V I I . DESERT FISHES
401
since they were not known to occur in the creek itself (Minckley, 1969b).
Riparian vegetation was sorely damaged by the flood, and the bottom of
the stream was scoured deeply. No data were obtained on the fishes, but
adults and young of all native species were common the following April.
In August, 1964, a smaller flood was observed in the same area, and
the fishes either moved laterally into vegetation inundated along the banks
(a poeciliid, Gambusia marshi), or seemingly remained in the channel,
despite pronounced increases in current (a catfish, Ictalurus lupus [?], and
the Mexican tetra, Astyanax jasciatus mexicanus). The catfish and tetra
are found frequently in swifter waters of the Cuatro Ciénegas area, at least
for part of the time (Minckley, 1969b). The only mortality seen was of
Gambusia trapped in shallow backwaters, which soon dried.
Effects of additional flooding were observed in August, 1964 in narrow
canyons east of Cuatro Ciénegas where headwaters of the Rio Salado de
los Nadadores pass out of the Sacramento basin toward the Rio Grande.
At this point the canyon is perhaps 100 meters wide and was almost
totally choked with a luxuriant stand of reeds (Phragmites communis) that
grew to more than 5 meters high. The entire stand was flattened to the
ground, and marks on canyon walls indicated that at least 4 meters of water
raced through the area, coming mostly from mountains to the north. No
flooding occurred through the canyon connecting the Cuatro Ciénegas and
Sacramento basins; water from the Rio Canon simply sank into an extensive alluvial fan. There was no evidence for significant damage to the fishes
of the Rio Salado de los Nadadores, and in April, 1965, few traces of
the spate remained; even the reeds had totally recovered.
An incident in India, quite different from those already discussed, involved failure of a dam that produced a flood said to have destroyed an
entire downstream fish fauna (Nikolsky, 1963). A similar happening in central Arizona followed heavy rains of 1965-1966 that prematurely melted
a montane snow-pack. Accumulation of runoff exceeded storage capacity
of reservoirs, and when flood gates were opened, flow in the channel
of the Salt River rose from a few tens of m
3
/minute to more than
1.2 X 10
5
m
3
/minute in a few hours. High discharge was maintained for
some days, and when water receded a remarkable number of fishes were
dead in the few trees that remained on terraces. Most were introduced
species, such as threadfin shad (Dorosoma petenense) and sunfishes
(Lepomis spp.) from upstream lakes. Fishes still living in abundance in
the channel were almost exclusively native suckers (Catostomus and Pantosteus), while introduced forms common there prior to the massive discharge were destroyed. A number of alien kinds, abundant in downstream
areas of waste-water ponds, have not again been found (Minckley and
Deacon, 1968; Minckley, 1971).
401
since they were not known to occur in the creek itself (Minckley, 1969b).
Riparian vegetation was sorely damaged by the flood, and the bottom of
the stream was scoured deeply. No data were obtained on the fishes, but
adults and young of all native species were common the following April.
In August, 1964, a smaller flood was observed in the same area, and
the fishes either moved laterally into vegetation inundated along the banks
(a poeciliid, Gambusia marshi), or seemingly remained in the channel,
despite pronounced increases in current (a catfish, Ictalurus lupus [?], and
the Mexican tetra, Astyanax jasciatus mexicanus). The catfish and tetra
are found frequently in swifter waters of the Cuatro Ciénegas area, at least
for part of the time (Minckley, 1969b). The only mortality seen was of
Gambusia trapped in shallow backwaters, which soon dried.
Effects of additional flooding were observed in August, 1964 in narrow
canyons east of Cuatro Ciénegas where headwaters of the Rio Salado de
los Nadadores pass out of the Sacramento basin toward the Rio Grande.
At this point the canyon is perhaps 100 meters wide and was almost
totally choked with a luxuriant stand of reeds (Phragmites communis) that
grew to more than 5 meters high. The entire stand was flattened to the
ground, and marks on canyon walls indicated that at least 4 meters of water
raced through the area, coming mostly from mountains to the north. No
flooding occurred through the canyon connecting the Cuatro Ciénegas and
Sacramento basins; water from the Rio Canon simply sank into an extensive alluvial fan. There was no evidence for significant damage to the fishes
of the Rio Salado de los Nadadores, and in April, 1965, few traces of
the spate remained; even the reeds had totally recovered.
An incident in India, quite different from those already discussed, involved failure of a dam that produced a flood said to have destroyed an
entire downstream fish fauna (Nikolsky, 1963). A similar happening in central Arizona followed heavy rains of 1965-1966 that prematurely melted
a montane snow-pack. Accumulation of runoff exceeded storage capacity
of reservoirs, and when flood gates were opened, flow in the channel
of the Salt River rose from a few tens of m
3
/minute to more than
1.2 X 10
5
m
3
/minute in a few hours. High discharge was maintained for
some days, and when water receded a remarkable number of fishes were
dead in the few trees that remained on terraces. Most were introduced
species, such as threadfin shad (Dorosoma petenense) and sunfishes
(Lepomis spp.) from upstream lakes. Fishes still living in abundance in
the channel were almost exclusively native suckers (Catostomus and Pantosteus), while introduced forms common there prior to the massive discharge were destroyed. A number of alien kinds, abundant in downstream
areas of waste-water ponds, have not again been found (Minckley and
Deacon, 1968; Minckley, 1971).