Assessment of the environmental sustainability of cobia fish farm (Rachycentron Canadum) in the bay of Ilha Grande - Brazil and the relationship with benthic macrofauna

Abstract

Studies on the sustainability of aquaculture have been carried out around the world. The input of organic matter in the sediment and the influence of current velocity on the deposition of particles produced by fish in captivity can be used to assess the distribution of benthic assemblages below marine farms. Sediment and benthic organisms were collected in April, September and December 2019 and in August and October 2020 in the fish farming area and in two control areas in the Bananal cove in Ilha Grande Bay. The measurement of the speed of local currents was carried out below the net-tank, in periods of 24 days in of April and July 2019. The heterogeneity of the biological data was evident between the collection points, indicating that several factors can influence the distribution of benthic macrofauna. There was no correlation between the values of organic matter and species richness and for organic matter and species diversity. The values of the Marine Biotic Index (AMBI) for the three collection stations were smaller than 1 (one), that is, there was a predominance of species sensitive to pollution and organic enrichment. The marine farm and the control areas were considered an unpolluted environment. The results also indicated that the local currents presented insufficient intensities to disperse the organic matter produced in the marine farm to the control areas.