Bioaccumulation is a phenomenon that is occurring more and more as our population increases.
In this lesson, We’ll define bioaccumulation, discuss its causes, and look at some examples.
If you have been studying biology for a little while now, then you’ve learned that you can break down many terms in biology and get a general understanding of the term. So what do you get when you breakdown the term bioaccumulation? Well, you know the word accumulation means the build-up of something and that the prefix bio- means life. Putting it together, you would get the build-up of something in living organisms for the definition of bioaccumulation.That’s it, but what’s building up? Bioaccumulation is used to refer to the build-up of chemicals inside of living organisms. Now we know that certain chemicals are needed and helpful inside of living organisms, so we aren’t really talking about those; rather, we are talking about the build-up of harmful chemicals.
Now that you know what bioaccumulation refers to, you probably have a very logical question: How does bioaccumulation occur? Glad you asked! It can occur in two main ways.
One way is by an amount of the chemical coming into the living organism faster than the organism can break it down and use it. This means that more is going in than is coming out, therefore causing the chemical to accumulate in the organism.The other main way that bioaccumulation occurs is by the chemical coming into the living organism and the organism not being able to break it down or excrete it in one way or another. In these instances, the chemical continues to accumulate until it eventually becomes deadly to the living organism.
Let’s look at some examples to help increase your understanding of bioaccumulation. Car emissions are a huge contributing factor to bioaccumulation. Most of us drive cars or ride in some type of transportation that releases chemicals into the air. This would already cause the build-up of these chemicals in the trees and birds. When it rains, the chemicals then get washed out of the air and return to the ground, where they’re certain to enter plants and animals that eat the plants. The harmful chemicals cannot be used by any of these organisms, so they build up to toxic levels.Another example that you may be familiar with has to do with the reason why you are told to limit how much fish you eat in a week.
Mercury is a chemical contaminate found in most bodies of water. Phytoplankton and bacteria both feed on the mercury, which is fine for them. However, some species of small fish then eat the bacteria and phytoplankton and then get eaten by larger fish. The small and large fish both accumulate mercury in their bodies.
Up to this point, it is bioaccumulation.The reason why you have to limit how much fish you eat is because eating fish, especially in large amounts, that have already accumulated mercury results in biomagnification in your body. Biomagnification is a type of bioaccumulation where the amount of a chemical multiplies every time it moves up the food chain.One last example is something that farmers use regularly to protect their crops and that we use regularly to control unwanted pests in our gardens and homes. Pesticides contain all kinds of different chemicals.
One set of chemicals from pesticides that cause some serious problems with bioaccumulation and subsequent biomagnification are chlorinated hydrocarbons.Newly-sprayed chemicals from pesticides can get washed into the water and soil when it rains or the grass is watered. This is where they are consumed or taken up by bacteria, fungi, or plants that are then eaten by small living organisms like worms that are then eaten by small birds. By this point, the chemical has gone through bioaccumulation, and any larger organism that eats the bird is going to experience biomagnification.
It’s time for us to make this short and sweet. Bioaccumulation is the build-up of chemicals inside of living organisms. The two causes of bioaccumulation are the amount of the chemical coming into the living organism faster than the organism can use it and the living organism not being able to break down or excrete the chemical. Biomagnification is a type of bioaccumulation where the amount of a chemical multiplies every time it moves up the food chain.Examples of bioaccumulation and biomagnification include:
- Car emission chemicals building up in birds and other animals
- Mercury building up in fish
- Pesticides building up in small animals