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Effects of flow fluctuations on the daily and seasonal drift of invertebrates in a tropical river

By Diego M. P. Castro, Robert M. Hughes and Marcos Callisto

Abstract

Invertebrate drift results from several factors, including accidental dislodgement from the substratum, interaction with other invertebrates and predators, and changes in water quality, discharge and current velocity. We evaluated the degree to which flow fluctuations from dam releases altered the daily and seasonal invertebrate drift patterns in a tropical river. We collected macroinvertebrates during fixed flow rates (323 m3.s−1 in the wet season and 111 m3.s−1 in the dry season) and when peak flows fluctuated (378–481 m3.s−1 in the wet season and 109–173 m3.s−1 in the dry season) in 2010. Of the 31 924 organisms collected, 8872 individuals and 43 taxa were collected in the wet season and 23 052 and 32 taxa were collected during the dry season. Seasonality had a strong influence on invertebrate assemblage composition and structure in the drift. During fixed flow periods, drift densities were greatest in the dry season and drift taxonomic richness was greatest in the wet season. In the wet season, fluctuating flows increased nocturnal drift density and richness, but decreased diurnal richness; in the dry season, fluctuating flows decreased drift densities and diurnal richness. In conclusion, the daily and seasonal invertebrate drift patterns are influenced by dam operations that alter flows and this knowledge can be used to reduce the downstream effects of dams

Topics: Hydropeaking, aquatic insects, dams, flow changes
Publisher: EDP Sciences
Year: 2013
DOI identifier: 10.1051/limn/2013051
OAI identifier: oai:edpsciences.org:dkey/10.1051/limn/2013051
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