Connections of a River - Connectivity
Continuum Concept (pg 3 of 9)
In the midreaches (fourth through sixth order),
the gradient decreases. The river has fewer rapids
and falls. The stream is too wide to remain shaded.
Sunlight reaches the water, allowing the growth of
aquatic plants. Leaf fall is proportionately less
important as a source of energy. Insects feed on
algae and living plants.
With a lower proportion of groundwater and high
proportion of runoff, stream temperatures are
warmer, with greater fluctuations daily and
seasonally. As the size of the stream grows, so
does the diversity of invertebrates and fish. In
the east and upper midwest these streams often
support smallmouth bass or rock bass, redhorse,
walleye, northern pike, catfish, and carp.