Distribuição espacial de uma espécie endêmica e insular de Hyalella (Crustacea, Amphipoda) em riachos da Mata Atlântica de Florianópolis, ilha de Santa Catarina

Abstract

Lotic ecosystems are biodiverse environments that form different mesohabitats suitable for some species of crustaceans, such as those of the genus Hyalella, endemic to the Americas. In the state of Santa Catarina, a new species was recently discovered – the first insular species of Hyalella in Brazil, on the island of Florianópolis – Hyalella insulae. The species was sampled in the Municipal Natural Monument of Lagoa do Peri (MONA), south of the island of Florianópolis, state of Santa Catarina, which has a large source of fresh water in the state of SC, consisting of two watersheds: Cachoeira Grande and Ribeirão Grande. Thus, this study aims to analyze the spatial distribution of H. insulae in two mesohabitats (backwater and rapids) of two watersheds (Cachoeira Grande and Ribeirão Grande) located in MONA. Specimens of that species were sampled in stretches of rifles and pools between winter/2010 and summer/2012, in three 1st to 3rd order streams inserted in the two watersheds, totaling 192 samples. It was observed that most samples with the presence of H. insulae occurred in the Cachoeira Grande watershed. The mean total abundance of H. insulae was higher in the pools stretches of Cachoeira Grande streams when compared to Ribeirão Grande. In the streams of both watersheds, in addition to males and females, juveniles of H. insulae were collected, which demonstrates that the species is reproducing in these streams. In addition, a higher concentration of dissolved oxygen and lower values of water temperature, water velocity, electrical conductivity and alkalinity were observed in Cachoeira Grande. This study demonstrated the preference of H. insulae for pools stretches of streams in Cachoeira Grande, which has primary and dense vegetation, unlike Ribeirão Grande, where areas with secondary vegetation and evidence of anthropic actions are observed in the surroundings. Thus, this study demonstrates the importance of studies regarding the distribution of endemic species, as well as the conservation and preservation of island streams and their biota.