Sampling Sufficiency in Fish Assemblage Surveys for Assessing Species Richness and Biotic Integrity in Atlantic Forest Streams in Southeastern Brazil

It is critical to know the adequacy of field sampling protocols for detecting species and assessing biological condition. Several studies have been conducted for estimating the appropriate electrofishing distance to estimate fish assemblage richness in temperate North American streams. We tested whether electrofishing 40 times the mean wetted channel width was sufficient for estimating species richness and developing precise metrics for Atlantic Forest streams in southeastern Brazil. We sampled 32 sites with differing gradients, substrates, and anthropogenic pressures. Our results show that 40 channel widths was not sufficient to estimate total species richness in those systems, presumably because of the high number of rare species).  However, 40 channel widths were sufficient for applying other metrics of assemblage condition (e.g. Number of common species, % Tolerant individuals,   % Characiform species, % Siluriform species, %Water column species, % Benthic species, Shannon diversity, Dominance). This suggests that 40 channel widths are an appropriate sampling distance for applying environmental assessment protocols to Atlantic Forest streams.