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Emily Iles

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Body Condition Analysis, Abundance and Diversity of Freshwater Fish Species in Pacaya

Samiria Peru 2009

Emily Iles

BSc Wildlife Conservation

Durrell Institute of Conservation and Ecology (DICE)

University of Kent at Canterbury

This dissertation is submitted as partial fulfilment for the

Bachelor of Science with Honours Degree in

Biodiversity Conservation and Management, at the University of Kent at Canterbury

2009 – 2010

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Acknowledgements

I would like to thank DICE and WCS for providing me with the extraordinary opportunity

to join a research expedition to the Amazon. During my time I learnt skills and

knowledge, which I will carry with me for the future. I would like to express my gratitude

to Dr Mike Walkey and to Dr Peter Bennett, for their knowledge, kindness and valuable

support during my project not just in the UK but also in Peru. I would also like to thank

my enthusiastic Peruvian friend Antonio, who carried out his own research during my

time in Peru, he was extremely good company and helped immensely with identification

and learning Spanish! Special thanks go to Sergio, our field guide, without his incredible

skills in fishing and his knowledge of fishing sites; data collection would have been much

harder. I would also like to thank Rebecca Russell who I shared the fish project with me

and was an excellent partner for data collection and identification; we became good

friends throughout the project and will share memories of Pacaya Samiria forever. I

would like to express my perpetual gratitude to my parents for emotional and financial

support throughout my studies at Kent University, without them I would not have been

able to go to Peru. Last but not least I would like to thank my boyfriend Tom Kingham

who was a great help with excel, I have learnt a lot from him.

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Contents Page

1. ABSTRACT................................................................................................................ 6

2. INTRODUCTION ....................................................................................................... 7

2.1. Amazon Aquatic Ecosystem ............................................................................. 7

2.2. The Flood Pulse ................................................................................................ 7

2.3. Current Threats to Fish Communities in the Amazon ....................................... 8

2.4. Species of this Study......................................................................................... 9

2.4.1. Species Biology and Ecology .................................................................... 9

2.5. Fish Growth..................................................................................................... 11

2.6. Pacaya Samiria National Nature Reserve....................................................... 12

2.6.1. Pacaya Samiria Conservation. ................................................................ 12

2.7. Fishing Sites.................................................................................................... 14

2.8. Rapid Habitat Assessment.............................................................................. 15

3. AIMS AND OBJECTIVES ........................................................................................ 18

4. METHODOLOGY..................................................................................................... 20

4.1. Fishing............................................................................................................. 20

4.2. Identification Weight and Length..................................................................... 20

4.3. Water Chemistry Analysis ............................................................................... 21

4.4. Data Analysis .................................................................................................. 22

5. RESULTS ................................................................................................................ 24

5.1. Weight-Length Relationships and Differences Between Sites. ....................... 24

5.2. Analysis of variance (ANOVA) ........................................................................ 30

5.2.1. Erithrinidae .............................................................................................. 30

5.2.2. Loricariidae.............................................................................................. 31

5.2.3. Cichlidae.................................................................................................. 32

5.3. Shannon Weiner Diversity Index..................................................................... 33

6. DISCUSSION........................................................................................................... 35

6.1. Methodology.................................................................................................... 35

6.2. Statistical models ............................................................................................ 37

6.3. Weight and length relationships ...................................................................... 39

6.3.1. ErythrinidaeWeight-Length Relationships ............................................... 40

6.3.2. LoricariidaeWeight-Length Relationships................................................ 40

6.3.3. CichlidaeWeight-Length Relationships.................................................... 41

6.4. Shannon Weiner Index.................................................................................... 42

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6.5. Trophic Cascades. .......................................................................................... 44

7. CONCLUSION ......................................................................................................... 45

8. References:.............................................................................................................. 56

List of Figures Page

Fig 1: The relationship between fish length and weight……………………………………..11

Fig 2: Correlation between weight and length of Erythrinidae species at site 1…………..25




Fig 6: Correlation between weight and length of Erythrinidae species across all sites…..25

Fig 7: Correlation between weight and length of Loricariidae species at site 1…………...26

Fig 8: Correlation between weight and length of Loricariidae species at site 2…………...26

Fig 9: Correlation between weight and length of Loricariidae species at site 3……………27

Fig 10:Correlation between weight and length of Loricariidae species at site 4………….27

Fig 11:Correlation between weight and length of Loricariidae species across all sites….27

Fig 12:Correlation between weight and length of Cichlidae species at site 1…………….28

Fig 13: Correlation between weight and length of Cichlidae species at site 2…………….28



Fig 16: Correlation between weight and length of Cichlidae species across all sites…….28

Fig 17: Graph showing ANOVA results for Erythrinidae species……………………………30

Fig 18: Graph showing ANOVA results for Loricariidae species…………………………….31

Fig 19: Graph showing ANOVA results for Cichlidae species……………………………….32

Fig 20: Graph showing Shannon Weiner Diversity Index results……………………………33

Fig 21: General Abundance results across all sites…………………………………………..33

Fig 22: Graph showing Family Diversity and Abundance at site 1………………………….34




List of Tables Page

Table 1: Scoring system used in the rapid habitat assessment……………………………..15

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Table 2: Site 1 habitat assessment……………………………………………………………..16




Table 6: Correlation results of Erythrinidae species across sites…………………………...24

Table 7: Standard error from regression for Erythrinidae…………………………………….24

Table 8:Correlation results of Loricariidae species across sites……………………………26

Table 9: Standard error from regression for Loricariidae…………………………………….26

Table 10: Correlation results of Cichlidae species across sites……………………………..27

Table 11: Standard error from regression for Cichlidae……………………………………...27

Table 12: ANOVA results table for Erythrinidae………………………………………………30

Table 13:ANOVA results table for Loricariidae……………………….………………………31

Table 14:ANOVA results table for Cichlidae………………………….………………………32

List of Plates Page

Plate 1: Arial view of meandering river and oxbow lake filled with water lettuce……………8

Plate 2: Erythrinidae (Hopleryhtrinus unitaeniatus)…………………………………………...11

Plate 3: Loricariidae (Pterygoplichthys pardalis)……………………………………………...11

Plate 4: Cichlidae (Aequidens tetramerus)………..…………………………………………...11

Plate 5:Map of study area Including Rio Samiria…………………………………………….13

Plate 6:Google Eath view of the study sites.………………………………………………...15

Plate 7: PV3 hut. Shows the colour and the height of the water…………………………….16

Plate 8: The red line shows the position of the caudal peduncle……………………………21

Plate 9: Balancing scales used in this study.…………………………………………………21

Appendices Page

Appendix 1: Identification and classification guide…….……………………………………..45

Appendix 2: List of taxonomy ……………………………………………………...…………..49

Appendix 3: Raw Data……………………………………………………...…………………...51

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1. ABSTRACT

Fish are an extremely important resource for people living in the Amazon Basin for

sustenance and livelihood. It is vital to manage this valuable resource for its intrinsic

value to natural systems but also its extrinsic value to humans. This study is part of an

ongoing monitoring scheme to safeguard the fish species in Pacaya Samiria. Fish were

caught in different sites in the National Reserve, species were identified and weights and

lengths were measured. The relationship between weight and length were examined to

give each individual a body condition value that can be compared across sites. Changes

in the condition value can potentially indicate good versus poor feeding and whether

species are growing at expected rates. This is related to the condition of the ecosystem,

which at the time of this study was experiencing very high waters. The first step of the

analysis was to group species into families to increase data size.The relationship

between weight and length were analysed using a correlation analysis followed by an

ANOVA to calculate body condition. Weight-length correlates are significant for all

species within the families of Erythrinidae, Loricariidae and Cichlidae. ANOVA

calculations show that there is a significant difference in body condition between sites,

suggesting fish were in and out of optimum habitats during the study.

The diversity and abundance of fish species was also measured using the Shannon

Weiner Diversity Index.Calculations showed abundance is greater in deeper water

habitats along the channel and diversity was greater in shallower and dense canopied

areas. Interesting results from this analysis showed that the diversity and abundance is

potentially governed by the piscivorous fish especially those belonging to Serrisalmidae

and Erythrinidae. Where these species out-compete one another for smaller species,

they also directly predate on the smaller species. Arapama gigas (Paiche) is a natural

predator of Erythrinidae and Serrisalmidae species; huge demand for this species has

seen dramatic decreases in populations potentially affecting trophic levels resulting in an

increase in secondary predators. This highlights the need for ongoing monitoring

schemes and further research, as many species such as the Paiche are still data

deficient (IUCN red list) and lack protection.

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2. INTRODUCTION

2.1. Amazon Aquatic Ecosystem

The Amazon is the world’s largest freshwater ecosystem, water is moved from the

Pacific to the Atlantic (Goulding et al. 1996, Araujo-Lima et al. 1997),discharging

175,000 cubic meters of freshwater into the Atlantic Ocean per second (Oltman 1967,

cited in Browne 2008). The main characteristic of the Amazon is the heterogeneity of

habitats; the main tributaries contain densely forested floodplains, known as varzea

habitat (Welcomme R.L, 1985). Thesehabitats harbor some of the highest species

diversity of fish, mammalian and floral species on earth (Pitman et al. 2003). The sheer

heterogeneity of habitats is a result of seasonal flooding, creating varying degrees of

connectivity between the ecologically distinct biotypes that comprise a floodplain, such

as oxbow lakes and smaller channels (Junk, W.1989).

Plate 1: Aerial view of the meandering river and oxbow lakes filled with water lettuce

2.2. The Flood Pulse

Seasonal inundations occur annually along the immense floodplains and are produced

by precipitation from the Pacific Ocean being pushed over the Andes by strong uplifting

winds.This causes heavy rainfall on the eastern Andes and runoff into the Amazon

basin. The result is large scale flooding along the major rivers (Bodmer R, et al 2008)

known as the high water season or a flood pulse. Junk, W.1989 was the first to coin the

term ‘flood pulse’, he described this event as the principal driving force responsible for

the existence, productivity and interactions of the major biota in river-floodplain systems.

The water levels fluctuate seasonally with rainfallfor example,in Iquitos, Perú there can

be a seven metre fluctuation(Barthem & Goulding 1997).In contrast to the high water

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periods, the winter months of June to September see a decrease in precipitation off the

Pacific Ocean and the rains in the eastern Andes are greatly reduced. This results in the

drying up of the western Amazonian rivers and the low water season (Bodmer R, et al

2008) wherefallen fruit and manure re-fertilize the ground. The Wildlife of the Amazon

therefore occupies an ecosystem that is characterised by large seasonal fluctuations.

Fish populations are also found to fluctuate greatly over the year (Saint-Paul et al. 2000).

The objective of this study is to gain an insight into thebody condition, abundance and

diversity of species in a snapshot of time during a flood pulse event that was occurring

during the study (See 3.1 Aims and Objectives) from May – June 2009.

2.3. Current Threats to Fish Communities in the Amazon

A rising demand for fish and natural resources by a quicklygrowing human population

begins to negatively affect the structures and functions of the ecosystem (Junk, W.

2000).The last 50 years, rivers and floodplains have undergone more environmental

change than ever before in human history (Goulding et al. 1996).Oil and gas

exploration and development in the western Amazon may increase rapidly, the direct

impacts include deforestation (for access roads), drilling platforms, and pipelines,

and contamination from oil spills and wastewater discharges (Finer, M. 2008).

Agricultural activities and more intense production will be needed to support a growing

population. However, anexpansion of cattle ranching would lead to heavydegradation of

the várzea vegetation and the subsequent loss of biodiversity (Junk, W. 2000).

Amazonian communities depend on large proportions of fish in their diets for protein

(Goulding et al. 1996, Araujo-Lima et al. 1997).When the waters recede during the dry

months, fish populations become condensed in the reduced lakes, rivers and channels

(Bodmer R, et al 2008) making them an easy target. This is well known by local

fishermen who exploit target fish stocks when these are congregated during low water

periods and more easily captured (Goulding et al. 1996) it is therefore important that fish

display r-selected life-history traits, for example a high fecundity and early maturity to

recuperate numbers during high water periods. Among the threats mentioned is the

appeared lack of data and research on Amazonian fish species; the main problem being

that this leads to a lack of control and overharvesting can occur. For example thePaiche

(Arapaima gigas),is native to areas of Peru, some say it is the largest freshwater fish in

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the world (Coomesa, O.T. 2004)but international trade and overfishing has reduced both

population size and occurrence (fishbase.org). However it is data deficient on the

International Union for the Conservation of Nature’s (IUCN) red list (list of threatened

species) (iucn.org). This highlights the need for Protected Areas, research and

monitoringof these cryptic species, in order to prevent losses in the future.

2.4. Species of this Study

The Amazon basin contains the most diverse fish fauna in the world (Val & Almeida-Val,

1995). However, only about 1,700 species have been described in the entire river

system, meaning that fish are thepoorest known group of vertebrates in the Amazon

Basin (Goulding et al. 1996). This increases the need for research projects. In 2008 a

similar study in the Samiria River caught 56 species belonging to 14 families in a lower

water period (Bodmer R, et al 2008). Fish that were caught and identified during this

project are listed in (Appendix 2). Further information on ecology can be found in

(Appendix 1).

2.4.1. Species Biology and Ecology

In flood rivers the feeding cycle is linked to the food supply and population density

(Welcomme R.L, 1985) competition and niche breadth change, as resources become

dispersed in high water. During the flooded periods fish can enter the flooded forests

and feed on the abundance of vegetative and animal production, especially the

abundance of fruits, invertebrates and other living organisms (Bodmer R, et al 2008). At

low water, when the aquatic environment is contracted fish are concentrated in a few

permanent reserves of water (oxbow lakes) and food sources are limited or

exhausted(Welcomme R.L, 1985). In order to maximize survival most species have

adapted their feeding behaviour according to the changing ecosystem.

Fish of the genus Prochilodus are widespread mud-eaters (Allochthonous) (Welcomme

R.L, 1985) and show great flexibility in the type of food consumed (Welcomme R.L,

1985). Goulding, 1980indicates that some Amazonian species of the family Characidae

specialise in fruit or seed eating during high water to the extent that over 87% of the total

food consumed in the wet season was fruit or seeds (Welcomme R.L, 1985).Carnivorous

fish are often described as the most important group which subdivide into, meso-

predators that feed mostly on insects and crustacea, and macro-predators such as

piranha (Serrasalmus natterer)ifrom the familySerrasalmidae,that feed mostly on other

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fish (piscivorous) or larger invertebrates such as decapods, crustaceans or insect larvae

(Welcomme R.L, 1985).

Plate 2: Erythrinidae Plate 3: Loricariidae Plate 4: Cichlidae

Hopleryhtrinus unitaeniatusPterygoplichthys pardalisAequidens tetramerus

Fish from the families Erythrinidae, Loricariidae and Ciclidae were chosen for this study

as they occurred across all sites and were all ecologically distinct with different feeding

behaviours. The Erythrinidae family is a small family of piscivorous fish, widely spread in

fresh water ecosystems in South America. This family is divided into three genera

Hoplias, Hoplerythrinus and Erythrinus containing a small number of species per genera.

Hoplerythrinus unitaeniatus is equipped with a modified part of the swim bladder that

allows aerial respiration.

The flooding regime seems to favor piscivores, as floods are associated with the

reproductive success of many of their prey species, meaning prey are readily available

and less energy expenditure is needed. However, due to the diluting effect of floods,

prey species become widely dispersed, so it is important for piscivores to locate their

optimum feeding niche. In addition, increased shelter from debris in the water may also

reduce prey availability, somicrohabitat could greatly affect the efficiency of hunting for

these species (Luz-Agostinho K.D.G. et al 2008).

Members of the Loricariidae family are bottom dwelling catfish, characterised by their

armoured bodies covered by large bony plates, and a ventral mouth. The mouth enables

adherence to a variety of substrates, specialized rasping teeth allow them to feed on

submerged substrates, such as algae, detritus and even wood (Adriaens, D. et al 2007).

This family has an extraordinary ability to adapt to a range of habitats and feeding

behaviours, explained by the diversity of species. They have evolved several

modifications in the digestive tract, which appear to function as respiratory organs in

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order for the fish to be able to cope with hypoxic events, associated with high water

periods (Armbruster JW 1998). Detritus feeders rely on coarser decomposing plant

material. These comprise a high proportion of species particularly in headwater streams

and forested habitats; where leaf-fall accumulates in pools or close to floating vegetation

where litter is also abundant.A recently recorded symbiotic relationship between

Loricariidae species and the manatee mentioned that these fish graze the epibiota on

the manatee’s skin. There has been no evidence to suggest if this is beneficial to the

manatee, however the paper byLoftus,W F. et al (2009)suggested that some manatees

appeared distressed and tried to dislodge the fish, which could effect these species in

the future if they are not monitored effectively.

The Cichlidae family is an abundant species the Amazon. Insect communities develop

on plants during the flooding season, which is an important food source for many

species within this family(Resende E.K. 1989) Cichlasoma amazonarum a species from

the family Cichlidae it is omnivorous and numbers fluctuate during the high water period

(Kullander 1983). Many neo-tropical fish have distinct annual breeding seasons that are

synchronized with the seasonal floods thatbring in nutrients and food that promote

juvenile growth.

2.5. Fish Growth

It has been found that a cubed relationship exists between weight and length of

fish.Using modelsto show the relationship between weight and length can be used to

monitor species and to make predictions of normal growth, it may also show

abnormalities. This type of data has also been used in fisheries to make predictions on

the maximum sustainable yield, which is important for economically viable species, so

overharvesting does not occur(Lanelli, J. et al 1997).

Fig 1: The relationship between fish length and weight:

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STUDY AREA

Plate 5: Includes Rio Samiria and other channels lakes of the study area.

2.6. Pacaya Samiria National Nature Reserve

The Pacaya-Samiria National Reserve is located between the Ucayali and Maranon

Rivers in the lowland Peruvian Amazon. The reserve extends over 2,150,770 hectares in

the area of Loreto and is the largest protected area in Peru. The reserve is dominated by

flooded forest known in Amazonia as varzea (Bodmer, R. et al 2008). The Pacaya and

the Samiria river basin are two major drainage systems. The reserve contains diverse

habitats including a rich mosaic of active flood plains, oxbow lakes, meander scrolls,

black swamps, small rivers, and channels that provide habitat for a diverse flora and

fauna. Amazonian waters can be classified in terms of their water quality. Three different

types can be distinguished: sediment-rich white-water, sediment-poor clear-water, and

black-water, darkened by tannins (Saint-Paul et al. 2000, Goulding et al. 1996).The

Samiria River is characterised by a blackish colour during high water, created by white

water from the Maranon entering the flooded forests and picking up tannins from the

leaf-litter (Bodmer R, et al 2008).

2.6.1. Pacaya Samiria Conservation.

The Pacaya-Samiria National Reserve has gone through a major shift in its management

policies over the past two decades, from an area of strict protection where local people

were excluded from the reserve to an area where the local indigenous people participate

with the reserve management. Many of the local people changed their attitude towards

the reserve and began to see the long-term benefits for their future (Bodmer R, et al

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2008). There are many different organisations involved within the reserve. However, the

success of the management groups and of the reserve overall will only be determined if

the diversity and abundance of wildlife is adequately monitored. The results of the

monitoring can then be used to determine if the threats to the reserve are being tackled

and conservation outcomes are being realised.

Samiria contains many fruiting tree species including Sacha maga (Grias peruviana) a

species extremely abundant along the lower Ucayali River forming dense groves in

flooded forests; Ungurahui (Jessinia bataua),a widespread species that is used to make

nutritious beverages, Camu Camu (Myrciaria dubia)this small shrub is a common

component of the seasonally flooded riparian vegetation found along the banks of rivers

and oxbow lakes. This species is particularly dense along the Ucayali and Maranon

rivers. It contains one of the highest concentrations of vitamin C in the plant kingdom

and has recently been used worldwide in vitamin replacement products. There is a

considerable local demand for this species for juices, ice creams and liqueurs.Finally the

Aguaje (Mauritia flexuosa)a widely distributed species, dense aggregations of this

species has been recorded along the Ucayali and Maranon rivers(Anderson, A.B et

al1989) and is traded in Iquitos. Market demand for such fruit species needs careful

monitoring as overharvesting could potentially result in the loss of important resource for

species and local people.

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2.7. Fishing Sites

Plate 6:Google Earth view of the study area, containing all sites higlighted with red circles. Note that the large oxbow lake, normally disconnected was connected up to the main channel due to flooding. All sites were measuered using GPS from PV3.

Four fishing sites were selected along the main channel and the oxbow lake; these were

selected for differing habitat type, for examplecanopy coverage or water depth. The sites

had to be selected on slow moving water as fast water often tangles nets; hence no sites

could be selected downstream past PV3.

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2.8. Rapid Habitat Assessment

Plate 7: View from PV3, showing (Pistia stratiotes) or water lettuce flowing out of the oxbow lake as it joined up to the main channel.

Physical habitat assessment is a useful tool to predict habitat quality or preference to a

certain species or family. The scoring system gives a rough impression of the habitat

availability and suitability for fish species and is somewhat subjective. To achieve a more

thorough analysis, additional factors could be combined for example; water chemistry

analysis and macro-invertebrate assemblage, as well as in depth ecology analysis of

each species caught.

Four sites were surveyed for a range of habitat characteristics including:

• Large woody debris (used for refugia and feeding)

• Bank presence (indicating shallower water)

• Lack of noise disturbance (that would deter fish from that site)

• Available fruit (for feeding)

• Canopy coverage (for shelter and insect habitat)

• Flow of water suitable for fishing (slow moving water was needed)

Field sites were ranked; poor (1-3) fair (4-5) good (6-7) excellent (8-10).

Table 1: Table showing the scoring system used to determine habitat availability and quality.

Score Rating

8 –10

6 – 7

4 – 5

1 – 3

Excellent

Good

Fair

Poor

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Table 2: Site 1

Site 1: (GPS Coordinates = 0558491/9439852). This site is situated 6300 metres approx

from the research vessel docked outside PV3. The site 1 is situated on the large flooded

oxbow lake located down-stream; nets were set 10 meters (approx) into the flooded

forest from the main stream. This site contained woody debris and some fruiting trees

such as Ungurahui (Jessinia bataua) with 90% canopy coverage. This site was located

where terrestrial habitat was available, occasional disturbance from other students

working on land and being collected by boats occurred. Our guide told us that the flow of

water was fast on some days that made fishing difficult.

Table 3: Site 2

Site 2: (GPS coordinates = 0551060 / 9440296). This site is 2500 metres approx from

the research vessel. Site 2 is located up stream over an old flooded transect that had

been well used by biologists studing terrestrial forest species, the water here was still but

very deep. This site contains many fruiting tree species including Sacha Manga (Grias

peruviana), Ungurahui (Jessinia bataua), Camu Camu (Myrciaria dubia) and the Aguaje

(Mauritia flexuosa) with 60% canopy coverage and some woody debris available. This

Site 1 Rating Score

large woody debris availability Excellent 8

bank presence Excellent 9

No noise disturbance Poor 3

fruiting trees available Fair 5

canopy cover Excellent 9

flow of water suitable for fishing Fair 4

Site 2 Rating Score

large woody debris availability Fair 5

bank presence Fair 4

No noise disturbance Good 6

fruiting trees available Excellent 9

Available canopy cover Fair 5

flow of water suitable for fishing Excellent 8

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site was near an access point toanother terrestrial study area so occasional boats

passed but were further away from our nets than site 1.

Table 4: Site 3

Site 3:(GPS coordinates = 0554075/9441328). Site 3 is located over the flooded oxbow

lake and was 1500 meters approx, the closest site to the research vessel and other

passing boats. The site is situated 10 meters in from the main river and is made up of

dense flooded forest, 90-100% canopy coverage was recorded with an abundance of

woody debris. It contains no fruiting tree species but an abundance of “guamo” a species

of water lettuce (Pistia stratiotes), making the water below turbid due to the lack of light.

Water was fairly fast flowing at times as it joined the main channel up stream.

Table 5: Site 4

Site 4:(GPS coordinates = 0554415/9441340). Site 4 is located over the flooded oxbow

lake 2000 meters away from the research vessel. The canopy coverage was 80 – 90%.

This site contained an abundance of water lettuce (Pistia stratiotes)again making the

water extremely turbid. There were very few fruiting trees available at this site and an

abundance of debris in the water.

Site 3 Rating Score

large woody debris availability Good 6

bank presence Poor 1

noise disturbance Poor 3

fruiting trees available Poor 3


flow of water suitable for fishing Fair 4

Site 4 Rating Score

large woody debris availability Excellent 9

bank presence Poor 2

No noise disturbance Good 6

fruiting trees available Poor 1


flow of water suitable for fishing Good 6

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3. AIMS AND OBJECTIVES

The first objective of this study is to determinethe body condition of three families of fish

(Erythrinidae, Loricariidae and Cichlidae) in different habitat sites along the Samiria

River. Species were grouped into families to increase sample sizes; the three families

are directly comparable because they occupy different feeding niches and prefer

different environments.Measuring body condition can indicate whether populations or

subgroups are growing and feeding at expected rates.A change in body condition

indicates periods of good versus poor feeding, success or disease (Collette,B.B et al

1997).Flood pulses affect floodplain enrichment andpositively affect the body condition

of aquatic organisms (Luz-Agostinho 2009). This study coincided with a flooding event,

the subsequent high watersmeant fish caught during this time represented a body

condition according to this event. This might not be a full-time representation all year

round.In order to carry out the objective, this study will use a correlation analysis that will

show the relationship between weight and length, then to calculate the standard error of

the regression to make predictions of growth and size. The second analysis uses a

simplified condition factor; where Lis length and W is weightthis can be used to calculate

the condition factor BC (BC = L/W). It can be used to estimate body condition and can

be compared to correlation to give a more rounded comparison. The subsequent

Analysis of Variance (ANOVA) was conducted to compare means between the sites to

determine whether habitat suitability affects tropic level associations and the body

condition of individuals. The second objective is to determine general species

abundance and diversity of all fish caught.Shannon Weiner Index will measure the

species abundance and diversity.Abundance and diversity measures can tell you the

health of the habitat, for example high species diversity is considered more valuable

than high species abundance. The analysis can also show if the habitat favours a

particular species or trophic level, for example insectivores and suggest if trophic

cascades or niche overlap occur.

There is a pressing need for additional research of neotropical fish and their relationship

to their environment, especially those with commercial value (Armbruster, J.W. 2005) as

the resource that many take for granted may face extinction. This investigation will

contribute to the ongoing monitoring scheme to safeguard fish species in Pacaya

Samiria.Analysis is completedusing the following hypotheses:

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Weight – length relationships:

H0: There is no correlation between overall weight and length of Erythrinidae.

There is no correlation between overall weight and length of Loricariidae.

There is no correlation between overall weight and length of Cichlidae

Body condition analysis

H0: There is no significant difference in Erythrinidae body condition between sites

There is no significant difference in Loricariidae body condition between sites

There is no significant difference in Cichlidae body condition between sites

H1: There is a significant difference in Erythrinidae body condition between sites

H1: There is a significant difference in Loricariidae body condition between sites

H1: There is a significant difference in Cichlidae body condition between sites

Abundance and Diversity analysis

H0: There is no significant difference in abundance and diversity between sites

H1: There is a significant difference in abundance and diversity between sites

H1: There is a statistically significant correlation between overall weight and length of Erythrinidae.

There is a statistically significant correlation between overall weight and length of Loricariidae.

There is a statistically significant correlation between overall weight and length of Ciclidae.

Emily Iles

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4. METHODOLOGY

The fish fauna was sampled through 17 sessions, data collection started on 29th May

2009, and ended on 15th June 2009.During the study period,water levels were unusually

high. Fishing site selection was decided upon on the first day, where their differing

habitat types selected sites.

4.1. Fishing

Three green gill-nets (30 m long, 2 ½ m deep, 9 cm stretch mesh) were placed a metre

from each other approx. Nets were set in the same place in each site every visit and

anchored to nearby vegetation to prevent tangling. On instruction nets were set before

9am every morning as this was the most productive time. All three nets were made of

the same material and had the same technique, with floats positioned along the upper

edge of the nets, no weights were used along the bottom edge. As Piranhas will attack

and consume fish if they are held captive in nets(Welcomme R.L, 1985), nets were left

for a two-hour period as we were told this was the optimum time to leave nets so fish in

the nets would not fall victim to Piranhas and other piscivores.

4.2. Identification Weight and Length

Plate 8: The red line shows the position of Plate 9: Balancing scales the caudal peduncle. used in this study

Fish caught in the nets were returned to the boat. Individuals were identified to a species

level if possible, identification guides were provided, any species that proved difficult to

Emily Iles

21

identify by this method were taken back to the study boat for further analysis. Fish length

was measured in centimetres from the tip of the mouth to the caudal peduncle (Plate 4),

by placing the individual on a wooden board with a ruler attached. Where fish had been

partially consumed by predators, they were discounted to reduce bias but this was rare.

The weight of all individuals was determined to the nearest 10 grams, using a set of

standard balancing scales to 1kg. Data were recorded on a datasheet together with the

individuals’ weight and length, the date, exact location, weather, and number of the net

an individual was caught in. Fish were either returned if they were gravid, juvenile or

freshly caught, most individuals had been in the nets too long and were used as food for

the guides.

4.3. Water Chemistry Analysis

Water chemistry measurements were taken next to each site. Dissolved oxygen,

temperature, conductivity, and pH, were measured using a portable dissolved oxygen

meter of the type “Eutec instruments” and a portable conductivity and pH meter of the

type “Hannah Instruments”. Depth and turbidity were measured using a 20m long rope

with meter markings and a Secchi disc. The Secchi disc measured the turbidity of the

water. Water Chemistry data was not the core of this analysis, however in ecology

terms, it may explain preference to a certain site by some of the species caught. Results

were not the main aim of this study but interesting results could help to further analyse

sites and species ecology if large variations occurred.

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4.4. Data Analysis

In order to understand the condition of the fish caught, a body condition (BC) value was

given to every individual (BC = L/W) where L is length and W this can be used to

calculate the condition factor BC,similar to a BMI in humans. Species were grouped to a

family level in order to increase sample data. Three families that occurred in relative

abundance across all sites were used; Erythrinidae, Loricariidae and Cichlidae. Intra-

specific differences within the families are low and species are extremely similar in

ecology, weight and length. However each family differs from the other in these factors,

making these families good to compare to another.

The relationships between weight and length of species in the three families over the

four sites were measured. Measurements were determined by means of regression

analysis. All linear regressions were calculated using the simple linear regression as

follows:

y = a + bx b = n Σxy – Σx Σy / n Σx² - (Σx)² a = – b

Correlation analysis of three families (Erythrinidae, Loricariidae and Cichlidae)was

conducted to measure the strength of the correlations between weight and length of all

individuals, and of individuals from each site and family separately. The product moment

correlation coefficient (PMCC) r was calculated using:

r = n Σxy – Σx Σy / √(n Σx² - (Σx)²)(n Σy² - (Σy)²)

To determine whether the strength of the correlation is significant, a table, showing the

PMCC critical values for every degree of freedom (d.f. (n-2)) at 0.05 and 0.01 levels of

significance, was used.

Analysisof variance (ANOVA) and subsequent T-test was then applied to each of the

three families to further investigate any differences in the four sites and if they were

significant, this was computed using an excel spreadsheet. The T test would determine if

differences occurred in just one of the sites or if there were multiple differences between

the sites. This analysis would give an indication of productive versus unproductive sites

for different fish families, which could be explained by further diversity and abundance

analysis and ecology information.

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23

Shannon Weiner Index was used to calculate species abundance and diversity in each

site, giving each site a value of H:

All statistics and calculations were completed using Microsoft Excel 2004.

The standard error of the y-value (weight) from the regression line was calculated using

the in-built Excel function of STEYX.

Emily Iles

24

5. RESULTS

5.1. Weight-Length Relationships and Differences Between Sites.

Overall 0.05 and 0.01 values were determined by interpolation from Cohen et al (1998)

appendix 5. The coefficient of determination r2 quantifies the proportion of variability in

one variable. Correlation results are visually understood with aid of the linear regression

lines and their equations.

Table 6: Shows Correlation between length and weight of Erythrinidae across sites.

The statistical calculations revealed that there are strong to very strong, positive

correlations between Erythrinidae weight and length. All correlations are statistically

significant, because the values obtained for r, the Product Moment Correlation

Coefficient (PMCC) indicating the strength of the correlation, were in all cases higher

than the PMCC critical values for the according degree of freedom at 0.05 and 0.01

levels of significance (Table 2). The results mean that the H1 Hypothesis can be

accepted to suggest that there is a statistically significant correlation between overall

weight and length of Erythrinidae species in Pacaya Samiria.

Site Standard error from regression 1 61.097 2 36.001 3 38.169 4 25.673 Total 42.378

Table 7: shows standard error from regression for Erythrinidae species.

Erythrinidae r r² d.f. (n -1) p<0.05 p<0.01 Significance Strength Character

Site 1 0.869 0.7566 22 0.404 0.515 Significant Strong Positive


Site 3 0.959 0.9211 23 0.396 0.505 Significant Very Strong Positive


Overall 0.9195 0.8455 111 0.186 0.243 Significant Very Strong Positive

Emily Iles

25

The standard error from regression shows the range in which the weight of the fish is

likely to fall based on the length of the fish.The larger the range, (site1) the worse the

regression and the more difficult it is to use the data to predict the condition of the fish in

that area.

Fig 2: Correlation of site 1 Fig 3: Correlation of site 2


y = 35.885x - 538.76 R² = 0.75662

0

100

200

300

400

500

600

0 5 10 15 20 25 30

Site 1

y = 36.18x - 535.95 R² = 0.80467

0

100

200

300

400

500

600

0 5 10 15 20 25 30

Site 2

y = 42.16x - 680.74 R² = 0.92114

0

100

200

300

400

500

600

0 5 10 15 20 25 30

Site 3

y = 30.774x - 422.75 R² = 0.96278

0

100

200

300

400

500

0 5 10 15 20 25 30

Site 4

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26

Fig 6: Correlation of Erythrinidae across all sites

Loricariidae r r² d.f. (n-1) p<0.05 p<0.01 Significance Strength Character


Site 2 0.6949 0.4828 5 0.754 0.874 Significant Modest Positive




Table 8: Correlation between length and of Loricariidae across sites.

Species belonging to the Loricariidae family showed a significant relationship between

weight and length. Sites 1, 3 and 4 retained very strong correlation values with the

highest being site 4 (r2= 0.9712). This did not follow on to site 2 however, displaying only

a modest correlation and there appears to be ananomolous individual. The H1

hypothesis was again accepted and the null hypothesis rejected and it is suggested that

there is a statistically significant correlation between overall weight and length of

Loricariidae species.

Site Standard error from regression 1 22.812 2 15.202 3 24.388 4 22.716 Total 21.351

Table 9: shows standard error from regression for Loricariidae species.

y = 36.836x - 554.25 R² = 0.84554

-‐100

0

100

200

300

400

500

600

0 5 10 15 20 25 30

Overall correlation

Emily Iles

27



Fig 11: Correlation of Loricariidae across all sites

y = 20.249x - 199.87 R² = 0.95069

0

100

200

300

400

0 5 10 15 20 25 30

Site 1

y = 13.54x - 99.469 R² = 0.48289

0

50

100

150

200

0 5 10 15 20

Site 2

y = 20.274x - 213.13 R² = 0.95177

0

100

200

300

400

0 10 20 30

Site 3

y = 20.584x - 204.41 R² = 0.97117

0

100

200

300

400

0 10 20 30

Site4

y = 20.283x - 201.51 R² = 0.96082

0

100

200

300

400

0 5 10 15 20 25 30

Overall Correlation

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Cichlidae r r² d.f. (n-1) p<0.05 p<0.01 Significance Strength Character






Table 10: Correlation between length and of Cichlidae across sites.

Sites Standard Error From regression 1 6.719 2 19.43 3 5.324 4 -‐ Total 13.883

Table 11: shows standard error from regression for Cichlidae species.

Values for site 4 are missing due to a small sample size; site 2 shows the largest range

in regression hence why it is shown as a strong correlation and the others very strong.

The overall correlation shown in Fig 16 show there is a statistically significant correlation

between weight and length of Cichlidae species, suggested by H1hypothesis.



y = 19.809x - 153.35 R² = 0.97704

0

50

100

150

200

0 5 10 15 20

Site 1

y = 13.836x - 84.634 R² = 0.70387

0

50

100

150

200

0 5 10 15 20

Site 2

y = 12.178x - 70.446 R² = 0.84628

0

20

40

60

80

100

9.5 10 10.5 11 11.5 12 12.5

Site 3

y = 2636x - 27648 R² = 1.8E-09

0

20

40

60

10.5 10.5 10.5 10.5 10.5

Site 4

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29

Fig 16: Correlation of Cichlidae across all sites

The Cichlidae species were found to all have a significant and positive correlation

between weight and length. However it cannot be suggested that Site 4 can be a

significant result as there was a lack of sample size forcing the correlation is extremely

close to the border at 99%.

y = 16.424x - 116.11 R² = 0.82741

0

50

100

150

200

0 5 10 15 20

Overall Correlation

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5.2. Analysis of variance (ANOVA)

Using an Fmax test the homogeneity of variance was tested on Erythrinidae, Loricariidae

and Cichlidae. All calculated F values were found to be lower than the critical values

therefore variances were homogenous.

5.2.1. Erithrinidae

A table of one tailed distribution of F was used to determine the Fcritical values of the

Ftest. The null hypothesis was rejected if the Ftest value was found to be higher than the

Fcritical value of with 5% error. The calculated value of F at 3 and 103 df is 2.70, as the

F value is 3.50 the null hypothesis was rejected. This concludes there is a significant

difference among Erythrinidae species in body condition across four sites and H1 can be

accepted.

H1 = The body condition of Erythrinidae species did significantly differ from site to site.

Source of variation SS df s2 F

P

Between 97.70 3 32.57 3.50

<5% Within 959.65 103 9.32 Total 1057.35 106

Table 12: ANOVA Table for Erythrinidae results

Fig 17: Graph showing ANOVA results for Erythrinidae species with standard error bars.

0

2

4

6

8

10

12

14

16

Bod

y co

nditi

on

Calculated body condition of Erythrinidae species

Site 1 Site 2 Site 3 Site 4

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5.2.2. Loricariidae



Fcritical value of with 5% error. The calculated value of F at 3 and 41 df is 2.70, as the F

value is 1.04 the null hypothesis was rejected. This concludes there is a significant

difference among Loricariidae species in body condition across four sites and H1 can

again be accepted with Ho being rejected.

H1 = The body condition of Loricariidae species did significantly differ from site to site.

Source of variation SS df s2 F P

Between 30.38 3 10.13 1.04

<5% Within 400.40 41 9.76

Total 430.78 44

Table 13: ANOVA Table for Loricariidae results

Fig 18: Graph showing ANOVA results for Loricariidae species with standard error bars.

0

2

4

6

8

10

12

14

Bod

y co

nditi

on

Calculated body condition for Loricariidae species


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32

5.2.3. Cichlidae



Fcritical value of with 5% error. The calculated value of F at 3 and 24 df is 3.00, as the F

value is 1.25 the null hypothesis was rejected. This concludes there is a significant

difference among Cichlidae species in body condition across four sites and H1 can be

accepted.

H1 = The body condition of Cichlidae species did significantly differ from site to site.

Source of variation SS df s2 F P

Between 10.62 3 3.54 1.25

<5% Within 68.06 24 2.84 Total 78.68 27

Table 14: ANOVA Table for Cichlidae results

Fig 19: Graph showing ANOVA results for Cichlidae species with standard error bars.

0

1

2

3

4

5

6

7

8

9

Bod

y C

ondi

tion

Body Condition of Cichlidae Across Sites

site 1 site 2 site 3 site 4

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5.3. Shannon Weiner Diversity Index.

Diversity is measured as the number of species present (Cohen, L et al 20081). The

Shannon Weiner Index uses pi as the proportion of a particular species in a sample

multiplied by the natural logarithm of itself. Summing the product for all species in the

sample derives H.

Fig 20: Shannon Weiner Diversity Index

Fig 21: Abundance of of fish caught per site

A total of 253 individuals, 8 families and 23 different species were caught during the

study. Fig 20 shows the Shannon Weiner Index results. Site 2 displayed a H value

of1.19, suggesting a low species diversity and site 4 a value of 2.43 suggesting a much

Site 1

Site 2

Site 3

Site 4

0

0.5

1

1.5

2

2.5

3

Spec

ies

Ric

hnes

s

Shannon Weiner Diversity Index

H

27% 30%

25%

17.0%

0 5

10 15 20 25 30 35

site 1 site 2 site 3 Site 4

Abundance of Fish Caught at Each Site

Percentage

H

Site 1 2.25

Site 2 1.19

Site 3 1.90

Site 4 2.43

Emily Iles

34

higher species diversity. Interestingly site 2 that had the least diversity was highest in

abundance, this suggests there was a dominant species at this site.

Fig 22: Site 1 Fig 23: Site 2

Fig 24: Site 3 Fig 25: Site 4

By comparing the family diversity with overall family abundance it is clear that

Erythrinidae was the most abundant across sites, at site 2 74% of all fish were from this

family.

23 18

8 9

0

9 1 1

0 5 10 15 20 25

Family Diversity and Abundance at Site 1 56

6 11 0 0 3 0 0

0 10 20 30 40 50 60

Family Diversity and Abundance at Site 2

24

6 6 0 2 0

21

3

0 5 10 15 20 25


9 15

2 4 0

8 2 1

0 5 10 15 20


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6. DISCUSSION

Three families of fish were extensively analysed and used as a focus for this study. The

Erythrinidae family were the piscivorous species, consisting of Hoplias malabaricus,

Hoplerythrinus unitaeniatusandErythrinus erythrinus. A total of 112 individuals were

caught predominantly Hoplerythrinus unitaeniatus and were by far the most abundant of

all familiesrecorded.

The Loricariidae family secondly, which is the largest catfish family in the world

(Armbruster, J.W. 20002) consisted of four species; they were Ancistrus heterorhynchus,

Liposarcus pardalis, Pseudorinelepis genibarbisandPterygoplichthys pardales. Species

from this family are debris feeders and occupy a benthic niche; at the bottom of the

riverbed and regularly surface for air. This means it was likely that the nets were

catching individuals that were surfacing.During the study a total of 45 individuals were

caught, predominantly Liposarcus pardalisand the second highest abundant family.

Thirdly the Cichlidae family are anextremely diverse and omnivorous group of fish. Three

species of Cichlidae were caught; these wereAequidens tetramerus, Chaetobranchus

flavescens andCichlasoma amazonarum. The most common of these species caught

across all sites was Cichlasoma amazonarum.

6.1. Methodology

In order to confidently establish causes of any variance in fish abundance and diversity,

it is important to be able to eliminate other possible influencing factors. One factor to

consider is the sampling timing, this study was conducted in early June, the end of the

high-water season. However water levels were extremely high, affecting methods

considerably, the oxbow lakes that were previously an ecologically distinct habitat had

merged into the larger River channels. The larger channels were not suitable for fishing

as the flow of water was too fast for nets, so habitat was not greatly comparable. In

previous studies, other methods such as spear, trap and cast-nets were used to

supplement gill-net catches, this study did not use other methods to supplement

numbers, however this could be taken into consideration for future studies.

During the study period,water levels were unusually high. Fishing site selection was

decided upon on the first day, where sites were selected by their differing habitat types,

Emily Iles

36

at times this became difficult due to language barriers between students and guides. The

guides seemed more interested in productivity rather than habitat selection, however it

was helpful to have guides that are knowledgeable of the area.

Gill nets are a commonly used method for local fishing and have been used to sample

fish fauna for many years, however nets would regularly become entangled on

vegetation, meaning that the whole length of the net was not in use and when this

occurred abundance decreased for that catch.

Fish length was measured in centimetres from the tip of the mouth to the caudal

peduncle; on occasion rigamortiswould prevent sound measurement, as fish would

curve into awkward positions so estimates were made. It was unsure how many smaller

fish were consumed in the nets by the larger piscivorous fish, when Serrisalmidae

occurred in abundance, no other species appeared in the net with them suggesting they

had consumed them. It might have been that the least diverse sites such as site 2 were

the most diverse, just heavily predated. On instruction a two-hour time period for the net

was allowed to avoid this situation but this could be experimented further.

The weight of all individuals was determined to the nearest 10 grams, using a set of

standard balancing scales to the nearest kilogram. The scales that were provided were

often tricky with larger species as they did not fit inside the scales and did not stay still

log enough making the needle jump. Fish weight measurements were taken by a

standard balancing scale; previous studies have used electronic scales, reducing

inaccurate readings when fish move during weighing. This also means that the

methodologies from this study are not directly comparable to those in other years.

Water chemistry measurements were taken next to each site, every fishing session.

These measurements could have been used to further analyse results and explain

differences between sites. Unfortunately only occasional and erratic measurements were

recorded as equipment regularly failed and was abandoned half way through the project,

hence why results are not displayed in this report, but would be an advantageous data

set to have when analysing ecology and habitat differences.

Emily Iles

37

6.2. Statistical models

In the context of body condition research a study by Luz-Agostinho(2009) examined

whether the effect of floods on the feeding activity and body condition of five piscivorous

fish species over four years. Feeding activity and body condition were evaluated using

the mean values of the standard residuals generatedby regression models between

body and stomach weights and standard length and body weight.Differences among

years and subsystems were evaluated via two-way analysis of variance. The results

showed that body condition varied across years. Hopliasmalabaricus(an ambusher

adapted to starvation) presented feeding activityindependent of the flooding regime and

presented better body condition in times of high water levels. Other species presented

poorer body condition in years or subsystems with regular floods, as they presented

different feeding strategies and adapted poorly. Theregular floods affected the feeding

activity and body condition of piscivorous fish as prey was widely distributed and the

response of each species depends on the existence or absence of pre-adaptation to

long periods of starvation.This study gained an insight into the body condition of fish in

localized habitats at a specific period from May – June, however it could not suggest

annual changes in condition due to the changing ecosystem. Therefore it would be

advantageous to carry on this study further to monitor this.

In order to discover the relationship between fish length and weight a correlation

analysis was used. Overall 0.05 and 0.01 values were determined by interpolation from

Cohen et al 1998 appendix 5. The coefficient of determination r2 quantifies the proportion

of variability in one variable. Correlation results are visually understood with aid of the

linear regression lines and their equations; the reasoning for using linear lines will be

explained in section 6.3. All correlations were statistically significant, because the values

obtained for r, the Product Moment Correlation Coefficient (PMCC) indicating the

strength of the correlation, were in all cases higher than the PMCC critical values for the

according degree of freedom at 0.05 and 0.01 levels of significance. The results mean

that the H1 Hypothesis can be accepted to suggest that there is a statistically significant

correlation between overall weight and length of species in Pacaya Samiria. This was an

appropriate statistic to use as it measured how strong the relationship between weight

and length is between sites. It also showed if there were any abnormalities in the fish

that were sampled in the individual sites.

Emily Iles

38

The analysis suggested that there is a linear relationship between weight and length of

fish species using the equipment in the methodology, it can be aided with the Standard

Error from the regression to work out where deviates from the line occur and to further

analyse if these individuals.

To analyse the body condition of species caught, a body condition (BC) value was given

to every individual (BC = L/W) where L is length and W is weightthis can be used to

calculate the condition factor BC,similar to a BMI in humans. Species were grouped to a

family level in order to increase sample data. Three families that occurred in relative

abundance across all sites were used; the average body condition in each site was

compared. It is assumed that fish with a long length and a high weight are considered to

have good body condition. Alternatively, fish with a long length but a low weight are

considered to be in poor body condition. This is an extremely simple calculation and no

other factors are considered for example stomach weight, age, sex or if it was a female if

she was gravid (carrying eggs). More in depth studies have analysed these factors but

no additional data was recorded for this study.

One-way ANOVA was used to analyse the significance of variance in body condition

within and across sites. This statistical model overcomes the problem of committing

Type 1 or Type 2 errors by allowing comparisons to be made between any number of

sample means through means of initial histogram testing of the normal distribution of the

data and Fmax tests to show the similarity of the variance of the samples (Cohen, L et al

2008) calculations can be considered reliable as all assumptions associated with this

model were accounted for.A subsequent T-test was used on the ANOVA data to find

where the differences between two means in relation to the variation in the data are;

these were expressed as the standard deviation of the difference between the means,

shown in the graphs.

The Shannon-Weiner Diversity Index was used to calculate diversity within and across

sites. The calculation also indicated species evenness and abundance. One limitation

however is that the accuracy of the results decreases with the proportion of the

community sampled, this is because the entire community cannot be completely

sampled by methods used. It is however extremely difficult to sample an entire

population for diversity when individuals are so widely dispersed, values usually fall

Emily Iles

39

between 1.5 and 3.5, as is the case in this study, suggesting that sufficient numbers of

species from the communities sampled were included.

6.3. Weight and length relationships

Correlation analysis of three families (Erythrinidae, Loricariidae and Cichlidae)in this

study was conducted to measure the strength of the correlations between weight and

length of all individuals, and of individuals from each site, using the product moment

correlation coefficient (PMCC). However as mentioned previously it has been found that

a cubed relationship exists between weight and length of fish and therefore growth

cannot be linear (Lanelli, J. et al 1997).

The reason whylinear regression lines were used to describe the data range in the

correlation is because the fishing nets used in the methodology (green gill-nets 30 m

long, 2 ½ m deep, 9 cm stretch mesh) did not catch the very small individuals or the very

large individuals, so a full representation of the fish fauna were not sampled. Using an

example from Fig 9 (the overall correlation of Erythrinidae species), it is clear to see

where the small individuals are missing from 0 to 12. The correlation of the graph below

is stronger than Fig 6 because weight is approximately proportional to the cube of the

length.

Instead of taking the cubed length into consideration, this study used the linear line for

each site then calculated the standard error from the regression because standard error

gives conservative estimate of fish size.The standard error from regression shows the

range in which the weight of the fish is likely to fall based on the length of the fish. If an

individuals’ weight is below the normal range it can be assumed that it is experiencing a

poor feeding period and that the habitat is unsuitable. The larger the range, (Table 9 site

y = 0.0107x3.2386 R² = 0.89297

0

100

200

300

400

500

600

0 5 10 15 20 25 30

Overall correlation

Emily Iles

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1) the worse the regression and the more difficult it is to use the data to predict the

condition of the fish in that area. Standard error gives conservative estimate of fish size

in reality if the cubed relationship is true, the actual size will be much closer to the cube-

proportional trend line. It is important to compare analyses to gain more of an

interdisciplinary understanding of fish growth and ecology, in this section the results from

correlation and ANOVA will be explained as one as they are very closely related and can

be used to understand the overall results.

6.3.1. ErythrinidaeWeight-Length Relationships

Erythrinidae species all showed a strong to very strong correlation between weight and

length. When comparing with the ANOVA results, it shows that site 4 displayed the

lowest body condition value for this family; it also contained the lowest abundance of this

family compared with other sites with 15 individuals. As the correlation is strong it means

that there is no anomalous result and these individuals are just likely to be juvenile.

Although there is no apparent research for neo-tropical fish it can be assumed that

juvenile fish group together in dense environments where they are safe from predation

by larger predators, if so they are safest in site 4 as the scoring system shows. Site 4 is

located over the flooded oxbow lake and canopy coverage was 80 to 90%. This site

contained an abundance of water lettuce (Pistia stratiotes) making the water extremely

turbid and safe from predators above the water and an abundance of debris where small

fish can hide from piscivores.

6.3.2. LoricariidaeWeight-Length Relationships

Species belonging to the Loricariidae family showed a significant relationship between

weight and length. Sites 1, 3 and 4 retained very strong correlation values with the

highest being site 4 (r2= 0.9712). Fig 3 shows the correlation results from site 2, this site

retained only a modest correlation, when further looking at the results, one individual

was heavier than others, this result was also compared to ANOVA results from Fig 18

which suggests that individuals were 100g lighter than those at other sites. The

percieved anomaly fell outside the range of standard error as calculated and shown in

Table 9, this further proved that the result was likely to be anomolous. To prove that this

one individual was creating this result, it was removed out of interest. The graph below

proves this individual is an anomoly because the r2 value changes to 0.89966 from

0.48289 and a very strong correlation.

Emily Iles

41

Adjusted site 2 to show very strong correlation.

This could have been due measurement errors in the methodology or inaccuracies when

recording results. The fish were weighed and measured by one person while calling out

readings to another member of the team to record the data, this could have led to the

wrong numbers being noted. It also could have been caused by habitat unsuitability for

these species, when returning to Table 3, site 2 was the deep water habitat. Loricariids

have evolved to cope with hypoxia events, an unusual adaptation is the ability to breath

air, where species swim to the surface and orient their body vertical to get the mouth out

of the water, species of Liposarcus and Ancistrus are included. This means they have to

expend more energy swimming a longer distance up to the surface to gulp air, also

increasing the likelihood of predation.The anomalous individual could have come from

the connecting up of habitats due to the flooding. Another potential area of bias came

from sample data, as species were grouped into families, further analysis into the raw

data suggested that both the anomalous individual and two of the individuals within the

expected range were the same species. Meaning that slight differences in morphology

did not make a difference in weight or length between species.

6.3.3. CichlidaeWeight-Length Relationships

The Cichlidae species were found to all have a significant and positive correlation

between weight and length. However it cannot be suggested that Site 4 can be a

significant result as there was a lack of sample size forcing the correlation extremely

close to the border at 99%.The ANOVA results for sites 3 and 4 Fig 19 show that fish

had a lower body condition value.Due to the positive correlation, if the average weights

y = 12.979x - 96.383 R² = 0.89966

0

50

100

150

200

0 5 10 15 20

Site 2 - Adjusted for Anomalous Result

Emily Iles

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and lengths are compared (see graphs below) it is clear that the lengths and weights

correlate so it is likely that these are juvenile individuals. Referring back to the habitat

data the results show a similar pattern to Erythrinidae species where juveniles are likely

to group in habitats characterised by refugia such as sites 3 and 4.

6.4. Shannon Weiner Index

Diversity is measured as the number of species present,H (Cohen, L et al 2008). Fig

20shows the Shannon Weiner diversity Indexresults. When looking at Fig 21

(Abundance) there is an opposite effect between diversity and abundance. The Shannon

Weiner Index gives a low value of 1.19 to site 2, suggesting there is low species diversity

and site 4 a value of 2.43 suggesting a much higher species diversity. However

comparing this to abundance, 30% of all fish were caught at site 2 where as only 17%

were caught atsite 4. This suggests that one species is being repetitively caught in site

2; in order to further investigate which species, graphs were drawn to indicate family

diversity and Abundance. This showed that Erythrinidae was the most abundant family

caught during the study and is responsible for the results in fig 20 and 21.

The abundance and diversity of species showed the most interesting results in terms of

ecology, as it seems that there is some element of inter-specific feeding competition.

74% of the total abundance in site 2 belonged to Erythrinidae species. It was mentioned

earlier that this family of fish are piscivores, the only other piscivorous family are

Serrisalmidae, including the Piranhas and Curuhuaras meaning these families directly

compete for food resources.In sites where Erythrinidae areparticularly high (site 2),

Serrisalmidae abundance was low but where Erythrinidae abundance was less,

Serrisalmidae was much higher, suggesting that Erythrinidae out-compete Serrisalmidae

for food resources.

5

10

15

Aver

age

leng

th

Average length of Cichlidae species

site 1 site 2 site 3 site 4 0

50

100

Aver

age

wei

ghts


Average weight of Cichlidae species

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A total of 253 individuals were recorded. Fig 21 shows the overall abundance of all fish

species during the study expressed in percentages.

Site 1 was an all rounded habitat containing shallow water, debris in the water and

fruiting trees with canopy coverage, a good representation of the different families were

present from all trophic levels. As the water was shallow it favoured Loricariidae species

as going to the surface for air was more efficient, this is reflected by the abundance of

this family caught shown in Fig 22. It was mentioned that Characidae species switch

feeding to fruit and seeds, site 2 was the site containing most fruit, however it had the

largest piscivore burden, so perhaps this species switched to site 1 where less predators

were caught.

Site two retained the highest overall percentage of fish with 28%. A total of two fish were

discounted in this site due to piscivore damage, they were both species from the genus

Sardinia. By comparing the family diversity with overall family abundance it is clear that

Erythrinidae was the most abundant with 74% of all fish from this family caught at site 2.

It appears that Erythrinidae are also out-competing smaller species because where they

occurred in abundance other species were absent.By looking at Fig 22 to 25: Site 4

shows where Erythrinidae numbers are low, results from Shannon Weiner suggest

diversity was highest.Site 3 presents a balance in piscivore numbers, Serrisalmidae and

Erythrinidae species appear to be balanced and therefore not out-competing one

another and suggesting that if there is enough food, they can occupy the same niche. It

is possible that this site was the most diverse but piscivores consumed the fish in the

56

6 11 0 0 3 0 0

0 10 20 30 40 50 60

Family Diversity and Abundance at Site 2 24

6 6 0 2 0

21

3

0 5 10 15 20 25


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nets changing the results. This site is similar to site 4 in the respect of habitat containing

dense flooded forest, 90-100% canopy coverage was recorded with an abundance of

woody debris, which is potentially optimum habitat for juveniles species, which are

targeted by piscivores.

Increased shelter in site 4 from debris in the water may also reduce prey availability, the

microhabitat greatly affects the efficiency of hunting for piscivores (Luz-Agostinho K.D.G.

et al 20083) hence why the lowest amount were recorded here. It was mentioned earlier

that Loricariidae have adapted to cope with hypoxic waters, water at site 4 was

particularly turbid resulting in low oxygen and good conditions for these fish, their

armoured bodies make them difficult prey for small piscivores and this explains the result

at site 4.

6.5. Trophic Cascades.

Site 1 Site 2 Site 3 Site 4 Detrivores

Loricariidae 18 6 6 15 Prochilodontidae 9 0 0 3 Curmitidae 1 0 3 1

Herbivores Anostomidae 0 0 3 0

Insectivores Charicidae 9 3 0 7

Omnivores Cichlidae 9 11 6 2

Piscivores Erythrinidae 23 56 24 9 Serrisalmidae 1 0 20 2

Families were split into different trophic levels, from this table it is clear that the

abundance of piscivores is higher than those lower down the scale. As piscivores feed

on species, zooplankton and aquatic plants can increase, if the predator-prey

relationships change in an ecosystem it can result in an event known as a trophic

cascade. In this instance, if such top predators such as caiman (caiman crocodylus)and

Paiche are drastically removed then secondary predators will thrive (the piscivores)

removing large amounts of smaller species that are important for taking away excess

algae and plankton in the water.

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7. CONCLUSION

This study coincided with a flooding event, mentioned in the Introduction. As the results

show there is some change in body condition of some individuals in the habitats along

the river systems, in order to gain a wider appreciation of the effect seasonal-patterns

have on body condition, yearly studies would have to be completed. Results show that it

is possible to carry out analysis based on simple methodologies such as the ones used

in this study. In order for a more in depth analysis there are several considerations to

consider for further work. Firstly, although an attempt was made to take water chemistry

results, including this into the study could have potentially supported data better, giving

more of a scientific approach to habitat assessment rather than the subjective approach

used here.

To gain a better insight into this analysis, firstly data would be collected over a longer

time period; this would allow a substantial amount of fish to be recorded without having

to group species into families. It would also be advantageous to record sex and age of

each individual, the age can be analysed by dissecting the otolith bone in head of the

fish. Although extra analysis would be time consuming, it is necessary to gain as much

sample data in order to come to conclusions when analysing results. Using the age and

sex of fish you could then be sure that anomalous results were in fact truthful such as

Erythrinidae individuals found at site 4. Another important aspect for this study to further

enhance it would be to sample the smaller and the larger fish by adapting the

methodology. However this would bring up the ethical side to field work, as juvenile fish

may perish in nets.

One very interesting aspect of this report focussed on the diversity and abundance of the

river system, as it is a crucial component in conservation monitoring,expressing the

quality of the ecosystem. In the results inter-specific competition was seen between two

piscivourous species also the relationship between predators and prey was seen. It

would be interesting to further research into this relationship, as tropic cascades can be

fatal for ecosystems.

Journals published in Neotropical Ichthyology are found to be the only publishers of

original contributions in Neotropical fish research. Otherwise material is scarce or out of

date. It is vital for monitoring to continue especially in Protected Areas such as Pacaya

Emily Iles

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Samiria as it shows that management is successful at protecting the ecological integrity

of such important biodiversity.

(Appendix 1) Identification and Classification Guide:

Pictures from fishbase.com, identification guide and taken personally

Local name: Shuyo Scientific name:

Hoplerythrinus unitaeniatus Erythrinus erythrinus

Ecology: Freshwater pelagic species. Piscivourous ambush predator on smaller fish. Status: Not evaluated. Important in fisheries and aquariums.

Local name: Carachama(Common Pleco) Scientific name:

Liposarcus pardalis Pseudorinelepis genibarbis Pterygoplichthys pardalis Ancistrus heterorhynchus

Local name: Fasaco Scientific name: Hoplias malabaricus Ecology: Fresh water pelargic species. Piscivourous ambush predator on smaller fish. Status: Not evaluated. fisheries: commercial; aquarium: commercial

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Ecology: Freshwater; pH range: 7.00 - 7.50.Facultative air breather.Lower, middle and upper Amazon River basin. Introduced to countries outside its native range.River basin. Bottom feeder (debris).

Status: Not evaluated. Fisheries: minor commercial; aquarium: commercially sold.

Local name: Bujurqui Scientific name:

Aequidens tetramerus Chaetobrachus flavescens Cichlasoma amazonarum

Ecology: benthopelagic; freshwater; pH range: 6.00 - 7.00.Occurs in coastal swamps and flooded grounds. South America: Amazon River basin, from the Ucayali, Huallaga, Amazon and Yavarí River drainages in Peru. Omnivorous.

Status: Not evaluated. fisheries: minor commercial; aquarium: commercial

Local name: Piraña blanca / roja

Local name: Curuhuara Scientific name: Colossoma macropomum Ecology: Benthopelagic; freshwater; pH range: 5.0 - 7.8.depths of 5 m This species

is usually solitary. Adults stay in flooded forests during first 5 months of flooding.Young and juveniles live in black waters of flood plains until their sexual maturity.

Status: Not evaluated.

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Scientific name: Serrasalmus rhombeus Pygocentrus nattereri

Ecology: Influences distribution and feeding of other fish and in areas of high primary production. Adults feed mainly at dusk and dawn. Piranhas will also attack and consume much larger fish ifcaptive in nets.

Status. Not evaluated. fisheries: commercial; aquarium: commercial

Local name: Boquichico Scientific name: Prochilodus nigricans Ecology: Benthopelagic; potamodromous. Status: Not evaluated. Fisheries: commercial; aquaculture: commercial;

aquarium: commercial

Local name: Sardinia Scientific name: Triportheus angulatus Ecology: Benthopelagic; potamodromous. freshwater; pH range: 5.0 - 9.0; depth

range 0 - 5 m. Occurs over sandy bottoms in rivers. Usually forms schools. Mainly diurnal. Feeds on the fruits and seeds of Moraceae, Myrtaceae, Euphorbiaceae; Coleoptera, Orthoptera, Lepidoptera, and on plankton, nekton, and crustaceans.

Status: Not evaluated. Fisheries: subsistence fisheries; bait: occasionally

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Local name: Sábalo Cola negra / Roja Scientific name:

Brycon melanopterus Brycon cephalus

Ecology: Benthopelagic; potamodromous freshwater; pH range: 6.0 - 7.5. South America: Upper Amazon River basin in Peru and Bolivia.

Status: Not evaluated. aquarium: commercial

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(Appendix 2) Shows the family, species and local name. The green highlighted boxes

indicate the families used in analysis that occurred across all four sites. Family Species Local name

Prochilodontidae

Prochilodus nigricans

Boquichico

Anostomidae Schizodon fasciatum Lisa

Erythrinidae

Hoplias malabaricus

Hoplerythrinus unitaeniatus

Erythrinus erythrinus

Fasaco

Shuyo

Characidae

Triportheus angulatus

Brycon melanopterus

Brcon Cephalus

Sardina

Sábalo Cola negra

Sábalo Cola roja

Serrasalmidae

Pygocentrus nattereri

Serrasalmus rhombeus

Colossoma macropomum

Mylossoma aureum

-

Piraña roja

Piraña blanca

Curuhuara

Ancistrus heterorhynchus Carachama ancistrus

Loricariidae

Liposarcus pardalis

Pseudorinelepis genibarbis

Pterygoplichthys pardalis

Carachama (Common Pleco)

Carachama

Carachama

Cichlidae

Aequidens tetramerus

Chaetobranchus flavescens

Cichlasoma amazonarum

Bujurqui

Bujurqui vaso

Bujurqui

Curimatidae Curimatoides ucayalensis -

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(Appendix 3) Raw Data.

Date Location Time Nets Sci. name Comm.Nam L(cm) Wt (gm) 03/06/2009 site 1 2hrs N1 Prochilodus nigicans Boquichico 16 110 03/06/2009 site 1 2hrs N3 Prochilodus nigicans Boquichico 21.5 210 03/06/2009 site 1 2hrs N3 Prochilodus nigicans Boquichico 26 340 03/06/2009 site 1 2hrs N3 Prochilodus nigicans Boquichico 23.5 270 03/06/2009 site 1 2hrs N3 Prochilodus nigicans Boquichico 23.5 260 03/06/2009 site 1 2hrs N3 Prochilodus nigicans Boquichico 24 255 03/06/2009 site 1 2hrs N3 Prochilodus nigicans Boquichico 13.5 50 11/06/2009 site 1 2hrs N3 Prochilodus nigicans Boquichico 16 100 11/06/2009 site 1 2hrs N3 Prochilodus nigicans Boquichico 14 70 06/06/2009 Site 4 2hrs N3 Prochilodus nigicans Boquichico 18 155 06/06/2009 Site 4 2hrs N3 Prochilodus nigicans Boquichico 21 225 14/06/2009 Site 4 2hrs N2 Prochilodus nigicans Boquichico 19 170 14/06/2009 Site 4 2hrs N3 Prochilodus nigicans Boquichico 19.5 175 11/06/2009 site 1 2hrs N3 curimatoides ucayalensis ? 15.5 75 09/06/2009 Site 3 2hrs N3 curimatoides ucayalensis ? 15.5 70 13/06/2009 Site 3 2hrs N3 curimatoides ucayalensis ? 14.5 60 13/06/2009 Site 3 2hrs N3 curimatoides ucayalensis ? 13.5 50 01/06/2009 Site 3 2hrs N1 hypoptopoma littorale ? 13 90 05/06/2009 Site 3 2hrs N1 hypoptopoma littorale ? 12.5 80 02/06/2009 Site 4 2hrs N1 curimatoides ucayalensis ? 14 60 06/06/2009 Site 4 2hrs N3 hypoptopoma littorale ? 17 155 10/06/2009 Site 4 2hrs N2 hypoptopoma littorale ? 12.5 50 06/06/2009 Site 4 2hrs N2 Triportheus genibarbis ? 16 145 11/06/2009 site 1 2hrs N1 Aequidens tetramerus Bujurqui 12 90 11/06/2009 site 1 2hrs N1 Aequidens tetramerus Bujurqui 12 90 11/06/2009 site 1 2hrs N3 Aequidens tetramerus Bujurqui 12 75 03/06/2009 site 1 2hrs N3 cichlasoma amazonarum Bujurqui 11.5 65 11/06/2009 site 1 2hrs N3 cichlasoma amazonarum Bujurqui 11 65 11/06/2009 site 1 2hrs N3 cichlasoma amazonarum Bujurqui 10 50 11/06/2009 site 1 2hrs N3 cichlasoma amazonarum Bujurqui 10 45 04/06/2009 Site 2 2hrs N1 Aequidens tetramerus Bujurqui 9.5 45 12/06/2009 Site 2 2hrs N1 Aequidens tetramerus Bujurqui 11.5 75 04/06/2009 Site 2 2hrs N1 cichlasoma amazonarum Bujurqui 13 90 04/06/2009 Site 2 2hrs N1 cichlasoma amazonarum Bujurqui 12 120 04/06/2009 Site 2 2hrs N1 cichlasoma amazonarum Bujurqui 12.5 75 04/06/2009 Site 2 2hrs N1 cichlasoma amazonarum Bujurqui 10 50 04/06/2009 Site 2 2hrs N1 cichlasoma amazonarum Bujurqui 10 50 04/06/2009 Site 2 2hrs N2 cichlasoma amazonarum Bujurqui 13.5 115 04/06/2009 Site 2 2hrs N3 cichlasoma amazonarum Bujurqui 15.5 100 08/06/2009 Site 2 2hrs N1 cichlasoma amazonarum Bujurqui 11.5 60 01/06/2009 Site 3 2hrs N1 Aequidens tetramerus Bujurqui 11 55 01/06/2009 Site 3 2hrs N1 Aequidens tetramerus Bujurqui 10 55 01/06/2009 Site 3 2hrs N2 Aequidens tetramerus Bujurqui 12 80 01/06/2009 Site 3 2hrs N2 Aequidens tetramerus Bujurqui 10 50 01/06/2009 Site 3 2hrs N2 Aequidens tetramerus Bujurqui 12 75 01/06/2009 Site 3 2hrs N2 Aequidens tetramerus Bujurqui 10.5 60 06/06/2009 Site 4 2hrs N2 cichlasoma amazonarum Bujurqui 10.5 55 03/06/2009 site 1 2hrs N3 Chaetobrachus flavescens Bujurqui vaso 16.5 175 08/06/2009 Site 2 2hrs N1 Chaetobrachus flavescens Bujurqui vaso 15.5 150 02/06/2009 Site 4 2hrs N1 Chaetobrachus flavescens Bujurqui vaso 10.5 40 30/05/2009 site 1 2hrs N1 Liposarcus pardalis carachama 24 350 03/06/2009 site 1 2hrs N2 Liposarcus pardalis carachama 22.5 250 03/06/2009 site 1 2hrs N2 Liposarcus pardalis carachama 25 280 03/06/2009 site 1 2hrs N2 Liposarcus pardalis carachama 22.5 230

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03/06/2009 site 1 2hrs N3 Liposarcus pardalis carachama 12.5 50 03/06/2009 site 1 2hrs N3 Liposarcus pardalis carachama 10.5 30 07/06/2009 site 1 2hrs N1 Liposarcus pardalis carachama 15.5 90 07/06/2009 site 1 2hrs N1 Liposarcus pardalis carachama 17 135 07/06/2009 site 1 2hrs N1 Liposarcus pardalis carachama 21.5 245 07/06/2009 site 1 2hrs N1 Liposarcus pardalis carachama 22.5 250 07/06/2009 site 1 2hrs N2 Liposarcus pardalis carachama 24 270 07/06/2009 site 1 2hrs N2 Liposarcus pardalis carachama 22 240 07/06/2009 site 1 2hrs N3 Liposarcus pardalis carachama 14 90 11/06/2009 site 1 2hrs N1 Liposarcus pardalis carachama 23 300 03/06/2009 site 1 2hrs N1 pseudorinelepis genibarbis carachama 15 95 03/06/2009 site 1 2hrs N1 pseudorinelepis genibarbis carachama 13.5 80 03/06/2009 site 1 2hrs N1 pterygoplichthys pardalis carachama 24 275 03/06/2009 site 1 2hrs N2 pterygoplichthys pardalis carachama 23 270 04/06/2009 Site 2 2hrs N1 Liposarcus pardalis carachama 15 90 04/06/2009 Site 2 2hrs N1 Liposarcus pardalis carachama 16.5 120 04/06/2009 Site 2 2hrs N1 Liposarcus pardalis carachama 14.5 95 08/06/2009 Site 2 2hrs N1 Liposarcus pardalis carachama 15 130 08/06/2009 Site 2 2hrs N1 Liposarcus pardalis carachama 15 100 08/06/2009 Site 2 2hrs N1 pseudorinelepis genibarbis carachama 13.5 80 01/06/2009 Site 3 2hrs N2 Liposarcus pardalis carachama 14 70 05/06/2009 Site 3 2hrs N3 Liposarcus pardalis carachama 25 330 05/06/2009 Site 3 2hrs N1 pterygoplichthys pardalis carachama 23.5 250 05/06/2009 Site 3 2hrs N1 pterygoplichthys pardalis carachama 23 250 05/06/2009 Site 3 2hrs N1 pterygoplichthys pardalis carachama 15 100 09/06/2009 Site 3 2hrs N2 pterygoplichthys pardalis carachama 23 225 06/06/2009 Site 4 2hrs N3 Liposarcus pardalis carachama 17.5 140 14/06/2009 Site 4 2hrs N1 Liposarcus pardalis carachama 28.5 390 14/06/2009 Site 4 2hrs N2 Liposarcus pardalis carachama 23 290 14/06/2009 Site 4 2hrs N2 Liposarcus pardalis carachama 16.5 105 02/06/2009 Site 4 2hrs N1 pseudorinelepis genibarbis carachama 12 40 06/06/2009 Site 4 2hrs N3 pseudorinelepis genibarbis carachama 14.5 105 06/06/2009 Site 4 2hrs N3 pseudorinelepis genibarbis carachama 14 90 06/06/2009 Site 4 2hrs N3 pseudorinelepis genibarbis carachama 16 135 14/06/2009 Site 4 2hrs N3 pseudorinelepis genibarbis carachama 14.5 100 06/06/2009 Site 4 2hrs N1 pterygoplichthys pardalis carachama 24.5 275 06/06/2009 Site 4 2hrs N1 pterygoplichthys pardalis carachama 25 345 10/06/2009 Site 4 2hrs N1 pterygoplichthys pardalis carachama 31 450 10/06/2009 Site 4 2hrs N1 pterygoplichthys pardalis carachama 26 280 10/06/2009 Site 4 2hrs N3 pterygoplichthys pardalis carachama 17 150 06/06/2009 Site 4 2hrs N2 Ancistrus heterorhynchus carachama ancistrus 13 70 07/06/2009 site 1 2hrs N1 Hoplias malabaricus Fasaco 25 270 01/06/2009 Site 3 2hrs N1 Schizodon fasciatus Lisa cachete amarillo 19 150 05/06/2009 Site 3 2hrs N2 Schizodon fasciatus Lisa cachete amarillo 20.5 150 30/05/2009 site 1 2hrs N1 colossoma macropomum Curuhuara 17 200 02/06/2009 Site 4 2hrs N2 mylossoma aureum Piraña ? 13 70 05/06/2009 Site 3 2hrs N2 Serrasalmus rhombeus Piraña blanca 11.5 35 09/06/2009 Site 3 2hrs N2 Serrasalmus rhombeus Piraña blanca 12 60 09/06/2009 Site 3 2hrs N2 Serrasalmus rhombeus Piraña blanca 11.5 50 09/06/2009 Site 3 2hrs N2 Serrasalmus rhombeus Piraña blanca 12 50 09/06/2009 Site 3 2hrs N2 Serrasalmus rhombeus Piraña blanca 11 50 09/06/2009 Site 3 2hrs N3 Serrasalmus rhombeus Piraña blanca 10 30 02/06/2009 Site 4 2hrs N1 Serrasalmus rhombeus Piraña blanca 10 25 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 18 205 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 17.5 275 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 21 325 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 18.5 235 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 15.5 155

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09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 18 225 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 17 205 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 17 210 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 17.5 175 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 17 225 09/06/2009 Site 3 2hrs N1 Pygocentrus nattereri. Piraña roja 18 210 09/06/2009 Site 3 2hrs N2 Pygocentrus nattereri. Piraña roja 18.5 300 09/06/2009 Site 3 2hrs N2 Pygocentrus nattereri. Piraña roja 19 290 09/06/2009 Site 3 2hrs N2 Pygocentrus nattereri. Piraña roja 16 155 09/06/2009 Site 3 2hrs N2 Pygocentrus nattereri. Piraña roja 15 110 03/06/2009 site 1 2hrs N3 Brycon melanopterus Sábalo Cola negra 15 70 03/06/2009 site 1 2hrs N3 Brycon melanopterus Sábalo Cola negra 16 75 03/06/2009 site 1 2hrs N3 Brycon melanopterus Sábalo Cola negra 15 70 03/06/2009 site 1 2hrs N3 Brycon melanopterus Sábalo Cola negra 15.5 70 03/06/2009 site 1 2hrs N3 Brycon melanopterus Sábalo Cola negra 15.5 70 02/06/2009 Site 4 2hrs N1 Brycon melanopterus Sábalo Cola negra 16 100 02/06/2009 Site 4 2hrs N1 Brycon melanopterus Sábalo Cola negra 15.5 80 02/06/2009 Site 4 2hrs N1 Brycon melanopterus Sábalo Cola negra 15 70 03/06/2009 site 1 2hrs N1 Brycon cephalus Sábalo Cola Roja 25 255 11/06/2009 site 1 2hrs N3 Triportheus angulatus Sardina 14 55 11/06/2009 site 1 2hrs N3 Triportheus angulatus Sardina 14 50 11/06/2009 site 1 2hrs N3 Triportheus angulatus Sardina 15 70 12/06/2009 Site 2 2hrs N1 Triportheus angulatus Sardina 15 60 12/06/2009 Site 2 2hrs N1 Triportheus angulatus Sardina 15 65 12/06/2009 Site 2 2hrs N2 Triportheus angulatus Sardina 17 65 06/06/2009 Site 4 2hrs N2 Triportheus angulatus Sardina 14.5 49 14/06/2009 Site 4 2hrs N2 Triportheus angulatus Sardina 15 75 14/06/2009 Site 4 2hrs N2 Triportheus angulatus Sardina 15.5 65 14/06/2009 Site 4 2hrs N2 Triportheus angulatus Sardina 15.5 50 11/06/2009 site 1 2hrs N1 erythrinus erythrinus Shuyo 22 255 30/05/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 28 570 03/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 24 300 03/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23.5 305 03/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 21.5 225 03/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 25.5 370 03/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 22 250 03/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 17.5 115 03/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 25.5 230 03/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 24.5 300 03/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 17.5 125 07/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23 265 07/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23 305 07/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 28.5 540 07/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 24.5 370 07/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 25 415 07/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 27.5 500 07/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 26 430 07/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 20.5 220 11/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 27.5 475 11/06/2009 site 1 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 24.5 350 11/06/2009 site 1 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 26 250 04/06/2009 Site 2 2hrs N1 erythrinus erythrinus Shuyo 18.5 130 08/06/2009 Site 2 2hrs N1 erythrinus erythrinus Shuyo 18.5 145 31/05/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 29 500 04/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 25 350 04/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 24 350 04/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 24.5 385 04/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 26.5 460

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04/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23 270 04/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23 260 04/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 22.5 300 04/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25.5 395 04/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23 300 04/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 22.5 260 08/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 25.5 370 08/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23 290 08/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23 260 08/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 20 185 08/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 25 380 08/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 26.5 400 08/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 20.5 160 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 20.5 350 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24 350 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24.5 375 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 380 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 340 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23 270 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24.5 355 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 315 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 350 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25.5 420 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23.5 280 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23.5 290 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24 310 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24.5 390 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 22.5 260 08/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24 380 12/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 26 470 12/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23 225 12/06/2009 Site 2 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23.5 280 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 26.5 430 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23.5 340 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23 330 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24 320 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 325 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24.5 305 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 26 355 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24.5 365 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23 300 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 29 560 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23 350 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 26 410 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24.5 350 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 22 260 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 390 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24 315 12/06/2009 Site 2 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24.5 350 01/06/2009 Site 3 2hrs N1 erythrinus erythrinus Shuyo 18.5 130 01/06/2009 Site 3 2hrs N2 erythrinus erythrinus Shuyo 16.5 70 01/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 24 350 01/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 24 300 01/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 25 360 01/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 27 460 01/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 19.5 160 01/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 22 210 01/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 22 160

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01/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 21 170 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 24.5 350 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23.5 340 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 27 420 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 27 545 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 400 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 28 520 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 27 500 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 28.5 500 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 380 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 23 250 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25.5 400 01/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 25 340 05/06/2009 Site 3 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 23 290 05/06/2009 Site 3 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 21.5 215 02/06/2009 Site 4 2hrs N1 Hopleryhtrinus unitaeniatus Shuyo 14 50 06/06/2009 Site 4 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 23.5 290 06/06/2009 Site 4 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 18.5 120 06/06/2009 Site 4 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 23 270 14/06/2009 Site 4 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 18.5 125 14/06/2009 Site 4 2hrs N2 Hopleryhtrinus unitaeniatus Shuyo 22 250 14/06/2009 Site 4 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 22 255 14/06/2009 Site 4 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 27.5 460 14/06/2009 Site 4 2hrs N3 Hopleryhtrinus unitaeniatus Shuyo 24.5 330

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8. References:

Dominique Adriaens and Tom Geerinck (2007) Ontogeny of the intermandibular and hyoid musculature in the suckermouth armoured catfish Ancistrus cf. triradiatus (Loricariidae, Siluriformes). Evolutionary Morphology of Vertebrates, Ghent University, Belgium Luz-Agostinho, KDG, Agostinho, AA, Gomes, LC, Júlio-Jr, HFand Fugi, R. (2009)Effects of flooding regime on the feeding activity and body condition of piscivorous fish in the Upper Paraná River floodplain. Braz. J. Biol. vol.69 no.2 AB Anderson, MJ Balick, F Kahn and CM Peters. (1989) Oligarchic forests of economic plants in Amazonia: utilization and conservation of an Imoportant Tropical Resource. Conservation Biology.Jstor.org

Jonathan W. Armbruster, Nathan K. Lujan, Mark H. Sabaj and David C. Werneke. (2005). Baryancistrus demantoides and Hemiancistrus subviridis, two new uniquely colored species of catfishes from Venezuela (Siluriformes: Loricariidae). Neotrop. ichthyol. vol.3 no.4

Jonathan Armbruster W. (1998). Modifications of the Digestive Tract for Holding Air in Loricariidae and Scoloplacid Catfishes. Jstor.org Barham B, Bradford L., Oliver T. Coomesa Yoshito Takasakic. (2004) Targeting conservation–development initiatives in tropical forests: insights from analyses of rain forest use and economic reliance among Amazonian peasants. ibcperu.org Richard Bodmer, Pablo Puertas, Miguel Antunez and Tula Fang (2008). Wildlife Conservation in the Samiria River Basin of the Pacaya Samiria National Reserve, Peru. www.kent.ac.uk/coursefiles DI512 Barthem R. and Goulding M. (1997). The Catfish Connection. Ecology, Migration, and Conservation of Amazon Predators. Columbia University Press, New York.

Berger U, Fabré N.N, García M, Junk W, Saint-Paul U, Villacorta Correa M.A, and Zuanon J. (2000). Fish communities in central Amazonian white- and blackwater floodplains. Environmental Biology of Fishes 57: 235 - 250. Lou Cohen, Jim Fowler and Phil Jarvis (2008). Practical Statistics For Field Biology. Second Edition. Gene S. Helfman, Bruce B. Collette, Douglas E. Facey. (1997). The Diversity of Fishes. 1997 by Blackwell Science, Inc. a Blackwell Publishing.

Matt Finer, Clinton N. Jenkins, Stuart L. Pimm, Brian Keane, and Carl Ross. (2008).Oil and Gas Projects in the Western Amazon: Threats to Wilderness, Biodiversity, and Indigenous Peoples. ncbi.nlm.nih.gov

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Goulding M., Smith N.J.H., and Mahar D.J. (1996). Floods of Fortune. Ecology and Economy along the Amazon. Columbia University Press, New York. Wolfgang Junk (2000).Concepts for the Sustainable Management of Natural Resources of the Middle Amazon Floodplain: a Summary. Jstor.org Wolfgang Junk (1989). The Flood Pulse Concept in River-Floodplain Systems. Jstor.org Emiko Kawakami de Resende (1989) THE FLOOD PULSE CONCEPT AND ITS RELATION TO FISH BIOLOGY IN THE PANTANAL. nrem.iastate.edu James Lanelli and David Witherell. (1997). A Guide to Stock Assessment of Bering Sea and Aleutian Islands Groundfish: North Pacific Fishery Management Council 605 West 4th Avenue, Suite 306 Anchorage, Alaska 99501. Noaa.org. William F. Loftus Leo G. Nicoand James P. Reid. (2009). Interactions between non-native armored suckermouth catfish (Loricariidae:Pterygoplichthys) and native Florida manatee (Trichechus manatus latirostris) in artesian springs. U.S. Geological Survey.

Karla D. G. Luz-Agostinho, Angelo A. Agostinho, Luiz C. Gomes andHora ́ cio, Ju ́ lio Jr. (2008). Influence of flood pulses on diet composition and trophic relationships among piscivorous fish in the upper Parana ́ River floodplain. Springerlink.com Val & Almeida-Val, (1995). EVOLUTIONARY FEATURES OF HYPOXIA TOLERANCEIN FISH OF THE AMAZON:FROM MOLECULAR TO BEHAVIORAL ASPECTS www-heb.pac.dfo-mpo.gc.ca.pdf http://www.iucnredlist.org/apps/redlist/details/1991/0

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