If the bald eagle was removed from this food web, what effect would this have on the population of the other species?
a) the bivalves would increase in population size because they are eaten by sea ducks and the phytoplankton would decrease in population size.
b) the tundra swans would decrease in population size because they are eaten by the bald eagle and the vegetation would increase in population size.
c) the benthic invertebrates would decrease in population size because they are eaten by the sea ducks and the phytoplankton would increase in population size.
d) the wading birds would increase in population size because they are eaten by the ospreys and the small planktivorous fish would increase in population size.

C) The benthic invertebrates would decrease in population size because they are eaten by the sea ducks and the phytoplankton would increase in population size.

Explanation:

The benthic invertebrates are eaten by sea ducks. Sea ducks are eaten by bald eagles. If the bald eagle was removed, there would be more sea ducks because they will have no more predators. Since there are more sea ducks, they will need to eat more food, like benthic invertebrates. The benthic invertebrates would have a lower population because the sea ducks eat more of them.

Why not the other answers:

A) The bivalves would not increase in population size. Without the bald eagle preying on sea ducks, there would be more sea ducks, who need to eat more food, such as eating more bivalves.

The phytoplankton would not decrease. With sea ducks eating more food, more benthic invertebrates are eaten. There would be less benthic invertebrates to eat phytoplankton.

B) Tundra swans were never eaten by bald eagles. There is no arrow connecting them.

D) Wading birds were never eaten by ospreys. There is no arrow connecting them.