the species Saccostrea cucullata were commonly observed

growing on Rhizophora mucronata prop roots in the area, such as here at Site V (Ruvuma Estuary)

39

B.4 In Site 1G (Ruvuma Estuary), there was high cutting pressure on mature Ceriops tagal trees, commonly used for building poles.

40

B.5 Erosion is very high on the seaward side of Site O (Ruvuma Estuary), since it is exposed to the open ocean waves, particularly at high tide.

46

B.6 Erosion commonly occurs on the outer side of bends in the tidal channels, such as is shown here on the eastern side of Site N (Ruvuma Estuary).

47

B.7 Accretion of sediments occurs on the inner side of bends in the tidal channels, such as is shown here on the western side of Site N (Ruvuma Estuary).

47

B.8 This channel in the Ruvuma Estuary, from Site Q to the non-mangrove forest in the distance, had previously been a continuous stand of mangroves, which was eroded away about 25 years ago.

50

B.9 A new islet of mangroves (Site R, Ruvuma Estuary), consisting only of Sonneratia alba, which started forming about 7 years ago due to accretion of sediments.

50

B.10 A recently formed mono-specific stand of Sonneratia alba (Site T, Ruvuma Estuary), which is continuing to expand outwards, through the establishment of new seedlings.

51

B.11 Eroded riverbank at Site 1V (Ruvuma Estuary). 60 B.12 Numerous stumps of Ceriops tagal at Site 1V (Ruvuma Estuary), indicating

the very high cutting pressure there. 60

B.13 Cut stumps of Ceriops tagal a short distance away from Site 1N (Ruvuma Estuary).

65

B.14 Luxurious growth of mangroves at Site 1X (Ruvuma Estuary). 66 B.15 Heritiera littoralis trees at Site 1Z (Ruvuma Estuary), photographed during

the dry season. They are apparently only healthy during the rainy season. 67

106 106

B.16 Site C (Ruvuma Estuary), probably the most attractive and interesting sites in the entire MBREMP area. The canopy was so dense that light penetration was minimal and thus getting a proper photograph was difficult.

69

B.17 A well-developed, mature and diverse mangrove ecosystem occurs at Site G (Ruvuma Estuary).

70

B.18 One of the investigators, Flora Akwilapo, standing beside a Bruguiera gymnorrhiza tree (Site G, Ruvuma Estuary), in order to demonstrate that almost 2 m of earth (vertical distance) have been eroded by Ruvuma River in recent times.

72

B.19 At Site G (Ruvuma Estuary), many meters have been eroded away (horizontal distance), causing many mangrove trees to fall over and die.

73

B.20 This channel has been eroded away such that it separates two parts of Bahasha Island in Ruvuma River, which was formerly one.

73

B.21 A fence trap, an environmentally friendly fishing device, fixed across Mipapaya channel, which flows into Ruvuma River.

74

B.22 Large areas of mud in the lowermost zone at Site A (Membelwa Island) were covered with mats of a colonial sea anemone (Order Zoanthidea).

81

B.23 A large heap of Cerithidea decollata shells seen near the village of Membelwa. This species is used as human food and fish bait.

81

B.24 A heap of shells of Pinna muricata (seen on Namponda Island), which is used as human food and fish bait.

82

B.25 A heap of shells of Anadara antiquata (seen on Namponda Island), which is used as human food and fish bait.

82

B.26 A noticeable number of mangroves were observed dead and overgrown with lichens at Sites C and E on Membelwa Island.

83

B.27 Numerous Yellow-billed Storks were present at Membelwa Island. 83 B.28 A luxurious growth of dense, healthy mangrove trees at Site P (Mnazi Bay). 93 B.29 Rhizophora mucronata trees, observed in the lower zone at Site P (Mnazi

Bay), have developed massive prop roots that are overgrown with oysters. 94

B.30 Heavy cutting was observed at Site P (Mnazi Bay) and, at the same time, the regeneration potential was very high, as indicated by this vast number of seedlings.

94

B.31 A kiln observed at Site N (Mnazi Bay), with a mixture of mollusc shells and hard corals, prepared for burning.

95

B.32 A degraded area near Site Q (Mnazi Bay) where seedlings had been transplanted by students and the village environmental committee.

95

PARTICIPATORY ASSESSMENT OF MANGROVES IN · reported five species of mangroves and several species...

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