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Survey of Vulnerable Amazonian Manatees Using Environmental DNA (eDNA): Methods for Surveys in Remote Field Settings
No full textThe Amazonian manatee (Trichechus inunguis) is the only exclusively freshwater manatee. The IUCN lists them as a vulnerable species, with population decline projected to continue during the coming decades. Threats to the T. inunguis population, such as illegal hunting, water pollution, and alteration and destruction of their habitat, make accurate survey methods necessary for assessing distribution and abundance. In this study, I used environmental DNA (eDNA) methods to test for T. inunguis presence in three locations along the Amazon River (Tef��, Manaus, Bel��m). At each location, water samples were collected at sites spanning a disturbance gradient from urban to protected reserves. I developed a field methodology to preserve DNA for up to 13 days or more without requiring freezing or cooling of samples. This method performed similarly to traditional cooling methods used for eDNA research. In the lab, samples were processed by DNA extraction, PCR amplification, and Illumina sequencing. Detection of Amazonian manatee DNA was more than three times greater in the Tef�� region of the western Amazon where human impacts were lowest, but manatee DNA also was detected at one or two sites in the Manaus (central Amazon) and Bel��m (eastern Amazon) regions. This methodology appears to be highly effective for detecting aquatic species in support of biodiversity conservation in tropical rivers
