Spatial-distribution of zooplankton in a natural reservoir - the Lalla-Takerkoust in Morocco

Abstract

The spatial repartition of the zooplankton (abundance, fecundity) was studied in a morocco reservoir during a period of thermic stability in relation to some environmental factors (temperature, algal resources, suspended matter, dissolved oxygen). The horizontal repartition follows the pattern described by MARZOLF with a maximal abundance at the 2/3 of the reservoir length. The zooplankton stays in the superficial waters, the richest in algal resources, and avoids the deeper waters (below -5 m) less oxygenated, with a low algal content and exposed, on the bottom, to bioturbation by fishes. The burrowing fishes produce turbulence and a higher concentration in suspended matter capable of interfering in the alimentation of zooplankton. The authors observe, moreover, a partage of space between the two cyclopoid species T. oblongatus and T. prasinus which have similar size, behavior and diet.