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<br />YlI, DESERT FISHES
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<br />425
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<br />(-35 gm/liter), and a few records imply survival at considerably greater
<br />concentrations. An early, questionable record by Coleman (1926) sug-
<br />gests tolerance of Cyprinodon macularius of 200 gm/liter. Barlow
<br />(l958b), on the other hand, found 90 gm/liter to be about the maximum
<br />tolerated by that fish at relatively high temperatures in shore pools of the
<br />Salton Sea. Simpson and Gunter (1956) documented survival of a substan-
<br />tial population of Cyprinodon variegatus at 142.4 gm/liter, and a total
<br />mortality of that species at 147 gm/liter. The fish occurred at 63 of 84
<br />stations they sampled along the south Texas coast, 26 of which were more
<br />saline than seawater, and three higher than 70 gm/liter.
<br />The Cyprinodon from Cotton ball Marsh, Death Valley, can survive in
<br />salinity of 78 gm/liter (LaBounty and Deacon, 1971), and data of Hunt
<br />et al. (1966) imply that concentrations of 160 gm/liter may sometimes
<br />occur in parts of their habitat. Cyprinodon atrorus successfully tolerates
<br />up to 95 gm/liter in the Cuatro Cienegas basin. Recently dead fish (not
<br />yet decomposed, a possible result of brine preservation) were found in
<br />August 1968 at 240 gm/liter (Arnold, 1970).
<br />An Australian atherinid, Taeniomembras sp., has an implied range of
<br />salinity tolerance from 20-130 gm/liter, and suffered no mortality
<br />under laboratory conditions between salinities of 10 and 100 gm/liter
<br />(Bayly and Williams, 1966; Lee, 1969; Lee and Williams, 1970). Acclim-
<br />ation seemed to have a remarkably small influence on upper or lower
<br />tolerances in this fish (Lee, 1969).
<br />Numerous other records of high salinity tolerances in fishes are avail-
<br />able, principally in cyprinodonts (Kosswig, 1961; Steinitz, 1951a), ina
<br />cichlid (Steinitz, 1951b), and in innumerable marine species (Gunter,
<br />1956, 1961, 1967), but specific data on concentrations present are lacking,
<br />or pertain to fishes that do not occur naturally under inland desert
<br />conditions.
<br />A fish kill in the lower Colorado River, downstream from Yuma, Ari-
<br />zona, was attributed (Sykes, 1937) to a small flood on the Gila River
<br />in the late 1800's. The Gila was considerably more saline than the Col-
<br />orado, and at the time was exceedingly low because of protracted drought
<br />(the Gila now is dry throughout its lower course as a result of upstream
<br />modifications). The alkali water of the Gila was retained by a dam to avoid
<br />contamination of irrigation supplies, and a small rise passing down the
<br />channel overrode the dam and emptied the toxic water into the Colorado.
<br />Fishes were reportedly destroyed in a matter of a few days from Yuma,
<br />Arizona, to the Gulf of California, Mexico, a distance of more than 125
<br />km.
<br />Euryhalinity of some desert fishes seems based upon highly specialized
<br />physiological and biochemical mechanisms. Insight into some of the prob-
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