Biomagnification and Bioaccumulation

Human Impact

By Anissa Rodriguez

Multiple Choice

The northern elephant seal was almost hunted to extinction in the 1800s. By the late 1890s, approximately one hundred seals were left, reducing the gene pool of the population. What will be the consequence of this reduction?

• Competition within the population will increase.

• The surviving elephant seals will be better able to adapt.

• Inbreeding will be less frequent among the remaining population.

• The elephant seals will be more vulnerable to environmental change.

Multiple Choice

Which of the following is a property of a nonrenewable resource?

• It will not run out no matter how much it is used.

• It takes tens of thousands to millions of years to replace if it is used up.

• It is recyclable after it is used through a quick and easy process.

• It releases oxygen into the atmosphere after it is used.

Multiple Choice

A ski resort installed a wind turbine  similar to those represented below to  supply some of  its energy needs. This turbine was most likely installed because wind power is:

• Renewable and does substantial  damage to the atmosphere.

• Renewable and does minimal  damage to the atmosphere.

• Nonrenewable and does substantial damage to the atmosphere.

• Nonrenewable and does minimal damage to the atmosphere

Multiple Choice

A community is concerned about the water quality of a nearby lake. Increased sedimentation in the lake is endangering the native habitat. The increased sedimentation is most likely caused by which of the following?

• trees planted along the shore of the lake

• construction of homes along the lake

• the amount of sunlight on the lake

• the amount of fish in the lake

Multiple Choice

Salt water is an abundant resource but unusable for irrigation and drinking. As demands on freshwater sources increase, the use of desalination processes to remove salt from ocean water is increasing. A concern of desalinating water is the large amounts of recovered salts that are returned to the ocean. Which of the following describes the most likely impact of desalination on the surrounding ocean environment?

• Methane gas would pollute the ocean environment as shoreline organisms begin to die and decay.

• Alteration in ocean salt levels would cause loss of species and unbalanced populations in marine food webs.

• Nonrenewable resources in the ocean environment would become depleted and upset the ecosystem's balance.

• Increased levels of salts and minerals in the ocean would result in overpopulation of marine bivalves due to strengthened shells.

Multiple Choice

An increase in the use of fossil fuels has increased the amount of sulfur compounds in Earth’s atmosphere. Which of these is a direct result of the increased amount of sulfur in the atmosphere? 

• an increase in acid rain

•  an increase in severe storms 

• an increase in global warming 

• an increase in the rate of ozone depletion 

Multiple Choice

A scientist wanted to find out if low numbers of fish found in a nearby lake were related to acid rain. During his three-year study, he analyzed rainwater and lake water samples. By gathering samples of fish, he estimated the number of fish in the lake. Each year he found that both the rainwater and lake water became more acidic, and the number of fish decreased. His data suggested that acid rain may be responsible for the decrease in the number of fish found in the lake. 

What most likely led to the rainwater’s increasing acidity? 

• ultraviolet radiation 

• sedimentation 

• burning fossil fuels

•  global warming 

Multiple Choice

When fertilizers run off farmland into streams and ponds, the nitrogen content of the water increases. This can lead to rapid growth of algae in a process called eutrophication. How can this process affect other organisms in the water?

• Oxygen is used up as algae is decomposed, reducing the amount available to other organisms.

• The water becomes better able to support aerobic organisms.

• The algae provide food for fishes and other organisms, leading to decreased algae populations.

• The extra nitrogen provides additional food for the other organisms, increasing their population.

Multiple Choice

Industries often spring up along major rivers, such as the Willamette in Central Oregon. Some of these industries used PCBs (toxic, cancer-causing chemicals), which are not biodegradable. If PCBs escaped into the river in large amounts and entered the lower levels of the food chain, what would be the likely outcome? 

• All species, except scavengers such as riparian crustaceans, would be harmed by the PCBs.

•   Only the small fish and crustaceans that are most exposed to the PCBs would be significantly harmed. 

•  Over time, PCBs would collect in top predators such as salmon, making them unsafe for human consumption. 

•  The PCBs would become harmless as they break down over time with exposure to the forces of nature and the environment. 

Multiple Choice

DDT and other pesticides used over 50 years ago are still affecting the environment today. Scientists have found these substances in recent glacier runoff. Glacier runoff occurs during the summer, when precipitation that has fallen on glaciers during the winter is released. Ice layers from existing glaciers have been analyzed. The results of this analysis show that the concentrations of DDT and other pesticides were highest about 10 years after the use of these substances was banned. This information shows that

• DDT and other pesticides cause glacier runoff during the summer.

• it takes humans over 50 years to analyze a glacier.

• precipitation helps to break down pesticides.

• the decision of one human generation may have an impact on future generations.

Multiple Choice

The zebra mussel is a highly invasive species that was accidentally introduced to the Great Lakes region of the United States in the 1980s. The map below shows the distribution of zebra mussels in 2010.  

What is the primary reason the  large-scale spread of zebra mussels concerns scientists? 

• Zebra mussels are a freshwater species. 

•  Zebra mussels are a desired food  for humans. 

•  Zebra mussels are eaten by some fish and birds. 

•  Zebra mussels outcompete native mussel species. 

Multiple Choice

A strip mining company wants to lease some land that is currently part of a national park. They promise to reclaim the land should any minerals be mined from the area, and they are willing to pay top dollar for the rights. As an ecologist, what factors would you raise with the local government?

• the threat to local biodiversity

• management of the land after the company leaves

• the new jobs that would be created

• the increased traffic in the area