2.4 Biomagnification and Bioaccumulation
Completion requirements
Unit A
Module 1 ~ Lesson 2
Biomagnification and Bioaccumulation
A variety of chemical compounds are released into the environment as a result of human activities. Some compounds, such as phosphates and nitrates in fertilizers, are used by organisms as nutrients without harmful effect on the organism. They may still
have a disruptive effect on the ecosystem but tend to be used or broken down over time.
Other compounds, such as methylmercury, are not used or broken down by organisms and do have a detrimental effect on plants and animals. Methylmercury is stored in plant and animal tissue without decomposing, so is entirely passed on to the next trophic level through feeding.
Other compounds, such as methylmercury, are not used or broken down by organisms and do have a detrimental effect on plants and animals. Methylmercury is stored in plant and animal tissue without decomposing, so is entirely passed on to the next trophic level through feeding.
Center for Instructional Technology. (2016). Used under the Fair Dealings Policy of the Canadian Copyright Act. Retrieved from https://blog.nus.edu.sg/agritated/2016/10/13/bioaccumulationandbiomagnification/
Bioaccumulation vs Biomagnification
Bioaccumulation is the build-up of a substance in an organism over time. If a fish feeds on plankton in polluted waters, they accumulate more of the toxin as they consume
more plankton. The toxin is never excreted.Biomagnification is the magnification of a toxin as it moves up the food chain. If a predatory bird feeds on fish that have stored toxin, the concentration of toxin in the bird will be higher than in the fish due to the quantity of fish that the bird eats.
Read
Read "Biomagnification: A Fish Story" on page 28 of your textbook.
Self-Check
Watch this video and answer the quiz questions in the video.
Dive Deeper
By reaching high levels of concentration at the top predator level, top predators can be affected by dying off or by becoming sick. If the predators die off, then there would be an increase in lower trophic level organisms. This would alter the transfer of energy.
More organisms would be alive at one point than is usual for the ecosystem, which would put a strain on the amount of oxygen in the water. A lake could begin to die. Also, as it is decomposed, the decaying fish would re-release the harmful chemical right back into the ecosystem. The cycle would be never ending until the chemical broke down or all of the organisms died.
The hydrologic cycle transports naturally occurring and artificial chemicals into water systems through runoff and precipitation.
The effects of biomagnification can be reduced by properly disposing of wastes and by reducing the need for these harmful chemicals in industries.