Login

What Is Eutrophication? - Definition, Causes & Effects

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Density-Independent Factors: Examples & Definition

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:01 Definition
  • 1:18 Causes
  • 2:10 Effects
  • 3:57 Prevention
  • 4:15 Lesson Summary
Add to Add to Add to

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Login or Sign up

Timeline
Autoplay
Autoplay
Create an account to start this course today
Try it free for 5 days!
Create An Account

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

Ever heard the phrase, 'too much of a good thing?' Eutrophication is a good example of this. When aquatic systems have an overabundance of nutrients, the entire system suffers and can ultimately become unlivable.

Definition

All living things need specific nutrients to survive. Usually, nature does a pretty good job of providing just the right amount of nutrients, because too many or too few can cause problems. This is especially true in aquatic ecosystems because they are so dynamic. When too few nutrients are present, the water is oligotrophic. It makes sense that when there is not enough nutrition available for the variety of organisms living in an aquatic environment, serious problems will arise.

However, problems can also arise when the aquatic system has an overabundance of nutrients. When this happens we get eutrophication. A eutrophic stream, river or lake occurs when too many nutrients, like nitrogen and phosphorous, are present, usually as a result of runoff from the surrounding land. Algae, plankton and other microorganisms love these types of nutrients, and when they are plentiful, these aquatic organisms can take over. When a lake, river or other aquatic system becomes eutrophic, it can have serious negative effects on other organisms like fish, birds and even people. But first, let's look at what causes eutrophication.

Causes

Eutrophication is most often the result of human activity. Farms, golf courses, lawns and other fields tend to be heavily fertilized by people. These fertilizers are the perfect type of nutrients to feed hungry algae and plankton, and when it rains, these fertilizers run off into lakes, streams, rivers and oceans. Concentrated animal feeding operations (CAFOs) are also a major source of polluting nutrients.

Eutrophication can also come from natural events. If a stream, river or lake floods, it may wash away any excess nutrients off the land and into the water. However, eutrophication is less likely to occur in areas that are not surrounded by fertilized lands.

Effects

Eutrophication can have serious, long-term effects. The most notable effect of eutrophication is algal blooms. When a bloom occurs, the stream, river, lake or ocean becomes covered with algae, which is usually bright green. In addition to looking pretty ugly, it also blocks light from reaching the water. This prevents the aquatic plants from photosynthesizing, a process which provides oxygen in the water to animals that need it, like fish and crabs.

Algae growth from eutrophication
eutrophication

If an algal bloom is so bad that it causes wide-spread death in the water, the organisms that die will all sink to the bottom and start to decompose. The microbes that break down these dead organisms use oxygen to do their work. So, in addition to the lack of oxygen from photosynthesis, there is also now a lack of oxygen from the decomposition of dead organisms.

To unlock this lesson you must be a Study.com Member.
Create your account

Register for a free trial

Are you a student or a teacher?
I am a teacher

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back

Earning College Credit

Did you know… We have over 95 college courses that prepare you to earn credit by exam that is accepted by over 2,000 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it free for 5 days!
Create An Account
Support