Abstract
Abstract The riparian vegetation in lakes and reservoirs is source of course wood structures such as trunks and branches and is used as sheltering, spawning and foraging habitats for fishes. The reduction of these submerged structures can thus, affect the composition and structure of fish assemblages in reservoirs. Aim To evaluate the influence of riparian vegetation on the biotic condition of fish assemblage by adapting the Reservoir Fish Assemblage Index (RFAI) to two reservoirs in the Upper Paranapanema river basin, São Paulo State, Brazil. Methods The RFAI was adapted from metrics related to the functional characteristics and composition of fish assemblages through a protocol of metric selection and validation, and to its response to the presence of riparian vegetation. Results The final RFAI was composed by nine metrics, been lower in sites without riparian vegetation as consequence of the predominance of larger individuals and the percent of piscivorous and detritivorous fishes. Conclusions These results suggest that increasing shore habitat complexity in reservoirs by maintaining riparian vegetation increases fish biotic integrity.
Highlights
Restoration actions in environments under anthropogenic pressures require identifying keystone structures that will help maintaining regional species diversity and biological condition (Tews et al, 2004)
Experimental studies proved that enhancing the underwater habitat complexity by means of artificial reefs or natural coarse woody habitats (CWH) structures increases fish diversity, and affects assemblage dynamics and trophic interactions
Our adaptation focusing on evaluate the effects of sections of shoreline with and without riparian vegetation and found that biotic condition of fish assemblages was higher in the first
Summary
Restoration actions in environments under anthropogenic pressures require identifying keystone structures that will help maintaining regional species diversity and biological condition (Tews et al, 2004). The loss of wood debris are among the highest sources of fish habitat degradation in reservoirs across United States (Miranda et al, 2010) Removal of these coarse woody habitats (CWH) has complex effects on ecosystem functioning by altering percent of sheltering and spawning habitats and predator‐prey interactions (Roth et al, 2007). Helmus & Sass (2008) for example, showed that experimental removal of CWH resulted in a rapid declining of the yellow perch (Perca flavescens (Mitchill, 1814)) abundance, probably due to losing of sheltering habitats and spawning structures In another experiment, the piscivorous fish largemonth bass (Micropterus salmoides (Lacepede, 1802)) reduced its home range and lowering its consumption rates after CWH removal, while the opposite pattern was observed after CWH placement (Ahrenstorff et al, 2009)
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