Alexandrov V. Vitality of individuals and coenopopulations of the mass seagrass species of the Black Sea

The complex of morphometric parameters of plant individuals, vitality structure and density of Zostera marina, Z. noltii, Potamogeton pectinatus coenopopulations were studied in their monospecific and mixed stands under various ecological conditions in the Sevastopol region (the Black Sea). Variation, asymmetry, excess of morphometric parameters and level of morphological integration of individuals were determined for each species. The most informative parameters of vitality of Z. marina, Z. noltii and P. pectinatus plants were revealed using factor analysis. The values of Z. marina shoot morphometric traits, coenopopulation vitality and density decreased along a depth gradient, but size hierarchy and morphological integration of individuals tended to increase. It’s revealed that the morphometric traits of individuals, vitality and density of Z. marina coenopopulations are positively correlated with clay, fine silt and shell content in bottom sediments. Content of coarse silt, sand and fine gravel effected plant and coenopopulation vitality negatively. Population density of Z. marina, Z. noltii and P. pectinatus was shown to have little effect on their plant and coenopopulation vitality, that points to low intensity of inter- and intra-specific interactions in the studied seagrass communities. The content of fine gravel and sand in the bottom sediments, depth and environment heterogeneity were more valuable factors affecting mass seagrass species in the Sevastopol region.