Eutrophication
Say it: yoo-troh-fih-KAY-shun
Eutrophication is the over-enrichment of a lake, river or coastal sea with nutrients, fueling algal blooms that later decay and use up the water's oxygen.
Definition
What is eutrophication?
Eutrophication happens when a body of water receives more nutrients, chiefly nitrogen and phosphorus, than its ecosystem can absorb. It can occur slowly in nature as lakes age, but most cases today are caused by people. Fertilizer washed off farmland, sewage, animal manure and some detergents, along with nitrogen oxides from burning fuels, all end up in rivers, lakes and estuaries.
The extra nutrients act as fertilizer for algae and cyanobacteria, which multiply into dense blooms that turn the water green or brown and shade out seagrasses and other rooted plants. When the bloom dies, bacteria decompose the dead cells and use up dissolved oxygen as they do so. The water becomes hypoxic, meaning very low in oxygen, and fish, crabs and shellfish that cannot move away suffocate. Large areas left in this state are called dead zones. Some blooms also release toxins that harm wildlife and people, and the carbon dioxide given off by decay makes coastal water more acidic.
One of the largest dead zones forms each summer in the Gulf of Mexico, fed by fertilizer carried down the Mississippi River. Cutting runoff, improving sewage treatment and restoring wetlands and filter-feeding oyster beds are the main ways to reverse it.
Word parts
Where does the word “eutrophication” come from?
- eu-
- well, goodGreek eu
- troph-
- nourishmentGreek trephein, to nourish
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Terms that go with it
- Nitrogen cycleThe nitrogen cycle is the set of mainly microbial processes that move nitrogen between atmospheric gas, ammonium, nitrate and living organisms.
- PhytoplanktonPhytoplankton are microscopic photosynthetic organisms that drift near the surface of oceans and lakes and form the base of most aquatic food webs.
- EstuaryAn estuary is a partly enclosed coastal body of water where river water meets and mixes with seawater, so that the water there is brackish.
- Ocean acidificationOcean acidification is the ongoing fall in the pH of seawater, driven mainly by the uptake of carbon dioxide that human activities release into the air.
- DecomposerA decomposer is an organism, mainly a bacterium or fungus, that breaks down dead organisms and wastes and returns their nutrients to the environment.
- EcosystemAn ecosystem is a community of living organisms together with the nonliving environment they interact with, linked by energy flow and nutrient cycling.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- NOAA National Ocean Service: What is eutrophication?
- OpenStax Biology 2e, 46.3 Biogeochemical Cycles
- American Heritage Dictionary: eutrophic
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