Nutrients over-enrichment, mainly nitrogen (N) and phosphorus (P), into ground and surface water is the cause of
eutrophication . The main effect of leaching of nutrients is the rapid growth of algae on the surface of the water, a phenomenon called “algae bloom”. When it occurs, the surface layer formed by algae prevents sunlight from getting through it and reaching the bottom, causing decreased water clarity and the death of larger plant species such as seagrass. The loss of plant life represents the destruction of habitats that provided shelter, food and nursery grounds for many marine animals. Moreover, the deposition of organic material – decomposed by bacteria – increases oxygen consumption on the seafloor, which leads to oxygen depletion and creates
dead zones . These now cover 20% of the Baltic Sea bottom. Some algae species are toxic for marine mammals and can also be dangerous for humans.
Eutrophication causes reduction of biodiversity, erosion of coasts and impoverishment in fish population. Despite some small improvements, the Baltic Sea is heavily affected by eutrophication (
97% of the surface area ) resulting from excess nutrient loads for many years.
Climate change could also have a negative impact on the Baltic Sea catchment area, exacerbating eutrophication – since water and air temperature rise could create better conditions for the growth of algae blooms.
Where does over-fertilization come from?
Most of the water quality problems in the Baltic Sea originate upstream from the thousands of rivers in the catchment area. Some 25% (25% for Baltic proper, 20% for Baltic Sea) of the nutrient load in the Baltic Sea comes from waste water and upstream sources of pollution – not only from farms, but also from households and ports.
According to CCB´s estimates potential losses from 22 million tons of fertilizers handled in the Baltic ports annually may account up to several thousand tons of directly bioavailable nitrogen and phosphorus.
Without engaging and building awareness with actors and stakeholders at all levels that are relevant for reducing nutrient inputs, including those in agriculture and water management sectors, it is impossible to move any further with nutrient reductions. Most actors and stakeholders often lack knowledge and opportunities for sharing best practices. The successful restart of the “Greener Agriculture for a Sustainable Sea” (GRASS) Conference and Baltic Sea Farmer of the Year Award has proven itself a catalyst for change.
Maps:
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