7718

• UCREFRP Catalog Number: 7718
• Author: Saiki, M. K., D. M. Kennedy and J. C. Tash
• Title: Effects of Water Development on the Lower Colorado River
• USFW Year: 1980
• USFW - Doc Type: Cal-Neva Wildlife Transactions
• Copyright Material: YES

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o J F M A M J J A S
1928

FIGURE 4. Mean concentrations of suspended sediments in. the lower Colorado River, 1926-28
(Ii::lward 1929b).

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Th~ invertebrates in the system of this period are virtually unknown. Small crustacea
(cladocerans, copepods, and ostracods) probably occurred because these organisms are
ubiquitous. Various aquatic insects also may have been present. According to Grinnell
(1914), there were no aquatic molluscs or decapod crustaceans in the Needles-to-Yuma area
in 1910.

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1926

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1927

Few species of fish were present. Minckley (1973) reported that eight freshwater species
occurred naturally in the lower Colorado River system; four cyprinids (bony tail. chub, GiZa
elegans; Colorado chub, G. robustc; woundfin, PZapopterus argentissimus; and Colorado
squawfi sh, PtychocheiZus LUcius); two catostomi ds (razorback suder, Xyrauchen ta.:ranus,
and flannelmouth sucker, Catostor.~s Zatipinnis); one cyprinodontid (desert pupfish,
c-:frinodon mcr'~laril.ls); and one poecil i i d (Gila topminnow, PoeciZiopsis occidentaZis).
Spe~ies were generally more numerous in backwaters than in the mainstream (Grinne1 1914).

CAl-NEVA WILDLIFE TRANSACTIONS 1980

103

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