The Baltic Sea is a semi-enclosed brackish water system, with a very limited water exchange to the North Sea. Strong north–south and east–west salinity and temperature gradients, together with a peculiar coastline morphology and bottom topography generate spatially differing environmental conditions resulting in distinct local habitats with different community structures and functioning. As typical for estuaries, Baltic Sea marine and freshwater organisms are found in a regional succession with different species-specific ranges of distribution. Depending on their specific adaptation and tolerance for environmental conditions, many freshwater and marine species are at the border of their distribution ranges in the Baltic Sea and may therefore show an increased vulnerability to changes in the environment.
Around 85 million people live within the Baltic Sea catchment area, exposing the environment to numerous human induced stresses. Nutrients and pollutants enter the Baltic Sea from farmland and industry as well as discarded World War II chemical warfare agents. Eutrophication is therefore among the greatest threats to the good environmental status of the ecosystem. The Baltic Sea is exposed to a high risk of pollution from shipping accidents as it is one of the busiest shipping areas in the world. Shipping is a major vector for the introduction of non-indigenous species to the ecosystem, which may cause significant ecological impacts and have substantial socio-economic consequences. Shipping intensity has steadily increased in the Baltic Sea during recent decades and further increases are expected. Overfishing continue to be a concern in the Baltic as fishing is an important driver influencing the structure of the Baltic ecosystems. New pressures may become important and increase in the future, such as windfarms and energy pipelines. Coastal tourism is a significant pressure in certain areas (e.g. at Polish and German coasts).
VECTORS research has focused on improving our understanding of the mechanisms by which human drivers and climate change impact on the Baltic Sea’s ecosystems. Research approaches have included experimental laboratory and field case studies, application of molecular methods, statistical analyses of time series of monitoring data, stakeholder interviews and different modelling approaches. Our research has used local case studies to enhance in-depth understanding of the ecological processes and the provision of ecosystem services at finer scales. Baltic wide activities have focused on addressing more generic questions (e.g. in relation to eutrophication, biological invasions, and distribution of major fish stocks); and holistic approaches have explicitly considered the spatial heterogeneity and marine spatial planning needs in the Baltic Sea.
A full understanding of the Baltic Sea systems in connection with relevant societal needs, uses and interactions is necessary for broader marine management and maritime spatial planning. It is important to evaluate the costs and benefits of ecosystem goods and services to manage them sustainably. Increasing pressures from eutrophication, climate change, pollution, fisheries, transport/shipping, renewable energy exploitation, and tourism induce major environmental and socio-economic impacts. Some of these pressures can be managed at local levels, but several of them require a regional management approach. Furthermore, national activities may have trans-boundary effects on the ecosystem as a whole. VECTORS results and scenarios of future changes can support decision makers in their management plans for a sustainable marine environment in the Baltic Sea. VECTORS has improved our understanding of how people perceive ecosystem changes and what is considered as important by societies. The outcomes of Baltic Sea case studies will contribute to improving scientific and applied methods in order to evaluate different marine and maritime policy options.