Monitoring of carcinofauna abundance and diversity during eight years of expressway construction in Santa Catarina, Brazil

Abstract

Crustaceans are important in estuarine ecosystems, transferring energy to higher trophic levels and contributing to artisanal and industrial fisheries. This paper aims to evaluate the carcinofauna diversity and abundance in Saco dos Limões and how this changed when affected by dredging during the construction of an expressway through South Bay, Florianópolis, Santa Catarina, Brazil. Collections were made onboard a commercial fishing boat for three months, day and night, at six sampling sites from 1997 to 2006. The families Penaeidae and Portunidae were the most diverse in terms of taxa, with the largest species abundances. Thedominant species were the shrimps Farfantepenaeus brasiliensis, F. paulensis, and Litopenaeus schmitti, and the crab Callinectes danae. The largest abundances were found in two areas, in the summer and at night. The diversity and equitability indices showed similar patterns, with the highest values in autumn and winter. Acording to the Jaccard index, the similarity of the crustacean composition was highest for the years 2005 and 2006 and lowest between 1997 and 2005. The structure of the carcinofauna changed over the years, with high mortalities during dredging operations followed by a recovery in the subsequent years. Our observations indicated that dredging did not have catastrophic effects nor did it produce long-term disturbances in the carcinofauna of the estuary. It is important to monitor natural resources in order to record the extent and limits of human impacts on the environment.