Sex ratios and seasonal changes in density of four ostracod species in relation to some ecological variables, Red Sea, Egypt

The present study examines ecological variables and their effect on sex ratios of four marine ostracod species of Red Sea which are exhibiting sexual dimorphism. These species are: Loxoconchella dorsobullata, Falsocythere maccagnoi, Tanella seminis and Bradleya reticulata. The study site locates at 28 km south of Qusier City along the Red Sea Coast, Egypt. Samples were collected monthly for two years (2011 and 2012). Ecological variables were measured through the collection period and correlated with density of the studied ostracod species. These ostracod species can live in alkaline water, resist high levels of salinities and tolerate with high conductivity. On the other hand, their sex ratio was biased to females for F. maccagnoi and biased to males for B. reticulata. The goodness of fit was 3:1 (female:male) for F. maccagnoi, 1:4 for B. reticulata, whereas, sex ratio for L. dorsobullata and T. seminis was 1:1.