Comparing Epibiont Recruitment Adjacent to Oyster Aquaculture and Natural Habitat in Delaware Bay, USA

• Jonluke O'Cain, Marine Science, University of Delaware

• Ed Hale, SMSP, University of Delaware

Epibionts, or organisms inhabiting surfaces on the seafloor and underwater structure, including oysters, corals and bryozoans, serve a critical ecological function by providing structural complexity to otherwise bare surfaces.  Additionally, these organisms provide a prey base that impacts the surrounding aquatic community. Composition of epibiont communities is driven by numerous factors, including hydrology, vertical relief, and adjacent habitats.  Aquaculture equipment changes the landscape by adding vertical relief and causing frequent disturbance, interfering with local ecological succession.  Although shellfish aquaculture has been shown to alter species composition in the surrounding environment, little research has directly analyzed these changes, particularly in the mid-Atlantic region. For this study, we placed mesh bags of cured oyster shell at two types of oyster aquaculture (longline cages and rack and bag) in addition to a wild oyster reef and a tidal marsh in the Delaware Bay, DE. From June 12^th – August 7th, 2025, we used a weekly random stratified point sampling method to assess coverage and community composition on cured oyster cultch at each location and measured dry mass for total fouling accumulation. Preliminary results suggest that the natural environments support more biomass than the aquaculture sites ( p < 0.001, Scheirer-Ray-Hare). Similarly, the longline aquaculture had the least surface coverage (p = 0.026, Two-way ANOVA). These findings suggest that although aquaculture can generate new habitat locally, the epibiont recruitment and corresponding community dynamics differ from wild oyster reefs.