Evaluation of the relationship between habitat structure, community structure, and community assembly in a Neotropical blackwater river /
Basic mechanisms structuring Neotropical fish communities are unclear, and aquatic communities in Neotropical rivers frequently have been characterized as "random associations." In this study, I examined patterns of local assembly of fishes and macroinvertebrates among habitats of varying...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2002.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=726465981&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Basic mechanisms structuring Neotropical fish communities are unclear, and aquatic communities in Neotropical rivers frequently have been characterized as "random associations." In this study, I examined patterns of local assembly of fishes and macroinvertebrates among habitats of varying structural complexity (sand beach, leaf litter, rock, and submerged wood) and between diel periods through an annual flood cycle. The study system, the Cinaruco River, is a floodplain river located in the southern llanos of Venezuela with > 260 fish species. I characterized structure of local aquatic communities among habitat types and between diel periods using indirect gradient analyses. Species distributions among habitats were evaluated using a randomization procedure. I used a direct gradient analysis to evaluate the influence of environmental variables (e.g., flow, depth) on community structure within each habitat type. I collected 348 standardized samples that contained 83,798 individual fishes representing 190 species, and 10,309 macroinvertebrates representing 9 families. Samples from similar habitats were clustered together in a non-random fashion. Non-random patterns were least variable during the low-water season and most variable during the rising-water and falling-water periods. Most taxa were non-randomly distributed among habitats, but this relationship was strongest during the low-water season. In addition to habitat structural complexity, diel periodicity and fine-scale environmental variables affected local community composition. In spite of the large magnitude of seasonal variation in hydrology and habitat availability in the Cinaruco River, species richness and abundance on sand beaches varied relatively little. These results reject the 'random associations' hypothesis and suggest that tropical river communities are continually disassembled and reassembled in a deterministic manner as the aquatic-terrestrial interface moves across the landscape in response to seasonal hydrology. Unexplained variation in community structure appears to be due to unsaturated local communities. Because species probably colonize patches in no particular sequence, partially-assembled, unsaturated communities should be more variable than saturated communities. Finally, I demonstrated the effect of colonization rate and habitat structural complexity on species richness of the local community. Interactions among seasonal hydrology, variability in habitat structural complexity, and landscape heterogeneity contribute to maintenance of high aquatic species richness in Neotropical lowland rivers. |
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| Item Description: | Vita. "Major Subject: Wildlife and Fisheries Sciences". |
| Physical Description: | xiii, 122 leaves : illustrations, map ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 93-111). |