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Drivers of change Fact sheet series VECTORS Vectors of change in European Marine Ecosystems and their Environmental and Socio-Economic Impacts The VECTORS project seeks to develop integrated, multidisciplinary research - based understanding of changes taking place in our marine environment, the mechanisms for them and the ecological impacts expected from them. VECTORS will examine how these changes may affect the range of goods and services provided by the oceans, the ensuing socio - economic impacts and some of the measures that could be developed to reduce or adapt to these changes. Regional seas vectors and drivers This VECTORS report identifies and disseminates the current understanding of drivers, pressures and vectors of change that could be affecting the main areas of concern to VECTORS: outbreaks, invasives, changes in species distribution and productivity. The full 220 page report, created through a desktop review exercise, is available to download from the VECTORS website, www.marine-vectors.eu. A series of twelve fact sheets, including this one, have been produced to summarise the key findings for each of the nine drivers studied and each of the three Regional Seas (Western Mediterranean, North Sea and Baltic Sea) that act as case studies for the VECTORS project. Land-based pollution Key points Eutrophication is a common problem in all three seas considered by VECTORS; the North Sea, the Western Mediterranean and the Baltic Sea. In the Baltic sea it is mainly related to waterborne nutrient run - off from farming and managed forestry. In the western Mediterranean Sea, eutrophic conditions have been increasingly reported in the last decades in coastal and transitional waters, leading to dystrophic crises and benthic and fish kills. Some regions of the North Sea receive large quantities of anthropogenic nutrients through large rivers, and to a lesser extent from atmospheric deposition and discharges from plants that treat wastewater. The main areas affected by hypoxia in the Mediterranean sea are coastal zones and lagoons where the key environmental features are: low depth, high productivity, organic matter enrichment and low hydrodynamic forces. In the Baltic Sea hypoxia is widespread in large areas both in the open deeper parts and at coastal sites. A side effect is increased release of phosphorous from sediments, causing further eutrophication. In the North Sea, hypoxia can occur seasonally particularly under stratified conditions in areas with high rates of production by phytoplankton. Hazardous substance concentrations in the Baltic used to be at levels where there were effects on marine mammals and other top predators, with some species such as the white tailed eagle even close to extinction. These hazardous substances are now seen to be decreasing in the Baltic. Biological contamination is caused by natural processes such as circulation, upwelling relaxation, and river flow; combined with anthropogenic loadings leading to eutrophication and toxic harmful algal blooms or transport of pathogens from wastewater and aquaculture. General effects Land-based pollution can cause eutrophication (an excess of nutrients), hypoxia (reduced oxygen in the water and sea-bed sediment), changes in turbidity, chemical and biological contamination. Eutrophication causes benthic algal blooms and affects regulation by grazers, favouring invading amphipods and polychaetes. Eutrophication can also influence the development and persistence of harmful algal blooms in the plankton, caused both by toxic and nuisance algae. Hypoxia in the water affects the behaviour, distribution and productivity of fish, through mass mortality or loss of habitat. On the other hand, prolonged hypoxia may favour species, such as jellyfish, which are known to tolerate lower dissolved oxygen concentrations in seawater. Hypoxia in sediment changes the penetration of oxygen altering the redox potential discontinuity depth and causing release of hydrogen sulphide in sediments. This can have huge impacts on bottom fauna, and when re - oxidation occurs, opportunistic species can be favoured in the changing areas. Turbidity in the water is increased by planktonic algal blooms, and can affect prey/predator behaviour in fish, as well as mating habits. Shadow effects of increased turbidity can alter habitats of macro algae and vascular plants (Zostera). Chemical contamination from both “classical” and novel contaminants can favour invading species with less sensitivity to contaminants, e.g. polychaetes and mud snails. Persistent toxic substances are especially worrying because of both their persistence and their toxic effects on animal and plant life if concentrations exceed certain thresholds. Biological contamination is less studied, often related to aquatic farms or wastewater outlets it can be linked to increasing infectious diseases in cetaceans. Contact Project coordinator: Mel Austen Project manager: Jenny Lockett VECTORS Project Office VECTORS V1: Feb 2013 Coordinated by Plymouth Marine Laboratory [email protected], www.marine-vectors.eu Western Mediterranean In recent decades, increased anthropogenic input of nitrogen and phosphorus has led to severe eutrophication problems through Europe, inducing higher phytoplankton primary production in many coastal areas. In the western Mediterranean Sea, the process of eutrophication also increases the frequency and intensity of phytoplankton and macroalgal growth, which can generate hypoxia / anoxia and high turbidity conditions particularly in the shallow coastal areas and lagoons. Land - based pollution may result in the enrichment of the marine environment both in nutrients and in organic matter. The former can cause eutrophication in the water column while the latter reduces the depth of the redox potential discontinuity in sediments. Hypoxia, turbidity and eutrophication in Europe. Hypoxia (oxygen< 2 mg / l) is shown as yellow dots, turbidity (> 0.5 g / l of suspended particles) as orange dots and eutrophication as red dots. Baltic Sea The Baltic Sea is characterised by a low water exchange rate, making it sensitive to eutrophication. Eutrophication forms the basis for increasing algal blooms, which in turn increases turbidity and hypoxia, followed by shallowing of the redox potential discontinuity and sulphide release from the sediment. Combined with chemical and biological contamination, tolerant invading species can gain footholds and suppress local species in parts of the Baltic Sea. The increased turbidity and change in algae composition can change foraging and habitats of fish and fish - larvae, as well as mating patterns hence disturbing the distribution and productivity of fish. From the 1960s to present time, improvements in chemical contaminants have resulted in improvements in the health of top predators such as marine mammals and white tailed eagles, but eutrophication and hypoxia are still wide - spread. Eutrophication status Good HELCOM 2010 Bad HELCOM integrated assessment of eutrophication status, based on Ecosystem Health of the Baltic Sea, HELCOM 2010. Areas in blue / green are areas “not affected by eutrophication”, yellow / red areas “affected by eutrophication”. Large circles indicate open basins and small circles represent coastal assessment sites. North Sea Nutrient discharges causing eutrophication and hypoxia have declined in the last 25 years but problem areas exist seasonally within larger river plumes, particularly in eastern waters. Eutrophication can alter phytoplankton species composition and cause seasonal hypoxia particularly within bottom waters in strongly stratified areas. Pelagic animals more tolerant to low dissolved oxygen, such as jellyfish, may become more prevalent and benthic community composition will be impacted by benefiting animals that can cope with the shallowing of the redox potential discontinuity layer in sediments. Adverse effects of chemicals present within sediments have been documented on organisms, particularly along shipping routes. Only a few coastal areas exceed threshold bacteria concentrations outlined in specific water quality directives but direct impacts of biological pollution on flora and fauna can occur in close proximity to sewage outflows including eutrophication - like effects as well as the transmission of faecal viruses and bacteria via suspended particulate matter (SPM) to shellfish and other filter feeders. Chemical and biological pollutants are often associated with SPM which occurs at higher concentrations in southern vs. northern waters and in coastal areas that are routinely dredged. Eutrophication status in the period 2001–2005 for the North Sea region. These areas are also largely problem areas for hypoxia in the North Sea: This figure was taken from the Ospar 2010 Quality Status Report. http://qsr2010.ospar.org/en/ch04_04.html#eutrophication). VECTORS VECTORS is a European project (26455) supported within Themes 2, 5, 6 and 7 of the European Commission Seventh Framework Programme Further information The leader for this driver and fact sheet creator is Paolo Domenici (CNR-IAMC, [email protected]) with input from Martin M. Larsen, Myron Peck and the Regional Seas review contributors.