Evaluating the Potential for Citizen Science Divers to Monitor Fish Biodiversity Through Passive eDNA Collection

This study tested whether citizen science SCUBA divers could help monitor marine biodiversity using environmental DNA (eDNA), or tiny genetic traces organisms leave behind in seawater. eDNA filters were attached to REEF volunteer divers, who concurrently conducted REEF Volunteer Fish Survey Project surveys. The DNA captured on those filters was then extracted and sequenced, and the species detected were compared to what divers recorded visually during their surveys.

The authors found that diver-collected eDNA produced consistent results and was less affected by differences between individual divers than traditional visual surveys, suggesting it could help reduce observer bias and make large-scale monitoring more standardized. However, eDNA detected fewer fine-scale differences in fish communities and would require substantially more sampling effort to match the detail captured by human observers. Excitingly, we detected DNA for Guadalupe Fur Seal (a species considered extinct after most of the population was killed in 1928 but it was rediscovered in 1954 and is now listed as Endangered by the IUCN) in one sample, suggesting that this method can be useful for rare or cryptic species detection. Overall, the study shows that while eDNA collected by citizen scientists is a powerful and scalable tool for tracking marine life, it works best as a complement to traditional underwater surveys.