Antifoul and Invasive Species
Antifouling paints work largely by releasing biocides (pesticides) into the water, thus preventing organisms from attaching themselves to the bottom of the boat. Whilst this is good for keeping the hull clean, improving efficiency through the water and preventing the spread of non native invasive species from location to location, it does mean that some of the toxic ingredients can leach into the water.
Even though this slow leaching can cause toxins to build up in the food chain, the main problems associated with antifouling occur when high concentrations of antifouling enter the water in runoff from high pressure hosing and scrapings from boat wash down. High concentrations of copper tend to be found in the sediment around lift out points in estuaries and rivers and can find their way into the food chain causing a wide range of environmental problems
Invasive Non-Native Species
Invasive non native species are introduced non-native species that have become established outside of their normal habitat or native country. Hitching a ride on a boat hulls, propellers or in ballast and bilge water, these aliens arrive in UK waters and can have extremely damaging effects on our eco systems and biodiversity. There are currently about 65 marine non native species in Britain, with many species thriving in both salt and fresh water.
Fast-growing species like Zebra mussels are already causing problems in many areas, blocking engine cooling water intakes resulting in engines over-heating. Didemnum Vexillum, known as Carpet Sea Squirt, has a smothering effect; covering aquatic habitats in thick sheet-like growths, interfering with fishery and aquaculture operations. Once established, non-native species become extremely difficult and expensive to eradicate.