ZOOPLANKTON COMMUNITY STRUCTURE IN THE HAMIZ LAKE AND ITS RELATIONSHIPS WITH ENVIRONMENTAL FACTORS

The present study reports ten identified species of zooplankton in an Algerian lake. Seven stations were chosen according to different criteria and eleven physicochemical parameters were estimated to describe the water quality of each station. Qualitative and quantitative samples were collected from the lower horizon to the surface monthly, in October 2006 and from January to March 2007. In January, the highest species richness (S=9) was recorded in the upper lake corresponding to greater diversity (H'=1.41). The maximum density (28101 ind./L) was observed at the most vegetated site. The crustacean community consisted of 5 Cladocerans, 2 Cyclopidae and 1 Calanoida, however, rotifers were scarce. The CCA analysis reveals that most cladocerans seem to be associated with water hardness contrary to rotifers and copepods. The zooplankton structure was dominated in the north by copepods. However, cladocerans showed an inverse pattern from north to south. Taken together, our data indicate that community structure changes over time during our sampling surveys and in the lake, three zooplanktocenoses were identified. Therefore, it seems that environmental factors linked to the Mediterranean climate play a fundamental role in shaping the architecture of the food webs and the distribution of zooplanktocenoses of the Hamiz reservoir.