Emily Iles
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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Emily Iles
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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Emily Iles
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
5.
4.1.
Fishing ........................................................................................................... 20
4.2.
Identification Weight and Length .................................................................... 20
4.3.
Water Chemistry Analysis .............................................................................. 21
4.4.
Data Analysis ................................................................................................. 22
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.
6.
Shannon Weiner Diversity Index. ................................................................... 33
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 3: Correlation between weight and length of Erythrinidae species at site 2…………..25
Fig 4: Correlation between weight and length of Erythrinidae species at site 3…………..25
Fig 5: Correlation between weight and length of Erythrinidae species at site 4…………..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 14: Correlation between weight and length of Cichlidae species at site 3…………….28
Fig 15: Correlation between weight and length of Cichlidae species at site 4…………….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
Fig 23: Graph showing Family Diversity and Abundance at site 2………………………….34
Fig 24: Graph showing Family Diversity and Abundance at site 3………………………….34
Fig 25: Graph showing Family Diversity and Abundance at site 4………………………….34
List of Tables
Page
Table 1: Scoring system used in the rapid habitat assessment……………………………..15
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Emily Iles
Table 2: Site 1 habitat assessment……………………………………………………………..16
Table 3: Site 2 habitat assessment……………………………………………………………..16
Table 4: Site 3 habitat assessment……………………………………………………………..17
Table 5: Site 4 habitat assessment……………………………………………………………..17
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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Emily Iles
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, mesopredators 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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Emily Iles
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).
Score
Rating
8 –10
Excellent
6–7
Good
4–5
Fair
1–3
Poor
Table 1: Table showing the scoring system used to determine habitat availability and
quality.
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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
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.
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
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
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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.
Site 3
Rating
Score
large woody debris availability
Good
6
bank presence
Poor
1
noise disturbance
Poor
3
fruiting trees available
Poor
3
canopy cover
Excellent
9
flow of water suitable for fishing
Fair
4
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.
Site 4
Rating
Score
large woody debris availability
Excellent
9
bank presence
Poor
2
No noise disturbance
Good
6
fruiting trees available
Poor
1
canopy cover
Excellent
9
flow of water suitable for fishing
Good
6
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.
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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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Emily Iles
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
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.
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
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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
the caudal peduncle.
Plate 9: Balancing scales
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
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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. Intraspecific 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 xy – x y / n x² - (x)²
a = Y – bX
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 xy – x y / n x² - (x)²)(n y² - (y)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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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.
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Emily Iles
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.
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 2
0.897
0.8046 55
0.261
0.338
Significant
Strong
Positive
Site 3
0.959
0.9211 23
0.396
0.505
Significant
Very Strong Positive
Site 4
0.981
0.9627 8
0.632
0.765
Significant
Very Strong Positive
Overall
0.9195 0.8455 111
0.186
0.243
Significant
Very Strong Positive
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
1
2
3
4
Total
Standard error from regression
61.097
36.001
38.169
25.673
42.378
Table 7: shows standard error from regression for Erythrinidae species.
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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.
600
600
Site 1
500
y = 35.885x - 538.76
R² = 0.7566
400
300
200
200
100
100
0
5
10
15
20
y = 36.18x - 535.95
R² = 0.8047
400
300
0
Site 2
500
25
30
0
0
Fig 2: Correlation of site 1
600
Site 4
400
y = 42.16x - 680.74
R² = 0.9211
200
100
100
0
10
Fig 4: Correlation of site 3
20
y = 30.774x - 422.75
R² = 0.9628
300
200
0
30
500
500
300
20
Fig 3: Correlation of site 2
Site 3
400
10
30
0
0
10
20
30
Fig 5: Correlation of site 4
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600
Overall correlation
500
y = 36.836x - 554.25
R² = 0.8455
400
300
200
100
0
-100
0
10
20
30
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 1
0.9750 0.9507
17
0.456
0.575
Significant
Very Strong
Positive
Site 2
0.6949 0.4828
5
0.754
0.874
Significant
Modest
Positive
Site 3
0.9756 0.9517
5
0.754
0.874
Significant
Very Strong
Positive
Site 4
0.9855 0.9712
14
0.497
0.623
Significant
Very Strong
Positive
Overall
0.9802 0.9608
44
0.291
0.376
Significant
Very Strong
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
1
2
3
4
Total
Standard error from regression
22.812
15.202
24.388
22.716
21.351
Table 9: shows standard error from regression for Loricariidae species.
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200
400
Site 2
Site 1
150
300
y = 20.249x - 199.87
R² = 0.95069
200
100
100
50
0
0
0
10
20
400
20
Site4
300
y = 20.274x - 213.13
R² = 0.9518
200
10
Fig 8: Correlation of site 2
Site 3
300
0
30
Fig 7: Correlation of site 1
400
y = 13.54x - 99.469
R² = 0.4829
y = 20.584x - 204.41
R² = 0.9712
200
100
100
0
0
0
10
20
0
30
Fig 9: Correlation of site 3
10
20
30
Fig 10: Correlation of site 4
400
Overall Correlation
300
y = 20.283x - 201.51
R² = 0.9608
200
100
0
0
10
20
30
Fig 11: Correlation of Loricariidae across all sites
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Emily Iles
Cichlidae
r
r²
d.f. (n-1)
p<0.05
p<0.01
Significance
Strength
Character
Site 1
0.9885
0.7566
7
0.666
0.798
Significant
Very Strong
Positive
Site 2
0.8389
0.8046
10
0.576
0.708
Significant
Strong
Positive
Site 3
0.9199
0.9211
5
0.754
0.874
Significant
Very Strong
Positive
Site 4
0.9999
0.9627
1
0.997
0.9999
Significant
Very Strong
Positive
Overall
0.9195
0.8455
26
0.374
0.479
Significant
Very Strong
Positive
Table 10: Correlation between length and of Cichlidae across sites.
Sites
1
2
3
4
Total
Standard Error From regression
6.719
19.43
5.324
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.
200
Site 1
200
y = 19.809x - 153.35
R² = 0.977
150
150
100
100
50
50
0
0
Site 2
10
y = 13.836x - 84.634
R² = 0.7039
0
20
0
Fig 12: Correlation of site 1
60
y = 12.178x - 70.446
R² = 0.8463
0
9.5
10
10.5
11
20
Site 4
60
20
15
80
Site 3
40
10
Fig 13: Correlation of site 2
100
80
5
11.5
Fig 14: Correlation of site 3
12
12.5
y = 2640x - 27648
R² = 2E-09
40
20
0
10.5
10.5
10.5
10.5
10.5
Fig 15: Correlation of site 4
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200
Overall Correlation
150
100
y = 16.424x - 116.11
R² = 0.82741
50
0
0
5
10
15
20
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%.
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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
Within
Total
97.70
959.65
1057.35
3
103
106
32.57
9.32
3.50
<5%
Table 12: ANOVA Table for Erythrinidae results
Calculated body condition of Erythrinidae species
16
Body condition
14
12
10
8
6
4
2
0
Site 1
Site 2
Site 3
Site 4
Fig 17: Graph showing ANOVA results for Erythrinidae species with standard error bars.
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Emily Iles
5.2.2. Loricariidae
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 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
Between
SS
df
s2
F
P
1.04
<5%
30.38
3
10.13
Within
400.40
41
9.76
Total
430.78
44
Table 13: ANOVA Table for Loricariidae results
Calculated body condition for Loricariidae species
14
Body condition
12
10
8
6
4
2
0
Site 1
Site 2
Site 3
Site 4
Fig 18: Graph showing ANOVA results for Loricariidae species with standard error bars.
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Emily Iles
5.2.3. Cichlidae
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 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
Within
Total
10.62
68.06
78.68
3
24
27
3.54
2.84
1.25
<5%
Table 14: ANOVA Table for Cichlidae results
Body Condition of Cichlidae Across Sites
9
Body Condition
8
7
6
5
4
3
2
1
0
site 1
site 2
site 3
site 4
Fig 19: Graph showing ANOVA results for Cichlidae species with standard error bars.
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Emily Iles
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.
H
Species Richness
3
2.5
Shannon Weiner Diversity Index
Site 4
Site 1
Site 3
2
1.5
Site 1
2.25
Site 2
1.19
Site 3
1.90
Site 4
2.43
Site 2
1
0.5
0
H
Fig 20: Shannon Weiner Diversity Index
Abundance of Fish Caught at Each Site
35
30
27%
30%
25%
25
17.0%
20
15
10
5
0
site 1
site 2
site 3
Site 4
Percentage
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
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Emily Iles
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.
25
20
15
10
5
0
23
Family Diversity and Abundance
at Site 1
18
8
9
9
1
0
1
Fig 22: Site 1
25
20
15
10
5
0
24
60
50
40
30
20
10
0
Family Diversity and Abundance
at Site 2
56
6
21
0
3
0
0
6
0
2
0
Family Diversity and Abundance
at Site 4
20
15
Fig 24: Site 3
0
Fig 23: Site 2
Family Diversity and Abundance
at Site 3
6
11
3
10
15
9
5
0
8
2
4
0
2
1
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.
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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,
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Emily Iles
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.
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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.
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Emily Iles
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
38
Emily Iles
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.
600
Overall correlation
500
y = 0.0107x3.2386
R² = 0.89297
400
300
200
100
0
0
10
20
30
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
39
Emily Iles
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 cubeproportional 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.
40
Emily Iles
200
Site 2 - Adjusted for Anomalous
Result
150
100
y = 12.979x - 96.383
R² = 0.89966
50
0
0
5
10
15
20
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
41
Emily Iles
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
15
Average length of Cichlidae
species
10
5
site 1
site 2
site 3
site 4
Average weight of Cichlidae
species
100
Average weights
Average length
to group in habitats characterised by refugia such as sites 3 and 4.
50
0
Site 1 Site 2 Site 3 Site 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.
42
Emily Iles
60
50
40
30
20
10
0
Family Diversity and Abundance
at Site 2
56
6
11
0
0
3
0
0
25
20
15
10
5
0
24
Family Diversity and Abundance
at Site 3
21
6
6
0
2
0
3
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
43
Emily Iles
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
Loricariidae
Prochilodontidae
Curmitidae
18
9
1
Anostomidae
0
Charicidae
9
Cichlidae
9
Erythrinidae
Serrisalmidae
23
1
Site 2
Detrivores
6
0
0
Herbivores
0
Insectivores
3
Omnivores
11
Piscivores
56
0
Site 3
Site 4
6
0
3
15
3
1
3
0
0
7
6
2
24
20
9
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.
44
Emily Iles
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
45
Emily Iles
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:
Scientific name:
Ecology:
Status:
Shuyo
Hoplerythrinus unitaeniatus
Erythrinus erythrinus
Freshwater pelagic species. Piscivourous ambush predator on smaller fish.
Not evaluated. Important in fisheries and aquariums.
Local name:
Scientific name:
Ecology:
Status:
Fasaco
Hoplias malabaricus
Fresh water pelargic species. Piscivourous ambush predator on smaller fish.
Not evaluated. fisheries: commercial; aquarium: commercial
Local name:
Scientific name:
Carachama(Common Pleco)
Liposarcus pardalis
Pseudorinelepis genibarbis
Pterygoplichthys pardalis
Ancistrus heterorhynchus
46
Emily Iles
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:
Scientific name:
Bujurqui
Aequidens tetramerus
Chaetobrachus flavescens
Cichlasoma amazonarum
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.
Not evaluated. fisheries: minor commercial; aquarium: commercial
Ecology:
Status:
Local name:
Scientific name:
Ecology:
Status:
Local name:
Curuhuara
Colossoma macropomum
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.
Not evaluated.
Piraña blanca / roja
47
Emily Iles
Scientific name:
Ecology:
Status.
Serrasalmus rhombeus
Pygocentrus nattereri
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.
Not evaluated. fisheries: commercial; aquarium: commercial
Local name:
Scientific name:
Ecology:
Status:
Boquichico
Prochilodus nigricans
Benthopelagic; potamodromous.
Not evaluated. Fisheries: commercial; aquaculture: commercial;
aquarium: commercial
Local name:
Scientific name:
Ecology:
Sardinia
Triportheus angulatus
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.
Not evaluated. Fisheries: subsistence fisheries; bait: occasionally
Status:
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Emily Iles
Local name:
Scientific name:
Ecology:
Status:
Sábalo Cola negra / Roja
Brycon melanopterus
Brycon cephalus
Benthopelagic; potamodromous freshwater; pH range: 6.0 - 7.5. South
America: Upper Amazon River basin in Peru and Bolivia.
Not evaluated. aquarium: commercial
49
Emily Iles
(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
Hoplias malabaricus
Fasaco
Hoplerythrinus unitaeniatus
Shuyo
Erythrinidae
Erythrinus erythrinus
Triportheus angulatus
Sardina
Brycon melanopterus
Sábalo Cola negra
Brcon Cephalus
Sábalo Cola roja
Pygocentrus nattereri
-
Serrasalmus rhombeus
Piraña roja
Colossoma macropomum
Piraña blanca
Mylossoma aureum
Curuhuara
Ancistrus heterorhynchus
Carachama ancistrus
Liposarcus pardalis
Carachama (Common Pleco)
Pseudorinelepis genibarbis
Carachama
Pterygoplichthys pardalis
Carachama
Aequidens tetramerus
Bujurqui
Chaetobranchus flavescens
Bujurqui vaso
Cichlidae
Cichlasoma amazonarum
Bujurqui
Curimatidae
Curimatoides ucayalensis
-
Characidae
Serrasalmidae
Loricariidae
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Emily Iles
(Appendix 3) Raw Data.
Date
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
11/06/2009
11/06/2009
06/06/2009
06/06/2009
14/06/2009
14/06/2009
11/06/2009
09/06/2009
13/06/2009
13/06/2009
01/06/2009
05/06/2009
02/06/2009
06/06/2009
10/06/2009
06/06/2009
11/06/2009
11/06/2009
11/06/2009
03/06/2009
11/06/2009
11/06/2009
11/06/2009
04/06/2009
12/06/2009
04/06/2009
04/06/2009
04/06/2009
04/06/2009
04/06/2009
04/06/2009
04/06/2009
08/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
06/06/2009
03/06/2009
08/06/2009
02/06/2009
30/05/2009
03/06/2009
03/06/2009
03/06/2009
Location
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
Site 4
Site 4
Site 4
Site 4
site 1
Site 3
Site 3
Site 3
Site 3
Site 3
Site 4
Site 4
Site 4
Site 4
site 1
site 1
site 1
site 1
site 1
site 1
site 1
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 4
site 1
Site 2
Site 4
site 1
site 1
site 1
site 1
Time
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
Nets
N1
N3
N3
N3
N3
N3
N3
N3
N3
N3
N3
N2
N3
N3
N3
N3
N3
N1
N1
N1
N3
N2
N2
N1
N1
N3
N3
N3
N3
N3
N1
N1
N1
N1
N1
N1
N1
N2
N3
N1
N1
N1
N2
N2
N2
N2
N2
N3
N1
N1
N1
N2
N2
N2
Sci. name
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
Prochilodus nigicans
curimatoides ucayalensis
curimatoides ucayalensis
curimatoides ucayalensis
curimatoides ucayalensis
hypoptopoma littorale
hypoptopoma littorale
curimatoides ucayalensis
hypoptopoma littorale
hypoptopoma littorale
Triportheus genibarbis
Aequidens tetramerus
Aequidens tetramerus
Aequidens tetramerus
cichlasoma amazonarum
cichlasoma amazonarum
cichlasoma amazonarum
cichlasoma amazonarum
Aequidens tetramerus
Aequidens tetramerus
cichlasoma amazonarum
cichlasoma amazonarum
cichlasoma amazonarum
cichlasoma amazonarum
cichlasoma amazonarum
cichlasoma amazonarum
cichlasoma amazonarum
cichlasoma amazonarum
Aequidens tetramerus
Aequidens tetramerus
Aequidens tetramerus
Aequidens tetramerus
Aequidens tetramerus
Aequidens tetramerus
cichlasoma amazonarum
Chaetobrachus flavescens
Chaetobrachus flavescens
Chaetobrachus flavescens
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Comm.Nam
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
Boquichico
?
?
?
?
?
?
?
?
?
?
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui
Bujurqui vaso
Bujurqui vaso
Bujurqui vaso
carachama
carachama
carachama
carachama
L(cm)
16
21.5
26
23.5
23.5
24
13.5
16
14
18
21
19
19.5
15.5
15.5
14.5
13.5
13
12.5
14
17
12.5
16
12
12
12
11.5
11
10
10
9.5
11.5
13
12
12.5
10
10
13.5
15.5
11.5
11
10
12
10
12
10.5
10.5
16.5
15.5
10.5
24
22.5
25
22.5
Wt (gm)
110
210
340
270
260
255
50
100
70
155
225
170
175
75
70
60
50
90
80
60
155
50
145
90
90
75
65
65
50
45
45
75
90
120
75
50
50
115
100
60
55
55
80
50
75
60
55
175
150
40
350
250
280
230
51
Emily Iles
03/06/2009
03/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
11/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
04/06/2009
04/06/2009
04/06/2009
08/06/2009
08/06/2009
08/06/2009
01/06/2009
05/06/2009
05/06/2009
05/06/2009
05/06/2009
09/06/2009
06/06/2009
14/06/2009
14/06/2009
14/06/2009
02/06/2009
06/06/2009
06/06/2009
06/06/2009
14/06/2009
06/06/2009
06/06/2009
10/06/2009
10/06/2009
10/06/2009
06/06/2009
07/06/2009
01/06/2009
05/06/2009
30/05/2009
02/06/2009
05/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
02/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
site 1
Site 3
Site 3
site 1
Site 4
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 4
Site 3
Site 3
Site 3
Site 3
Site 3
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
N3
N3
N1
N1
N1
N1
N2
N2
N3
N1
N1
N1
N1
N2
N1
N1
N1
N1
N1
N1
N2
N3
N1
N1
N1
N2
N3
N1
N2
N2
N1
N3
N3
N3
N3
N1
N1
N1
N1
N3
N2
N1
N1
N2
N1
N2
N2
N2
N2
N2
N2
N3
N1
N1
N1
N1
N1
N1
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
pseudorinelepis genibarbis
pseudorinelepis genibarbis
pterygoplichthys pardalis
pterygoplichthys pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
pseudorinelepis genibarbis
Liposarcus pardalis
Liposarcus pardalis
pterygoplichthys pardalis
pterygoplichthys pardalis
pterygoplichthys pardalis
pterygoplichthys pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
Liposarcus pardalis
pseudorinelepis genibarbis
pseudorinelepis genibarbis
pseudorinelepis genibarbis
pseudorinelepis genibarbis
pseudorinelepis genibarbis
pterygoplichthys pardalis
pterygoplichthys pardalis
pterygoplichthys pardalis
pterygoplichthys pardalis
pterygoplichthys pardalis
Ancistrus heterorhynchus
Hoplias malabaricus
Schizodon fasciatus
Schizodon fasciatus
colossoma macropomum
mylossoma aureum
Serrasalmus rhombeus
Serrasalmus rhombeus
Serrasalmus rhombeus
Serrasalmus rhombeus
Serrasalmus rhombeus
Serrasalmus rhombeus
Serrasalmus rhombeus
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama
carachama ancistrus
Fasaco
Lisa cachete amarillo
Lisa cachete amarillo
Curuhuara
Piraña ?
Piraña blanca
Piraña blanca
Piraña blanca
Piraña blanca
Piraña blanca
Piraña blanca
Piraña blanca
Piraña roja
Piraña roja
Piraña roja
Piraña roja
Piraña roja
12.5
10.5
15.5
17
21.5
22.5
24
22
14
23
15
13.5
24
23
15
16.5
14.5
15
15
13.5
14
25
23.5
23
15
23
17.5
28.5
23
16.5
12
14.5
14
16
14.5
24.5
25
31
26
17
13
25
19
20.5
17
13
11.5
12
11.5
12
11
10
10
18
17.5
21
18.5
15.5
50
30
90
135
245
250
270
240
90
300
95
80
275
270
90
120
95
130
100
80
70
330
250
250
100
225
140
390
290
105
40
105
90
135
100
275
345
450
280
150
70
270
150
150
200
70
35
60
50
50
50
30
25
205
275
325
235
155
52
Emily Iles
09/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
09/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
02/06/2009
02/06/2009
02/06/2009
03/06/2009
11/06/2009
11/06/2009
11/06/2009
12/06/2009
12/06/2009
12/06/2009
06/06/2009
14/06/2009
14/06/2009
14/06/2009
11/06/2009
30/05/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
03/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
07/06/2009
11/06/2009
11/06/2009
11/06/2009
04/06/2009
08/06/2009
31/05/2009
04/06/2009
04/06/2009
04/06/2009
04/06/2009
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
site 1
site 1
site 1
site 1
site 1
Site 4
Site 4
Site 4
site 1
site 1
site 1
site 1
Site 2
Site 2
Site 2
Site 4
Site 4
Site 4
Site 4
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
site 1
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
N1
N1
N1
N1
N1
N1
N2
N2
N2
N2
N3
N3
N3
N3
N3
N1
N1
N1
N1
N3
N3
N3
N1
N1
N2
N2
N2
N2
N2
N1
N1
N1
N1
N1
N1
N1
N3
N3
N3
N3
N1
N1
N1
N3
N3
N3
N3
N3
N1
N1
N3
N1
N1
N2
N1
N1
N1
N1
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Pygocentrus nattereri.
Brycon melanopterus
Brycon melanopterus
Brycon melanopterus
Brycon melanopterus
Brycon melanopterus
Brycon melanopterus
Brycon melanopterus
Brycon melanopterus
Brycon cephalus
Triportheus angulatus
Triportheus angulatus
Triportheus angulatus
Triportheus angulatus
Triportheus angulatus
Triportheus angulatus
Triportheus angulatus
Triportheus angulatus
Triportheus angulatus
Triportheus angulatus
erythrinus erythrinus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
erythrinus erythrinus
erythrinus erythrinus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Piraña roja
Piraña roja
Piraña roja
Piraña roja
Piraña roja
Piraña roja
Piraña roja
Piraña roja
Piraña roja
Piraña roja
Sábalo Cola negra
Sábalo Cola negra
Sábalo Cola negra
Sábalo Cola negra
Sábalo Cola negra
Sábalo Cola negra
Sábalo Cola negra
Sábalo Cola negra
Sábalo Cola Roja
Sardina
Sardina
Sardina
Sardina
Sardina
Sardina
Sardina
Sardina
Sardina
Sardina
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
18
17
17
17.5
17
18
18.5
19
16
15
15
16
15
15.5
15.5
16
15.5
15
25
14
14
15
15
15
17
14.5
15
15.5
15.5
22
28
24
23.5
21.5
25.5
22
17.5
25.5
24.5
17.5
23
23
28.5
24.5
25
27.5
26
20.5
27.5
24.5
26
18.5
18.5
29
25
24
24.5
26.5
225
205
210
175
225
210
300
290
155
110
70
75
70
70
70
100
80
70
255
55
50
70
60
65
65
49
75
65
50
255
570
300
305
225
370
250
115
230
300
125
265
305
540
370
415
500
430
220
475
350
250
130
145
500
350
350
385
460
53
Emily Iles
04/06/2009
04/06/2009
04/06/2009
04/06/2009
04/06/2009
04/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
08/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
12/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 2
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
N1
N2
N2
N2
N2
N2
N1
N1
N1
N1
N1
N1
N1
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N1
N1
N1
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N1
N2
N1
N1
N1
N1
N1
N1
N1
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
erythrinus erythrinus
erythrinus erythrinus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
23
23
22.5
25.5
23
22.5
25.5
23
23
20
25
26.5
20.5
20.5
24
24.5
25
25
23
24.5
25
25
25.5
23.5
23.5
24
24.5
22.5
24
26
23
23.5
26.5
23.5
23
24
25
24.5
26
24.5
23
29
23
26
24.5
22
25
24
24.5
18.5
16.5
24
24
25
27
19.5
22
22
270
260
300
395
300
260
370
290
260
185
380
400
160
350
350
375
380
340
270
355
315
350
420
280
290
310
390
260
380
470
225
280
430
340
330
320
325
305
355
365
300
560
350
410
350
260
390
315
350
130
70
350
300
360
460
160
210
160
54
Emily Iles
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
01/06/2009
05/06/2009
05/06/2009
02/06/2009
06/06/2009
06/06/2009
06/06/2009
14/06/2009
14/06/2009
14/06/2009
14/06/2009
14/06/2009
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 3
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
Site 4
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
2hrs
N1
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N2
N1
N2
N1
N3
N2
N3
N2
N2
N3
N3
N3
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Hopleryhtrinus unitaeniatus
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
Shuyo
21
24.5
23.5
27
27
25
28
27
28.5
25
23
25.5
25
23
21.5
14
23.5
18.5
23
18.5
22
22
27.5
24.5
170
350
340
420
545
400
520
500
500
380
250
400
340
290
215
50
290
120
270
125
250
255
460
330
55
Emily Iles
8. References:
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hyoid musculature in the suckermouth armoured catfish Ancistrus cf. triradiatus
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Luz-Agostinho, KDG, Agostinho, AA, Gomes, LC, Júlio-Jr, HFand Fugi, R. (2009)Effects
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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.
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Jonathan W. Armbruster, Nathan K. Lujan, Mark H. Sabaj and David C. Werneke.
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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
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conservation–development initiatives in tropical forests: insights from analyses of rain
forest use and economic reliance among Amazonian peasants. ibcperu.org
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Conservation in the Samiria River Basin of the Pacaya Samiria National Reserve, Peru.
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Barthem R. and Goulding M. (1997). The Catfish Connection. Ecology, Migration, and
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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
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Second Edition.
Gene S. Helfman, Bruce B. Collette, Douglas E. Facey. (1997). The Diversity of Fishes.
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Goulding M., Smith N.J.H., and Mahar D.J. (1996). Floods of Fortune. Ecology and
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Wolfgang Junk (2000).Concepts for the Sustainable Management of Natural Resources
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Emiko Kawakami de Resende (1989) THE FLOOD PULSE CONCEPT AND ITS
RELATION TO FISH BIOLOGY IN THE PANTANAL. nrem.iastate.edu
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William F. Loftus Leo G. Nicoand James P. Reid. (2009). Interactions between nonnative armored suckermouth catfish (Loricariidae:Pterygoplichthys) and native Florida
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(2008). Influence of flood pulses on diet composition and trophic relationships among
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Val & Almeida-Val, (1995). EVOLUTIONARY FEATURES OF HYPOXIA
TOLERANCEIN FISH OF THE AMAZON:FROM MOLECULAR TO BEHAVIORAL
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www-heb.pac.dfo-mpo.gc.ca.pdf
http://www.iucnredlist.org/apps/redlist/details/1991/0
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