Centropages kroyeri pontica (Karawaev, 1895)
Common names: None.
Order (Scientific): CALANOIDA.
Family (Scientific): CENTROPAGIDAE.
Taxonomic description: Centropagidae are formed from 6 segments. All segments have almost the same length. The last one is with elongated side angles. The second antennae have 6-segmented exopodit, significantly longer than the 2-segmented endopodit. The second segment of the fourth pair thorax legs of the male has a large prong on the posterior end. The length of the female is 1.60 mm and of the male - 1.40 mm. The side angles of the last thorax segment of the female are extended into pattern-like antennae.
Black Sea Regional level:
Subregion level: EN
Habitats type, Critical habitats, Limiting factors: The most favourable conditions for development of this species are in Black Sea coastal surface waters during spring, summer and autumn at water temperature 14-23°C. During the same seasons can be found in the open sea although in more insignificant quantities. The high degree of eutrophication in the coastal zone and the large number of the ctenophore Mnemiopsis leidyi appear as limiting factors. Thus, the first is presented as a degree and form of contamination and the second as a predatory pressure.
Biology: Inhabits mainly the upper sea layers (up to 50 m) and performs incessant migrations within a limited range over the thermocline. In the Black Sea it propagates from May to November whereupon the eggs laid by a female reach 200. During the propagation period the female lays 10 times, 20 eggs at a time. C. kroyeri feeds mainly on phytoplankton. Representatives of the class Infusoria are included in the food of its larvae.
Population trends: For the period 1967-1988 in the Black Sea coastal waters in front of the Bulgarian coast C. kroyeri has been registered with an average number of 732 ind/m3. For the period 1974-1988 the mean number of the species was 236 ind/m3, and for 1988-1995 the records show 3 - 4 ind/m3. After 1996 its number in the samples from coastal waters amounted to 10-14 ind/m3.
Threats: High degree of eutrophication in the Black Sea coastal surface waters and the presence of the ctenophore M. leidyi.
Conservation measures taken: None.
Conservation measures proposed: Reduction of eutrophication in the coastal zone which will also limit to a certain extent the quantitative presence of M. Leidyi.
Compiled by: A.Konsulov.