THE SEX RATIO AT THE DIFFERENT PHENOTYPES OF LEKANESPHAERA MONODI (ARCANGELI, 1934) (CRUSTACEA, ISOPODA) IN THE FOULING COMMUNITY OF THE ODESSA BAY, BLACK SEA

The sex ratio at the different phenotypes of isopods Lekanesphaera monodi in the fouling community of the coastal zone of Odessa Bay, Black Sea are identified. The ratio of males and females in the five phenotypes L. monodi (uniformis, maculosa, lineata, albus and rubrum), living on the surface of the underwater hydrotechnical structures in three areas of the bay at a depth of 1 to 2,5 m in conditions of varying degrees of water exchange with the open sea are determined. The variability in the sex ratio at L. monodi at the transition from the open water area to the half-closed with a difficult water exchange is established. The sex ratio among different phenotypes L. monodi depends on the specific environmental conditions in the fouling community of Odessa Bay, Black Sea. The greatest number of males observed in the first open area among individuals phenotype lineata. The second and third parts of most males were among individuals phenotypes maculosa and uniformis, respectively. The incidence of these three phenotypes was highest in all the areas studied. In the transition from the open area to area with the release of drainage water, and then – to the half-closed, the total share of these phenotypes was increased from 84,5 to 88,6 and 91%, respectively. At the same time, phenotypes albus and rubrum were quite rare. Their occurrence in the same range of districts respectively decreased from 15,5 to 11,4 and 9%. In all areas studied quantitatively females prevailed over males. The largest relative number of females was found among the phenotype maculosa, and males – among individuals of phenotypes lineata, maculosa and uniformis. Among individuals of phenotypes albus and rubrum to one male had between two and three females. Coloration of the integument of L. monodi has an adaptive character. All five investigated phenotypes inconspicuous on the general background of fouling communities, allowing them to avoid predators.