Brackish-water polychaetes, good descriptors of environmental changes in space and time

1 - -The aim of this study is to review the knowledge on the distribution of soft bottoms polychaete assemblage in Mediterranean brackish-waters. 2 - -The Polychaete distribution of several biotopes located along the Tyrrhenian and Adriatic coast, which has been the object of authors’ past studies, is reported and discussed. 3 - -Polychaete species composition was used to identify patterns of distribution inside the same biotope and among different biotopes, as well as changes in time in the same biotope. 4 - -Polychaetes was revealed good descriptors of biotope characteristics, reflecting a pattern similar to that arising from the examination of the entire benthic community. 5 - -We propose the use of polychaete assemblage fearures in assessing the ecological quality status of brackish-water bodies. For this purpose a general model of species distribution is given.