Ecology help please!?!?

Question

Use the concept of biological magnification and trophic levels in food webs to explain why low levels of toxic industrial wastes can ultimately kill large carnivores.

Answer 1

Alright, let's start at the bottom of the food web, and say that one tiny krill has 0.1 mg of toxin in it that it absorbed from the sea water.  Now a little fish, the next level in the food chain comes along, and eats 50 krill to fill himself up.  So now the little fish has 5 mg of toxin.  A slightly bigger fish comes along, and he needs to eat 10 little fish to get full.  He eats them, now he has 50 mg of toxin.  Finally, an eagle comes along, and he needs to eat 5 big fish to get full, giving him 250 mg of toxin.

So as you can see, since each step up the food chain eats several of whatever is below it, each trophic level accumulates more and more of the toxin.  I hope this explanation worked for you!