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    Effect of starvation on the biochemical compositions and respiration rates of ctenophores Mnemiopsis leidyi and Beroe ovata in the Black Sea
    (Cambridge Univ Press, 2005) Anninsky, BE; Finenko, FA; Abolmasova, GI; Hubareva, ES; Svetlichny, LS; Bat, L; Kideys, AL
    The proximate biochemical composition and metabolic rates of ctenophores Mnemiopsis leidyi and Beroe ovata from the Black Sea were examined with respect to starvation conditions. Although organic matter content in B. ovata was two times higher than that of M. leidyi (2.51 +/- 0.53 and 1.4 +/- 0.17 mg g(-1) of wet weight, respectively), these species did not significantly differ in their biochemical composition. In both species protein formed about 80% of the total organic matter, lipids amounted to about 10%. Carbohydrate and amino acids measured separately made up less than 6.5% of the total organic matter. Under experimental starvation (18 days at 16-18 degrees C for B. ovata and 8 days at 12.4 degrees C for M. leidyi), wet weights of both ctenophore species were reduced by 9.4% and 9.3% d(-1), respectively. The rate of organic matter decrease was nearly two times lower than that of wet weight being on average 5.9% d(-1) in M. leidyi and 5.5% d(-1) in B. ovata. There was no trend in percentage of the four major biochemical categories with starvation time. The glycogen content in polysaccharides reached maximum values in freshly collected ctenophores (76.0 +/- 7.9% in B. ovata, and 86.6% in M. leidyi), but it was reduced substantially (34.4 +/- 2.7% in B. ovata and 18.3-28.8% in M. leidyi) with starvation. Monosaccharide content, expressed as a percentage of total carbohydrate, decreased from 39.9% to 13.5% in B. ovata, and from 45.8% to 14.3-23.2% in M. leidyi. The relationship between respiration rate (R) and wet weight (W) of individuals during the starvation can be expressed by power function R = R-1 W-k (r(2)=0.85-0.94; P<0.001) for both ctenophore species. On average, k values were 0.95 and 0.83 in B. ovata and in M. leidyi, respectively. By the end of the starvation, metabolic rate per unit wet weight decreased by 33% in B. ovata and 46% in M. leidyi. Organic matter utilization was almost totally explained by respiration of ctenophores in the experiments and exceeded metabolic requirements of studied species by 11% and 15%, correspondingly. As compared with Mnemiopsis, Beroe has better tolerance to starvation which explains to some extent the success of the species survival during prolonged periods of food shortage in the Black Sea conditions.
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    Population dynamics, ingestion, growth and reproduction rates of the invader Beroe ovata and its impact on plankton community in Sevastopol Bay, the Black Sea
    (Oxford Univ Press, 2003) Finenko, GA; Romanova, ZA; Abolmasova, GI; Anninsky, BE; Svetlichny, LS; Hubareva, ES; Bat, L
    The impact of the introduced ctenophore Beroe ovata on its prey Mnemiopsis leidyi, another invader ctenophore voraciously feeding on mesozooplankton, and consequently on the mesozooplankton community, was evaluated by undertaking both laboratory and field studies in the northern Black Sea. Ingestion and growth rates as well as the gross growth efficiency of B. ovata were estimated from laboratory experiments. The daily ration of ctenophores was related to food abundance within a wide range of prey concentration and never reached saturation. Beroe ovata required high food rations (not less than 20% of body weight per day) for growth. The abundances, biomasses and population structures of these two introduced ctenophore species were also monitored, along with mesozooplankton, in inshore waters of the northern Black Sea (i.e. Sevastopol Bay and adjacent regions) over a period of 3 years (1999-2001) which is after B. ovata's arrival. The annual dynamics of the M. leidyi population were similar for the last 3 years: very low abundances and biomass values were observed during most of the year (unlike the previous years), with a sudden increase in summer-early autumn, but only for about a 2 month period. The B. ovata bloom during the peak M. leidyi biomass resulted in the M. leidyi biomass falling sharply to extremely low values. The predatory impact of M. leidyi on prey zooplanton was found to be reduced during the period of study compared with before.