SPATIAL-DISTRIBUTION OF ZOOPLANKTON IN A NATURAL RESERVOIR - THE LALLA-TAKERKOUST IN MOROCCO

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 follo ws the pattern described by MARZOLF with a maximal abundance at the 2/ 3 of the reservoir length. The zooplankton stays in the superficial wa ters, the richest in algal resources, and avoids the deeper waters (be low -5 m) less oxygenated, with a low algal content and exposed, on th e bottom, to bioturbation by fishes. The burrowing fishes produce turb ulence and a higher concentration in suspended matter capable of inter fering in the alimentation of zooplankton. The authors observe, moreov er, a partage of space between the two cyclopoid species T. oblongatus and T. prasinus which have similar size, behavior and diet.