Contribution to the typological study of a lagoon exposed to pollution, Nador lagoon (Morocco): Crustaceans distribution.

Contribution to the typological study of a lagoon exposed to pollution, Nad or lagoon (Morocco): Crustaceans distribution. The Nador lagoon is currentl y being heavily polluted from two different sources. First, an anthropogeni c source by waste waters and solid wastes directly discharged on its shores causing thereby an increase of the eutrophication phenomenon. Second, a na tural source related to the narrowing of its pass that prevents water mixin g and increases the confining of the environment. The aim of this work is to establish a zonation of this lagoon on the basis of the distribution of the benthic crustaceans and the physico-chemical pa rameters. Annual mean values of principal components were used to process t he physicochemical data (salinity, depth, pH, dissolved oxygen, chlorophyll a, nitrate nitrogen, phosphorus and organic matter). This allowed us to di stinguish different stations with respect to the nature of their substratum and their degree of pollution. The processing of the faunistical data was done by factorial components analysis using mean annual abundances. This le d us to better visualize the distribution of the species with respect to co nditions of the environment. This study shows a pronounced adaptation of crustaceans to environmental co nditions prevailing in three different areas, which differ by their natural ecological conditions, associated to pollution.