VII. DESERT FISHES
427
cellular bones (Anguilla anguilla, Ictalurus melas). This effect was not
demonstrated in Fundulus heteroclitus, a species with acellular bone.
These mechanisms are called into play immediately when there is a
change in the osmotic composition of the environment. In Fundulus kansae
complete adaptation to seawater after direct transfer from fresh water occurs in 20 days. Hypertonie environments become lethal to fishes when
the capacity of the secretory cells of the gills (and oral epithelium) and
kidney is exceeded and salt begins to accumulate in the tissues.
Salinity tolerances of different stages in a life cycle may vary radically.
Kinne (1960) and Kinne and Kinne (1962a,b) demonstrated that eggs of
Cyprinodon macularius will develop in salinities up to 70 gm/liter (with
varying rates and structural consequences), whereas adults live in salinities
up to 80 to 85 gm/liter. Barlow (1958b) indicates that juveniles of C.
macularius are capable of surviving in salinities up to 90 gm/liter, but that
most adults die sooner. Renfro (1960) reported survival of yolk-sac larvae
of sheepshead pupfish at 110 gm/liter. Our observations of other species
of pupfishes in drying pools indicate a greater tolerance of subadults than
of either tiny young, or larger old individuals.
Minimum salinity tolerances have been infrequently reported. LaBounty
and Deacon (1971) maintained adult Cyprinodon salinus and Cyprinodon
sp. from Death Valley in distilled water. Kinne and Kinne (1962a) found
that some eggs of C. macularius developed in glass-distilled water, although
mortality was quite high. They documented normal development over a
wide range of temperature in water made up of half tap water and half
distilled water. Simpson and Gunter (1956) caught C. variegatus at
1.8 gm/liter, and Gunter (1950) recorded it at 0.4 gm/liter. Kilby (1955)
recorded a minimum for that species of 0.0 gm/liter, a highly unlikely
total dissolved solids determination from natural water. The Australian
Taeniomembras studied by Lee (1969) lived for a week after direct transfer from 70 gm/liter to 2.0 gm/liter salinity, but mortality was about 50%.
Such changes in nature, in an almost instantaneous manner, certainly occur
when marginal pools are rapidly flooded by rising streams or lakes, or during heavy, seasonal rainfall, or when waves suddenly fill shore pools along
margins of desert lakes.
3. Dissolved Gases
Dissolved gases have been far less studied relative to desert fishes
than have physical and more easily analyzed chemical features. Incidental
analyses have been generally omitted here, unless directly pertaining to
a species or group of fishes; references to broad limnological works dealing
in part with dissolved gases are given earlier. Flowing waters, other than
427
cellular bones (Anguilla anguilla, Ictalurus melas). This effect was not
demonstrated in Fundulus heteroclitus, a species with acellular bone.
These mechanisms are called into play immediately when there is a
change in the osmotic composition of the environment. In Fundulus kansae
complete adaptation to seawater after direct transfer from fresh water occurs in 20 days. Hypertonie environments become lethal to fishes when
the capacity of the secretory cells of the gills (and oral epithelium) and
kidney is exceeded and salt begins to accumulate in the tissues.
Salinity tolerances of different stages in a life cycle may vary radically.
Kinne (1960) and Kinne and Kinne (1962a,b) demonstrated that eggs of
Cyprinodon macularius will develop in salinities up to 70 gm/liter (with
varying rates and structural consequences), whereas adults live in salinities
up to 80 to 85 gm/liter. Barlow (1958b) indicates that juveniles of C.
macularius are capable of surviving in salinities up to 90 gm/liter, but that
most adults die sooner. Renfro (1960) reported survival of yolk-sac larvae
of sheepshead pupfish at 110 gm/liter. Our observations of other species
of pupfishes in drying pools indicate a greater tolerance of subadults than
of either tiny young, or larger old individuals.
Minimum salinity tolerances have been infrequently reported. LaBounty
and Deacon (1971) maintained adult Cyprinodon salinus and Cyprinodon
sp. from Death Valley in distilled water. Kinne and Kinne (1962a) found
that some eggs of C. macularius developed in glass-distilled water, although
mortality was quite high. They documented normal development over a
wide range of temperature in water made up of half tap water and half
distilled water. Simpson and Gunter (1956) caught C. variegatus at
1.8 gm/liter, and Gunter (1950) recorded it at 0.4 gm/liter. Kilby (1955)
recorded a minimum for that species of 0.0 gm/liter, a highly unlikely
total dissolved solids determination from natural water. The Australian
Taeniomembras studied by Lee (1969) lived for a week after direct transfer from 70 gm/liter to 2.0 gm/liter salinity, but mortality was about 50%.
Such changes in nature, in an almost instantaneous manner, certainly occur
when marginal pools are rapidly flooded by rising streams or lakes, or during heavy, seasonal rainfall, or when waves suddenly fill shore pools along
margins of desert lakes.
3. Dissolved Gases
Dissolved gases have been far less studied relative to desert fishes
than have physical and more easily analyzed chemical features. Incidental
analyses have been generally omitted here, unless directly pertaining to
a species or group of fishes; references to broad limnological works dealing
in part with dissolved gases are given earlier. Flowing waters, other than