Global warming may increase harmful algal blooms in the Baltic Sea. Increase in water temperature in the Baltic sea may lead to low oxygen levels which promotes blue-green algal blooms. This type of algae is also called as cyanobacteria.
Photo Credit: Jeff Schmaltz - NASA/Modis
Massive algal blooms have been spreading in the Baltic. This occurs along with low oxygen level conditions affecting life. The spread may be due to more nutrients such as nitrogen and phosphorus that get released through agricultural activities.
Karoline Kabel and Matthias Moros led a group of scientists at the Baltic Sea Institute in Warnemunde, Germany, in a study and found that in addition to nutrients from agriculture, the increase in temperatures have also played a major role in the massive blooms of cyanobacteria. Further increase in temperature due to global warming will further aggravate the situation.
The scientists considered the climate before large-scale industrialized agriculture was started, as this period was associated with large utilization of nutrients. They studied the Medieval warm period that occurred 800 to 1000 years ago. They investigated sediment cores in the Baltic and found that in the past deoxygenated conditions and algal blooms occurred due to warm periods. This warm period was followed by "The Little Ice Age", when the temperatures decreased by 3 - 4 degrees. This cold period increased the health conditions in the Baltic. However, in the 20th century, the cyanobacteria blooms and low oxygen levels started to form again.
In order to estimate the temperatures in the past, the team utilized the new TEX-86 method. They interpreted information about sediments and utilized ecosystem models to decide on the effect of nutrient and temperature combinations in the Baltic Sea.
The scientists have published the study in the journal Nature Climate Change.
Source: http://uni.no/
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