Effects of a nuclear power plant thermal discharge on habitat complexity and fish community structure in Una Grande Bay, Brazil

摘要

Fish communities and habitat structures were evaluated by underwater visual censuses a rocky location impacted by thermal discharge (I) and at two control locations, one in a Sargassum bed (C1) and the other in a rocky shore with higher structural complexity (C2). Habitat indicators and fish communities exhibited significant differences between the impacted and control locations, with the impacted one showing a significant decrease in fish species richness and diversity, as well as a decrease in benthic cover. At the I location, only 13 fish species were described, and the average water temperature was 32 ± 0.4 ℃, compared with 44 species at C1 (25.9 ± 0.3 ℃) and 33 species at C2 (24.6 ± 0.2 ℃). Significant differences in fish communities among locations were found by ANOSIM with Eucinostomus argenteus, Mugil sp. and Haemulon steindachneri typical of location I, while Abudefduf saxatilis, Stegastes fuscus and Malacoct-enus delalandi were typical of the control locations. Our study shows that thermal pollution alters benthic cover and influences fish assemblages by altering composition and decreasing richness.