Question

You go on a canoe trip to the Boundary Waters Canoe Area (BWCA) in northern Minnesota. This ecosystem is cold most of the year and receives plenty of rainfall. It has many lakes that are full of walleye pike. You know that walleye like to eat minnows. In turn, the minnows feed on scuds (zooplankton), which eat algae (phytoplankton)Mercury released from coal burning power plants would be at the highest concentration ina. the walleyeb. the zooplanktonc. the phytoplanktond. eagles that eat the walleyee. the minnows

Answer 1

Answer: d. Eagles that eat the walleye

Explanation: there is a process called biomagnification in which organisms of higher trophic levels accumulate toxic substances from the entire food chain.

In this case, mercury is a heavy metal that cannot be eliminated easily in excretion, so algae absorb this metal and then zooplanckton (scrubs) that feed on them absorb the mercury concentrated on their tissues. Then minnows feed on scrubs, walleye on minnows and so on as the food chain goes. As the thropic chain moves up, predators have to eat higher amounts of preys in order to get enough energy so they absorb a lot of mercury from different organisms, that is why eagles that eat walleye would have higher concentration of mercury on their tissues