Determining the Origin and Fate of Marine eDNA

Trawling has been the traditional method for monitoring diversity of benthic communities. Offshore wind is rapidly developing within the Mid Atlantic waters of the United States. Construction of wind turbines will pose challenges to traditional sampling methods because trawling gear in the vicinity of turbine foundations will be limited. Environmental DNA (eDNA) has emerged as a new tool for monitoring marine ecosystems and biodiversity. The use of eDNA is a cost-effective approach to replace traditional sampling. However, there is limited information on the origin, fate and transport of eDNA in the ocean. Therefore, we utilized surface current data from a High Frequency radar network to advect particles backward in time to assess the origin of water that was collected as part of an eDNA sampling campaign. eDNA was sampled west of Cape May, NJ on December 8, 2021. Twenty surface particles were released in the HFR surface current field and allowed to drift backwards in time for five days. Surface and bottom currents from the DOPPIO regional ocean model were also used to transport the passive tracers backwards in time. In this one instance using the HFR surface currents the particles advected to the northwest over the five days originating in the back bays of Cape May NJ. The particles traveled approximately 35 km over the five days. Similarly, the DOPPIO surface currents also indicated a reverse drift to the northwest but after 2 days the currents weakened and particles remained near the sampling location. In contrast the DOPPIO bottom currents displayed a different trajectory indicating source waters originated from the south. These findings underscore the significance of considering various data sources and models when analyzing eDNA transport, as well as the potential for HF radar surface current data to provide valuable insights into the origin and transport of marine genetic material. Such research is crucial as the offshore wind energy industry continues to expand, emphasizing the need for innovative monitoring methods to ensure effective environmental stewardship in the changing coastal landscape.