Collecting Clues: How REEF volunteers can help unmask hidden diversity with eDNA

REEF and the Semmens Lab at Scripps Institution of Oceanography (SIO) are collaborating on an exciting new project that uses cutting-edge technology to improve our understanding of ocean ecosystems. The idea is simple: enable REEF volunteers to collect bits of environmental DNA (eDNA), the genetic material that animals shed into their surroundings.  REEF surveyors, who are already in the water conducting fish surveys as part of the Volunteer Fish Survey Project (VFSP), are excellent candidates to help gather eDNA samples. Since 1993, recreational divers and snorkelers have conducted visual REEF surveys by recording the marine life they observe in the water. These data have been used in hundreds of scientific papers and studies. Combining this new eDNA initiative with the VFSP will leverage the power of REEF's global reach and help make eDNA a more accessible tool.

REEF and the Semmens Lab developed an innovative approach to collect eDNA by attaching a small piece of filtering mesh to a REEF surveyor's scuba tank. As the diver moved around a dive site, water containing eDNA passed over the mesh, collecting genetic material. This technique was pilot tested on the REEF Field Survey Trip to the Sea of Cortez in 2022, and resulted in eDNA being collected by over 90% of samples! Researchers used the eDNA collected during that trip to study marker genes, which act as “fingerprints” for different taxa. They compared these results with the divers’ visual REEF survey data. There were 17 species detected by eDNA and on REEF surveys, including the most commonly observed fish on REEF surveys. The eDNA filter method also detected some species not recorded by REEF surveyors, including the rare Guadalupe fur seal! These results suggest that eDNA can complement visual surveys for a wide variety of species. The collaboration is ongoing, and there are plans to continue eDNA field testing on future REEF Field Survey Trips. Stay tuned for more information about this exciting work, and to learn more about the Volunteer Fish Survey Project, visit www.REEF.org/vfsp.