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The major tasks of the Baltic Sea Experiment (BALTEX) are to simulate the water and energy cycles of the Baltic Sea catchment and to identify important processes, which are relevant to the climate in the Baltic region. A fully coupled regional climate model system for the Baltic Sea region, called BALTIMOS, was developed in the framework of the German climate research program DEKLIM by linking existing model components for the atmosphere, for the ocean including sea ice, and for hydrology. With this system, it is possible to model the complete water and energy cycles for the Baltic Sea catchment for today's climate, as well as for the future with climate scenarios. The emphasis in this paper is given to the description of the modelling system and on the comparison of the results of the fully coupled BALTIMOS system against the results of the uncoupled atmospheric component REMO for today's climate. Both simulations are driven at the atmospheric lateral boundaries with ECMWF analysis data from the European Centre for Medium Range Weather Forecast (ECMWF) for 5 years each. In the uncoupled run, the sea surface temperature (SST) and ice surface temperature (IST) analysed by ECMWF are prescribed, while in the coupled run, SST and IST are provided by the ocean/sea ice model BSIOM. Several analysed parameters are very similar for the land part of the Baltic Sea catchment, while there are differences especially for surface and near-surface temperatures for the fraction of the Baltic Sea itself that indicate further research efforts. As no corrections for the modelled air-sea fluxes are applied for the coupled model system, it is a good result that no drift of the coupled model system is visible in the 5-year integration. The present paper gives an overview about the development of the coupled model system and shows results from first integrations of the system. [ABSTRACT FROM AUTHOR]

Eutrophication is a major problem in the Baltic Sea caused by the inflow of large loads of nutrients. This is largely due to diffuse and point sources of pollution such as wastewater treatment plants (WWTPs), which discharge poorly treated wastewater via rivers to the sea. The paper quantifies the problem of point source pollution in the Pilica River catchment (central Poland), one of the largest, second order subcatchments of the Vistula River. The main objectives of the research were: (i) quantification of nutrients transfer along the Pilica River continuum from the source to the estuary into the Vistula River, and (ii) evaluation of the influence of WWTPs on eutrophication of the Pilica River and the Baltic Sea. The study showed that the average total phosphorus (TP) and total nitrogen (TN) load discharged from the Pilica catchment amounted to 0.057 t TP km-2 and 1.655 t TN km-2, respectively, and was two and three times higher, respectively, compared to the annual average loads in the Polish territory and the Baltic States. Moreover, the paper presents possible solutions of sustainable planning and management in river catchments based on the ecohydrological concept and ecological engineering. [ABSTRACT FROM AUTHOR]

Finding suitable state indicators is challenging and cumbersome in stochastic and complex ecological systems. Typically, a great focus is given to criteria such as data availability, scientific basis, or measurability. Features associated with the indicator's performance such as sensitivity or robustness are often neglected due to the lack of quantitative validation tools. In this paper, we present a simple but flexible framework for selecting and validating the performance of food web indicators. In specific, we suggest a 7-step process in which indicator performances at a regional scale are quantified and visualized allowing for the selection of complementary indicator suites. We demonstrate its application by comparing the performance of pelagic food web indicators for three basins of the Baltic Sea and by assessing the food web status based on selected indicator suites. Our analysis sheds light on spatial differences in indicator performances with respect to direct and indirect pressures, the role of non-linearity and non-additivity in pressure responses, as well as relationships between indicators caused by species interactions. Moreover, our results suggest that the present food web states in the Bornholm and Gotland basins of the Baltic Sea deviate distinctly from an earlier reference period. We advocate the use of our quantitative framework as decision-support tool for selecting suites of complementary indicators under given management schemes such as the EU Marine Strategy Framework Directive. [ABSTRACT FROM AUTHOR]

The paper studies the vulnerability and protection of marine environments of two semi-closed seas, the Baltic and the Adriatic, in terms of physical and socio-economic factors. Institutional and technical instruments and policies of protection, at global, pan-European, EU and regional levels, are reviewed. The pioneering role (for Baltic) of the Helsinki Convention, signed in 1974 by the Baltic coastal states, is highlighted, whereby all sources of pollution were made subject to one single instrument. There is no similar comprehensive agreement yet on the semi-closed Adriatic Sea, but protection of the Adriatic Sea is included in the Barcelona Convention signed in 1976 by 16 states and the European Union (presently there are 22 parties to the convention) which was a follow up of the pioneering (for Adriatic) Mediterranean Action Plan signed by contracting parties in 1975. The Baltic region, with 90 million people in its catchment area, is economically well developed; out of nine of its coastal states, eight are EU members. The catchment area of the Adriatic, home to about 15 million people, is characterised by even larger socio-economic contrasts, with Italy as the dominating player as for population size and the economy. The marine and coastal environmental burdens of both the Baltic and the Adriatic are mainly due to agriculture, industry, shipping, fisheries, and tourism, not to forget the legacies of unsustainable past. The Adriatic, a busy transportation route for oil vessels, is one of the most vulnerable areas in the Mediterranean. [ABSTRACT FROM AUTHOR]

In this paper, we estimate the surface water retention of nitrogen (N) in all the 117 drainage basins to the Baltic Sea with the use of a statistical model (MESAW) for source apportionment of riverine loads of pollutants. Our results show that the MESAWmodel was able to estimate the N load at the river mouth of 88 Baltic Sea rivers, for which we had observed data, with a sufficient degree of precision and accuracy. The estimated retention parameters were also statistically significant. Our results show that around 380 000 t of N are annually retained in surface waters draining to the Baltic Sea. The total annual riverine load from the 117 basins to the Baltic Sea was estimated at 570 000 t of N, giving a total surface water N retention of around 40 %. In terms of absolute retention values, three major river basins account for 50% of the total retention in the 117 basins; i.e. around 104 000 t of N are retained in Neva, 55 000 t in Vistula and 32 000 t in Oder. The largest retention was found in river basins with a high percentage of lakes as indicated by a strong relationship between N retention (%) and share of lake area in the river drainage areas. For example in Göta älv, we estimated a total N retention of 72 %, whereof 67% of the retention occurred in the lakes of that drainage area (Lake Vänern primarily). The obtained results will hopefully enable the Helsinki Commission (HELCOM) to refine the nutrient load targets in the Baltic Sea Action Plan (BSAP), as well as to better identify cost-efficient measures to reduce nutrient loadings to the Baltic Sea. [ABSTRACT FROM AUTHOR]

Currently, there is a major concern about the future of nutrient loads discharged into the Baltic Sea from Polish rivers because they are main contributors to its eutrophication. To date, no watershed-scale studies have properly addressed this issue. This paper fills this gap by using a scenario-modeling framework applied in the Reda watershed, a small (482 km) agricultural coastal area in northern Poland. We used the SWAT model to quantify the effects of future climate, land cover, and management changes under multiple scenarios up to the 2050s. The combined effect of climate and land use change on N-NO and P-PO loads is an increase by 20-60 and 24-31 %, respectively, depending on the intensity of future agricultural usage. Using a scenario that assumes a major shift toward a more intensive agriculture following the Danish model would bring significantly higher crop yields but cause a great deterioration of water quality. Using vegetative cover in winter and spring (VC) would be a very efficient way to reduce future P-PO loads so that they are lower than levels observed at present. However, even the best combination of measures (VC, buffer zones, reduced fertilization, and constructed wetlands) would not help to remediate heavily increased N-NO loads due to climate change and agricultural intensification. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a coupled economic–ecological model that integrates a catchment model with a marine model and incorporates economic data to analyse the long-term economic and ecological consequences of nutrient abatement in the Baltic Sea. The spatially explicit model describes dynamics of soil phosphorus in arable land, developments of nutrient concentrations and phytoplankton biomass in the sea basins, and inter-annual variation in nutrient loads and biophysical processes. The performance of the model is demonstrated by computing the least-cost solution to reach the good environmental state of the sea – as implied by the Baltic Sea Action Plan – within a time span of 40 years. The total cost of achieving this target is 1487 M€ annually. Spatially optimal allocation of load reductions differs from the load reduction targets of the Baltic Sea Action Plan, and focuses more on the control of phosphorus loads. [Copyright &y& Elsevier]