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How Catfish And Algae Might Become The Chicago River’s Saviors


Two very different projects are using a couple of aquatic species – catfish and algae to try and heal the Chicago River, a river that has traditionally been one of the most polluted waterways in the United States.

The Chicago River, one of the main reasons why Chicago became an important city in the United States, has traditionally been negatively affected by industrial and residential development which has led to many harmful substances being discharged in the Chicago River system over the decades. Despite the fact that certain parts of the system hold names as ominous as Bubbly Creek, the river is still extremely popular for recreational fishing. If the two projects work out, one day it might even become possible to enjoy one’s catch without fearing for one’s health.

The first of the two projects was undertaken by a nonprofit organization called the Friends of the Chicago River and included releasing almost 200,000 baby channel catfish into the system and creating nesting areas for them by placing permeable concrete tubes in the river.

The reason why they decided to introduce this non-native species into the aquatic ecosystem of the Chicago River was that channel catfish are considered a rather hardy species whose potential thriving in the environment will show that it is possible to make the river a healthy environment. Conversely, if they do not survive and thrive, things will be looking quite bleak for the rest of the river’s ecosystem.

shutterstock_101601940The second project is somewhat connected with this one, mostly because of the species that is also being used to heal the river – the algae. This is very interesting since the algae are actually the main culprit in killing off other species in the Chicago River (the humans actually being the main culprit of course, albeit indirectly).  Namely, due to increased levels of phosphorus and nitrogen, the algae thrive in the Chicago River, using up all the air and pretty much suffocating the rest of the aquatic life.

The increased levels of nitrogen and phosphorus are found in the river mostly because the city of Chicago does not have enough sewage treatment plants and also because the state of Illinois does not control how much phosphorus can be released into the river.

This second project will actually use algae in order to take the phosphorus and nitrogen from the wastewater before it is released into the river system. The Metropolitan Water Reclamation District will test a revolving algal biofilm reactor which was developed at Iowa State University. This system uses huge vertical conveyor belts covered in algae  which will be lowered in the waste water, then revolved to let algae grow before they are scraped off and used as organic waste or fertilizer. In short, the algae might actually become part of the solution instead part of the problem.

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