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

Long-term variations of surface chlorophyll a and primary production in the open Black Sea

Extensive data sets on surface chlorophyll a (chl a), depth-integrated primary production (DIPP) and phosphate (PO4, muM) averaged for the upper 25 m layer in 1964, 1973, 1978 and for a period (1980 to 1996) of regular measurements have been used to evaluate long-term changes in the upper portion of the euphotic layer of the entire open (>1000 m) Black Sea. After preliminary analysis of seasonal dynamics, special attention was given to data obtained during those periods of the year with relatively stable values, revealing interannual and long-term fluctuations and trends. Of 2 phytoplankton characteristics (chl a and DIPP), long-term trends were obtained only for chl a since only these data covered the entire open sea and all periods investiged. A positive correlation was found between DIPP (using 2 different C-14 methods: actual in situ and simulated in situ) and the more numerous chl a data for different monthly intervals, with significant correlation coefficients (r = 0.51 to 0.82). This means that the observed patterns in long-term variability for chl a may be valid also for DIPP, The results show that interannual fluctuations in chl a are more pronounced during the warm months, from approximately May to September. Chl a levels within this interval were moderate, with a mean of 0.15 +/- 0.04 mg m(-3) during the first 'quiet' period (1964 to 1986), but increased steadily at a rate of 0.06 mg m(-3) yr(-1) during 1988 to 1991 and sharply in 1992 (mainly due to high July values) to 0,99 +/- 0.7 mg m(-3). In contrast, negative trends were characteristic of the third period (1993 to 1996): an abrupt decrease in chl a to 0,26 +/- 0.08 mg m(-3) in 1993 and a negative trend (-0.02 mg m(-3) yr(-1)) during 1993 to 1996. Low concentrations Of PO4 (0.015 to 0.138 muM) in the upper 25 In layer throughout the year and the absence of statistically reliable interannual trends in distribution suggest that this nutrient was limiting the level of primary production during the second period. This means that phosphate concentration in the upper 25 m layer cannot be considered a reliable indicator of the presence or absence of anthropogenic eutrophication in the open Black Sea. This long-term variability in phytoplankton characteristics agrees well with the data on interannual changes in other ecological variables of the open Black Sea characterized by a collapse of the Black Sea ecosystem during the second period and its recovery after 1992. Comparison of changes in the open and shelf areas of the Black Sea between these 3 periods, and similar changes in the plankton community and in pelagic fish stocks in the second half of the 1980s to the beginning of the 1990s in other regions of the northern hemisphere, connected with changes in the climatic regime during this period, have led us to conclude that global climatic processes have played an important role in changing the phytoplankton characteristics of the open Black Sea and affecting the whole pelagic ecosystem, especially over the last 2 decades

Physical, Chemical, and Biological Data Sets of the TU Black Sea Data Base: Description and Evaluation

The data set of the TU Black Sea Data Base consists of the individual cruise data sets of the Data Contributing Partner Institutions and of several 'external' cruises which data are freely accessible (available) from other sources (databases). Basically, the paper constitutes a brief description of the data of the TU Black Sea Data Base (physical, biogeochemical and biological), and covers the issues of data quality and coverage as well as of sampling techniques and methods of samples treatment