Stream Classification& Abiotic Factors

Watershed

• A contiguous area that is contained with an elevated ridge such that rainfall within the area flows down and ultimately out through one point (the lowest in elevation).

Lotic Ecosystem

• Lotic ecosystems are freshwater systems with flowing water.

• Examples include rivers, streams, creeks, and brooks.

• Ambiguity of commonly used terminology has led to the “stream orders” system of classification.

Stream Orders

• 1st order streams occur where the stream originates

• 2nd order streams arise where two 1st order streams join

• The order doesn’t change where two streams of different orders come together

• 3rd order streams arise where two 2nd order streams join

Stream Ecology

• Ecology is the study of the interactions between the non-living (abiotic) and living (biotic) components of an ecosystem, and the interactions between the living components with each other.

• What are important abiotic factors that help to distinguish the low order, headwater streams, from the high order, riverine habitat?

Headwaters

• Lower order streams compose the headwaters.

• Important abiotic factors include elevation, water velocity, temperature, dissolved oxygen, and turbidity, available sunlight, substrate size, and stream width and depth.

Riverine Habitat

• Higher order streams compose the riverine habitat

• Important abiotic factors are the same as those found in the headwater streams but are generally opposite in nature

Lotic to Lentic Ecosystems