Bioaccumulation and the Food Chain

Now, that I am an Environmental Science major, I am finding that my classes are incorporating much more of a “hands-on” technique and how small acts can affect us all. One thing that I had always been told was not to eat too much tuna fish in a short period of time. I was only told not to eat it because tuna contained high levels of mercury. Until I got to my Environmental Toxicology class, I then learned it was because mercury and other chemicals or toxins can bio-accumulate and that’s why chemical levels are much higher in larger organisms than smaller ones. What’s happening is that when chemicals are disposed of incorrectly, they leak into runoff that goes into the oceans, rivers and lakes.

Another way for chemicals to enter the food chain is through the spraying of pesticides. Pesticides are not the only chemicals that can enter the food chain; there are also persistent organic pollutants (POPs), which are carbon-based compounds that stay in the environment and the ecosystem for a very long time. As a side note, when pesticides are sprayed, they are supposed to remove the pests, but a habitat is being sprayed instead. This is destroying and entire area that is crucial to the environment and not removing the pests.

Even though the runoff may contain trace amounts of chemicals when it first enters the water, it enters the smallest organism and doesn’t hurt them as much. When another organism eats the smallest one, there are more chemicals in the system and so on. Since larger fish, like tuna are at the top of the food chain, they are the ones that are being blamed for having large amounts of mercury in their system, when it is really because of improper disposal of chemicals. That’s why eating too much tuna in a short period of time can seriously hurt the human body and it is important to dispose of chemicals in the most environmentally friendly way.

When eating fish or any other food, it is important to know where your food comes from. This is important especially when buying salmon. Farm-raised salmon eat powdered fish that are high in fat, whereas wild salmon eat krill. Wild Alaskan salmon is the best kind of salmon to eat, but the problem is that is very expensive and would take quite a toll on your budget, especially as a student in college.

It’s important to know where your food comes from and eat everything in moderation and to avoid large amounts of toxins entering your body.



  1. nicoleahedgepeth · February 23, 2016

    I agree that bioaccumulation is a big problem, not only for wildlife but humans as well. My senior year in AP Environmental Science we discussed the tragedy with bird eggs, in particular bald eagles, and the fragility of the egg caused by pesticides. One of my teachers remembers being outside when they use to spray and getting misted with the stuff. Even though many known toxins like that have been limited or banned there is still a problem.


  2. andrewwingfield · March 1, 2016

    As Nicole points out, bioaccumulation affects humans directly because we, like tunas, are at the top of the food chain. Studies of human breast milk have shown that it contains alarmingly high concentrations of many toxic substances.


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