The ecology of Lepas-based biofouling communities on moored and drifting objects, with applications for marine forensic science

Abstract

Pelagic biofoulers such as barnacles or bryozoans settle and raft on natural debris like pumice or seeds. Recent influxes of marine debris into the world’s oceans, especially plastic, have increased habitat availability for these biofoulers. Goose barnacles in the genus Lepas are some of the most common biofouling taxa globally, and play an important role in biofouling communities as foundation species. We examined community succession, growth rates and isotopic composition in Lepas and their associated biofouling communities in coastal waters of eastern Australia. Community succession on a fixed surface mooring showed an increase in species diversity over 25 weeks. Using the abundances of L. anserifera, L. anatifera, and the amphipods Caprella danilevskii and Jassa slatteryi, we created an equation to estimate minimum duration at sea. Predators such as the polychaete Amphinome rostrata may influence the biofouling community, as can beach scavengers once floating debris is cast ashore. We report a new maximum growth rate for L. anserifera of 1.45 mm−1, and our study is the first to report growth rates for any species of Lepas faster than 1 mm day−1. Lepas were larger on moored floats than on smaller, free-floating drifters. δ18O content of Lepas shells was a robust predictor of sea surface temperatures during formation for L. anatifera and L. anserifera. Our findings have important applications for estimating drift duration and trajectories of marine debris.