Data_Sheet_1_Hatchery tanks induce intense reduction in microbiota diversity associated with gills and guts of two endemic species of the São Francisco River.doc

The São Francisco River (SFR), one of the main Brazilian rivers, has suffered cumulative anthropogenic impacts, leading to ever-decreasing fish stocks and environmental, economic, and social consequences. Rhinelepis aspera and Prochilodus argenteus are medium-sized, bottom-feeding, and rheophilic fishes from the SFR that suffer from these actions. Both species are targeted for spawning and restocking operations due to their relevance in artisanal fisheries, commercial activities, and conservation concerns. Using high-throughput sequencing of the 16S rRNA gene, we characterized the microbiome present in the gills and guts of these species recruited from an impacted SFR region and hatchery tanks (HT). Our results showed that bacterial diversity from the gill and gut at the genera level in both fish species from HT is 87% smaller than in species from the SFR. Furthermore, only 15 and 29% of bacterial genera are shared between gills and guts in R. aspera and P. argenteus from SFR, respectively, showing an intimate relationship between functional differences in organs. In both species from SFR, pathogenic, xenobiont-degrading, and cyanotoxin-producer bacterial genera were found, indicating the critical pollution scenario in which the river finds itself. This study allowed us to conclude that the conditions imposed on fish in the HT act as important modulators of microbial diversity in the analyzed tissues. It also raises questions regarding the effects of these conditions on hatchery spawn fish and their suitability for restocking activities, aggravated by the narrow genetic diversity associated with such freshwater systems.

圣弗朗西斯科河（SFR），作为巴西主要河流之一，遭受了累积的人为影响，导致鱼类资源持续减少，并引发环境、经济和社会的诸多后果。Rhinelepis aspera 和 Prochilodus argenteus 是来自 SFR 的中型底栖、喜流鱼类，它们受到这些影响。这两种物种因其在手工艺渔业、商业活动及保护关注中的重要性，而成为繁殖和补充种群的目标。通过16S rRNA基因的高通量测序技术，我们对来自受影响SFR区域及孵化池（HT）的这些物种的鳃部和肠道微生物群落进行了表征。我们的研究结果表明，来自孵化池的两种鱼类鳃部和肠道的细菌多样性在属水平上比来自SFR的物种减少了87%。此外，在SFR的R. aspera 和 P. argenteus 的鳃部和肠道中，仅有15%和29%的细菌属是共有的，这显示了器官功能差异之间的密切关系。在SFR的两种鱼类中，均发现了病原体、异生物降解者和蓝藻毒素产生菌属，这表明河流正处于一个关键的污染情境中。本研究使我们得出结论，孵化池对鱼类的限制条件是分析组织微生物多样性的重要调节因素。同时，这也引发了关于这些条件对孵化池繁殖鱼的影响及其是否适合补充种群活动的疑问，尤其是在与这类淡水系统相关的狭窄遗传多样性加剧了这一情况。