Appendix G - Ecological Impact Report - La Cambuse Hotel

Appendix G

Ecological Impact Report

Diospyros Ltd Telephone /Fax Registration No 28A Dr de Chazal Rd (230) 696 4353 067521 Vacoas Cell Phone VAT Registration No Mauritius (230) 423 6032 20375152

Le Chaland Resort Hotel Project

Ecological Impact Report

Prepared By

Consultant Ecologists

Pierre de B. Baissac BSc (Hons), MSc (Cape Town)

August 2012

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Le Chaland Resort Hotel Ecological Survey

Diospyros Ltd Ecological Consultants

28A Dr de Chazal Rd, Vacoas, Mauritius. Tel (230) 696 4353 Email: [email protected]

Table of Contents 1. Introduction

2. Site Location and Description

3. Survey Methodology

3.1 Natural Features of Outstanding Value

3.2 Ecology

3.3 Survey Limitations

3.4 Evaluation Methodology

4. Site Survey

4.1 General Description and Topography

4.2 Ecology

4.3 Wildlife

4.4 Vegetation and Habitats

4.4.1 Littoral Zone

4.4.1.1 Outpost Vegetation

4.4.1.2 Mixed Scrub

4.4.2 Inner Littoral Vegetation

4.4.3 Inland Vegetation

4.5 Sand Dune Formation

4.5.1 Calcareous Deposits and Sand Dunes of Mauritius

4.5.2 Sea-level Rise and the Formation of sedimentary Deposits

4.5.3 Aeolianite or Dune Rock

4.5.4 Le Chaland Unconsolidated Sand Dune

5. Evaluation

5.1 Ecology

5.2 Sand Dune Geology

6. Discussion

7. Recommendations

8. References

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1. Introduction 33 Arpents of Pas Géometrique belonging to the State and leased to Currimjee Jeewanjee Properties Ltd. have been earmarked for a Hotel project. Diospyros Ltd was commissioned to prepare the ecological report for EIA purposes. The site was surveyed on the 1st and 6th June 2009 for an earlier project proposal and revisited on the 31st August for the modified project proposal. The objectives of the study are to:

Identify and describe the terrestrial ecological environment and its associated biodiversity;

Identify endemic, native and alien vegetation of botanical and ecological interest, with the location and description of key nature conservation features such as the sand dune;

Identify potential impacts on the ecosystem; and Prepare recommendations for impact mitigation measures where necessary during

the construction and operational phases of the project; and Prepare recommendations for the protection and conservation of the ecosystem

2. Site Location and Description The 33 Arpents site, located at La Cambuse, Le Chaland, is situated between a portion of land to be occupied by the National Coast Guards to the East and the La Cambuse Public Beach to the West (Figure 1). It has a sea frontage of about 415m on the Blue Bay Marine Park The hotel will occupy the site currently occupied by the National Coast Guards Training Centre which will be moved to a portion of land situated between the Shandrani Hotel and the Le Chaland Resort Hotel as the result of a lease swap. Inland the site is bordered by free hold land cultivated with sugar cane purchased by Currimjee Jeewanjee Properties Ltd from Mon Tresor Mon Désert SE. A gravel road leading to the public beach separates the two portions of land. A tarred road which serves as access to the Coast Guard Training Centre runs from the Shadrani Hotel along the length of the site about 150m inland. The disposition of the hotel and resort on the site is shown in Figure 2.

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Figure1 Site Location and Topography

Figure 2 Hotel and Resort Master plan and Layout

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3. Survey Methodology

3.1 Natural Features of Outstanding Value

The coastal sand dune is the single most important natural feature of outstanding value and ecological significance on the site. The study methodology has consisted of:

i. Literature review of sand dune formations in Mauritius;

ii. Site survey of the sand dune to examine the structure and formation.

The sand dune structure was examined twice in August 2012. 3.2 Ecology

3.2.1 The site survey was conducted in August 2012.

3.2.2 The survey was undertaken to identify ecological types, the flora and the fauna

present on the site. Aerial identification of the ecological zones and vegetation types was done with the help of Google Earth Satellite Photographs. The site was walked through its length and breadth for ground survey purposes to identify the flora and fauna present and to locate all native vegetation and other plants of aesthetic value present.

3.2.3 Photographs were taken to identify and record vegetation and plant types. Plant material was identified from the literature. Literature consulted was Atkinson, R. Et al (2005), Bosser, J. et al (1980-2008), Rouillard, G. et al (1999). Plant species found on site are presented in Table 1 (Indigenous Plants) and Table 2 (Alien Plants).

3.2.4 All stands of vegetation and habitats were described and evaluated. The principal and constant plant species within the site boundary were determined with estimates of the distribution, abundance and constancy of individual species. The estimation of abundance was based on the DAFOR system where D = Dominant, A = Abundant, F = Frequent, O = Occasional, R = Rare, this being a widely used and accepted system employed by ecological surveyors.

3.2.5 Fauna (birds, butterflies and reptiles) was evaluated by visual observations. Butterflies were identified from Williams, J.R. (2007). No counts or population estimates were made.

3.2.6 Searches were made for uncommon, rare and statutorily protected plant species, those species listed as protected in the Wildlife and National Parks Act 1994, and the Forests and Reserves Act 1983. Native or indigenous vegetation or animals (i.e. naturally present in Mauritius) are classed as either indigenous, meaning plants or animals that live and occur naturally in Mauritius but also occur naturally in other parts of the world, or endemic, referring to those that naturally and exclusively occur in Mauritius).

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3.2.7 The presence of invasive plant and animal species was recorded. All non-indigenous or non-native animals or plants recorded on site were classified as Alien. Alien means animals and plants that occur naturally in other parts of the world but have been introduced in an area by man, whether accidentally or voluntarily. When taken to new environments, these plants and animals often take over, become invasive and are a problem and a threat to the indigenous flora, fauna and environment of that land, and to the ecosystem services they provide.

Invasiveness of alien species found on the site was defined according to Kueffer and Maureemootoo (2004).Their conservation threat is given as either No Conservation Threat (i.e. they pose no particular threat to the environment or the indigenous flora and fauna), Weed (a plant considered undesirable, unattractive, or troublesome but not invasive), or Invasive (plants that economically, environmentally or ecologically adversely affect the habitats they aggressively invade).

3.3 Survey Limitations

The surveys were carried out in suitable conditions. No significant survey limitations were experienced. 3.4 Evaluation Methodology The habitats, vegetation and animal life were evaluated with reference to standard nature conservation criteria as described by Ratcliffe (1977). These are; size (extent), diversity, naturalness, rarity, fragility, typicalness, recorded history, position in an ecological or geographical unit, potential value and intrinsic appeal. 4 Site Survey 4.1 General Description and Topography The site is made up of two distinct portions in the form of an armchair (Figure 1). The larger portion is the coastal block facing the lagoon which forms part of the Blue Bay Marine Park. The second and smaller one corresponds to the back rest of the arm chair and extends inland. The coastal portion is essentially sandy and consists of a beach made of fairly coarse sand followed by a sand dune system. On the eastern half of the site up to the area currently occupied by the Coast Guard Training Centre the beach consists of fairly coarse sand and has a relatively steep swash zone. This is followed by a swash berm and a dip, the dune then rising to crest at 10m above MSL about 140m inland of HWM. The back dune slopes gently down to meet the basaltic rock formation about 250m from HWM, slightly on the seaward of the access road to the public beach. This zone forms a

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slight depression. The basaltic formation is part of the Late Lavas of the Younger or Recent Series of volcanic activity of Mauritius (Mc Dougall et al 1969) and extends inland to form the Plaine Savanne. Fossil coral and calcarenite blocks can be seen at the interface zone between the sand dune and the basalt. This typical beach and coastal sand dune profile is given in Figure 3.

Figure 3 Typical beach and coastal dune profile (From Coastal Engineering Manual)

Westward, from about the Coast Guard base to the end of the public beach, the beach profile is flatter and wider, sloping gently to the top of the dune about 100m inland. The coral reef barrier extends along the length of the beach from Ile aux Deux Cocos to Pointe Vacoa and is only about 200m from the shore. Consequently it offers very little protection to the beach from the waves which can hit the coast with great force during stormy and cyclonic conditions. 4.2 Ecology

A distinctive Zonation or banding parallel to the shoreline, a well known ecological phenomenon on exposed sandy shores (Sauer 1960), is observed on the site. This follows the geology and topography of the site. Two main ecological zones and plant communities have been identified (Appendix 1) and are classified as follows:

a. Littoral zone occupying the sand dune and its outer slope is divided into two

classes giving three distinct bands of vegetation (Figure 4):

i. The outer littoral or outpost species zone occupying the dune outer slope (beach swash zone and berm in Figure 3).

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The outpost species zone consists of two bands:

Coastal turf which extends from the high water mark inland; Mixed scrub, typically a one-layered thicket with little undergrowth.

The vegetation is centred very close to the water’s edge and strongly subject to the sea’s influence, waves and spray. At high tides waves will frequently wash right up to (Figure 5), and even over the berm past this row of plants (Figure 6); during cyclonic conditions they can wash well past this outpost zone.

ii. The inner littoral zone occupying the sand dune and its inner slope: This is

dominated by a continuous stand of trees with a dense ground cover of grasses, growing beyond the reach of ordinary storm waves and heavy spray. The outpost species and the inner littoral zones meet in an extremely narrow contact zone.

b. Inland, back of dune vegetation occupying the rocky soil area.

© P. Baissac

Figure 4 Succession of vegetation zones showing coastal turf, mixed scrub outpost species, and inner littoral vegetation, mainly filao trees (right to left)

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© P. Baissac

Figure 5 Waves swashing up to vegetation row

© P. Baissac

Figure 6 Debris washed up by waves (foreground) past the outpost vegetation

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4.3 Wildlife Very little fauna was observed during the visits. Insects Insects were rare throughout the site. The moth Utetheisa cruentata and the butterfly Amauris phoedon can be seen occasionally on Tournefortia argentaea bushes where they feed on the pollen and nectar of the plant. Two species of butterflies, Henotesia narcissus and Phalanta phalantha were fairly common in the bushes and undergrowth behind the Coast Guard station. Retiles No endemic lizards were seen throughout the visits. The only lizard rarely seen was the alien agamid (camaleon) Calotes versicolor. Birds Very few birds were seen on the site during the site visits. The only birds of interest were small flocks of the endemics Pic Pic or Mauritian Grey White-eye (Zosterops chloronothus). These could be seen hopping around in bushes of Veloutier vert (Scaevola taccada) looking for insect and occasionally amongst the filao trees. The Red- whiskered Bulbul Pycnonotus jocosus and Magascar fody Foudia madagascariensis were occasionally seen. Mammals One hare Lepus nigricolis was seen. Evidence of foraging tenrec (tendrac) Tenrec ecaudatus was occasionally seen in undergrowth. No other animals were seen. 4.4 Vegetation and Habitats Species of indigenous and alien vegetation found on the project site have been recorded. A list of the indigenous plants including their distribution, their conservation status, and their occurrence within the study site is provided in Table 1. A list of the alien plants and their conservation threat is given in Table 2. Of the 33 plant species recorded, 12 are indigenous. No endemic plants to Mauritius or the Mascarenes were found.

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Table I: Native species recorded on site: distribution, status, and occurrence.

Family Genus Species Common Name

Distrib. Conservation Status

Occurrence on Site

Boraginaceae Hilsenbergia petiolaris Bois pipe N Least concern R

Boringaceae Tournefortia argentea Veloutier N Least concern C

Convolvulaceae Ipomoea pes-caprae Batatran N Least concern R

Cyperaceae Cyperus stoloniferus N Least concern O

Goodeniaceae Scaevola taccada Veloutier vert N Least concern C

Gramineae Paspalum vaginatum Herbe la mare N Least concern O

Gramineae Sporobolus virginicus Chiendent N Least concern C

Gramineae Stenotaphrum dimidiatum Chiendent bourrique

N Least concern VC

Leguminosae Canavalia rosea Liane cocorico

N Least concern C

Draceanaceae Dracaena reflexa Bois de chandelle

N Least concern O

Surianaceae Suriana maritima Bois matelot N Least concern C

Umbelliferrae Hydrocotyle bonariensis Herbe bol N Least concern C

Note: N-Native to Mauritius VC- Very Common C- Common O- Occasional R- Rare

Table 2: Alien Vegetation: Occurrence and Conservation Threat

Family Genus Species Common Name Conservation Threat

Occurrence on Site

Anacardiaceae Mangifera indica Manguier NCT Single spec.

Anacardiaceae Schinus terebinthifolius Poivre marron Very invasive Common

Araucariaceae Araucaria columnaris Pin de Cook NCT Single tree

Boraginaceae Cordia curassavica Herbe condé Invasive Occasional

Caricaceae Carica papaya Pawpaw NCT Occasional

Casuarinaceae Casuarina equisitifolia Filaos NCT Abundant

Combretaceae Terminalia catappa Badamier NCT Occasional

Fabaceae Leucaena leucocephala Acacia Very invasive Common

Fabaceae Pithecellobium dulce Cassie de manille Very invasive Common

Fabaceae Pongamia pinnata Coqueluche Invasive Occasional

Fabaceae Senna occidentalis Casse puante Weed Occasional

Lauraceae Listea glutinosa Bois d'oiseau Very invasive Common

Leguminosae Haematoxylum campechicum Campêche Very invasive Common

Nyctaginaceae Bougainvllea spp Bougainvillier NCT Occasional

Palmae Cocos nucifera Cocotier NCT Common

Rubiaceae Morinda citrifolia Bois tortue NCT Common

Sapotaceae Chrysophyllum oliviform Satin leaf NCT Occasional

Sapotaceae Mimusops coriacea Pomme jacot NCT Occasional

Thymelaceae Wickstroemia indica Herbe tourterelle Invasive Occasional

Verbenaceae Lantana camara Vieille fille Very invasive Occasional

Verbenaceae Stachytarpheta jamaicensis Queue de rat Weed Common

Note: NCT- No Conservation Threat (i.e. No threat to conservation)

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4.4.1 Littoral Zone 4.4.1.1 Outpost Vegetation 4.4.1.1.1 Coastal Turf This outer band of the outpost vegetation is present right through the site. It is the first vegetation band and occupies the area from the top of the swash zone to the beach crest at about the high water mark (Figure 7). This vegetation type grows on well drained beach sand. The community characteristically consists of a sparse fringe of grasses and creeping plants. The grasses are dominantly chiendent Sporobolus virginicus and herbe la mare Paspalum vaginatum amongst which grow fairly densely the deep rooted herbe bol Hydrocotile bonariensis and less commonly an unidentified Cyperaceae, probably Cyperus stoloniferus. These species favour loose coral as a growing environment (Sauer 1960) and are particularly good sand retention plants. The creepers, which can form dense patches, are largely dominated by liane cocorico Canavalia rosea with the occasional liane batatran Ipomoea pes-caprae. Freshly germinated and young plants of Scaevola taccada are fairly common growing at the HWM tide line.

© P. Baissac

Figure 7 Coastal Turf Zone of Outpost Vegetation 4.4.1.2 Mixed Scrub This band of vegetation is present throughout most of the site but has become impoverished or entirely removed in front of the Coast Guard station. It consists of a one-layered or single row mosaic of wind-shorn native shrubs consisting mainly of Veloutier vert Scaevola

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taccada, Veloutier argenté Tournefortia argentea and Bois matelot Suriana maritima (Figures 8 & 9). Though Scaevola taccada and Tournefortia argentea can grow equally well on a variety of substrates, the Bois matelot Suriana maritime tends to favour coral sand.

© P. Baissac

Figure 8 Mixed Scrub Zone of Outpost Vegetation

© P. Baissac

Figure 9 Outpost Vegetation Mixed Scrub with Inner Littoral Vegetation In Background

The vegetation is wedge shaped, the back portion reaching up to about 4m height and tapering to almost nothing on the beach side. In this way the force of the wind is deflected upwards, protecting the environment behind. The surface of the canopy is very irregular. The foliage density of Suriana maritima and Scaevola taccada which are generally in the

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foreground is high allowing little sunlight penetrates to the ground. Tournefortia generally grows behind the other two species as it tends to form a taller and more rigid bush. There is little understory development in this zone, but where there is undergrowth, particularly between the thickets, it is dominated by the grass Chiendent Bourrique (Stenotaphrum dimidiatum) with the occasional Canavalia rosea. 4.4.2 Inner Littoral Vegetation The inner littoral vegetation grows on the whole front slope of the sand dune. It is entirely a recent artefact replacing the ancient ebony and palm coastal forest which has long since been exterminated. On the sand dune it consists of a plantation of tall filao Casuarina equisetifolia trees with a lush and dense carpet cover of the grass Chiendent bourrique Stenotaphrum dimidiatum (Figure 10). This mix extends to a portion if the back slopes behind the tarred access road. A few shrubs of Pomme jacot Mimusops coriacea can be found within the filao trees in the lower areas close to the outpost fringe. Some bushes of Bois tortue Morinda citrifolia and a few coconut trees can be found within the filao on the edge of the road. The portion occupied by the National Coast Guards (NCG) has been completely cleared of all vegetation and replanted with a cluster of trees, now 10-12m tall in the middle of the compound. These are one Araucaria columnaris, two Mimusops coriacea, two Terminalia catappa, and about 50 filao trees. On the ffront edge of the parade ground there is a very attractive Mimusops coriacea.

© P. Baissac

Figure 10 Casuarina plantation

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4.4.3 Inland Vegetation This zone covers the area behind the dune. It is highly degraded and is largely overgrown by a dense thicket of 5-6m tall shrub consisting of mixed alien invasive plants consisting of false acacia Leucaena leucocephala, bois d’oiseau petite feuilles Litsea glutinosa and Poivrier marron Schinus terebinthifolius. A few filao, coconut, and pawpaw trees can be also befound. No vegetation of conservation value is present. The gravel road at the edge of the site is bordered along much of its length by tall badamier Terminalia catapa trees. A few tall bushes of Satin Leaf Chrysophyllum oliviform are also present. Though both these are alien plants and have no conservation value alien they are attractive and should be preserved for their decorative value if possible. No features of significance or conservation value, such as wetlands, are present on this portion of the site. A list of alien plants in the zone is provided in Table 2. 4.5 Sand Dune Formation The Le Chaland sand dune is part of a large coastal sand dune complex found around the East and South coasts of Mauritius, on the windward side of the island. Windblown sediments often form dunes and these are said to be of Aeolian origin. An ideal dune has a long windward slope (i.e. facing the wind) rising to a crest and a much steeper leeward slope. The latter is determined by the fact that sand blown over the crest falls into a wind shadow (downwind), and comes to rest at its natural angle of repose-about 30° to 35° for dry sand (Figure 11).

Figure 11 Section through windblown sand dune illustration stratification (From Holmes, A 1965).

The sand dune formation is the result of a complex history of events which will be reviewed below.

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4.5.1 Calcareous Deposits and Sand Dunes in Mauritius Mauritius is a volcanic island, with most of the geology consisting of and topography resulting from lava flows which reach the sea along the greater portion of the shoreline. Along the portion of the coastline bordered by sea cliffs, particularly along the South and West coasts, there is an absence of coral reefs. Elsewhere reefs, reef flats, and lagoons are present with widths up to 5 km. Inland from these, beaches consist of coral sand and gravel, basaltic gravel and boulders, and mud. Various sand accumulations occur behind the beaches, such as single or multiple ridges and aeolian deposits. Masses of older aeolianite (dune rock) and fossil reef rock are preserved in some localities. Both the occurrence and volume of sandy beaches are related directly to the presence of coral reefs, and to the width of the belt between reef and shore. Beach development is most pronounced where the distance to the outer face of the reef is shortest. In cases where well-developed beaches face prevailing winds they may be backed by vegetated, single-crested aeolian ridges that rise as much as thirty feet above sea level.’ (McIntyre et al 1964). A basic consideration in coastal studies is the recognition that each coastal segment has its own "personality". The forces of wind, waves, currents, tides, and storms in different combinations depend on the gross configuration of the shoreline, the relative sea level at the time of action of these forces, and the material that is being worked upon. Thus, over the millennia, different types of calcareous deposits (aeolianite, dunes, beach rock, and beaches) have been formed in Mauritius, of which evidence remains around the coast (Figure 12). Of particular interest here are the aeolianites or dune rock and the unconsolidated sand dunes, their dates and causes of formation, their structure or morphology, and their presence around the coast. 4.5.2 Sea-level Rise and the Formation of Sedimentary Deposits The geology of the ancient and present coral reefs and associated sedimentary rocks in Mauritius and the Mascarenes Archipelago is well documented (Faure et al 1971, McIntyre 1961, McIntire et al 1964, Montaggioni 1972, Montaggioni 1974, and Russel, R.J. et al 1965). The relation between sea-level fluctuations and the formation of calcareous sedimentary deposits in Mauritius is also well documented (Camoin et al 2004, McIntyre 1961, Montaggioni 1974, Montaggioni 1976, Montaggioni et al 1997). The last 200 000 years has seen a series of fluctuations in global temperatures, from the very cold glacial periods to the much warmer inter-glacials. These have led to great fluctuations and changes in the sea level around the globe relative to the present sea level (Figure 13). These fluctuations, however, vary from region to region. The changes relating to the South West Indian Ocean and Mauritius as given in the scientific literature will be discussed further.

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Figure 12 Geological map showing Aeolianite (dune rock) deposits, and Beaches and Sand Dune deposits (Holocene deposits) (Montaggioni 1974).

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Figure 13 Illustration of Changes in global sea level over the last 200 000 years (Not representative of Western Indian Ocean).

4.5.3 Aeolianite or Dune Rock In the Western Indian Ocean, during the late Pleistocene, about 80 000 years before present (BP), the sea level (SL) fell to more than one hundred metres below present sea level exposing vast areas of previously submerged platforms and their marine sediments. This low stand remained still until 40 000 years BP. The SE trade-winds drifted the emerged marine sedimentary particles, sand and other calcareous debris accumulated on the submerged platform over the millennia, to form a large dune system, 35 to 40m thick along the eastern and southern coasts of Mauritius. Subsequent sea level changes have, over time both submerged and exposed these deposits, consolidating and cementing them, and eroding them during sea level regressions to give the present relics of fossilised sand dunes (aeolianite) dating back to the late Pleistocene (Montaggioni 1974). Aeolianite or dune rock is present on the mainland and the calcareous islets in the Mahebourg area, as well as along the south coast between Souillac and Le Morne Brabant (Figure 5) (McIntire et al 1964, Montaggioni 1974). Aeolianites are not present at Le Chaland and La Cambuse area.

Aeolianites are composed primarily of cemented layers, or bedded, coral sand. The layers are usually sloping, representing the slip face of migrating dunes (Figure 11) and may vary in thickness depending on the climatic event that caused the layer formation (Figure 14).

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© P. Baissac Figure 14 Aeolianite deposits on Ile de la Passe showing sloping layers on the down wind or slip face of the dune. Thick layer probably represents a storm event and the thin layers normal wind events sufficient to blow the sand over the dune crest.

4.5.4 Le Chaland Unconsolidated Sand Dunes (Holocene Deposits) These events were followed by the last glacial period (18 000 – 20 000 yr BP) at the end of the Pleistocene era. Research suggests that sea level in the Western Indian Ocean between 18 000 and 17 000 BP may have been lower than 120m below present sea level (Camoin et al 2004). About 13 500 BP (Late Pleistocene) sea level started rising with warming setting in and continued to rise rapidly between 10 000 and 7 500 yr BP (the beginning of the Holocene or Modern era) at about 6mm/yr, to around 18m below present sea level. During the so-called Flandrian Period of the Holocene, from 7 500 yr BP sea level rose at a reduced rate of about 1.1 mm /yr to stabilised close to its present position at about 2 500 yr BP (Camoin et al 2004, Montaggioni et al 1997). During this period of transgression alluvial sand accumulated in the lagoon was reworked with the landward movement of the coastline, providing a sufficient supply of sand for its accumulation by wind to form the present sand dune system along the south and east coasts as reviewed above from McIntire et al 1964. The sand dune of Le Chaland was formed during this period, from 7 500 yr BP to stabilise at its present level (2 500 yr BP) when transgression stopped.

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The Le Chaland sand dune is typically single crested dunes as defined by McIntire et al 1964:

‘A distinctive type of sand ridge is well developed in the vicinity of Butte aux Sables and at the other places along the south and east coasts. The ridge is single crested, parallels the beach, is commonly long and continuous, and may attain a height such as forty feet, which is well above wash limits of waves during extreme storm conditions. This type of ridge occurs only where there is direct exposure to prevailing southeast winds and where the reef lies close to the strand line.’ All coastal sand dunes are dynamic and constantly subject to external forces such as wind and waves causing erosion and reconstruction creating apparently multi-crested dunes which are, in fact berm crests with a single dune crest (Figures 3). In the case of Le Chaland, the beach crest is followed by a berm (Figure 15) which in turn is followed by one or two berm crests. The dune crest or ridge (Figure 16) corresponds to the portion above the 9.0m contour with peaks up to 10m. The back dune slopes down to the contact point with basalt rock. The presence of fossil coral and calcarenite blocs at the interface suggests the presence of an ancient reef there exposed at the time of deposition (Figures 17 & 18).

© P. Baissac © P. Baissac Fig. 15 Beach Crest and Berm on Left Figure 16 Dune Crest or Ridge

© P. Baissac © P. Baissac Figure 17 Fossil Coral Block Figure 18 Calcarenite Block

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5. Evaluation 5.1 Ecology Ecologically the whole of the site, with the exception of the very narrow coastal outpost fringe, is totally degraded and no longer has any native vegetation left except a few scattered specimens. Of the 33 plant species recorded, 12 are indigenous. No endemic plants to Mauritius or any threatened species were found. Of the 21 alien plant species present, 9 are classed as invasive or highly invasive in Mauritius (Kueffer et al 2004). As with the flora there is a particular absence of native fauna and except for the three species of butterflies and the only endemic species present, the Pic Pic or Mauritian Grey White-eye Zosterops chloronothus no other native wildlife is present. The outpost zone is the zone of highest sensitivity. It is the only portion of the site that is fairly intact ecologically. It is populated by native vegetation and has no elements of alien or invasive vegetation. It represents the highest degree of biological diversity, naturalness and typicalness of the whole site. Because of their abundance in Mauritius and in the Indo-Pacific zone the species present are not threatened and represent no element of rarity and conservation threat. However, because of human and development pressures there is a considerable element of fragility. The inner littoral zone in the sand dune portion of the site is highly degraded and is entirely planted with Casuarina, a relatively recent artefact replacing the ancient ebony and palm coastal forest which has long since disappeared. Though this zone is highly modified, has no elements of diversity, naturalness, rarity remaining and has no conservation value as far as ecology and biodiversity are concerned, it is a very sensitive zone and at least has vegetation cover. The western portion of the inner littoral zone occupied by the NCG is almost entirely devoid of vegetation. The station consists of a series of buildings surrounding a large tarred parade ground. A tarred road leads to the station. The buildings and tarmac closest to the sea are situated just over 40m from the HWM, inside the initial critical buffer zone of 50m and far inside the 100m buffer zone. This zone is totally modified and totally degraded. The inland vegetation zone is completely degraded and overgrown by alien invasive plants amongst which can be found very few and sparse native plants. This zone is also highly modified, has no elements of diversity, naturalness, rarity remaining and has no conservation value as far as ecology and biodiversity are concerned. It is a zone of low sensitivity. 5.2 Sand dune geology The sand dune, except for the area occupied by the Coast Guards which has been levelled many years ago to make way for the various military installations, is relatively intact. The

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front slope is generally intact but the back slope has been modified to some degree in the past for levelling and construction purposes. The dune is still active and very dynamic. It is constantly being subjected to external forces such as wind and waves which cause erosion and reconstruction along the shoreline. During cyclonic conditions it is likely that the effects will be felt right up to, and past the berm during the normal cycle of beach and dune erosion and accretion.

It is very typical of coastal sand dunes according to the criteria defined by McIntire et al 1964 and has high dune naturalness as far as the geology is concerned. It has a fairly high element of rarity as a result of the high degree of modification that has taken place for construction and ‘development’ purposes with most of the coastal sand dunes of Mauritius. A loss of the outpost vegetation would seriously threaten the stability and integrity of the dune.

The system is also fairly vulnerable to erosion with respect to climate change and sea level rise. Degradation and loss of the vegetation fringe would similarly seriously threaten the stability and integrity of the dune.

6. Discussion The Blue Bay Marine Park (BBMP), on which the project has a frontage of about 425m, covers a marine area of 353 hectares. It was proclaimed National Park under the Wild Life and National Parks Act in October 1997 and subsequently declared a Marine Protected Area and designated a Marine Park in June 2000, under the Fisheries and Marine Resources Act 1998. BBMP was nominated as a RAMSAR site in 2008.

Figure 19 Blue Bay Marine Park Zonation (Courtesy Ministry of Fisheries & Rodrigues)

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The Fisheries and Marine Resources (Marine Protected Areas) Regulations were amended in 2007, introducing a zoning system to control permissible activities in the marine park (Figure 19). The portion of the park where the hotel will be situated is classified as a Conservation Zone. A specific set of regulations apply concerning activities within the park. Beaches and dunes occur in tropical and temperate coastal areas worldwide. They are among the most dynamic landscapes, shifting with the winds, incoming waves and storm tides (Chan et al 2009; Cochard, 2008). Plant communities of coastal dunes and beaches in most Indo-Pacific islands consist of three zones (e.g. BPA, 2004 and Craft et al., 2008; from Chan et al 2009). In Mauritius they are: 1) The outer outpost zone with primary stabilising plants.

These consist essentially of creeping plants (Ipomoea pes-caprae, Canavalia rosea), and herbaceous plants which include sedges (Cyperus) and grasses at the high tide level.

2) The inner outpost or shrub zone with secondary stabilising plants consisting of shrubs,

herbs and grasses. The shrub zone consists of Scaevola taccada, Tournefortia argentea, Pemphis acidula, Hibiscus tiliaceus, and Sophora tomentosa.

3) The forest zone consisting of shrubs and trees.

Formerly this was a forest of endemic trees which included Pandanus, the ebonies (Diospyros tesselaria, D. egrettarum, D. melanida), Bois d’Olive (Cassine orientalis), Bois de Boeuf (Gastonia mauritiana), Bois de Fer (Sideroxylon boutonianum).

The forest zone has been entirely destroyed in Mauritius and replaced by plantations, essentially of Casuarina equisetifolia. Consequently, though the pattern is still partly evident in places, coastal vegetation zones are less fully developed than on many other tropical coasts, no doubt because the natural series is so generally truncated and disturbed at the rear by tree plantations (Sauer, J.D 1960). The natural succession has been even further destroyed in areas where development has taken place along the coast. Plant communities of coastal dunes and beaches, or strand vegetation, plays an important part in the formation and stabilisation of coastal dunes (BPA, 2004). Pioneer plants trap and hold wind-blown sand in the fore-dune and beach top and help create conditions which encourage the establishment and growth of other plant communities such as scrub and coastal forests. All plants have a role in the development of vegetative cover and together they bring about dune and beach stabilisation. Sand trapped in the fore-dune by strand vegetation serves as a reservoir of sand for the beach during periods of erosion. In the absence of dune vegetation, or with the wrong vegetation cover, erosion can take place resulting in coastline recession. The grass cover of the coastal turf zone serves a very important function as it acts as a holdfast for the unstable sand on which it grows, preventing erosion of the beach by waves, except during strong cyclones when it can be washed away by very strong waves. Thus, this

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fringe must be protected at all times, and the grasses and the creepers may not be removed to “clean” the beach for hotel residents. Similarly, the mixed scrub of Scaevola, Suriana and Tournefortia acts as a holdfast against erosion and is a very effective barrier against the wind and salt spray for the inland zones. This zone must also be protected and the vegetation may not be cut down. Scattered invasions of the old coastal vegetation by alien plants undoubtedly began as soon as people arrived on the island with the cutting down of forests and the introduction of plants from elsewhere (Sauer 1960). Plantation of the Pas Géometrique around Mauritius with Casuarina started following a Government Ordinance of 1874 that authorised leases of the Pas Géometrique land for tree planting. By 1905 virtually all the available Pas Géometrique land was under lease for Casuarina planting, replacing the original forests that no longer existed. The Inner Littoral Zone of La Cambuse consequently was also planted with Casuarina. These trees have no conservation importance. It must be noted that these trees are old, many of them storm damaged, with broken or dying branches. The remainder of the site, which makes up the Inland Vegetation zone, is totally invaded by alien vegetation with the exception of the rare native plants present and has no features of importance such as wetlands. The zone has no conservation value and may, thus, be used for development. Zonation conditions were imposed on the lease by Government authorities as follows:

The sea frontage of 400m with a setback of 100m from the high water mark is restricted as a no-development area.

The surplus of the site beyond that line does not fall under this restriction and is targeted for the hotel development.

The construction and development limitations imposed on this zone offer an important conservation opportunity to recreate the unique coastal vegetation and ecosystem once present in the area and of which only the outpost species present remain. This would enhance the value and prestige of the hotel and also serve the aesthetic and recreational objectives a hotel resort must offer. However, the NCG buildings to the West are well inside the 100m buffer zone and the site has very little vegetation except the row of outpost vegetation. In addition to this, the waste and sewage water of the station is treated in septic tanks, the leachates pouring directly into the sea next to the public beach. It is the only portion of the site that can be considered as being a polluting risk to the environment generally and to the Marine Park in particular. The restoration, which will include the outpost zone, will also help to protect the beach and dune structure from damages due to trampling, climate change and will be beneficial for the carbon sequestration as a result of the number of new trees that will have to be planted.

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The greatest impact is, however, likely to take place during the operational phase of the hotel. Sources of impact during the operational phases, e.g. trampling and littering, will have to be examined and appropriate mitigation measures provided. For example, the careful routing of paths to avoid uncontrolled access and the consequent trampling is recommended. 7. Recommendations 1. The site is situated on the edge of the Blue Bay Marine Park, an important environmental

asset of biological significance for the project. This zone is protected by law and hotel

activities will have to conform to these.

2. The lagoon and sand dune are proclaimed Environmentally Sensitive Areas and must be

protected from negative impacts during the construction and operation of the resort and

hotel.

3. The 100m no construction buffer zone must be respected.

4. The portion of the site occupied by the NCG is totally modified and degraded in terms of sand

dune topography, structural geology, and in terms of the ecosystem. Additionally the station is a

pollution risk because of the septic tank system. Thus the removal of the NCG station is highly

desirable and recommended.

5. The trees within the Pas Géometrique fall within the authority of the Forestry Service of

the Ministry of Agro-Industry & Food Security and are protected under the Forests and

Reserves Act 1983. Authorisation will have to be obtained before any trees in this zone

are cut.

6. The remainder of the site is highly degraded and overgrown with alien and invasive

vegetation. It has no conservation value and may thus be developed for hotel purposes.

7. It is recommended that, in view of the proximity to the sea and to saline spray, and to

harmonise the site with the marine park environment, emphasis be placed on the use of

appropriate native vegetation for the general landscaping of the resort and hotel.

8. No landscaping should be done with alien plants that are known to be invasive or could

potentially be invasive.

9. Every effort should be made to use native vegetation throughout the project. Native

plants have evolved and adapted to their particular environment, and are very resistant

to local climatic conditions including cyclones and droughts. In addition, their

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attractiveness and uniqueness value must be considered as an asset, and contrarily to

common belief, endemic plants, if planted correctly, are quite fast growing. Their use in

landscaping offers many additional and important benefits such as decrease of

maintenance costs, reduction of storm water runoff, beautification of the landscape and

preservation of endangered species, thereby adding a uniqueness quality to the project

as a whole. Thus every effort should be made to harmonise the hotel and resort

landscape with that of the natural environment and the restored sand dune.

10. Natural Landscaping, a process which tries to capture the character and spirit of nature

in a designed landscape situation by arranging plants in a community context similar to

their arrangement in nature, should be encouraged.

11. The ecological restoration of the sand dune ecosystem is strongly recommended. The

sand dune ecosystem has been highly modified by man, the original native forest long

gone.

The construction and development limitations imposed on this zone and the necessary cleaning up of the Casuarinas offer an important conservation opportunity to recreate and restore the unique coastal vegetation and ecosystem once present in the area and of which only the outpost species remain.

The sand dune and coastal ecosystem restoration will not only enhance the value and

prestige of the hotel and serve the aesthetic and recreational objectives a hotel resort. It

will also restore the important ecosystem service, adding a buffer to the potential

impacts of climate change and sea level rise.

12. An Ecological and Environmentally sustainable strategy should be adopted for the long

term preservation, enhancement and best use policy of these precious and unique

assets. This will have to be encapsulated in an Environmental Master Plan.

13. The following is a partial list of endemic and native coastal plant species that could be

advantageously used in the landscaping both for their resistance to environmental

conditions and their attractiveness:

Trees: Bois d’Olive (Cassine orientalis), Bois de Bœuf (Gastonia mauritiana), Bois d’ébène (2 species Diospyros egrettarum and D. melanida), Bois de Juda (Cossinia pinnata), Vacoas ( 2 species Pandanus utilis and P. vadermeerschii in particular).

Small trees and bushes : Bois de reinette (Dodonea viscosa), Bois de ronde

(Erythroxylon sideroxyloides), Bois mozambique (Ludia mauritiana), Bois de sagaïe blanc (Molinaea laevis), Bois de sagaïe rouge (Doratoxylon apetalum), Bois patte de poule (Vepris lanceolata), Bois quivi (Turrea thoursiana), Bois Cabris (Clerodendron heterophylum), Bois Clous (2 species Eugenia lucida, Eugenia sieberi), Bois bouquet banané (Ochna mauritiana), Bois de chandelle (2 species

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Dracaena concinna and D. reflexa), Hibiscus genevii, and Baume de l’île Plate (Psiadia arguta).

9. References BOSSER, J. et al. Flore des Mascareignes. Royal Botanic Gardens, Kew, United Kingdom; ORSTOM, Paris, France; MSIRI, Réduit, Mauritius. Chan, H.T. & S. Baba, 2009. Manual on guidelines for rehabilitation of coastal forests damaged by natural hazards in the asia-pacific region. International Society for Mangrove Ecosystems (ISME) and International Tropical Timber Organization (ITTO). Cochard, R. 2008. The 2004 tsunami in Aceh and Southern Thailand: a review on coastal ecosystems, wave hazards and vulnerability. Perspectives in Plant Ecology, Evolution and Systematics 10(1): 3–40. Faure, G. & Montaggioni, L.. 1971. Les Récifs coralliens Sous-le – Vent de l’Ile Maurice (Archipel des Mascareignes, Océan Indien): morphologie et bionomie de la pente externe. C.r. hebd. Séanc. Acad. Sci. Paris (D) 273:1914-1916. Forest and Reserves Act 41 of 1983, Government of Mauritius Holmes, A. 1965. Principles of Physical Geology. Thomas Nelson & Sons, London. Pp 1288. Kueffer, C and J. Mauremootoo (2004) Case Studies on the Status of Invasive Woody Plant Species in the Western Indian Ocean 3. Mauritius(Islands of Mauritius and Rodrigues). Forest Health & Biosecurity Working Papers, FAO, Rome. Mc Dougall, I. & Chamalaun, F.G 1969. Isotopic Dating and Geomagnetic Polarity Studies on Volcanic Rocks from Mauritius, Indian Ocean. Geol. Soc. Am. Bull. Vol. 80. Pp1419-1442. McIntire, W.G. 1961. Mauritius: river-mouth terraces and present eustatic sea-stand. Z. Geomorph. (N.F.) Suppl. 3: 39-47. McIntire, W.G. & Walker, H.J. 1964. Tropical Cyclones and Coastal Morphology of Mauritius. Annals Assoc. Amer. Geogr. Vol. 54, No. 4, pp582-596. Montaggioni, L. 1972. Essai de chronologie relative des stationnements marins quaternaires à l’île Maurice (Archipel des Mascareignes, Océan Indien). Cr. Hebd. Séanc. Acad. Sci. Paris (D) 274: 2936-2939. Montaggioni, L. 1974. Coral reefs and the Quaternary shore-lines in the Mascarenes Archipelago (Indian Ocean). Procs. Sec. Intern. Coral Reef Symp. 2. Great Barrier Reef Committee, Brisbane.

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Montaggioni, L. 1976. Histoire géologique des récifs coralliens del’Archipel des Mascareignes. Travaux et Documents de l’O.R.S.T.O.M. Montaggioni, L. & Faure, G. 1997. Response of reef coral communities to sea-level rise: a Holocene model from Mauritius (Western Indian Ocean). Sedimentology 44: 1053 -1070. Ratcliffe, D. A. (ed.) (1977). A Nature Conservation Review. Cambridge University Press, Cambridge. ROUILLARD, G. and GUEHO, J. (2002). Les plantes et leur histoire à l’Ile Maurice. MSM, Maurice. Russell, R.J. & McIntire, W.G. 1965. Southern Hemisphere Dune Rock. Geog. Rev. Vol. 55, No. 1, pp17-45. Sauer, J.D. 1960. Coastal Plant Geography of Mauritius. Technical Report No 15, Part A. Coastal Studies Institute, Louisana State University, Baton Rouge, LA. Contribution No 61-3 Williams, J.R. 2007 Butterflies of Mauritius, Revised Edition, Bioculture Press, Mauritius

Appendix G - Ecological Impact Report - La Cambuse Hotel

Environment

Transcript of Appendix G - Ecological Impact Report - La Cambuse Hotel