Morphology and Niche Partitioning of Fish Assemblage in the Tonle Sap Biosphere Reserve – a Case Study of the Prek Toal Core Area Lan Thi Ngoc Nguyen’18 Supervised by: Dr. Chouly Ou The School for Field Studies, Center for Mekong Studies, Siem Reap, Cambodia Abstract Fish sampled at the edge of a flooded forest in the Prek Toal Core Area of TSBR during the beginning of the dry season from November 18 to November 28, 2015. Classified 27 fish species into 5 trophic groups, 2 habitat types, and 3 migration patterns. 31 morphological features from 1-3 largest individuals of each species were measured and analyzed using principal component analysis and cluster analysis, based on the findings in Winemiller’s paper (1991). Microbial swab in the field Cleaning control egg Introduction BELKI would like to thank Professor Dr. Chouly Ou for her close guidance and support throughout the planning, data collection, and writing stages of this project. I also thank our SAM Mackenzie Klema and intern Maura Monagan for their assistance during data collection on the field, especially Maura for her helpful edits on my paper. I want to thank Ben Stablow for his aid with species identification. I would like to thank Mr. Sun Visal for his support and the two rangers from the Ministry of Environment in Prek Toal who helped us collect the fish every morning. I am grateful to the host family for allowing us to stay and conduct our research in their household in Prek Toal. Finally, I want to thank donors from SFS and Hollins University for offering generous financial aid, A relationship between certain morphological characteristics and habitat/trophic groups were identified. The study exhibited evidence of niche partitioning within a structurally diverse community of fish assemblage to support stable coexistence of competing species. TSBR has high fish biodiversity due to seasonal and habitat variability that allows fish to occupy different niches. Understanding the relationship of these morphological characteristics to niche partitioning may aid in the management of the fisheries in this important ecosystem. Future work with a larger sample sizes per species as well as samples throughout the annual cycle are warranted as seasonal hydrology plays an important role in this ecosystem. Objectives: To examine the relationship between morphology and niche partitioning in TSBR. To determine morphological features that strongly influence niche partitioning. Morphological studies illustrate community structure and ecological adjustments among different species in the same habitat. The coexistence of competing species in a diverse community results in niche partitioning to increase stabilization. This study tests the relationship between morphology and niche partitioning to understand the coexistence of diverse fish assemblages in the Tonle Sap Biosphere Reserve, one of the world’s most productive inland wetlands, a tropical river ecosystem that supports high biodiversity, especially fish population. By measuring 31 morphological variables and gathering ecological data of the collected 27 fish species, this study applied principal component analysis and cluster analysis to examine the influence of morphology on the ecological niches of the fish assemblage. The results of the study demonstrate that the diversification in morphological characters directly determine niche partitioning of the fish assemblage in the Tonle Sap Biosphere Reserve. Results and Discussions Method and Materials Conclusion Ecomorphology is the link between form and function of an organism (Winemiller 1991; Wainwright 1996) Niche partitioning refers to the adaptations of coexisting species for resources and space (Scoener 1974; Gatz 1979) Tonle Sap Biosphere Reserve (TSBR) is the largest freshwater lake in Southeast Asia that supports more than 150 species of fish. Tasha Mae Ashleigh MUST – Mustard Hill ELK – Elkhorn BRFI – Branching Fire GROBRA – Grooved Brain Coral Acknowledgments ELK MUST Figure 1: Location of the study site (red dot) in the Prek Toal core area 20.99% of total variance 39.73% of total variance Figure 3: Dendrogram from the cluster analysis of 27 species from 3 families and 7 orders. Cluster analysis divided the fish assemblage into 5 groups by trophic categories and habitat type. The different characteristics of body shape, tooth shape, and mouth orientation, indicated that the 5 groups utilize different habitats, feed at various water- column depth, and have different diets. Species Code Identification N.n = Notopterus notopterus, P.t = Paralaubuca typus, R.a = Rasbora aurotaenia, C.a = Cyclocheilichthys apogon, H.l = Hypsibarbus lagleri, H.m = Hampala macrolepidota, P.b = Puntius brevis, P.l = Puntius leiacanthus, Th.t = Thynnichthys Thynnoides, D.s = Dangila spilopleura, H.s = Henicorhynchus siamensis, O.h = Osteochilus hasselti, M.m = Mystus multiradiatus, M.a = Micronema apogon, O.b = Ompok bimaculatus, O.e = Ompok eugeneiatus, X.c = Xenentodon cancila, M.s = Macrognathus siamensis, A.k = Ambassis kopsi, To.m = Toxotes microlepis, P.f = Pristolepis fasciata, A.t = Anabas testudineus, Tr.m = Trichogaster microlepis, Tr.p = Trichogaster pectoralis, Tr.t = Trichogaster trichopterus, C.s = Channa striata, M.f = Monotreta fangi. Figure 2: Ordination diagram from PCA for the 31 morphological variables of 27 studied species from 13 families and 7 orders. Symbols represent TROPHIC groups (squares – algaevores; dots - insectivores, plus - omnivores, and diamonds - piscivores.) Colors represent habitat type (Brown represents species of the flood plain and BLUE represents species in river channels. PCA component 1 was most closely associated with separating fish in the various trophic groups while PCA 2 was more closely associated with separating groups by habitat type. References Gatz, A 1979, ‘Community organization in fishes as indicated by morphological features’, Ecological Society of America, vol. 60, pp. 711-718. Schoener, T 1974, ‘Resource partitioning in ecological communities’, Science, vol. 185, pp 27- 39. Wainwright, P 1996, ‘Ecological explanation through functional morphology: the feeding biology of sunfishes’, Ecological Society of America, vol. 77, pp 1336-1343. Winemiller, K 1991, ‘Ecomorphological diversification in lowland freshwater fish assemblages from five biotic regions’, Ecological Monographs, vol. 61, pp. 343-365.
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Morphology and Niche Partitioning of Fish Assemblage in the Tonle Sap Biosphere Reserve – a Case Study of the Prek Toal Core Area
Lan Thi Ngoc Nguyen’18Supervised by: Dr. Chouly Ou
The School for Field Studies, Center for Mekong Studies, Siem Reap, CambodiaAbstract
Fish sampled at the edge of a flooded forest in the Prek Toal Core Area of TSBR during the beginning of the dry season from November 18 to November 28, 2015.
Classified 27 fish species into 5 trophic groups, 2 habitat types, and 3 migration patterns.
31 morphological features from 1-3 largest individuals of each species were measured and analyzed using principal component analysis and cluster analysis, based on the findings in Winemiller’s paper (1991).
Microbial swab in the fieldCleaning control egg
Introduction
BELKI would like to thank Professor Dr. Chouly Ou for her close guidance and support throughout the planning, data collection, and writing stages of this project. I also thank our SAM Mackenzie Klema and intern Maura Monagan for their assistance during data collection on the field, especially Maura for her helpful edits on my paper. I want to thank Ben Stablow for his aid with species identification. I would like to thank Mr. Sun Visal for his support and the two rangers from the Ministry of Environment in Prek Toal who helped us collect the fish every morning. I am grateful to the host family for allowing us to stay and conduct our research in their household in Prek Toal. Finally, I want to thank donors from SFS and Hollins University for offering generous financial aid, especially the Hobbie Trust Fund, Janet McDonald Fund, Claudia W. Belk International Scholarship Fund, and the SGA Instructional Endowment Fund for making this experience possible.
A relationship between certain morphological characteristics and habitat/trophic groups were identified.
The study exhibited evidence of niche partitioning within a structurally diverse community of fish assemblage to support stable coexistence of competing species.
TSBR has high fish biodiversity due to seasonal and habitat variability that allows fish to occupy different niches.
Understanding the relationship of these morphological characteristics to niche partitioning may aid in the management of the fisheries in this important ecosystem.
Future work with a larger sample sizes per species as well as samples throughout the annual cycle are warranted as seasonal hydrology plays an important role in this ecosystem.
Objectives: To examine the relationship between morphology and niche partitioning in TSBR.To determine morphological features that strongly influence niche partitioning.
Morphological studies illustrate community structure and ecological adjustments among different species in the same habitat. The coexistence of competing species in a diverse community results in niche partitioning to increase stabilization. This study tests the relationship between morphology and niche partitioning to understand the coexistence of diverse fish assemblages in the Tonle Sap Biosphere Reserve, one of the world’s most productive inland wetlands, a tropical river ecosystem that supports high biodiversity, especially fish population. By measuring 31 morphological variables and gathering ecological data of the collected 27 fish species, this study applied principal component analysis and cluster analysis to examine the influence of morphology on the ecological niches of the fish assemblage. The results of the study demonstrate that the diversification in morphological characters directly determine niche partitioning of the fish assemblage in the Tonle Sap Biosphere Reserve.
Results and Discussions
Method and Materials
Conclusion
Ecomorphology is the link between form and function of an organism (Winemiller 1991; Wainwright 1996)
Niche partitioning refers to the adaptations of coexisting species for resources and space (Scoener 1974; Gatz 1979)
Tonle Sap Biosphere Reserve (TSBR) is the largest freshwater lake in Southeast Asia that supports more than 150 species of fish.
Tasha Mae Ashleigh
MUST – Mustard Hill ELK – Elkhorn
BRFI – Branching Fire
GROBRA – Grooved Brain Coral
Acknowledgments
ELK
MUST
Figure 1: Location of the study site (red dot) in the Prek Toal core area
20.9
9% o
f tot
al v
aria
nce
39.73% of total variance
Figure 3: Dendrogram from the cluster analysis of 27 species from 3 families and 7 orders. Cluster analysis divided the fish assemblage into 5 groups by trophic categories and habitat type. The different characteristics of body shape, tooth shape, and mouth orientation, indicated that the 5 groups utilize different habitats, feed at various water-column depth, and have different diets.
Species Code IdentificationN.n = Notopterus notopterus, P.t = Paralaubuca typus, R.a = Rasbora aurotaenia, C.a = Cyclocheilichthys apogon, H.l = Hypsibarbus lagleri, H.m = Hampala macrolepidota, P.b = Puntius brevis, P.l = Puntius leiacanthus, Th.t = Thynnichthys Thynnoides, D.s = Dangila spilopleura, H.s = Henicorhynchus siamensis, O.h = Osteochilus hasselti, M.m = Mystus multiradiatus, M.a = Micronema apogon, O.b = Ompok bimaculatus, O.e = Ompok eugeneiatus, X.c = Xenentodon cancila, M.s = Macrognathus siamensis, A.k = Ambassis kopsi, To.m = Toxotes microlepis, P.f = Pristolepis fasciata, A.t = Anabas testudineus, Tr.m = Trichogaster microlepis, Tr.p = Trichogaster pectoralis, Tr.t = Trichogaster trichopterus, C.s = Channa striata, M.f = Monotreta fangi.
Figure 2: Ordination diagram from PCA for the 31 morphological variables of 27 studied species from 13 families and 7 orders. Symbols represent TROPHIC groups (squares – algaevores; dots - insectivores, plus - omnivores, and diamonds - piscivores.) Colors represent habitat type (Brown represents species of the flood plain and BLUE represents species in river channels. PCA component 1 was most closely associated with separating fish in the various trophic groups while PCA 2 was more closely associated with separating groups by habitat type.
ReferencesGatz, A 1979, ‘Community organization in fishes as indicated by morphological features’, Ecological Society of America, vol. 60, pp. 711-718.Schoener, T 1974, ‘Resource partitioning in ecological communities’, Science, vol. 185, pp 27-39.Wainwright, P 1996, ‘Ecological explanation through functional morphology: the feeding biology of sunfishes’, Ecological Society of America, vol. 77, pp 1336-1343. Winemiller, K 1991, ‘Ecomorphological diversification in lowland freshwater fish assemblages from five biotic regions’, Ecological Monographs, vol. 61, pp. 343-365.
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