The following schedule is from the 72nd Annual Conference of the Southeastern Association of Fish & Wildlife Agencies which was held October 21-24, 2018 in Mobile, Alabama.
AUTHORS: Nicole M. Phillips, Katherine E. Schweiss, Ryan N. Lehman – The University of Southern Mississippi, Department of Biological Sciences; J. Marcus Drymon, Mississippi State University, Coastal Research & Extension Center; Gregg R. Poulakis, Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, Charlotte Harbor Field Laboratory; Jill M. Hendon, The University of Southern Mississippi, Center for Fisheries Research and Development
ABSTRACT: One quarter of elasmobranchs are threatened with extinction according to the International Union for Conservation of Nature and nearly one half are categorized as Data Deficient, meaning there is insufficient data to assess their statuses. Environmental DNA (eDNA) has emerged as a non-invasive approach to fill data gaps on the distribution of elasmobranchs, however, the extent to which these data can be used to guide management decisions for threatened species, which are typically rare, is dependent upon the sensitivity of the methods employed. False negatives occur when a target species is present, but is not detected due to detection limits of the assays or sampling regimes that do not consider habitat use. In eDNA studies, water samples are filtered, DNA extractions performed on the particulate, and primers are developed to amplify DNA in only the target species. To date, most eDNA studies have used quantitative real-time PCR (qRT-PCR) to determine the presence/absence of species in marine systems, where DNA may have low residency time due to the large area, tides, and currents. We compared the detection limits of qRT-PCR and droplet digital PCR (ddPCR) by obtaining positive water samples using the bull shark, Carcharhinus leucas, as a model species. DdPCR was the more sensitive platform, making it the ideal approach for eDNA studies targeting threatened species. We then used ddPCR to investigate the persistence of elasmobranch eDNA in a flow-through mesocosm designed to mimic natural flow regimes, which will facilitate interpretation of elasmobranch eDNA surveys in the Gulf of Mexico.
