| Resumo: |
I investigated changes in abundance and spatial distribution of medium- and large-sized fishes (>100 mm) in an oxbow lake of the lower Apaporis River, Colombian Amazon, across three seasons (falling, low, and rising water). Fifty-three species in 13 families were collected from six habitats: lagoon channels, stream, flooded forests, isolated shrub patches, muddy beaches, and rocks. Abundance, biomass, and species richness were higher during the rising-water season and lower during falling-water season. Correspondence analysis (CA) showed that fish assemblages were associated to two basic habitat types. One assemblage of fishes was associated with densely vegetated and structurally complex habitats (flooded forest, lagoon channels, stream, and isolated shrub patches), and a second assemblage of fishes was associated with muddy beaches. These assemblages persisted despite seasonal fluctuations in water level. Species in the structurally complex habitats assemblage were mostly omnivores, whereas the beach habitat assemblage included mainly piscivores and detritivores. Results from this study suggest that overall abundance of fishes in habitats within and surrounding Taraira Lake is highly variable among seasons, but species habitat affinity is maintained through seasons.
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