Streams Cleaned by Algae

One’s first thought of algae might be of green goopy stuff resembling moss that lines lake shores and river banks. However, recent research has shown algae biodiversity can remove harmful pollutants from stream water. University of Michigan researcher Brad Cardinale constructed over 100 manmade streams in a lab to study how the number of algae species in freshwater impacts the rate of nitrate removal. Cardinale found that a combination of eight algae species in freshwater resulted in the removal of nitrate 4.5 times faster than when only one algae species was present.

Mr. Cardinale said, “If we were to maintain streams in their naturally diverse state, these streams that we love for their recreation, for their beauty, for fishing, etc. … have the tangential benefit of cleaning up our water for us. One implication (of the study) is, if we let nature do its thing, we don’t have to run around creating very expensive water treatment plants all over the planet.” (Source:

Nitrate is a naturally occurring form of nitrogen and is a nutrient for plants such as algae. In streams near farmland though, it is often artificially elevated by runoff from chemical fertilizers used nearby, and manure. Excessive nitrate in water supplies can lead to algal blooms where there is too much algae, and lack of oxygen in the water for aquatic species like fish. Also excessive nitrate in drinking water can harm humans.

Additionally, related research found nitrate levels in streams may be connected to their production of a greenhouse gas called nitrous oxide. This study indicated that reducing nitrate levels from agricultural runoff would likely reduce the greenhouse gas production. Biodiversity of algae in streams therefore might play a role in reducing both nitrate and nitrous oxide production, which would limit the greenhouse gas generation. Nitrous oxide has a capacity to trap heat in the atmosphere 300 times greater than that of CO2.

Dead zones in the oceans are areas with oxygen levels low enough they can’t support marine life in the normal way. These areas are in part created by the extra nitrogen introduced into river and marine systems by intensive agriculture.

Image Credit: Eugene Zelenko

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Duane B.
.5 years ago

Thank you for sharing.

Christa Deanne
Oceana Ellingson6 years ago

I'm so glad this Earth can heal itself, but we just need to do our parts (such as recycle or don't litter or harm the waters or anything in the first place) and let it actually just have time to heal.

Bonnie B.
Bonnie B6 years ago

The trick is, we have to stop using chemical fertilizers and pesticides so nature is not overwhelmed and can do the amazing self-healing it has built into the system. I'm glad the algae blooms are a part of the solution, but if we keep letting the run off create them, the fish and other wildlife will still be dead and they will not really get to do what they can really do...clean our water supply and restore the balance. Balance is the key word. Isn't it nice to know that all we have to do is stop polluting and then just step away and let Mom clean up the mess (as usual)? Oh right, THAT"S the hard part...stopping the polluters who only believe in their own profit, not responsibility for their actions. I hope we can change before it's too late.

Edwin Krkljus
Ed K6 years ago

an even easier and faster natural way to clean lakes:
When Bob Laing, a creationist, looked for a solution to this problem, the first question he asked was, "Did God design a solution to this problem?" The answer is found in the way lakes turn themselves upside down twice a year. In the spring and fall, as water temperatures change through 39 (F), the bottom waters are pushed to the surface by heavier, 39 water. At the surface, these "bottom waters" give up their poisonous gasses and absorb oxygen. Laing went on to prove, using huge air bubbles and other equipment, that lakes could be saved by stopping the original source of the problem and then artificially duplicating the Creator's built-in system.

Environmentalists at first rejected his solution. However, today, Bob Laing and his Clean-Flo Laboratories, has restored over 1,000 lakes and ponds worldwide, including the Tokyo Garden Ponds, where each fish is worth up to $100,000!


Once again....leave nature alone, it knows what it's doing.

Deb Lewis
debbie Lewis6 years ago


Megan S.
Megan S6 years ago

Just more evidence that nature is so much more prepared to keep things balanced than us humans are!
Mother Earth wins again! :)

Alixis Lind
Alixis Lind6 years ago

I love when algae grows in my fresh water aquarium, it gives my fish a nice free snack c:

Elizabeth M.
Elizabeth M6 years ago

Thanks for another interesting post Jake.
Learned something new today! Let nature do the work!!

Piotr M.
Piotr M6 years ago

But nitrate stays in the water, isn't it? It's just not dissolved but built-in algal cells...