Fouling communities are groups of marine organisms found on artificial surfaces such as docks and boats. These are typically sessile animals such as corals, barnacles, sponges, and mussels, which provide food and habitat to animals such as fish and crabs. Settlement plates offer information regarding larval recruitment and settlement patterns and are often used to monitor marine ecology by comparing findings to historic patterns. In a recent study which replicated Sutherland and Karlson’s 1977 study that tested the succession of community development in marine fouling communities, Clavelina oblonga, a non-native colonial tunicate, was discovered in Beaufort, NC, and found to dominate the plates. These studies used downward-facing settlement plates to study the marine fouling communities. This project uses similar settlement plates to study the effects of light exposure on C. oblonga.
Settlement plates were submerged off docks of Duke University Marine Lab in summer 2018 and were allowed to establish before being flipped to increase light exposure. The plates were sampled monthly before the new moon, removed from the water and carefully documented. Using GIS software, 50 points were generated on a standardized photo of each plate and the species under each point was identified.
Results/Conclusions
The percent coverage of C. oblonga decreased drastically when their settlement plate was flipped and exposed to sunlight for three months. The remaining colonies of C. oblonga were observed around Ascidia interrupta, a larger solitary tunicate, and tangled in Eudendrium carneum, a branching hydroid, which suggests that it is seeking protection from exposure. C. oblonga is a growing concern in Beaufort and Morehead City, NC. If it continues to spread, there may be a problem to the growing shellfish industry of North Carolina. C. oblonga grows aggressively and has been found to decrease shellfish yields in other areas. If light deters its growth, this could be used to develop a method to reduce the impact of C. oblonga on shellfish aquaculture. Better understanding of this species will help us develop solutions and adapt to changes in the fouling community.