Toxins and food webs

Toxic materials in a food chain

Food webs can be affected by harmful substances like pesticides that build up in food chains. This happens when lower-level organisms in the food web come into contact with these substances.

These substances can then move up the food chain as higher-level organisms eat them. This process, called bioaccumulation, can damage whole ecosystems. It can cause population declines and even extinction of some species.

An example of this is when pesticides are used in farming and get into the food chain. In this case, the pesticides do not only affect the pests they are meant for. They also hurt other organisms.

Let’s see an example:

This image is a diagram illustrating the bioaccumulation of toxic materials, specifically traces of pesticide, in a food chain. It shows how pesticides sprayed on crops can accumulate in higher concentrations as they move up the food chain from producer to tertiary consumer.

Toxic materials in a food chain

The pesticides stay in the bodies of organisms and build up over time. This is because these substances are hard to get rid of by organisms.

The hawk, which is the top animal in the food chain, will get the most pesticides. This is because it eats lower-level organisms that already have pesticides in them.
The gradual build-up of pesticides can make the hawk sick, which can even lead to death. Also, these pesticides can affect other organisms in the food chain, which can lead to the extinction of certain species.

This image is a diagram illustrating the accumulation of toxic materials, specifically pesticides, in a food chain. It shows how pesticides used on corn can move up the food chain affecting mice, snakes, and hawks.

Toxic materials in a food chain

DDT

DDT is a chemical that kills and keeps away mosquitoes. It was used a lot to stop malaria, which is a disease spread by mosquitoes, and also to protect crops. But DDT is a harmful substance that can move up the food chain from insects to small birds. This can lead to the death of many predatory birds.
The organisms in a food web need each other for food, so the build-up of DDT can damage the ecosystem. If one of the organisms in a food web dies out, the whole web can suffer. This is one of the reasons why DDT is not allowed in many countries.

Summary:

All living things in an ecosystem need each other.
Food chains show how energy moves from one living thing to another.
Food chains show who eats who among living things.
Food webs show how all the food chains in an ecosystem are connected.