Pulau Hantu - A celebration of marine life

Secret lives and secret worlds hidden in Singapore's most popular coral reef.

Monday, April 05, 2004

Anti-fouling agents

Damage to marine life isn't always caused by something visible.

"Each day spent soaking in Singapore waters gives chemicals applied onto the hulls of ships, time to dissolve into the waters, killing marine life and affecting the food chain. There's little harm when one ship crosses the sea as the dissolved amounts are in less than trace values, but when hundreds of ships congreate and dock for days or weeks in Singapore, the concentration of leaked chemicals becomes significant. This affects the quality of the water both to people and marine life."
- Chemist Sylvain Tourel, German exchange-researcher at the NUS

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Anti-fouling paints are used to coat the bottoms of ships to prevent sealife such as algae and molluscs attaching themselves to the hull – thereby slowing down the ship and increasing fuel consumption.

The new Convention defines “anti-fouling systems” as “a coating, paint, surface treatment, surface or device that is used on a ship to control or prevent attachment of unwanted organisms”.

In the early days of sailing ships, lime and later arsenic were used to coat ships' hulls, until the modern chemicals industry developed effective anti-fouling paints using metallic compounds.

These compounds slowly "leach" into the sea water, killing barnacles and other marine life that have attached to the ship. But the studies have shown that these compounds persist in the water, killing sealife, harming the environment and possibly entering the food chain. One of the most effective anti-fouling paints, developed in the 1960s, contains the organotin tributylin (TBT), which has been proven to cause deformations in oysters and sex changes in whelks.

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Read more about anti-fouling agents on the International Maritime Organisation (IMO) website