Oithona davisae: naturalization in the Black sea, inter-annual and seasonal dynamics, effect on the structure of the planktonic copepod community

Abstract

Long-term (20032014) routine observations of zooplankton in Sevastopol Bay (the Black Sea) have allowed the naturalization of the invasive copepod Oithona davisae to be studied in the Black Sea coastal waters. Inter-annual and seasonal variability of the species and their impact on the native copepod community have been analyzed. The invasion of O. davisae and their undoubted dominance in terms of abundance were shown to alter the community structure but, at the same time, the abundances of the native species did not decrease, excepting the Black Sea earlier invader Acartia tonsa. A significant decline in A. tonsa numbers over the stages of O. davisae establishment and naturalization provided evidence of competition between the species. O. davisae have been demonstrated to gain competitive advantage over A. tonsa, that ensured their fast dispersal in the Black Sea, acclimatization in the new habitat and the successful competition over native species.