Boat Paint May Deform Newport Harbor Oysters

A pesticide commonly found in boat paint to kill marine organisms may be causing mutations in oysters in Newport Harbor, a state water quality official said.

Testifying this week at a hearing on whether to ban the chemical known as tributyltin (TBT), Ed Liu of the Santa Ana Regional Water Quality Control Board said oysters from the bay examined recently have “gross malformations.”

The oysters, one of the marine animals most sensitive to changes in water quality, were transplanted into Upper Newport Bay and Rhine Channel last year so state officials could monitor bay pollution.

Liu told a panel from the state Department of Food and Agriculture that TBT may be “stunting” the growth of oysters. He said oysters taken from the Rhine Channel near the Lido Peninsula were alive but had thicker shells than normal oysters and were generally smaller.

There is no definitive link between TBT and the oyster deformities, Liu said, but the waters in Newport Harbor have high concentrations of the chemical. It is too early to draw conclusions about the long-term impact of TBT on oysters or other marine life, he added.

However, he said “it is clear that something is having a negative impact” on oysters, and “our best guess is TBT.”

Because of the chemical’s toxicity, state food and agriculture officials have proposed a state ban on its use, beginning next month. A decision is expected by Christmas, although some paint manufacturers are seeking to delay the ban so paint supplies containing TBT can be sold rather than dumped, Liu said.

Paints with TBT, known as anti-fouling paints or coatings, are used on boats to retard the growth on hulls of marine organisms, which can contribute to a craft’s drag and increase fuel consumption. The chemical has been blamed for problems in heavily-traveled waterways in France, England, Canada and in other ports along the California coast, a state report supporting the TBT ban said.

The chemical is not known to be toxic to people, Liu said.

A similar experiment using oysters is being conducted in Huntington Harbour. Those oysters will not be examined until spring, with the results made public next summer, Liu said.