Chapter8_KEY

What creates ice block lakes?

Buried ice blocks melt after glacial retreat, resulting in deep kettle lakes.

How are oxbow lakes formed?

Differential erosion and sedimentation causes rivers to meander, leading to the formation of a 'U' shaped lake isolated from the river.

What causes glacial lakes to form?

Dams block natural drainage ways, creating a lake.

Where are very few lakes located in Minnesota?

In the southern prairie region.

What influences the chemistry of a lake?

Factors include drainage basin, runoff, groundwater, size, depth, soil, land use, and pollution.

What happens when more phosphorus enters a lake?

Productivity of algae and aquatic plants will increase.

Which winter factors reduce light entering a lake?

Snow cover and ice.

What can reduce the transparency of lake water?

Color of water and amount of suspended material (sediment and algae).

What is a Secchi disk used for?

To measure water clarity in a lake.

What are the oxygen sources in summer for lakes?

Photosynthetic organisms.

What are the oxygen removers in winter for lakes?

Animals and other heterotrophic organisms.

What causes temperature stratification in summer lakes?

Sun warms the epilimnion and wind creates mixing, but deeper layers experience a sharp temperature decline.

Why don’t shallow lakes stratify during summer?

They are not deep enough to form distinct temperature layers due to sunlight reaching almost to the bottom.

What ecological role do zooplankton play?

Zooplankton like water fleas feed on phytoplankton and can improve water clarity when abundant.

Define a filter feeder. Provide two examples.

An organism that collects food by allowing water to pass through appendages. Examples: copepods and rotifers.

What defines oligotrophic lakes?

They are deep, cold, high in dissolved oxygen, low in nutrients, and have high water clarity.

How is lake productivity measured?

By phosphorus concentration, transparency, and chlorophyll a concentration.

What is cultural eutrophication?

The process by which lakes become enriched with nutrients, often due to human activity, leading to increased productivity.

What defines Lake Superior's ecological features?

It's oligotrophic, 1,333 feet deep, low productivity, well oxygenated, and the largest freshwater lake in North America.

What are common sources of lake contamination?

Sediment, surface runoff, sewage, industrial wastes, and atmospheric deposition.

What are contaminants of emerging concern?

Pharmaceuticals and personal care products like deet and antidepressants.

What is the Chain of Lakes of Minneapolis restoration success story?

Impaired water quality was restored through public education and regulation reducing phosphorus in fertilizers, improving conditions in three lakes.