The degree of phenotypic plasticity in the Idotea baltica basteri Audouin, 1827 (Crustacea, Isopoda) sex ratio of the fouling community in the Odessa bay of the Black Sea was determined. The ratio of males and females in three main phenotypes of I. baltica basteri, namely: uniformis, albafusca and lineata was found. Crustaceans were collected on the underwater surface of traverses, located in three sea districts with the different degrees of water exchange intensity with the open sea. Water depth at the wall of traverses ranged from 1 to2,5 m. In the first most opened district among the individuals of uniformis phenotype the ratio of males and females was equal to 1:4, that for albafusca – 1:1,3 and lineata – 1:1. In the second area with the release of drainage waters among the individuals of uniformis phenotype this ratio was equal to 1:4,5, while the albafusca and lineata figures were 1:1,5 and 1:1, accordingly. In the third region, with the most difficult water exchange, among the individuals of phenotypes the ratios of males and females were as follows: uniformis – 1:8, albafusca – 1:2, and lineata – 1:1. When moving from the opened to semi-enclosed area among the individuals of all phenotypes there was a gradual decline in the proportion of males and accordingly, increases of the proportion of females. The greatest number of males in all areas under study is observed among the individuals of lineata phenotype, and that of females – among the individuals of uniformis phenotype. It is found that monochromatic colored females prefer to stay in the shaded places among the seagrass beds and brightly colored males usually move actively along the outside of the substrata.
Investigation of Sea Water Exchange in the Omura Bay by Satellite Remote Sensing Technique and a Test for Confirming Similarity of a Numerical Simulation System