black sea red data book - Department of Biology

Biology. Inhabits the upper water layers (up to 50 m) and performs diurnal
migrations down to the thermocline. In the Black Sea, it propagates from May to
November. The number of eggs laid by a female reaches c. 200. A female lays 10
cluches of, c. 20 eggs each. C. kroyeri feeds mainly on phytoplankton. Infusoria are
part of the food of its larvae.
Population trends. In coastal waters in front of the Bulgarian coast, C. kroyeri
reached average numbers of 732 ind.m 3
in 1967-1988. In 1974-1988, their mean
number was 236 ind.m" 3
, in 1988-1995 only 3-4 ind.m 3
. After 1996, numbers in
coastal waters rose back to 10-14 ind.m .
Threats. High degree of eutrophication in the Black Sea coastal surface waters and
the presence of the ctenophore Mnemiopsis leidyi.
Conservation measures taken. None.
Conservation measures proposed. Reduction of eutrophication in the coastal zone
which may also limit the abundance of M. Leidyi.
References
Opredelitel fauni Chernogo i Azovskogo morej, 1969. Kiev, Naukova Dumka: 2:49-
50.
Konsulov, A., 1991. Izsledvania varhu biologiata, ecologiata I znachenieto na
zooplanktona na Cherno more pred balgarskia briag. Dr. Sci. Thesis, Varna: 300 pp.
Konsulov, A. & L. Kamburska, 1997. Sensitivity to anthropogenic factors of the
plankton Fauna adjacent to the Bulgarian coast of the Black Sea. In: Sensitivity to
Change: Black Sea, Baltic Sea and North Sea. NATO ASI Series 2. Environment, 27:
95-104.
Compiled by A. Konsulov.
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