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Changes in hard bottom communities related to boat mooring and tributyltin in San Diego Bay a natural experiment

1990; Inter-Research; Volume: 60; Linguagem: Inglês

10.3354/meps060147

1616-1599

HS Lenihan, JS Oliver, MA Stephenson,

Marine Ecology and Invasive Species

San Dlego Bay contalns a number of harbors and other s~m~lar-s~zed embayments Some contaln many boats and others relatively few, prov~ding an unique natural experiment where the ecological Impact of mooring many boats was evaluated.Back-bay areas with many boats contained depauperate hard-bottom or foullng communit~es (less cover, b~omass, and fewer specles) compared to simllar areas In embayments with few boats.Embayments w ~t h many boats were characterized by serpulid polychaete worms, filamentous algae, and a solltary tunicate, Ciona jntestinaljs L. These groups apparently tolerated the physical and chem~cal stresses associated with many boats, but were replaced by other sessile invertebrates, such as mussels, sponges, bryozoans, and other tunicates, in embayments with few boats.These groups are more character~st~c of hard bottom communities on many natural reefs.Unl~ke the sessile organisms, the motile crustaceans and polychaetes that nestled among the sesslle groups were strongly associated w ~t h microhabitats, such as patches of algae and dense serpulid mats, rather than the presence of many or few boats However, there were more species of nestling Invertebrates in embayments w ~t h few boats In comparing embayments with many and few boats, sampling was confined to back-bay areas Hard bottom communltles at the front of embayments were slmllar to back-bay areas where there were few boats The concentrat~on of tributyltin (TBT, a toxic addit~ve to paint) was also hlgher in embayments w ~t h many boats.We hypothesize that TBT is a cause of the changes in hard bottom communities Hydrograph~c variat~ons among embayments w ~t h many and few harbors could not explain the cons~stent commun~ty patterns