It is in the middle of summer and the water has just turned into lumpy, green, vicious goo rubbing against the grass on the edge of the water. The sun I setting over the lake, and even though it is full of this vicious goo, the water surface glisten in it’s reflection. I crave to get into the glistening water but just as I take one step into it I can feel the algae embracing my feet inhabiting every poor. The middle of the summer is the most prosperous time for algal blooms since the algae thrive in warm and less windy weather.1 We have ourselves to blame for this over-fertilization of lakes since we are responsible for the large amounts of contaminated water that we let into the lakes. Several pump stations in the Järlasjön have disaster emissions from surrounding households and industries.2 Even though algal blooms are a natural process the nitrogen and phosphorous we let into the environment increases the blooming. During algal blooms large amounts of plant algae creates a layer on the surface of the water. When the algae then die, they sink to the lake floor where they are decomposed by microorganisms. Decomposition occurs naturally, but under the influence of over-fertilization it becomes so large that it often leads to oxygen deficiency at the bottom of the lake. This causes the organisms living on the bottom, but in need of oxygen, to die out.3
The human species have for a long time taken active part in changing the natural ecosystem. A particularly strong influence is our ability and willingness to move plants and animals, which has had major consequences throughout history. Trophic cascade, the implementation or removal of super-predators is one known method of human controlling the ecosystem.4 In the lake Järlasjön the use of biomanipulation is no news. For example implementation of fish is being made to control the amount of toxic plankton in the water.2 Release of mallards for hunting is also a common phenomenon. In Sweden more than 250 000 birds are released each year and several millions in Europe. We simply place what ingredients we prefer in this big stew we call the “natural” ecosystem.
Felicia Svensson
Readings:
Swanson, Heather, Tsing, Anna, Bubandt, Nils, Gan, Elaine, eds. ‘Introduction: Bodies Tumbled into Bodies’ in Arts of Living on a Damaged Planet, Minneapolis: University of Minnesota Press, 2017.
Links:
1. Havet.nu, Sommarens algblommningar, https://www.havet.nu/?d=3551
2. Nacka kommun, Järlasjöns Vattenutbyte, https://www.nacka.se/4a5097/globalassets/boende-miljo/dokument/park-natur/sjoar/jarlasjons-vatteutbyte.pdf, September 2016
3. Havs- och vattenmyndigheten, Övergödning, https://www.havochvatten.se/hav/fiske–fritid/miljopaverkan/overgodning.html, 2017-05-11
4. Encyclopedia Britannica, Trophic cascade, https://www.britannica.com/science/trophic-cascade#ref1088235
5. Sveriges Lantbruksuniversitet (SLU), Storskaliga utsättningar av inhemska arter: gräsand som modellart, https://www.slu.se/ew-nyheter/nyhetsarkiv/2015/3/par-soderquist/, 26 Mars 2015
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