Recent decades have seen a degradation of the environmental quality in semi-enclosed seas, which are particularly sensitive to population pressures due to their naturally low flushing rates related to their geometry. The North Sea, Baltic Sea and the Black Sea are amongst the most seriously threatened seas in the Euro-Asian region. Each semi-enclosed sea has a distinct pattern of circulation, transport, mixing, associated with the particular geometry, topography, boundary processes, interior stratification, atmospheric forcing, ice fonnation, straits / sill controls, and the specific inputs of freshwater, nutrients and pollutants. The workshop investigated the distinctive physical and ecological characteristics of the three seas in a comparative manner, in order to identify the types of driving forces and dynamic controls operating on productivity, nutrient cycling, physical transport and mixing mechanisms. A comparative study of these controlling mechanisms would allow us to better understand ecosystem sensitivity in these different environments. The workshop presentations highlighted the complexity of the semi-enclosed seas related to the interaction amongst the physical, chemical and biological fields, and differences in time and space scales in each of the systems. Further, a strong climate signal exists in these systems, manifest in the interannual, interdecadal and longer term variability. Part of the variability appears connected with background climatic variability.

Inhalt

Preface. A Synopsis and Recommendations for Future Studies. Changes of Mean Sea Level and Ice Conditions in Gdynia as Indicators of Climate Changes in the Gulf of Gdansk; M. Sztobryn, et al. Variability of Northwestern Black Sea Hydrography and River Discharges as Part of the Global Ocean-Atmosphere Fluctuations; A. Polonsky, et al. Recent Man-Made Changes in the Black Sea Ecosystem; Yu.P. Zaitse, B.G. Alexandrov. Seasonal and Long-Term Variability of the Black Sea Optical Parameters; V.L. Vladimirov, et al. The Nutrient Stock of the Romanian Shelf of the Black Sea During the Last Three Decades; A. Cociasu, et al. Distribution and Fluctuation of Dominant Zooplankton Species in the Southern Black Sea in Comparison to the North Sea and Baltic Sea; U. Niermann, W. Greve. Some Aspects of Phytoplankton Long-Term Alterations off Bulgarian Black Sea Shelf; S. Moncheva, A. Krastev. Sensitivity to Anthropogenic Factors of the Plankton Fauna Adjacent to the Bulgarian oast of the Black Sea; A. Konsulov, L. Kamburska. Long-Term Variability of Phytoplankton Communities in Open Black Sea in Relation to Environmental Changes; A.S. Mikaelyan. Mnemiopsis Leidyi Abundance in the Black Sea and Its Impact on the Pelagic Community; T.A. Shiganova. Seasonal Variation of Surface Pigment Distribution in the Black Sea on CZCS Data; N.P. Nezlin. The Effect of Hydrological Conditions on the State of Herring Stocks in the Baltic Sea; T. Raid. Role of Fishing in the Black Sea Ecosystem; A.C. Gücü. Environmental Impact on Fish Resources in the Black Sea; K. Prodanov, et al. Variations in the Vertical Structure of Water Chemistry within the Three Hydrodynamically Different Regions of the Black Sea; Ö. Bastürk, et al. Spatial Isopycnal Analysis of the Main Pycnocline Chemistry of the BlackSea: Seasonal and Interannual Variations; S. Konovalov, et al. Suspended Matter as an Index of Productivity in the Western Black Sea (Application for Productivity and Eutrophication Control); S.V. Vostokov. Particulate Organic Matter of Black Sea Euphotic Zone: Seasonal and Long-Term Variation of Spatial Distribution and Composition; Z.P. Burlakova, et al. Time-Series Profiles of 134Cs, 134Cs and 90Sr in the Black Sea; K.O. Buesseler, H.D. Livingston. Physical Oceanography Variability in the Black Sea Pycnocline; L.I. Ivanov, et al. The Black Sea Bottom Homogeneous Layer: A Simple Model of Formation; V.N. Eremeev, et al. Physical Processes of Surface-Deep Layers Exchange in The Black Sea; E. Demirov, et al. Convection in the Baltic Sea: A Numerical Process Study; J.O. Backhaus, H. Wehde. An Ice/Ocean Model for North and Baltic Sea; C. Schrum. Quantification of Transports to Skagerrak: A Modeling Approach; M.D. Skogen, et al. Eddy Dynamics Controlled by Basin Scale, Coastline and Topography; N.H. Rachev, E.V. Stanev. Seasonal Variability of the Black Sea Climatic Circulation; D.I. Trukhchev, R.A. Ibrayev. Cold Intermediate Water Formation in the Black Sea. Analysis on Numerical Model Simulations; J.V. Staneva, E.V. Stanev. Circulation in Semi-Enclosed Seas Induced by Buoyancy Flux Through A Strait; G.K. Korotaev. Modelling of Strait Dynamics: The Baltic Experiments; E. Sayin. Heat and Salt Intrusions in the Pycnocline from Sinking Plumes. Test Case for the Entrainment in the Black Sea; J.A. Simeonov, et al. Coastal Eutrophication of the Southern Bight of the North Sea: Assessment and Modelling; C. Lancelot, et al. Modelling the Functioning of the North-Western Black Sea Ecosystem from 1960 to Present; D. van Eeckhou