Robson Heather L A, Noble Tansyn H, Saunders Richard J, Robson Simon K A, Burrows Damien W, Jerry Dean R
College of Marine and Environmental Sciences, James Cook University, Townsville, Qld, 4811, Australia.
TropWATER-Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Townsville, Qld, 4811, Australia.
Mol Ecol Resour. 2016 Jul;16(4):922-32. doi: 10.1111/1755-0998.12505. Epub 2016 Feb 24.
Invasive species pose a major threat to aquatic ecosystems. Their impact can be particularly severe in tropical regions, like those in northern Australia, where >20 invasive fish species are recorded. In temperate regions, environmental DNA (eDNA) technology is gaining momentum as a tool to detect aquatic pests, but the technology's effectiveness has not been fully explored in tropical systems with their unique climatic challenges (i.e. high turbidity, temperatures and ultraviolet light). In this study, we modified conventional eDNA protocols for use in tropical environments using the invasive fish, Mozambique tilapia (Oreochromis mossambicus) as a detection model. We evaluated the effects of high water temperatures and fish density on the detection of tilapia eDNA, using filters with larger pores to facilitate filtration. Large-pore filters (20 μm) were effective in filtering turbid waters and retaining sufficient eDNA, whilst achieving filtration times of 2-3 min per 2-L sample. High water temperatures, often experienced in the tropics (23, 29, 35 °C), did not affect eDNA degradation rates, although high temperatures (35 °C) did significantly increase fish eDNA shedding rates. We established a minimum detection limit for tilapia (1 fish/0.4 megalitres/after 4 days) and found that low water flow (3.17 L/s) into ponds with high fish density (>16 fish/0.4 megalitres) did not affect eDNA detection. These results demonstrate that eDNA technology can be effectively used in tropical ecosystems to detect invasive fish species.
入侵物种对水生生态系统构成重大威胁。它们的影响在热带地区可能尤为严重，比如澳大利亚北部地区，那里记录有超过20种入侵鱼类。在温带地区，环境DNA（eDNA）技术作为检测水生害虫的工具正日益受到关注，但在面临独特气候挑战（即高浊度、高温和紫外线）的热带系统中，该技术的有效性尚未得到充分探索。在本研究中，我们以入侵鱼类莫桑比克罗非鱼（Oreochromis mossambicus）为检测模型，对传统eDNA方案进行了改进，以用于热带环境。我们使用孔径较大的过滤器以方便过滤，评估了高水温及鱼类密度对罗非鱼eDNA检测的影响。大孔径过滤器（20μm）在过滤浑浊水体和保留足够的eDNA方面效果良好，同时每2升样品的过滤时间为2至3分钟。热带地区常见的高水温（23、29、35°C）并未影响eDNA降解速率，不过高温（35°C）确实显著提高了鱼类eDNA的释放速率。我们确定了罗非鱼的最低检测限（1条鱼/0.4百万升/4天后），并发现低水流速（3.17升/秒）流入高密度鱼类池塘（>16条鱼/0.4百万升）并不影响eDNA检测。这些结果表明，eDNA技术可有效用于热带生态系统中检测入侵鱼类物种。
