Baltic sea: Climate modify counteracts turn down inwards eutrophication

Off the coast of Schleswig-Holstein at the larn out of Eckernförde Bay is a hidden treasure, only it is non i of chests total of argent in addition to gold. It is a unique scientific record. Since 1957, environmental parameters such every bit oxygen concentrations, temperature, salinity in addition to nutrients accept been measured monthly at the Boknis Eck fourth dimension serial station. “It is i of the oldest active fourth dimension serial stations for this form of information worldwide,” explains the scientific coordinator Prof. doc Hermann Bange from GEOMAR Helmholtz Centre for Ocean Research Kiel. To date, however, the long time-series has solely been partially evaluated. Bange in addition to his squad accept now, for the get time, analyzed chemical, biological in addition to physical information for the entire menstruum since 1957. Their results accept shown that measures to protect the Baltic Sea accept been somewhat effective, however, full general climate alter has, to roughly degree, buffered against these measures. The report has instantly been published inwards the international periodical Biogeosciences.
A natural phenomenon of the Baltic Sea is the lack of oxygen inwards the deeper H2O layers. The stratification of the Baltic Sea H2O is quite stable, alongside fresh saline in addition to oxygen-rich H2O solely reaching its inner regions from the North Sea through the Danish islands. “We run across this besides inwards Boknis Eck, from near twenty meters depth,” explains Sinikka Lennartz, M.Sc., from GEOMAR in addition to Pb writer of the novel study. In the instant one-half of the 20th century this natural phenomenon was augmented because countries bordering the Baltic Sea dumped large amounts of agricultural fertilizers in addition to sewage into the sea. “That meant an oversupply of nutrients. Algae were so able to proliferate, in addition to every bit before long every bit they transcend away in addition to sink to the bottom, microorganisms decompose the biomass in addition to eat a lot of oxygen; this resulted inwards large oxygen-free zones at the bottom of the Baltic Sea to last formed ” explains Lennartz.
In the mid-1980s, the Baltic countries agreed to ameliorate the protection of the sea. An increasing issue of sewage handling plants were built in addition to the purpose of fertilizers inwards agriculture declined. “This tendency nosotros tin clearly demonstrate inwards Boknis Eck. Since the belatedly 80s, the concentration of nutrients has decreased,” says Professor Bange. The promise that this would restore to a greater extent than oxygen inwards the lower layers of water, however, has non been realized. “The oxygen tendency is soundless downwards significantly,” explains Lennartz, “we run across to a greater extent than in addition to to a greater extent than events at Boknis Eck when no oxygen is measured below twenty meters depth.”
One possible explanation the researchers constitute for the continued refuse of oxygen concentrations is related to changes inwards H2O temperature. “In belatedly summers the temperature on the seafloor has risen past times an average of 0.4 degrees per decade. Higher temperatures besides hateful a to a greater extent than efficient degradation of biomass in addition to thence to a greater extent than consumption of oxygen,” says Professor Bange. Thus, the information suggests that rising seawater temperature caused past times climate alter has buffered against measures for the protection of the Baltic Sea. “Nevertheless, the bordering countries should non subside inwards their efforts to protect the environment. With increasing temperatures, the Baltic Sea would larn eutrophic a lot faster if nosotros reintroduced to a greater extent than waste,” says marine pharmacist Bange.
At the same time, the report demonstrates the high value of long time-series measurements such every bit those at Boknis Eck. “In lodge to position long-term trends inwards the environs in addition to distinguish anthropogenic changes of natural fluctuations, short-term criterion campaigns are non sufficient. Therefore, nosotros actually accept a treasure alongside the Boknis Eck information that is besides irreplaceable for global comparisons,” says Bange.