Detecting the marine gastropod Lacuna vincta at seaweed farms using a novel environmental DNA (eDNA) assay

The small marine gastropod Lacuna vincta is species of concern for kelp ( Saccharina latissima, S. angustissima ) farmers and processors because snails attach their egg sacs to the blades of cultivated kelp and are difficult to remove. Larval dispersal patterns and post-metamorphic migratory behavior have allowed L. vincta to encounter and settle on kelp blades suspended from farms. Snail infestations can force farmers to harvest early or redirect biomass into lower-value products. We created and tested a novel species-specific environmental DNA (eDNA) assay for L. vincta throughout two kelp growing seasons in conjunction with traditional visual surveying for snails on farms. We were able to detect and amplify L. vincta DNA from environmental field samples interannually and across multiple sites as well as to link the presence of L. vincta on farms to the presence of L. vincta DNA at farm sites. This and future research will contribute to best management practices for kelp farmers when it comes to choosing lease sites for aquaculture farms and determining when to harvest biomass in the spring. • A novel Lacuna vincta primer can detect environmental DNA from biofouling snails at marine kelp farms. • Marine snail Lacuna vincta DNA is detectable in seawater regardless of water temperature. • The presence and absence of Lacuna vincta snails on seaweed farms is linked to detection of their DNA in water column.