Posted on May, 09 2009

WWF report on the distribution of so called “spring blooms” in the Baltic Sea. In 2009, the northern Baltic Proper witnessed the strongest spring bloom of the past 15 years, with production peaking just a few weeks ago. The spring blooms are well known to scientists, but as they take place from March to May when not so many people are out on (or in) the sea, their impact on the environment is not well known or discussed outside of scientific circles.

The intensity of the spring bloom is mainly governed by the amount of nitrogen entering the sea from sources like farming, waste water and the combustion of fossil fuels. Dead zones created by decomposing spring bloom algae can release more phosphorus through internal loading. Phosphorus is the limiting factor for the summer blue-green algae blooms, and these algae have the capacity to enrich the water with nitrogen.