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EN
The spatial distributions of basic water parameters in the Puck Bay, a small semi-closed water body located on the southern coast of the Baltic Sea, were often typical of upwelling phenomenon. In such situations, like those observed in July of 1999, temperature decreased locally and water transparency increased locally. The present study analyzed conditions under which upwelling occurred using maps of horizontal currents at different depths, which were obtained from an operational hydrodynamic model. With north, northwest winds the upwelling in Puck Bay looked like the shallow-water upwelling arising as a direct dynamic response of the water body to the wind direction, without a distinct effect of the Coriolis force. However, upwelling water circulation during other wind directions, i.e. west and northeast winds, did not match this simple scheme and was affected by coastline configuration. The results of many years’ measurements pointed at an important role of upwelling in hydrological regime formation in the shallow parts of the Puck Bay.
2
EN
Among over 150 maps of sea surface temperature in the Polish Baltic coastal region derived from satellite data during the warm period of the year (April-October) in 2000-2002, 41 cases were noted where its distribution showed characteristic features indicating the occurrence of coastal upwelling. The fundamental parameters of range, probability of occurrence and temperature modification caused by water from deeper sea layers raised by an upwelling event and spreading across the surface were established for three regions (Hel, Łeba and Kołobrzeg). The Kołobrzeg upwelling region had the largest spatial range (up to 5000 km2). The region with the smallest spatial range (Hel, up to 1400 km2) had the largest surface temperature amplitude (to 14°C), the largest maximum temperature gradient (5°C km2) and the largest average sea surface temperature decrease in the centre in relation to the background value.
EN
Space-time variations in chlorophyll a (Chl a) concentrations in the surface water of upwelling regions along the Polish coast of the Baltic Sea were analysed. Carried out between 1998 and 2002 in the warmer season (from April till October), the measurements were targeted mainly at the Hel upwelling. Satellite-derived sea surface temperature (AVHRR) and Chl a data (SeaWiFS) were used. Generally speaking, the Chl a concentration increased in the upwelling plume, except along the Hel Peninsula, where two scenarios took place: a reduction in Chl a concentration in spring and an increase in autumn.
4
Content available remote Ecohydrodynamic model of the Baltic Sea. Part 2. Validation of the model
EN
The ecohydrodynamic model for the Baltic Sea consists of two interacting parts: one describes the hydrodynamics of the water (3HD), the other organic matter production and destruction (ProDeMo). The results of the simulation were validated. The modelled processes were compared with direct observations, which demonstrated the recurrence of cycles, from the spring diatom blooms through the summer depletion of nutrient salts and algal blooms, to autumn blooms of diatoms and the subsequent destruction of organic matter, and intensified mineralisation of detritus in winter. Calibration yielded a set of coefficients complementing the algorithm of equations describing the production and destruction of organic matter in the coastal zone. Verification of the model has demonstrated that in multi-year simulations it is stable and also that it follows the laws of conservation of mass and energy. The third procedural stage of the model investigation was validation, in which statistical measures in the form of bias, correlation coefficients and effectiveness between simulations and observations not used in calibration describe the quality of ecohydrodynamic modelling in southern Baltic Sea waters.
5
Content available remote Ecohydrodynamic model of the Baltic Sea. Part 1. Description of the ProDeMo model
EN
The ProDeMo (Production and Destruction of Organic Matter Model), a 3D coupled hydrodynamic-ecological model, was formulated and applied to the whole Baltic Sea and the subregion of the Gulf of Gdansk. It describes nutrient cycles (phosphorus, nitrogen, silicon) through the food web with 15 state variables, oxygen conditions and the parameterisation of water-sediment interactions. The present version of the model takes two groups of phytoplankton - diatoms and non-diatoms - as well as zooplankton into consideration. It covers the flow of matter and energy in the sea, including river discharges and atmospheric deposition. Numerical applications are embedded on a 1 NM grid for the Gulf of Gdansk and a 5 NM grid for the Baltic Sea. Since the model results largely concur with observations, the model can be regarded as a reliable tool for analysing the behaviour of the Baltic ecosystem. Some examples of the spatial-temporal variability of the most important biological and chemical parameters are presented. The model results are compared with those of other modelling research in the Baltic Sea. Both the ProDeMo model algorithm and its computing procedures need to be further developed. The next version should therefore enable more phytoplankton groups to be defined, for example cyanobacteria, which are able to take up molecular nitrogen from the atmosphere (nitrogen fixation). Additionally, the sediment phase should be divided into active and non-active layers.
EN
Low water salinity values were recorded during upwelling events along the marine side of the Hel Peninsula. The most probable explanation of those unexpected results is a submarine groundwater discharge in this region. The hydrogeological structure of the area and some previous studies on salinity anomalies observed in the Gulf of Gdansk seem to confirm the hypothesis. This report encourages further complex research aimed at studying this phenomenon.
EN
Unlike dunes, sandy beaches and the littoral zone are usually regarded as non-vulnerable. The biodiversity and biomass of interstitial organisms are low. How-ever, recent findings have shown that marine sands transfer energy very ef-fectively, and that chemical and biological reactions take place faster there than in fine-grained sediments. The importance of the microphytobenthos and bacteria to this system is little known. The effects of recreational pressure (trampling, beach cleaning and nourishment) are not well understood. A pilot study from the Baltic Sea shows the importance of trampling as a form of bioturbation, a very effective way of fragmenting and mixing organic matter with the sand. The high diversity of diatoms and meiofauna in undisturbed beaches may act as an effective biological filter for some types of pollutants, while less diverse, but more abundant biota in disturbed areas are more effective in processing organic matter (self-cleaning of the beach).
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