The understanding of key physical and biogeochemical processes in an ecosystem is the basis for successful process modeling. Compared to the oceans, the Black Sea ecosystem is relatively simpler in terms of the key species, and considerable research has already been carried out to date. In spite of this fact, many basic processes governing the functioning of the ecosystem are still not well defined. To fill this gap, a process oriented sub-project is defined with an objective to design and conduct process studies, organised around research and modeling of the effects of physical and biogeochemical processes on the dynamics of the lower trophic levels of the Black Sea marine ecosystem. This sub-project will focus on the following set of critical and poorly understood processes and key elements of the Black Sea ecosystem:

TASK II.1. Interactions between the physical, biological, and chemical processes of the oxic, suboxic, and anoxic layers, including redox processes involving nitrogen, sulfur, iron, and manganese cycling, in regard to pathways and regulation of rates, the dynamics of nitrogen fluxes among nutrient and particulate pools and lower trophic levels.

TASK II.1.A. A study of the Oxic/Anoxic interface the formation of anoxia.
The following topics have to be studied:

High resolution vertical distributions of H2S and S reduced forms, NH4, dissolved Mn, CH4, Alkalinity, pH, PO4, SiO3 and transparency,.
The vertical distributions of the isotopic forms of sulphates and hydrogen sulfide to have a background estimates of sulfide oxidation and sulfate reduction,
N-15 vertical distribution for background assessment of N2 fixation and denitrification,
Particulate matter composition (size fractions, organic and inorganic, biota),
Particulate matter sedimentation rates,
Redox layer vertical turbulent mechanism,
Nepheloid Redox Layer ecosystem, anaerobic photosynthesis.


TASK II.1.B. The roles of chemical element fluxes in the Global Biogeochemical Cycles
The main objective is to obtain numerical estimates of the integrated S, N, C and P fluxes, as elements of the global biogeochemical cycles, including nutrient cycles, sulphate reduction and denitrification. The main efforts will be focused on the distribution of elements in the redox zone and the anoxic media.

TASK II.1.C. Euphotic layer chemical structure in conjunction to the biological and physical processes
The basis of this topic is the investigation of the distribution and variability of the nutrients in connection with the synthesis and decay of organic matter and the circulation processes.

TASK II.1.D. The role of Mn and Fe in the in the redox processes.

TASK II.2. Understanding the roles of new and regenerated production in ecosystem dynamics, sources of new nutrients and their transport mechanisms for the new production, capacity of new production in the Black Sea, f-ratio, contribution to total production.

TASK II.3. Parameterisation and estimation of growth, grazing, mortality, and reproduction rates of plankton, especially in conjunction with the environmental conditions (for phytoplankton) and the diet composition and availability of food (for zooplankton);

TASK II.3.A. The structural and functional analysis of the Black Sea ecosystem.
The following important parameters of plankton community will be evaluated;

Intensity of production processes,
Intensity of destruction processes,
Balance between the primary production and destruction,
Intensity of the trophic relationships in community,
Selectivity in grazing of various groups of organisms,
Importance of different groups of organisms in the trophic net of community.

The goal of this sub-task is to determine similarity and differences in the functioning of plankton communities in different parts of the Black Sea in different seasons.

TASK II.3.B. Studies of the dynamics of main phytoplankton populations, growth rates and mortality rates in relation to the environmental conditions and the other trophic groups of plankton communities.
The target of the sub-program is to express the relationship between phytoplankton populations and the changes in the biotic and abiotic environmental conditions, using the laboratory and in situ experiments as well as field data.

TASK II.3.C. Studies of the zooplankton population dynamics, respiration and grazing rates, generation cycle characteristics, in relation to the basin scale circulation features and trophic interactions.
The sub-program would resolve the mechanisms controlling the initiation, the duration and the termination of the diapause phase, and attempt to determine if this phase is obligatory in the life cycle of Calanus euxinus and if the formation of diapausal stock is permanent or sporadic.

TASK II.3.D. Studies on the response of phytoplankton communities to the abiotic environment (meteorological, hydrophysical, anthropogenic) using remote sensing
The goals of this sub-program are;

Accumulating the SeaWiFS data for the Black Sea region, beginning in September, 1997,
Accumulating the relevant information, analysis of the accumulated information in separate parts of the Black Sea taking into account both the smoothed averaged values of surface chlorophyll concentration and the patterns of its spatial variability,
Utilization of the analysis based on the results of ecosystem models.

TASK II.4. Spatial and temporal changes of the primary production, based on the algorithms connecting the satellite data with chlorophyll "a" concentration and photosynthesis rates.
This sub-program envisages the following;

Development of a "regional" algorithm for the assessment of surface chlorophyll via satellite ocean color sensors,
Development of an algorithm for the assessment of the daily values of surface and underwater PAR ,
Determination of the typical vertical structure of chlorophyll distribution and seasonally-differentiated parameters of the photosynthesis-light curves,
Analysis of the seasonal and spatial variability in chlorophyll "a’ concentration and primary production.

TASK II.5. Exchanges between the coastal seas, the shelf seas, and the Black Sea interior, including those induced by the Rim Current instabilities and cross-shelf structures such as filaments, mushroom eddies, and squirts.

Key scientist: Dr. Alexander Mikaelyan



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