Data from: Estimating fish abundance and biomass from eDNA concentrations: variability among capture methods and environmental conditions

Environmental DNA (eDNA) promises to ease non-invasive quantification of fish biomass or abundance, but its integration within conservation and fisheries management is currently limited by a lack of understanding of the influence of eDNA collection method and environmental conditions on eDNA concentrations in water samples. Water temperature is known to influence the metabolism of fish and consequently could strongly affect eDNA release rate. As water temperature varies in temperate regions (both seasonally and geographically), the unknown effect of water temperature on eDNA concentrations poses practical limitations on quantifying fish populations using eDNA from water samples. This study aims to clarify how water temperature and the eDNA capture method alter the relationships between eDNA concentration and fish abundance/biomass. Water samples (1 L) were collected from 30 aquaria including triplicate of 0, 5, 10, 15 and 20 Brook Charr specimens at two different temperatures. Water samples were filtered with five different types of filters. The eDNA concentration obtained by quantitative PCR (qPCR) varied significantly with fish abundance and biomass and type of filters (Mixed-design ANOVA, P < 0.001). Results also show that fish released more eDNA in warm water than cold water and that eDNA concentration better reflects fish abundance/biomass at high temperature. From a technical standpoint, higher levels of eDNA were captured with glass fiber (GF) than mixed cellulose ester (MCE) filters and support the importance of adequate filters to quantify fish abundance based on the eDNA method. This study supports the importance of including water temperature in fish abundance/biomass prediction models based on eDNA.

环境DNA（eDNA）为鱼类生物量或丰度的无创定量提供了可行途径，但目前其在保护与渔业管理中的应用仍受限于对eDNA采集方法与环境条件如何影响水样中eDNA浓度的认知不足。已知水温会影响鱼类代谢，进而可能显著影响eDNA的释放速率。由于温带地区的水温存在季节性与地理性差异，水温对eDNA浓度的未知影响，给利用水样eDNA定量鱼类种群带来了实际限制。本研究旨在阐明水温和eDNA捕获方法如何改变eDNA浓度与鱼类丰度/生物量之间的相关关系。研究从30个水族箱中采集了1升水样，涵盖0、5、10、15、20尾白斑红点鲑（Brook Charr）各三组重复样本，并设置了两种不同水温条件。水样采用五种不同类型的滤膜进行过滤。通过定量聚合酶链式反应（qPCR）测得的eDNA浓度，随鱼类丰度、生物量以及滤膜类型的变化呈现显著差异（混合设计方差分析，P<0.001）。研究结果还显示，相较于低温环境，鱼类在温水中释放的eDNA更多，且在高温条件下eDNA浓度能更好地反映鱼类丰度/生物量。从技术层面来看，玻璃纤维（GF）滤膜捕获的eDNA水平高于混合纤维素酯（MCE）滤膜，这证实了基于eDNA方法定量鱼类丰度时选用合适滤膜的重要性。本研究证实，在基于eDNA的鱼类丰度/生物量预测模型中纳入水温参数具有重要意义。