Chapter9_KEY

What are the four ways a river might originate?

Paths developed under glacial ice, drainage of glacial lakes, begin as wetlands or lakes, and spring-fed.

How does the form of the Mississippi River differ at Itasca compared to its flow out of Minnesota?

At Itasca, it is shallow, narrow, fast-moving, and cold; at the Iowa border, it is wide, deep, slow, and warm.

Where does most of the water flowing in rivers and streams come from?

Subsurface flow, also known as groundwater.

What factors determine discharge rate in rivers?

Current velocity, depth, and width (shape of riverbed).

What are typical features of lowland downstream rivers?

Deeper water, warm, slow moving, higher loads of sediment, reduced transparency (high turbidity), and low algae growth.

What seasonal event is most associated with dislodging invertebrates from the stream bed?

Seasonal flooding, most often associated with spring.

Why are headwater streams generally cooler than downstream streams?

Headwaters are often spring-fed and more shaded, resulting in lower temperatures.

What is the relationship between water temperature and dissolved oxygen levels?

Cold water can hold more oxygen than warm water.

Where does nitrogen and phosphorus come from in streams?

Significant portions enter from the atmosphere, runoff, and groundwater, primarily from agriculture.

What are the primary sources of oxygen in streams?

Agitation of water infuses streams with oxygen and photosynthetic organisms are the primary input.

What adaptations help organisms cope with stream currents?

Attachment devices, streamlined bodies, heavy cases or shells, flattened bodies, lifelines, and hiding from current.

What are the categories of energy sources in a stream and their associated organisms?

Producers (algae, phytoplankton), CPOM (leaves, branches, fungi), FPOM (broken down CPOM), DOM (dissolved organic matter).

In which parts of a river system would you find the most bacteria and fungi?

Upper stream.

What is the most nutritious part of food eaten by shredders?

Fungi and bacteria, which are high in protein.

How does primary productivity vary across sections of a river?

Headwaters have CPOM, middle section has FPOM and DOM, while lower reaches may have algae and plankton.

What was the history of beaver populations in Minnesota?

Populations were reduced due to hunting for pelts in the 1700s but have recovered significantly.

What are the positive and negative aspects of beaver activity?

Beavers create and maintain habitats but can cause flooding in valuable farmland.

What locations are known for cold water streams in Minnesota?

SE Minnesota in the Driftless Area and along the North Shore; these are managed for trout and fly fishing.

What are the differences between point and non-point source pollutants?

Point source pollutants are from identifiable sources (e.g. waste from factories), while non-point source pollutants are diffuse and harder to regulate (e.g. nitrogen from farmland).

What are some conservation practices to improve stream and river health?

Designating rivers as wild and scenic, removing locks and dams, creating natural buffer zones, regulating industries, and dredging to clean out contaminants.