Evaluating eDNA survey capabilities to improve Endangered Species Act consultation associated with permitting bridge projects

Environmental DNA (eDNA) Detection for Endangered Freshwater Mussels

In Florida, the Choctawhatchee River is a special place where four endangered species of freshwater mussels make their homes, with two species found only in this river. The Office of Environmental Management (OEM) of the Florida Department of Transportation (FDOT) contracted us to develop and implement an environmental DNA (eDNA) pilot study to facilitate detection—the presence or probable absence—of freshwater mussels.

This study compares the efficiency of eDNA to visual surveys in addressing Endangered Species Act consultations for permitting requirements. The comparison study also extends to efficiencies in providing mussel assemblage data, reducing overall costs of projects, expediting timeframes for project delivery, and reducing safety concerns. In addition, the eDNA survey may be completed with less effort, averaging 6.67 person hours, compared to 15.5 person hours for the visual surveys, and can be completed with a smaller field crew in safer conditions. Other advantages of eDNA surveys include providing comparable information to a visual qualitative survey, implementation in environments that challenge tactile surveys, and completion without a federal mussel permit holder.

Our eDNA survey within the Choctawhatchee River basin successfully detected the four federally protected mussel species observed with visual surveys—confirming their presence with less effort.