7601

• UCREFRP Catalog Number: 7601
• Author: Minckley, W. L.
• Title: Native Fishes of Arid Lands
• USFW Year: 1991.
• USFW - Doc Type: A Dwindling Resource of the Desert Southwest.
• Copyright Material: NO

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Figure 26. Sequence of flash flooding in Sycamore Creek,
Maricopa County, Arizona, 1977. The elapsed time between
Band C was that required to advance film between frames.
Photographs by S. G. Fisher.

streams, in part because of evaporation and often
due to inflow of salty groundwaters. Their chemistry
varies with runoff, low in salts at high flow and
more concentrated in drought. Other variations,
often spectacular, occur with biological activity. All
these streams are highly productive. Under intense
sunlight, and with clear water at low flow,
remarkable changes occur in dissolved gasses and
ions associated with algal photosynthesis. Aquatic
insects and some other invertebrates with short life
histories respond quickly to the rich food source,
and secondary productivity is high as well.

Fishes of Intermediate Elevations

Fishes occupying this zone include some species
that may have been forced upward with increasing
aridity, and another group more closely related to
species occupying eastern, more temperate zones. In
the natural state, creeks and smaller rivers of the

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