7923

• UCREFRP Catalog Number: 7923
• Author: Carter, J. G. and V. A. Lamarra.
• Title: An Ecosystem Approach To Environmental Management, Chapter 17.
• USFW Year: n.d.
• USFW - Doc Type: 261-287
• Copyright Material: YES

thus far been observed to have a higher standing crop of
periphyton and macro invertebrates than small
substrates, such as gravel and sand (Figure 7).

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Figure 7. The distribution of biological
parameters by substrate sizes in the White
River, Utah. Bars denote 95% confidence
intervals.

Even among the rocky substrates, large differences have
been observed in algal standing crop between rock types,
probably due to textural and mineral differences. Thus,
the distribution of habitat types (pools and riffles)
which result from the dissipation of energy within the
study sections should be mapped and the size, texture and
chemistry of substrate types determined.

The response of primary producers is often
stochastic, depending upon random changes in flow and,
hence, sediment movement. Overall, increased levels of
suspended sediment reduce light intensity and limit
photosynthesis; however, the presence of associated

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