Base your answers to questions 1 through 3 on
the diagram below and on your knowledge of biology. The diagram represents a food web typical of the
Great Lakes area of New York State.
Some people have argued for the removal of cormorants from the eastern shores of Lake Ontario
because of their negative effects on the fishing industry. Describe the consequences of this action.
1. Describe one action, other than removing a population of organisms from the environment, that humans
could take to preserve the fishing industry in Lake Ontario.
2. State one possible effect of removing the cormorants on a species other than fish and support your answer.
3. State one reason why removing the cormorants from the food web could have a positive impact on the
fishing industry.
Base your answers to questions 4 through 6 on the diagram below and on your knowledge of biology. The
diagram represents a food web.
4. State the role of the decomposers in this food web.
5. Even though both hawks and owls have two sources of food, explain why hawks would be less likely to
survive if a disease wiped out the mice.
6. Identify two herbivores that compete for food in the food web above.
Answer Key
Ecology written hwk
1.
2.
3.
– Add more forage
4.
fish/food supply for
the salmon/lake trout
to eat. – Increase
breeding programs for
fish/Stock lakes. –
Pass laws restricting
fishing for forage fish.
– Limit pollution by
regulating industries
on the Great Lakes. –
Grow fish in fish
5.
farms.
– The number of
eagles will decrease
because of fewer
cormorants to eat. –
The number of eagles
will increase because
there are more forage
fish to eat. – The
number of plankton
will decrease because
there are more forage
fish eating them. –
The number of
invertebrates will
decrease because
there are more forage
fish eating them.
– There could be more
lake trout/salmon
available to be caught
by fisherman. – There
could be more fish
available for fishing.
– There would be
more forage fish for
the salmon/lake trout
to eat.
6.
– break down organic
compounds and return
nutrients to the
environment, – break
down dead plants and
animals and release
nutriets to the
environment, –
prevent the build-up
of dead organisms, –
recycle nutrients
– The hawks eat mine
and snakes, which
also eat mice; while
the owls eat mice and
frogs, which eat
crickets not mice. –
The hawk's second
food source also feeds
on mice. – The owl's
second food source is
not dependent on
mice. – Snakes also
eat mice, but frogs do
not.
– mice and crickets