Eutrophication – too much of the good stuff

sail_alfredAt the turn of the century, the Baltic Sea was not nutrient rich. Water toilets, the use of fertilizers and draining wetlands in the coastal area has caused a great increase in the load on the marine environment. The amount of nitrogen and phosphorus has increased by 4 and 8 times respectively in the Baltic Sea, which has had a significant impact on the ecosystem.

Major initiatives have been undertaken to treat wastewater, improve agricultural methods and protecting remaining wetlands, the uncontrolled flow of nutrients from point sources has been limited.

The coastlines are continuously exposed to the increasing amounts of nutrients. It is impossible to trace the origin of the nutrients in the open water. They have their origin in all of the surrounding countries, which makes limiting nutrient input a truly regional and transboundary issue. No country can solve this issue alone. The work to limit nutrients in the Baltic Sea area has become highly prioritized, taking place both on the European scale and regionally through the Baltic Sea Action Plan elaborated by HELCOM (Helsinki Commission).

Nutrients - nitrogen and phosphorous
Nutrients make everything grow better. It makes plankton and fine-fibred algae grow faster, at the expense of perennial species such as kelp, eel grasses and bladder wrack. Too much plankton in the water makes the water less transparent and prevents light from reaching down to the deep. Eventually plankton begin to sink to the bottom where they begin decomposing, a process which consumes large amounts of oxygen. In many coastal areas and in the deeps of the Baltic proper, the bottoms are depleted of oxygen for long periods. Almost all organisms in these areas die or have to move elsewhere.

Increase of algal blooms
Eutrophication results in massive blooms of blue-green algae. This has led to closed beaches and causes frequent public concern about the future suitability of the Baltic Sea as a site for recreation purposes. The occurrence of algal blooms has increased since the 1960s.

Difficult to curb and reverse
Once the process caused by excessive eutrophication has begun, it is hard to curb. Even if external loads of nutrients that enter aquatic ecosystems may be limited, nutrients have accumulated over many years in the sea bottom. A self-perpetuating process continues as internal loads of stored nutrients are repeatedly released into the water, where they feed the renewed growth of plants.