Robotic eDNA Sampling to Track Ocean Life Around Offshore Wind

The United States plans to install 30 gigawatts of offshore wind energy by 2030. Offshore renewable energy development (ORED) is central to global plans to decarbonize electricity and address climate change, but building and running its infrastructure is expected to change marine habitat. New structures and the human activity around them may overlap with animal migrations or feeding, and communities of species may change as their ranges shift.

To avoid harm, federal agencies — the National Oceanic and Atmospheric Administration, the Department of the Interior and the Department of Energy among them — and state agencies need to understand how these projects may alter the sea and its biodiversity. That knowledge supports regulatory requirements and guides management and conservation, including for species of conservation concern: those in steep decline, naturally rare, or limited in range.

Reading life from a water sample

Monitoring life offshore is hard and expensive because marine communities are so diverse and complex. But organisms such as fish, reptiles and mammals leave traces of genetic material — DNA and RNA — in the water, and analyzing it shows which species were likely present. This environmental DNA (eDNA), together with environmental RNA, can be collected by simply taking a water sample, reducing the need for costly research ships and staff time.

Paired with autonomous robotic samplers, eDNA collection can cover everything from microbes to mammals, more often and in more places than would otherwise be possible. That gives the detailed, fuller picture needed for accurate monitoring, letting scientists track species over time and space, set a genetic baseline and detect changes in biodiversity.

Sampling marine eDNA: (A) today's ship-deployed conductivity/temperature/depth instruments, and experimental (B) autonomous underwater vehicles and (C) moored robotic samplers. After filtering, the eDNA is analyzed to infer which species are present. USGS.

What USGS already does

• Deep-sea eDNA. In studies with NOAA, USGS has collected eDNA from the surface to the sea floor, 60 to 4,500 meters deep, using remotely operated vehicles and instruments deployed from ships and autonomously. The results link the deep-water food web to the more productive surface and, with environmental data, give a baseline of biodiversity, help define water masses and food webs, and show how the ecosystem works.
• Robotic samplers. In proof-of-concept tests, robotic samplers at river streamgages monitored invasive mussels, introduced fishes, and human and fish pathogens; taking several samples a day for weeks or months, they cut false-negative detections and gave a fuller picture of biodiversity. USGS has also put samplers on autonomous underwater vehicles in the Great Lakes to monitor fish, and is working with the Monterey Bay Aquarium Research Institute on scalable, robust, easy-to-run samplers for routine monitoring.
• Statistics. USGS led the development of occupancy models, which correct for imperfect detection — a site looking empty when a species is there, or the reverse — and show where and when to survey to reach a monitoring goal, such as a set precision for marine mammals at an offshore wind site. USGS has extended them to eDNA, for example in studies of vulnerable manatee populations, with software such as EDNAOCCUPANCY and msocc, and is adding eDNA concentrations to model rare species and combining eDNA with acoustics, imagery and trawls.

What still needs work

Like any new technology, robotic eDNA sampling has gaps. Vehicles need to sample at different depths and process samples on board. Interpreting results means identifying species more accurately, tying eDNA to where species actually are (since eDNA drifts away from its source), deciding where and when to deploy samplers, and building models that detect real change over time and space. USGS lists three priorities:

1. Validate robotic samplers at sea, comparing them with manual and other sampling and making their results interoperable.
2. Understand what eDNA can and cannot say, by building a complete, curated DNA reference library, identifying factors such as eDNA breakdown and movement that bias conclusions, and validating models that allow comparison with other survey tools.
3. Build analytical tools that map offshore fish and wildlife for planning and monitoring wind projects, including interactive distribution models for species of conservation concern and methods combining eDNA with bioacoustics and microscopy.

USGS is working with partners on these needs, in line with the national strategy on aquatic eDNA, aiming for faster, cheaper and better robotic sampling and new tools such as onboard processing and air eDNA sampling alongside water. The fact sheet argues that eDNA could do for monitoring living resources what satellite remote sensing did for understanding and predicting weather and climate.

Sources

Rewritten from the U.S. Geological Survey Fact Sheet 2024–3019, "Realizing the potential of eDNA biodiversity monitoring tools in the marine environment with application to offshore renewable energy development" (public domain), in hubnx's own words.