Manatee Detectives: Aqueous eDNA vs. sedaDNA

All Manatees are protected under the U.S. Endangered Species Act of 1973, with not all listed as endangered.  Research is being conducted to determine if manatee numbers are dwindling to endangered levels from human impacts such as boat strikes and noise pollution.  Aircraft surveys (1991-2014 winters) observed manatee abundance along Florida’s coasts however manatees submerged deep underwater or seagrass skewed abundance estimations.  Knowing the population levels of the West Indian Manatee, Trichechus manatus will better inform conservation efforts.  Recently, environmental DNA methods have been developed, for the manatees that may be present at sites but not seen aerially.  A primer to latch onto the manatee eDNA was developed, specifically targeting 69 base pairs in the cytochrome b region (mitochondrial DNA).  We sampled five different locations dispersed around Tampa Bay for water and sediment.  We hypothesized that there will be a higher detection rate of manatee eDNA in sediment samples compared to water column samples.  eDNA accumulated in sediment lasts longer than suspended in the above water due to protection from temperature, water state, UV rays, and water pH.  Manatee fecal matter would sink into the soil therefore more of the eDNA for the manatee would be integrated into the sediment after settling.‌  There was no detection of manatee eDNA in the PCR or in the qPCR.  This could be due to the slow metabolism of manatees causing low DNA concentrations, therefore more trials or larger water samples are needed. 

For more information email: cjwallace@eckerd.edu