Why does biomagnification happen

In many cases, animals near the top of the food chain are most affected because of a process called biomagnification. Many of the most dangerous toxins settle to the seafloor and then are taken in by organisms that live or feed on bottom sediments.

Because these compounds aren't digested, they accumulate within the animals that ingest them, and become more and more concentrated as they pass along the food chain as animals eat and then are eaten in turn. This is biomagnification, and it means that higher-level predators-fish, birds, and marine mammals-build up greater and more dangerous amounts of toxic materials than animals lower on the food chain.

In this activity you will explore the biomaginification of toxic chemical, mercury, through a simple marine food chain. In the simulation below, the marine environment is contaminated with mercury. Although all animals are exposed to this toxic chemical, seabirds are more severely affected than other organisms. Feed the bird by dragging clams and fish into it until it is full. First, feed the bird clams only, then just fish, and finally feed it a mixed diet.

Try each feeding strategy several times. Only after you understand how diet affects the seabird, click on the "show toxins" button to reveal the relative environmental distribution of mercury, represented by the orange dots. Check Answer. Erosion breaks down rocks and releases their chemical components into streams and groundwater.

They are very minute even in terms of weight. Phytoplankton refers to small plants that float in the seas that normally absorb toxins. Once absorbed, the toxins stay in their tissues without being excreted or broken down. With time, the toxins accumulate to high concentrations up to parts a trillion which represents a toxin accumulation increase by about four fold.

Zooplankton refers to small marine animals that float in the seas. They consume the phytoplankton and thus take in the toxin. Over time, the toxin concentration increases up to two parts per billion which represents about a ten-fold increase over the previous concentration. Whenever the small fish feed on the zooplanktons, they consequently take up the toxins which get absorbed in their fatty tissues.

As a result, accumulation occurs and the concentrations build up to about 20 parts per billion which is another ten-fold increase. Again, when the large fish graze on the smaller fish for food, they consume the toxins that accumulate in their fatty tissues. The concentrations become higher up to ranges of 80 to parts per billion. This is about four to five fold increase in the toxic levels. The organisms at the top of the food chain including the marine mammals such as dolphin, sea birds, and humans gradually build up the toxins in their tissues such as their liver when they consume the large fish.

The levels of concentrations here increase to the highest ranges of 10, to 15, parts per billion. Sonia Madaan is a writer and founding editor of the science education blog EarthEclipse.

She loves writing on topics related to space, environment, chemistry, biology, geology and geography. When she is not writing, she loves watching sci-fi movies on Netflix. What is Biomagnification? Once you pick a region, you can view the best choices in sustainable seafood and which types of seafood are prone to mercury and other contaminants.

You will see that some of the best choices have the little red star indicating possible contamination. These fish are to be limited in the quantity consumed by individuals per month. Sustainable seafood does not mean stop eating seafood, but rather a guideline towards making healthy choices for yourself and our oceans.

Just like in the paper Mull et al. Different areas where seafood is harvested have varying types and levels of pollutants. I could go on and on about ways to help the oceans but I hope this blog post has inspired you to do some research of your own and find at least one simple but effective way to make a difference. Every little bit counts. Coelho, J. Mercury bioaccumulation in the spotted dogfish Scyliorhinus canicula from the Atlantic Ocean.

Marine pollution bulletin, 60 8 , —5. Accumulation and mother-to-calf transfer of anthropogenic and natural organohalogens in killer whales Orcinus orca stranded on the Pacific coast of Japan.

The Science of the total environment, 8 , —9. Heavy metals, trace elements, and organochlorine contaminants in muscle and liver tissue of juvenile white sharks, Carcharodon carcharias, from the Southern California Bight. In Global perspectives on the biology and life history of the white shark pp. Domeier, M.

Wiener, J. Ecotoxicology of mercury. In Handbook of ecotoxicology, second edition pp. Hoffman, D. Dunlap Marine Conservation Programme. Your email address will not be published. This site uses cookies. By continuing to browse the site, you are agreeing to our use of cookies. We may request cookies to be set on your device. We use cookies to let us know when you visit our websites, how you interact with us, to enrich your user experience, and to customize your relationship with our website.

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