Ichthyofauna as an environmental quality indicator of the Bertioga Channel, São Paulo (Brazil)

Abstract

The aim of this study was to investigate the ichthyofauna structure in the region of the north outfall of the Bertioga Channel (São Paulo, Brazil) and the possible effects of the environmental quality loss. The samples were collected in a monthly basis, from September to December 2005, at two oceanographic stations with an otter-trawl. The fish fauna structure was evaluated by ecological indicators and the environmental quality evaluated by the ABC analysis and the Estuarine Fish Communities Index (EFCI). A total of 1553 individuals from 50 species were sampled. Ariidae and Sciaenidae amounted to 60 % and Cathorops spixii represented 36 % of all specimens collected. The highest richness and ecological diversity were recorded in December, while the highest numerical abundance was found in October. The majority of the species were represented by juveniles. The cluster analysis and canonical correspondence analysis showed a consistent and clear difference between the sampling stations, and the abiotic factors analyzed (temperature, depth and salinity) do not seem to have influence on the community structure. The ABC analysis suggested a moderate disturbed environment and the EFCI allowed classifying the area as "poor", due to the 12 metrics analyzed, concerning the reduction of the species diversity, composition and abundance, and modifications in the nursery function and trophic integrity of the area. Future studies should focus on jointly analyze chemical indicators of water and sediment with the biological indicators, to confirm the ichthyofaunal condition of the north outfall of the Bertioga Channel.