NIWA research has found paint used to protect boats from marine life could in fact be harming the creatures.
The research has found copper levels in many New Zealand marinas are above the guidelines for protecting marine life.
A primary concern is antifouling paint, which is used to prevent unwanted marine life from attaching to boats. The paint is commonly made using copper designed to leach into waterways.
The Marine Antifoulant Model to Predict Environmental Concentrations was used by NIWA scientists to predict concentrations of antifouling compounds at 11 ports and 13 marinas around New Zealand.
It found high levels in Nelson and Fiordland’s Milford Sound.
“Based on the results from this study, and information compiled from previous studies, leaching of antifouling paints from vessel hulls appears to be the major source of copper in marina waters,” says NIWA principal scientist Dr Chris Hickey.
The issue of copper contamination from anti-fouling paint has been investigated overseas as well. Washington State has passed a law which may lead to a ban on copper anti-fouling coatings on vessels.
The US Coast Guard has switched from a copper-based solution to the more environmental friendly EPaint.
Copper was also found at high levels in several Auckland marinas including Westpark and Milford, though all were near urban stormwater drains which can carry copper to sea and areas where boats are cleaned and repainted.
“The modelling indicated that copper levels could be quite elevated in marina waters and the sampling broadly confirmed that,” says Auckland Council stormwater contaminant scientist Marcus Cameron.
“On top of this the estimates of copper being exported from marinas were also significant, with as much copper exported from the four marinas in the Waitemata Harbour as from inputs of stormwater for the whole Waitemata Harbour catchment.”
The lowest concentrations recorded were at Bayswater Marina.