V I I . DESERT FISHES
425
( ~ 3 5 gm/liter), and a few records imply survival at considerably greater
concentrations. An early, questionable record by Coleman (1926) suggests tolerance of Cyprinodon macularius of 200 gm/liter. Barlow
(1958b), on the other hand, found 90 gm/liter to be about the maximum
tolerated by that fish at relatively high temperatures in shore pools of the
Salton Sea. Simpson and Gunter (1956) documented survival of a substantial population of Cyprinodon variegatus at 142.4 gm/liter, and a total
mortality of that species at 147 gm/liter. The fish occurred at 63 of 84
stations they sampled along the south Texas coast, 26 of which were more
saline than seawater, and three higher than 70 gm/liter.
The Cyprinodon from Cottonball Marsh, Death Valley, can survive in
salinity of 78 gm/liter (LaBounty and Deacon, 1971), and data of Hunt
et al (1966) imply that concentrations of 160 gm/liter may sometimes
occur in parts of their habitat. Cyprinodon atrorus successfully tolerates
up to 95 gm/liter in the Cuatro Ciénegas basin. Recently dead fish (not
yet decomposed, a possible result of brine preservation) were found in
August 1968 at 240 gm/liter (Arnold, 1970).
An Australian atherinid, Taeniomembras sp., has an implied range of
salinity tolerance from 20-130 gm/liter, and suffered no mortality
under laboratory conditions between salinities of 10 and 100 gm/liter
(Bayly and Williams, 1966; Lee, 1969; Lee and Williams, 1970). Acclimation seemed to have a remarkably small influence on upper or lower
tolerances in this fish (Lee, 1969).
Numerous other records of high salinity tolerances in fishes are available, principally in cyprinodonts (Kosswig, 1961; Steinitz, 1951a), in a
cichlid (Steinitz, 1951b), and in innumerable marine species (Gunter,
1956, 1961, 1967), but specific data on concentrations present are lacking,
or pertain to fishes that do not occur naturally under inland desert
conditions.
A fish kill in the lower Colorado River, downstream from Yuma, Arizona, was attributed (Sykes, 1937) to a small flood on the Gila River
in the late 1800's. The Gila was considerably more saline than the Colorado, and at the time was exceedingly low because of protracted drought
(the Gila now is dry throughout its lower course as a result of upstream
modifications ). The alkali water of the Gila was retained by a dam to avoid
contamination of irrigation supplies, and a small rise passing down the
channel overrode the dam and emptied the toxic water into the Colorado.
Fishes were reportedly destroyed in a matter of a few days from Yuma,
Arizona, to the Gulf of California, Mexico, a distance of more than 125
km.
Euryhalinity of some desert fishes seems based upon highly specialized
physiological and biochemical mechanisms. Insight into some of the prob-
425
( ~ 3 5 gm/liter), and a few records imply survival at considerably greater
concentrations. An early, questionable record by Coleman (1926) suggests tolerance of Cyprinodon macularius of 200 gm/liter. Barlow
(1958b), on the other hand, found 90 gm/liter to be about the maximum
tolerated by that fish at relatively high temperatures in shore pools of the
Salton Sea. Simpson and Gunter (1956) documented survival of a substantial population of Cyprinodon variegatus at 142.4 gm/liter, and a total
mortality of that species at 147 gm/liter. The fish occurred at 63 of 84
stations they sampled along the south Texas coast, 26 of which were more
saline than seawater, and three higher than 70 gm/liter.
The Cyprinodon from Cottonball Marsh, Death Valley, can survive in
salinity of 78 gm/liter (LaBounty and Deacon, 1971), and data of Hunt
et al (1966) imply that concentrations of 160 gm/liter may sometimes
occur in parts of their habitat. Cyprinodon atrorus successfully tolerates
up to 95 gm/liter in the Cuatro Ciénegas basin. Recently dead fish (not
yet decomposed, a possible result of brine preservation) were found in
August 1968 at 240 gm/liter (Arnold, 1970).
An Australian atherinid, Taeniomembras sp., has an implied range of
salinity tolerance from 20-130 gm/liter, and suffered no mortality
under laboratory conditions between salinities of 10 and 100 gm/liter
(Bayly and Williams, 1966; Lee, 1969; Lee and Williams, 1970). Acclimation seemed to have a remarkably small influence on upper or lower
tolerances in this fish (Lee, 1969).
Numerous other records of high salinity tolerances in fishes are available, principally in cyprinodonts (Kosswig, 1961; Steinitz, 1951a), in a
cichlid (Steinitz, 1951b), and in innumerable marine species (Gunter,
1956, 1961, 1967), but specific data on concentrations present are lacking,
or pertain to fishes that do not occur naturally under inland desert
conditions.
A fish kill in the lower Colorado River, downstream from Yuma, Arizona, was attributed (Sykes, 1937) to a small flood on the Gila River
in the late 1800's. The Gila was considerably more saline than the Colorado, and at the time was exceedingly low because of protracted drought
(the Gila now is dry throughout its lower course as a result of upstream
modifications ). The alkali water of the Gila was retained by a dam to avoid
contamination of irrigation supplies, and a small rise passing down the
channel overrode the dam and emptied the toxic water into the Colorado.
Fishes were reportedly destroyed in a matter of a few days from Yuma,
Arizona, to the Gulf of California, Mexico, a distance of more than 125
km.
Euryhalinity of some desert fishes seems based upon highly specialized
physiological and biochemical mechanisms. Insight into some of the prob-