Fish farming can have a negative impact on water quality and aquatic organisms due to emerging blooms of Cyanobacteria and the production of cyanotoxins. In this study, the effect of aquaculture in hydroelectric reservoirs in Brazil was evaluated in six fish farms and in upstream and downstream water through analysis of the microbiome, Cyanobacteria and microcystin concentrations. Synechococcus and Microcystis were observed at all six locations, while Limnothrix was also observed abundantly at two locations. An increase in the relative abundance of Cyanobacteria inside the fish farms was observed at two locations, while an increase of Cyanobacteria was observed in downstream at five of the six locations. Microcystins were detected in significant and high values in all locations, with concentrations up to 1.59 μg/L. The trend in microcystin concentrations was mirrored in copy numbers of the mcyE gene (encodes microcystin synthetase) and presence of Microcystis, but not in any of the other observed cyanobacterial groups. In summary, the study shows that aquaculture production influenced the water microbiome inside and downstream the fish farms, and a direct correlation was found between mcyE gene copies, microcystin production and abundance of Microcystis, but not for the total abundance of Cyanobacteria.

由于蓝藻的大量繁殖和蓝藻毒素的产生，养鱼业可能对水质和水生生物产生负面影响。在这项研究中，通过分析微生物组，蓝细菌和微囊藻毒素浓度，对六个水产养殖场以及上游和下游水域中水产养殖的影响进行了评估。在所有六个位置均观察到了球菌和微囊藻，而在两个位置也均观察到了林氏菌。在两个地点观察到养鱼场内蓝细菌的相对丰度增加，而蓝细菌的增加在六个地点中有五个在下游观察到。在所有位置检测到的微囊藻毒素均显着较高值，浓度高达1.59μg/ L。微囊藻毒素浓度的趋势反映在mcyE基因的拷贝数（编码微囊藻毒素合成酶）和微囊藻的存在上，但在其他观察到的蓝细菌组中却没有。总而言之，研究表明水产养殖产量影响了养鱼场内部和下游的水微生物组，并且发现mcyE基因拷贝，微囊藻毒素产量与微囊藻的丰度之间存在直接相关性，但与蓝细菌的总丰度没有直接相关性。