The studied break-water is an ecological system, exposed at high variable and extreme conditions: exposed medium, often violent wind, very cold in winter and sometimes hot during summertime. Even more, the coast water is polluated by the mouth of the Schelde. The fauna here is essentially northern, very reduced in relation to species, but with an abondance of individuals, specialized to this extreme conditions. This few species are distributed in very precise zones on the breakwater. We put the attention on these animal and plant-associations, caracteristic for each important species
