Factors affecting Oithona nana and Oithona similis along a salinity gradient

Spatial and temporal variations of reproduction variables the two cyclopoid copepods Oithona nana Giesbrecht, 1893 similis Claus, 1866 were evaluated monthly from September 2007 to August 2008 in four ponds at different salinities solar saltern Sfax, Tunisia, under hypersaline conditions. Along salinity gradient abundance O. declined 14,900 ± 15,200 ind. m-3 (A1) 6,800 7,200 (C31) 13,800 17,100 3,700 5,800 (C31), respectively. The findings showed that these species, particularly ovigerous females, was positively correlated with Diatomeae, negatively salinity. egg production rate (EPR), diameter, clutch size, as well cephalothorax length mature all Diatomeae. existing gradient, EPR decreased 4.7 0.39 3.2 0.13 eggs female-1 day-1 5.19 0.46 3.66 0.05 for similis, respectively, this could mainly be attributed positive relationship between Diatomeae traits shows, may a vital component diet investigated species. reduction body size along demonstrates such character due network causes, related confinement not only