Concentrations of Irgarol in selected marinas of Oahu, Hawaii and effects on settlement of coral larval.

This study examined concentrations of Irgarol 1051(®) in selected marinas on the island of Oahu, Hawaii and used laboratory bioassays to assess effects of Irgarol on coral larval settlement. Field surveys of small boat marinas performed in 2006-2007 revealed low concentrations of Irgarol 1051(®), an antifouling paint additive, ranging from non-detected (<17 ng/l) to 283 ng/l. The highest concentrations of Irgarol 1051(®) were found in marinas with low flushing rates and a high density of moored boats and boat traffic. The potential effect of Irgarol 1051(®) on coral larval settlement was evaluated in the laboratory using planulae from Porites hawaiiensis, a zooxanthellate shade-dwelling coral found in Hawaiian waters. Exposure to Irgarol 1051(®) at 100 ng/l resulted in a statistically significant reduction in settlement of coral larvae. This was within the range of Irgarol 1051(®) concentrations found in some of the marinas surveyed on the island of Oahu but Irgarol was not detected in seawater samples at offshore reefs.