Anthropogenic transport of macrofauna through a sand transfer plant

The South Lake Worth Inlet Sand Transfer Plant in Palm Beach County, Florida pumps subtidal sediment from the upcurrent to the downcurrent side of the jetty to correct jetty-induced sediment transport disruption. This pumping accounts for 35% of the overall net longshore transport. We investigated if living macrofauna could survive the sediment pumping process. We also examined the effects this activity had on the subtidal macrofaunal invertebrate communities. Subtidal sediment cores were taken near the intake pipe, at the outflow pipe, and just outside the direct effects of the sand transfer plant. Benthic macrofauna and sand grain size were examined and compared. Macrofauna, live and preserved, were confirmed exiting the outflow pipe. Low diversity, low abundance macrofaunal communities were found at all sample sites. Macrofaunal abundance was primarily isopods (79%) and polychaetes (14%). Three isopod and one polychaete species constituted 89% of the community diversity. Both inflow borrow pit and outflow deposition sampling sites exhibited different community structure compared to adjacent control sites. The inflow borrow pit presented a high population of the isopod Eurydice personata. The outflow deposition site had the highest species diversity. The outflow deposition site also showed much coarser mean sediment grain size compared to other sites. The differences found at the sites direct associated with the sand transfer plant demonstrated localized disturbance. We concluded that although the plant disturbs the adjacent community it also helps maintain the macrofaunal community structure and sand grain size on the downdrift side of the South Lake Worth Inlet. Further studies integrating abiotic and biotic components will assist in management practices and our understanding of nearshore systems.