Long-term effects of a ship-grounding on coral reef fish assemblages at Rose Atoll, American Samoa

Green, A

Rose Atoll is a small, remote coral atoll in the central South Pacific that was impacted by a major ship grounding and associated contaminant spill in October 1993. Nine years later, in February 2002, coral reef fish assemblages were surveyed at the impacted site and compared to other ("control") stations, also on its outer reef slope. Both the numbers and biomass of pooled herbivores (surgeonfish, parrotfish, and angelfish families) were several-fold greater at the wreck site than elsewhere around the atoll in 2002. The greater abundance of herbivores at the impact site, where corroding steel debris was still present, was associated with significantly greater substrate cover of turf algae/cyanobacteria. Some differences also were noted in the composition of common fish species at the wreck site, as compared to post-impact monitoring surveys by other investigators within 2-yr of the grounding. After nearly a decade, recovery to pre-grounding conditions had not yet been attained, as effects of the shipwreck may still be impacting the local reef ecosystem. Continuing long-term periodic surveys, to monitor fishes and other ecosystem components at Rose Atoll, should contribute to our understanding of recovery rates by coral reef fish assemblages from such major anthropogenic disturbances, and contribute to the scientific basis for management.