Fouling

the settling of aquatic organisms in water-intake pipes and on rocks and stones, buoys, underwater cables, port and other hydrotechnical structures, and the bottom of ships.

The principal fouling organisms are sessile animals and plants—for example, cirripeds (acorn barnacles and goose barnacles), bivalve mollusks (mussels), hydroids, mosses, sponges, ascidians, Sedentaria, and algae. Motile animals, primarily worms and crustaceans, settle among the sessile organisms. One of the most important components of fouling are bacteria, which generally settle first on unfouled surfaces.

The majority of fouling organisms, as a result of reproduction, produce spores or planktonic larvae, which are distributed by currents and subsequently settle on a substrate, where they transfer to a sessile way of life. Marine fouling is more varied and extensive (up to 100 or more kg per sq m) than freshwater fouling. Fouling animals generally feed on tiny food particles, which they filter out of or capture in the water.

There are many known cases of fouling organisms being extensively distributed by means of ships. For example, after the completion of the Volga-Don Canal, more than 20 species of invertebrates and algae were transferred on the bottom of ships from the Sea of Azov to the Caspian Sea, where the organisms settled.

Fouling decreases the speed of ships and impedes the flow of water in pipes leading to industrial enterprises. It also cuts down on the efficiency of cooling installations. Fouling adds to the exposure of piers and docks to the action of waves, and it promotes the corrosion of metal and concrete underwater structures.

Control measures include cleaning fouled surfaces regularly, rinsing water pipes with hot water or chemical solutions that are toxic to fouling organisms, and covering overgrown surfaces with poisonous paints.