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Inside the sea chest

Rough surfaces or areas on ships are more prone to fouling. A particularly common place to find hitchhikers is inside the “sea chest”, a recessed area of the hull, usually towards the stern (back end), in which water intake openings (for engine cooling water and ballast water) are located. Other areas on ships’ hulls where fouling organisms are likely to be found include:

  • Beneath bilge keels
  • Inside bow-thrusters ports
  • On and around the rudder
  • On the propeller boss
  • On anchors which have been lying in sediment on the sea floor.

If a spotless and sterile piece of stainless steel is placed into seawater, in about a minute, a layer of slime starts to cover it. The slime is a layer of living algae and other tiny organisms. This initial slime layer is known as ‘primary biofouling’

If left on the metal, the slime layer will continue to grow and become an attractive place for larger marine organisms to make a home. Marine weeds and barnacles .  will attach themselves to the steel and thrive on the nutrient rich surface. This is known as ‘secondary biofouling’.

If seaweeds and other organisms are not removed, small fish can also find a home.  They eat a hole in the marine growth. The weed feeds the fish and also shelters them from the turbulence as the ship moves through the sea. This type of fouling is known as ‘tertiary biofouling’.

Adapted from an article by Tony Snell AQIS, (Australian Quarantine Inspection Service), National Ballast Water Advisor (for use at educational lectures about introduced marine species)

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