Use of environmental DNA (eDNA) and water quality data to predict protozoan parasites outbreaks in fish farms
Use of environmental DNA (eDNA) and water quality data to predict protozoan parasites outbreaks in fish farms
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DOI：
10.1016/j.aquaculture.2017.06.021
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发表时间：
2017-10-01
期刊：
影响因子：
4.5
通讯作者：
Jerry, Dean R.
中科院分区：
文献类型：
--
作者：
Bastos Gomes, Giana;Hutson, Kate S.;Jerry, Dean R.
在全球范围内，疾病约占水产养殖产量损失的40%。通常，疾病的发生是由于农场管理人员无法准确量化其生产系统中致病物质的丰富程度而导致的疾病风险，以及对疫情如何与水质参数变化联系在一起的了解不足。与分子技术相关的环境DNA(EDNA)采样方法适合于快速评估养鱼场中病原体的背景存在，从而为管理者提供可用于减轻疾病威胁的关键信息。本研究以纤毛虫原生动物六条虫为模型，研究了六条虫的环境DNA和临界水分参数与商业Barramundi Lates Calcarifer养殖场疾病暴发的关系，该养殖场在一年的时间内每月采集水样。采用基于核糖体小亚基基因的定量聚合酶链式反应技术，对池塘水中六尾轮虫的丰度(SSU-rDNA拷贝数/亩L)进行了监测。六条线虫水平的增加与后期鱼类死亡事件的发生高度相关(r=0.402；P<；0.001)，与鱼的大小也高度相关(r=-0.189；P<；0.05)；较小的鱼更容易受到寄生虫流行病的影响。然而，测量的任何水质参数(降雨量、水温和溶解氧)与这种寄生虫的丰度之间没有发现相关性，尽管在更温暖、更潮湿的季风季节观察到的鱼死亡明显多于更凉爽、干燥的季节(分别为1280对135死亡；P<；0.05)。这项研究强调了EDNA方法作为一种管理工具的潜力，以快速评估水中的寄生虫负载，并将水产养殖系统中疾病暴发的风险降至最低。
Globally, disease accounts for around 40% of lost aquaculture production. Commonly, disease occurs due to an inability of farm managers to accurately quantify disease risk due to the abundance of the pathogenic agent in their production systems, along with a poor understanding of how outbreaks are linked to changes in water quality parameters. Environmental DNA (eDNA) sampling methodology associated with molecular techniques is suited to rapidly assess the background presence of pathogens in fish farms, thereby providing managers with critical information that can be used to mitigate disease threats. Adopting the ciliate protozoan Chilodonella hexasticha as a model, this study examined the relationship between environmental DNA of C. hexasticha, critical water parameters and the occurrence of disease outbreaks on a commercial barramundi Lates calcarifer farm, where water was sampled monthly over a 1 year timeframe. A qPCR assay based on the small subunit ribosomal DNA gene was used to monitor the abundance of C. hexasticha in pond water (SSU-rDNA copies/mu L). Increased C. hexasticha eDNA levels were found to be highly correlated with occurrence of later fish mortality events (r = 0.402; P < 0.001) and also with size of fish (r = - 0.189; P < 0.05); smaller fish were more prone to being impacted by an epizootic of the parasite. However, no correlations were found between any of the water quality parameters measured (rainfall, water temperature and dissolved oxygen) and abundance of this parasite, although there were significantly more fish mortalities observed during the warmer, wetter monsoonal season compared to the cooler, dry season (1280 vs. 135 mortalities, respectively; P < 0.05). This study highlights the potential of an eDNA approach as a management tool to quickly assess parasite loads in water and minimise the risk of disease outbreaks in aquaculture systems.