Biofloc removal by the oyster Crassostrea gasar as a candidate species to an Integrated Multi-Trophic Aquaculture (IMTA) system with the marine shrimp Litopenaeus vannamei

Abstract

Currently, aquaculture seeks to implement production models that keep up with the global demands for sustainability and reduced environmental impacts. One of the options adopted is integrated multi-trophic aquaculture (IMTA), which cultivates species of different trophic levels, improving the use of nutrients and increasing the economic profitability of the system. On the other hand, the Biofloc Technology system (BFT) has also been highlighted as an important eco-friendly activity. In an attempt to reduce total suspended solids (TSS) and in accordance with the IMTA principles, the present work evaluated the action of the oyster Crassostrea gasar on the reduction of TSS and its influence on the microbial community present on the bioflocs. An experiment with two treatments (With and Without Oyster) was carried out in waters from an ongoing marine shrimp crop. The experiment lasted for 5 days, when water samples and oyster stomach content were collected for analysis of microorganisms. The water quality parameters did not show significant differences. The TSS and aggregates number also showed no differences between treatments, indicating that the presence of oysters did not influence the amount of total suspended solids. However, the predominance of flagellates in the stomach contents of the bivalves indicates a prey selectivity by C. gasar by this microorganism. Thus, it is likely that C. gasar is not an effective tool to reduce suspended solids in IMTA, but this organism can highly benefited from protozoan present in BFT system.