Ecological Spectrum of Gammarus lacustris (Sars, 1863) (Malacostraca, Amphipoda, Gammaridae) of the Araz Water Reservoir

The relation of the dominant species of macrozoobenthos of Araz reservoir Gammarus lacustris to substrate, depth, water transparency, illumination, temperature, oxygen regime and organic pollution of aquatic environment was studied. It is established that the freshwater shrimp has high ecological plasticity to abiotic factors of the environment. It was confirmed that in aquatic conditions the abundance of sunlight causes a clear negative phototropism in individuals of the higher crayfish. The species proved to be resistant to the average degree of environmental pollution by organic substances (s = 0.5 oligo - 2.5 β - mesosaprob) in the Araz reservoir. It was found that there are favorable ecological conditions for the development of the crayfish population in the ecosystem. The average annual number of crayfish individuals in the reservoir was 23 individuals/m2, biomass — 0.120 g/m2. The quantitative composition of the population is subject to seasonal changes. The highest values of freshwater shrimp abundance and biomass were calculated in spring and autumn.