Copepods Oithona similis and Oithona davisae: Two strategies of ecological–physiological adaptation in the Black Sea

Abstract

Salinity tolerance, energy metabolism, buoyancy, and passive sinking and swimming speeds have been studied for comparative assessment of the adaptive potential of two species of cyclopoid copepods in the Black Sea, the native Oithona similis and new invader Oithona davisae. Both species were considered marine euryhaline copepods, but the range of salinity tolerance of O. davisae was much broader (5–55‰). The energy metabolism, locomotor activity, mean body mass density, and speed of passive sinking at the same temperature were significantly higher in O. davisae than in O. similis. The relationship between the physiological and behavioral parameters and ecological characteristics of the species are discussed.