Trophic Relationships and Food Supply of Heterotrophic Animals in the Pelagic Ecosystem of the Black Sea

During recent decades, the Black Sea has been affected by many negative factors that strongly changed the condition of its ecosystem. Especially trophic relationships in the Black Sea pelagic system became very vulnerable influencing the food supply, productivity and abundance of many species and populations of this marine basin. Food is one of most important link between biota and its environment. In this monograph, the role and variability of trophodynamic processes that effect the well-being (health) of main heterotrophic components of ecosystem were analysed in detail for a few key species as indicators for estimation of ecosystem condition in whole. These are most significant mass species of the Black Sea pelagic ecosystem. Among copepods this is Calanus euxinus that dominates the mesozooplankton which makes up the fodder base of planktivorous fishes. Among gelatinous these are medusa Aurelia aurita and the alien ctenophores Mnemiopsis leidyi and Beroe ovata which affected strongly mesozooplankton composition. Lastly among fishes the anchovy Engraulis encrasicolus ponticus and sprat Sprattus sprattus phalericus that dominate small pelagic fishery. We considered in this monograph: • Diel feeding behaviour, in situ feeding rate of Calanus euxinus and impact of mesozooplankton on primary production and phytoplankton biomass. • The effect of vertical migrations on energy budget and its components in C. euxinus; metabolic substrates used in catabolic processes under both aerobic and hypoxic conditions, the role of reserve lipids and effect of abiotic factors on individual growth and population structure of this species. • The intensity and efficiency of ingestion and energy transformation in three gelatinous species ( jellyfish Aurelia aurita, ctenophores Mnemiopsis leidyi and Beroe ovata) and their predatory impact on zooplankton community. • Nutritional condition and food supply of anchovy and sprat in the close interaction with natural biotic and abiotic and anthropogenic factors. • Tendencies in this interaction during long time space: since 1960 s till present years. • Estimation of population condition of these species and its long-term change. This monograph is the collective work of Ukrainian and Turkish scientists studying complex hydrobiological problems of the Black Sea. Its aim is to reveal the significance of nutritional factors on the ecology of Black Sea biota, including changes which have already occurred, as well as offering some insight into changes that may happen in the future. Our joint investigations started in the first half of the 1990s, when conditions for the close cooperation of researchers from the two countries were suitable after the collapse of the Soviet era. This spirit continues to the present day. Professor Ümit Unluata, Director of Erdemli Institute of Marine Sciences (Middle East Technical University, Ankara) was of paramount importance in organising and fostering the work undertaken. We would like to devote this monograph to the memory of him, who died so prematurely. We are also grateful to Academician Professor V. N. Eremeev, Director of the Sevastopol Institute of Biology of the Southern Sea (National Academy of Sciences of Ukraine), and to the directors of Erdemli Institute of Marine Sciences (Professor Ilkay Salihoglu, Professor Sukru Besiktepe and Professor Ferit Bingel) who also made significant contributions to the Ukrainian–Turkish collaboration. We are grateful to Dr Bill Parr from the Black Sea Ecosystem Recovery Project for his valuable efforts in improving earlier drafts. All these investigations were carried out within the framework of the following five NATO linkage-grants: • Pelagic animal food supply in the unstable Black Sea environment, • Will the new alien ctenophore Beroe ovata control the plankton community in the Black Sea? • Grazing, growth and production of Calanus euxinus in the Black Sea, • Bioindicators for assessment of Black Sea ecosystem recovery, • Adaptability and vulnerability of marine species in changing environments. And four TUBITAK - NASU joint projects: • Quantification of the recent ctenophore invader Beroe ovata impact in the Black Sea • Monitoring of the Black Sea anchovy and sprat, • Salinity tolerance as a key factor of invasion success of the copepods of Calanus genus into the Sea of Marmara, • Salinity tolerance as a key factor of invasion success of the mesozooplankton species into the Sea of Marmara. We hope that this publication will make a substantial contribution to future studies of the Black Sea ecosystem and offers further understanding of those features regulating biological processes in this unique marine basin

Interpopulation dynamics between Acartia clausi (Copepoda) and Noctiluca scintillans (Dinoflagellata) in the Bosphorus area of the Black and the Marmara Seas

The dynamics of abundance and biomass of Noctiluca scintillans (Dinoflagellata) and Acartia clausi (Copepoda) in the Bosphorus area of the Black and Marmara Seas during 2005-2009 has been analyzed. Despite the fact that the more abundant Black Sea zooplankton community permanently enters the Marmara Sea, A. clausi and N. scintillans have formed independent populations in the northeast of the Marmara Sea. This may be confirmed on the one hand by the positive correlations between the numbers of A. clausi and N. scintillans individuals in the Marmara Sea near the Bosphorus Strait and near the Prince Islands and, on the other hand, by a lack of correlation between the abundance of these species in the Marmara Sea and in the Bosphorus area of the Black Sea. The abundance of N. scintillans was 6-10 times lower in the Black Sea near the Bosphorus Strait than that in the Marmara Sea. A high correlation (r = 0.84) between the abundance of N. scintillans and the number of dead A. clausi females near the Bosphorus Strait in the Marmara Sea suggests an important role of necrozooplankton in the development of the dinoflagellate

Respiration of the Black Sea Turbot (Scophthalmus maeoticus) Eggs as an Indicator of its Development

Исследовано дыхание черноморского калкана (Scophthalmus maeoticus) в течение раннего онтогенеза в зависимости от стадии, наличия морфологических аномалий развития и температуры (11 и 16 °С). Скорость потребления кислорода была наименьшей на стадии бластулы и незначимо варьировала от 0,0057 до 0,0061 мкг О2 экз-1ч-1 между икрой разных серий и при разных температурах. При нормальном морфологическом развитии аэробный метаболизм возрастает от бластулы до стадии подвижного эмбриона в 22 раза, равняясь (0,1348±0,0205) мкг О2 экз-1ч-1 при 16 °C и только в 13 раз при 11 °C. Температурный коэффициент Q10 составил в среднем 2,6 для аэробного метаболизма калкана в течение эмбриогенеза. Аэробный метаболизм на стадии гаструлы оказался вдвое ниже у икры, для которой на более поздних стадиях, начиная с образования хвостовой почки, обнаруживали аномалии развития, не совместимые с развитием до жизнеспособной личинки, по сравнению с нормально развивавшейся икройRate of oxygen consumption of the Black Sea turbot (Scophthalmus maeoticus) during early ontogenesis depending on stage of development, morphological norm and temperature (11 and 16 °C) was studied. Oxygen consumption at blastula stage was the lowest, varied between 0.0057 and 0.0061 mg O2 ind-1 h-1 and was independent among egg batches in studied temperature range. Aerobic metabolism increased 22 times at 16 °C, reaching 0.1348±0.0205 mg O2 ind-1 h-1, and only 13 times at 11 °C from blastula to active embryo stage. Temperature interval 5 °С gave a mean Q10 of 2.6 for the rate of oxygen consumption of the Black Sea turbot during embryogenesis. Aerobic metabolism appeared twice lower at gastrula stage in embryos with morphological defects revealed from tail bud stage onwards incompatible with the development to a viable larvae, than that in normally developing embryo

Adaptability and vulnerability of zooplankton species in the adjacent regions of the Black and Marmara Seas

During 2005-2008 species composition, abundance patterns, natural mortality rates and salinity effects on zooplankton were studied in the Bosphorus regions of the Black and Marmara Seas. The tendencies to diminish for abundance and biomass of the Black Sea originated zooplankton species and to increase for the proportion of their carcasses in the direction from the Black Sea toward the Marmara Sea were found. The mortality in the Black Sea species increased with depth in the Marmara Sea. The contribution of organic matter of carcasses of the Black Sea originated organisms to bacterial processes in the deep strata of the Marmara Sea was estimated. Different salinity and temperature regimes restrict mutual penetration of the species in these seas. (C) 2010 Elsevier B.V. All rights reserved

Population dynamics and morphological variability of Calanus euxinus in the Black and Marmara Seas

Temporal and spatial changes in abundance, prosome length, oil sac volume, molting patterns and morphometric parameters were studied in Calanus euxinus from the Black and Marmara Seas. In the south-western part of the Black Sea and deep shelf zone near Sinop the abundance of C. euxinus was high during the whole studied period (2000-2005), with a maximum 23,400 ind m-2 in March 2004. In the Marmara Sea near the Prince Islands in the deep zone the mean annual abundance of C. euxinus was 47 times lower than in the deep zone of the Black Sea (during 2000-2007). However, this parameter reached a significant magnitude of 12,264 ind m-2 in spring in Izmit Bay. During the warm season, C. euxinus are rare in the Marmara Sea. The high temperature and salinity accelerate development in this species; therefore, preadults and adults possess reduced prosome length and oil sac volume. In the cold period in the Marmara Sea the size and lipid content in late copepodite stages increase, especially in Izmit Bay. Similar size of eggs, prosome length of early copepodite stages in the Black and Marmara Seas indicate that the C. euxinus population in the Marmara Sea originates from the individuals penetrating from the Black Sea through the Bosphorus

Adaptability and vulnerability of zooplankton species in the adjacent regions of the Black and Marmara Seas.

During 2005–2008 species composition, abundance patterns, natural mortality rates and salinity effects on zooplankton were studied in the Bosphorus regions of the Black and Marmara Seas. The tendencies to diminish for abundance and biomass of the Black Sea originated zooplankton species and to increase for the proportion of their carcasses in the direction from the Black Sea toward the Marmara Sea were found. The mortality in the Black Sea species increased with depth in the Marmara Sea. The contribution of organic matter of carcasses of the Black Sea originated organisms to bacterial processes in the deep strata of the Marmara Sea was estimated. Different salinity and temperature regimes restrict mutual penetration of the species in these seas

Vulnerability of copepod eggs in salinity and temperature gradients of the Marmara and Black Seas

Mass density, sinking speed and hatching success of eggs in Calanus euxinus, Acartia clausi and A. tonsa have been examined in response to salinity and temperature of the Marmara and Black Seas. Eggs of C. euxinus from the Marmara and Black Sea populations (mean mass density of 1.036 to 1.040 g cm–3) laid in brackish (18 to 22 psu) upper layers of the Marmara Sea could sink to high-saline (~38.5 psu) deep layers during embryonic development. Gradual salinity increase from 22 to 38.5 psu in laboratory experiments reduced egg hatching success in C. euxinus from the Marmara Sea from 97 ± 4 to 47 ± 11% (means ± SD) while all eggs of the Black Sea C. euxinus did not hatch. Mean mass density of eggs in A. tonsa and A. clausi amounted to 1.062 and 1.044 g cm–3, respectively. Eggs of A. tonsa with higher mass density and longer development time than those of A. clausi could descend to high salinity strata in the Marmara Sea, or to a cold intermediate layer in the Black Sea. On the contrary, sinking depth of eggs of A. clausi should not exceed 30 m both in the Black and Marmara Seas, as this increases predator pressure. Hatching success in A. tonsa eggs laid at 18 psu decreased from 77.7 ± 18.5% at 20°C to 46.7 ± 21.5% at 7°C, and reduced to 10.2 ± 4.7% at 7°C and 39 psu. Egg hatching success in A. clausi from the Black Sea did not depend upon temperature, whilst it decreased dramatically from 80 to 90% to 3.3 to 10% after salinity increase from 18 to 38 psu

Respiration of the Black Sea Turbot (Scophthalmus maeoticus) Eggs as an Indicator of its Development

Исследовано дыхание черноморского калкана (Scophthalmus maeoticus) в течение раннего онтогенеза в зависимости от стадии, наличия морфологических аномалий развития и температуры (11 и 16 °С). Скорость потребления кислорода была наименьшей на стадии бластулы и незначимо варьировала от 0,0057 до 0,0061 мкг О2 экз-1ч-1 между икрой разных серий и при разных температурах. При нормальном морфологическом развитии аэробный метаболизм возрастает от бластулы до стадии подвижного эмбриона в 22 раза, равняясь (0,1348±0,0205) мкг О2 экз-1ч-1 при 16 °C и только в 13 раз при 11 °C. Температурный коэффициент Q10 составил в среднем 2,6 для аэробного метаболизма калкана в течение эмбриогенеза. Аэробный метаболизм на стадии гаструлы оказался вдвое ниже у икры, для которой на более поздних стадиях, начиная с образования хвостовой почки, обнаруживали аномалии развития, не совместимые с развитием до жизнеспособной личинки, по сравнению с нормально развивавшейся икройRate of oxygen consumption of the Black Sea turbot (Scophthalmus maeoticus) during early ontogenesis depending on stage of development, morphological norm and temperature (11 and 16 °C) was studied. Oxygen consumption at blastula stage was the lowest, varied between 0.0057 and 0.0061 mg O2 ind-1 h-1 and was independent among egg batches in studied temperature range. Aerobic metabolism increased 22 times at 16 °C, reaching 0.1348±0.0205 mg O2 ind-1 h-1, and only 13 times at 11 °C from blastula to active embryo stage. Temperature interval 5 °С gave a mean Q10 of 2.6 for the rate of oxygen consumption of the Black Sea turbot during embryogenesis. Aerobic metabolism appeared twice lower at gastrula stage in embryos with morphological defects revealed from tail bud stage onwards incompatible with the development to a viable larvae, than that in normally developing embryo