Sandy beaches and their adjacent surf zones more than a third of the coastline in southern California. Surf zones are highly dynamic marine ecosystems (as well as one of the most visited and enjoyed marine habitats) and provide critical ecosystem services, supporting local marine biodiversity through the provisioning of forage habitat, refuge from predators, spawning sites, and nurseries for commercially and recreationally important fish species. 
Despite their tremendous societal and ecological value, our understanding of the status, and spatial and temporal dynamics of surf zone fish communities in southern California and around the world is lacking, and sandy beaches and surf zones are rarely included in conservation management plans. Sandy beaches and associated surf zone biological communities face both local and global anthropogenic stressors that threaten their biodiversity and ecosystem function. Sea-level rise coupled with coastal armoring is contributing to coastal squeeze, compressing or eliminating sandy beaches and altering surf zone habitats. Coastal urban development and engineering are increasing erosion along shorelines, increasing turbidity and altering surf zone characteristics. ​
Compounding these stressors, pollutants from stormwater, sewage, oil spills, and agricultural runoff often spill directly into surf zone habitats. As urban development and climate change continues to impact these important coastal ecosystems, our ability to effectively manage sandy beaches hinges on accurate assessments and monitoring of the species and communities that depend on them. ​
PicturePC: Dugan Lab
Traditional surf zone biomonitoring methods such as seines and hook and line surveys are often labor intensive, taxonomically biased, and can be physically hazardous. Emerging techniques, such as baited remote underwater video (BRUV) and environmental DNA (eDNA) are promising nondestructive tools for assessing marine biodiversity in surf zones of sandy beaches. Working with a wonderful team of collaborators at UCSB, we compare the relative performance of beach seines, BRUV, and eDNA in characterizing community composition of bony (teleost) and cartilaginous (elasmobranch) fishes of surf zones at 18 open coast sandy beaches in southern California. See manuscript here
Our results demonstrate that eDNA metabarcoding is highly effective at monitoring fish communities within surf zone ecosystems, capturing the majority of species observed in seine and BRUV surveys plus 59 additional species, including 13 that frequent surf zone habitats. eDNA approaches showed significantly higher sensitivity than seine and BRUV methods and more consistently detected nearly all jointly observed species across beaches. eDNA has room for improvement - the six species detected by BRUV/seines, but not eDNA either lacked reference sequences, were only resolved at higher taxonomic ranks (e.g. Embiotocidae surfperches), or were detected below occupancy thresholds. Together eDNA can provide a cost-effective tool for long-term surf zone monitoring that complements data from seines and BRUVs, allowing more comprehensive surveys of fish diversity in surf zone habitats.