Production and biomass of Acartia clausi in the Black Sea during summer before and after the Mnemiopsis outburst

An estimation of the biomass and production of the A. clausi population in the Black Sea is given for the summer period before the mass development of the ctenophora Mnemiopsis (1957-1988) and afterwards (1989-1996). The mathematical model used to achieve this also described. Data from the Kamish Bay monitoring program during 1960 - 1969 was used in addition with data of recent studies carried out by the IBSS-NASU and the IMS-METU on the distribution of Black Sea zooplankton. Results have shown, that the Acartia productivity has decreased 1.5-4 fold depending on the region. The maximal decrease took place in the north-western Black Sea. Decrease in the total copepod production, caused by the mass invasion of Mnemiopsis, was estimated as no less than ten fold in the north-western inshore areas of the sea.