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

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 <em>Crassostrea</em><em> gasar</em> 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 <em>C. gasar</em> by this microorganism. Thus, it is likely that <em>C. gasar</em> is not an effective tool to reduce suspended solids in IMTA, but this organism can highly benefited from protozoan present in BFT system.当前，水产养殖业正致力于构建契合全球可持续发展需求且降低环境影响的生产模式。其中一项被广泛采纳的技术路径为多营养层级综合水产养殖（integrated multi-trophic aquaculture, IMTA）：该模式通过养殖不同营养级别的物种，提升养分利用效率并提升养殖系统的经济收益。与此同时，生物絮团技术系统（Biofloc Technology system, BFT）作为一项极具潜力的环保养殖技术也受到广泛关注。为遵循IMTA原则并降低总悬浮颗粒物（total suspended solids, TSS），本研究评估了牡蛎<em>Crassostrea gasar</em>对TSS的去除效果，及其对生物絮团中微生物群落的影响。本实验以正在开展的海水虾养殖水体为实验载体，设置两组处理：添加牡蛎组与无牡蛎对照组，实验周期为5天，期间定期采集水样与牡蛎胃容物用于微生物组成分析。两组的水质参数均未呈现显著差异，总悬浮颗粒物含量与絮团总数也无显著差异，表明牡蛎的存在并未对总悬浮颗粒物总量产生影响。然而，双壳类动物的胃容物中鞭毛虫占绝对优势，这说明<em>Crassostrea gasar</em>对该类微生物存在捕食选择性。综上，<em>Crassostrea gasar</em>或许并非降低IMTA系统中悬浮颗粒物的有效工具，但该物种可从BFT系统中的原生动物处获取充足的营养来源。