Department of Biological Sciences, Florida International University, 3000 NE 151st Street, North Miami, FL, 33181, USA.
Division of Natural Sciences, New College of Florida, 5800 Bayshore Rd, Sarasota, FL, 34243, USA.
Sci Rep. 2020 Jul 16;10(1):11847. doi: 10.1038/s41598-020-68843-0.
The integration of eDNA analysis into the population assessment and monitoring of sharks could greatly improve temporal and spatial data used for management purposes. This study aimed to compare eDNA detection against well-established seasonal changes in blacktip shark (Carcharhinus limbatus) abundance in Terra Ceia Bay (FL, USA). We used a species-specific real-time PCR approach to detect C. limbatus eDNA in the bay on a near monthly basis from spring through mid-fall in 2018 and 2019. Previous studies have shown that C. limbatus give birth in the bay in early summer and immature sharks occur there until late fall, when decreasing water temperatures cause them to move offshore and southwards. Water samples (2 L) were collected (4-6 per month) and filtered in the field, with each then being subjected to real-time PCR. Carcharhinus limbatus 'positive' filters were significantly more commonly collected during the April-July sampling period than during the August-October sampling period. While following the predicted pattern, eDNA concentration was generally too low for accurate quantification. Our results show that C. limbatus eDNA detection follows known seasonal residency patterns consistently over 2 years of monitoring. Species-specific eDNA analysis using real-time PCR could therefore represent a cost-effective, scalable sampling tool to facilitate improved shark population monitoring in semi-enclosed marine habitats.
将环境 DNA 分析纳入鲨鱼种群评估和监测中，可以大大改善用于管理目的的时间和空间数据。本研究旨在比较环境 DNA 检测与黑鳍鲨（Carcharhinus limbatus）丰度的既定季节性变化，该研究地点为美国佛罗里达州 Terra Ceia 湾。我们使用特定于物种的实时 PCR 方法，于 2018 年和 2019 年春季至初秋，近乎每月在湾内检测 C. limbatus 的环境 DNA。先前的研究表明，C. limbatus 于初夏在湾内分娩，幼鲨在湾内存在直至深秋，此时水温下降导致它们向近海和南部移动。采集（每月 4-6 次）并在现场过滤（2 升）水样，然后对每个水样进行实时 PCR 分析。与预期模式一致，在 4 月至 7 月采样期间，C. limbatus“阳性”过滤器的采集频率明显高于 8 月至 10 月采样期间。虽然遵循预测模式，但由于环境 DNA 浓度通常太低，无法进行准确的定量。我们的结果表明，在 2 年的监测过程中，C. limbatus 的环境 DNA 检测始终遵循已知的季节性居留模式。因此，使用实时 PCR 的特定于物种的环境 DNA 分析可以成为一种具有成本效益、可扩展的采样工具，以促进半封闭海洋栖息地中鲨鱼种群的监测。
