Question

10. Isle Royale is a small island located in Lake Superior. The island is home to a population of wolves and moose that are held in a delicate balance with one another. In the past, this balance has been maintained. However, the moose population is currently the lowest it has been in many years. The island was home to only 385 moose in 2007, having fallen from 450 in 2006. The moose’s primary predators are wolves. Foxes also feed on the moose carcasses if there is anything remaining, along with grass-eating snowshoe hares. Insects such as ticks and mosquitoes feed on moose blood. Moose themselves are primary consumers that eat a variety of woody plant materials, including balsam fir and birch. Aquatic plants make up a large percentage of the herbivore’s summer food resource.

a) Create a food web for Isle Royale that includes the organisms mentioned above.

b) List the trophic level of each organism.

d) A moose consumes 3500 kJ of energy from a balsam fir tree. Using the rule of 10, estimate how much of this energy would be available to a wolf that consumes the moose.

e) Write a paragraph explaining what you think may have caused the decline in the moose population on Isle Royale.

Answer 1

Answer of the question no 10.a.

The food web for Isle Royale island is created on the attached image.

The answer of the question no 10.b. is-

Woody Plant (Balsam fir, Birch) ,Aquatic plant, grass belong to the 1st tropic level and they are the producers.

Moose,Snowshoe hares belong to the 2nd tropic level and they are primary consumers who feed upon producers.

Wolves,foxes,insects (ticks,mosquitoes) belong to 3rd tropic level and they are secondary consumers who feed upon primary consumers.

Answer of the question no 10.d. is-

According to the information provided in the question, a moose consumes 3500 KJ of energy from a balsam fir tree.And according to the rule of 10, only 10% of energy from a tropic level passes to the next higher tropic level and rest amount of energy is lost due to various physiological activities of the organisms belong to that tropic level.

So, Using the rule of 10, if a moose consumes 3500KJ of energy from a balsam fir tree, then the wolf that consumes this moose will get only (3500*10/100) KJ=350 KJ of energy.

Answer of the question no 10.e. is-

Decline in the moose population on Isle Royale island can be caused due to many reasons such as due to climate change. It can also occur due to over predation of moose by the large population of wolves. Moreover, habitat loss and infection by parasities can also be the cause of decline in the moose population on Isle Royale island.