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<br />118
<br />
<br />is unknown. However, it is known that larval and juvenile fish some-
<br />
<br />times do not survive environmental changes that have little or nO effect
<br />
<br />on adult fish, The ionic regulation, circulation, and respiration of
<br />
<br />small fish can be impaired rather easily by changing the chemistry of
<br />
<br />their environments (Hoar and Randall, 1969, 1970). Since curtailed
<br />
<br />reproduction of the endemic fish species has been established (Vanicek
<br />
<br />and Kramer, 1969; Holden and Stalnaker, 1975), it appears desirable to
<br />
<br />establish the tolerance limits of the species considered to be threat-
<br />
<br />
<br />NUMBER OF
<br />ORGANISMS
<br />PER SQ. YD.
<br />500
<br />
<br />NUMBER OF
<br />SPECIES
<br />"6 400
<br />
<br />ened or endangered (Colorado Squawfish, humpback chub, and bonytall
<br />
<br />
<br />chub), as well as of the endemic fish that appear to be stable in num-
<br />
<br />WEIGHT OF
<br />ORGANISMS
<br />(GM./SQ. YD.)
<br />
<br />12 12
<br />
<br />bers (e.g., the bluehead sucker) or perhaps even increasing (e.g.,
<br />
<br />the flannelmouth sucker).
<br />
<br />Bishop and PDrcella (in this volume) indicated that significant con-
<br />
<br />centrations of heavy metals may occur in several tributaries of the Colo-
<br />
<br />rado River that would seriously affect water quality. Mining operations
<br />
<br />in Idaho destroyed anadromous runs of salmon and trout when high metal
<br />
<br />concentrations (copper and iron), decreased pH, and other adverse factors
<br />
<br />caused fish kills or an avoidance of the stream by the fish (McKim and
<br />
<br />coauthors, 1975). McKim and eoauthors summarized the recent published
<br />
<br />literature on the effects of pollution on freshwater fish, The effects
<br />
<br />of surface mining on fish and wildlife in Appalachia were reviewed by
<br />
<br />Boccardy and Spaulding (1968), Although such a review is not available
<br />
<br />for the Colorado River, the effects of mining on this river system can
<br />
<br />
<br />also be drastic (Tsivoglov and coauthors, 1959; figure 6). Bottom macro-
<br />
<br />invertebrates were scarce for about 28 miles downstream from a uranium-
<br />
<br />vanadium mine on the Animas River that drains into the Colorado River
<br />
<br />.
<br />
<br />(figure 6). This scarcity of organisms was attributed to toxicity from
<br />
<br />8 8
<br />
<br />4 4
<br />
<br />o
<br />
<br />o
<br />
<br />300
<br />
<br />200
<br />
<br />
<br />I
<br />I
<br />I
<br />I
<br />I
<br />
<br />NUMBER OF SPECIES,
<br />\'"
<br />: e.
<br />. .
<br />. "
<br />: '
<br />.
<br />,
<br />.
<br />,
<br />,
<br />.
<br />,
<br />.
<br />.
<br />.
<br />.
<br />.
<br />.
<br />.
<br />.
<br />.
<br />..
<br />
<br />.....
<br />
<br />......
<br />......
<br />....
<br />....
<br />
<br />100
<br />
<br />o
<br />
<br />o
<br />
<br />10
<br />
<br />20
<br />
<br />30
<br />
<br />40
<br />
<br />50
<br />
<br />60
<br />
<br />RIVER MILES BELOW MILL
<br />
<br />RIVER MILES BELOW MILL
<br />
<br />Figure 6, Number of Species and Density of Bottom Fauna Above and
<br />Below a Uranium-Vanadium Millon the Animas River,
<br />Colorado, in 1958,
<br />
<br />Source: E, C, Tsivoglov, S. D. Schearer, R, M. Shaw, Jr.,
<br />J. D. Jones, J, B, Anderson, C, E, Sponables, and D. A. Clark, Survey
<br />of Interstate Pollution of the Animas River, Colorado-New Mexico
<br />(Cincinnati, Ohio, U.S, Department of Health, Education, and Welfare,
<br />Public Health Service, Robert A, Taft Engineering Center, 1959),
<br />
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