11. HYDROSTATIC PRESSURE
459
remain the only work the author knows of on the effects of high pressures
on the developing eggs of fishes. Regnard exposed salmonid eggs to
pressures of 100-650 atm for periods of 6 hr. He then followed the
course of their development. Control eggs and eggs exposed to 100 and
200 atm hatched in 21 days. Eggs exposed to 300 atm hatched normally,
but 2 days later. All other eggs died, those exposed to 400 and 500 atm
after 6 days, and those exposed to 650 atm after 2 days.
Draper and Edwards exposed killifish, Fundulus sp., eggs for periods
of up to 3 hr to pressures up to 130 atm. No observable effects on cell
constituents occurred. Cleavage rates were slowed, and cases of abnormal
development occurred. The hearts of young embryos beat more slowly
under pressure, sometimes stopping altogether if pressure was continued.
This stoppage was usually reversed within a few minutes after pressure
release. Pressure also induced cardiac arrhythmia, types of local block,
and isolated fibrillary activity. The cardiac effects of pressure apparently
resulted from direct influences. Similar effects occurred in still noninnervated hearts of young embryos and in de-innervated hearts of
older embryos.
High pressure effects on intact fishes have received very little attention since Cattell’s review (1936). The author knows of only one brief,
entirely behavioral paper ( Nishiyama, 1965). Cattell himself cites only
three substantial papers ( Regnard, 1891; Fontaine, 1930; Ebbecke,
1935b). The papers by Regnard and Fontaine both completely summarize previously published series of shorter papers by the same authors.
Nishiyama (1965) observed the behavior of rainbow trout, goldfish,
bitterling, and loach during exposures of up to 5 days’ duration to
pressures up to about 25 atm. Abnormal behavior patterns were observed
in all species (e.g., unusual swimming postures or cessation of swimming,
irregular respiratory rhythms, and “convulsions” during pressure
changes ) . Paling of body color because of melanophore contraction also
occurred in the trout.
A brief description of the major features of the results previously
reviewed by Cattell seems useful here as well. Regnard, Fontaine, and
Ebbecke each observed behavioral changes and tolerances for high
pressures (to lo00 atm for Regnard, about 700 atm for Fontaine, and
500 atm for Ebbecke) in a variety of both freshwater and marine shallow
water fishes, including forms with and without swim bladders. Details
varied somewhat between species, but the basic pattern of response to
quickly applied and released pressures, usually over durations of a few
minutes to at most a few hours, was an increase in physical activity
under moderate pressures, then depression of activity, ultimately leading
to cessation at higher pressures. The region of stimulation extended to
459
remain the only work the author knows of on the effects of high pressures
on the developing eggs of fishes. Regnard exposed salmonid eggs to
pressures of 100-650 atm for periods of 6 hr. He then followed the
course of their development. Control eggs and eggs exposed to 100 and
200 atm hatched in 21 days. Eggs exposed to 300 atm hatched normally,
but 2 days later. All other eggs died, those exposed to 400 and 500 atm
after 6 days, and those exposed to 650 atm after 2 days.
Draper and Edwards exposed killifish, Fundulus sp., eggs for periods
of up to 3 hr to pressures up to 130 atm. No observable effects on cell
constituents occurred. Cleavage rates were slowed, and cases of abnormal
development occurred. The hearts of young embryos beat more slowly
under pressure, sometimes stopping altogether if pressure was continued.
This stoppage was usually reversed within a few minutes after pressure
release. Pressure also induced cardiac arrhythmia, types of local block,
and isolated fibrillary activity. The cardiac effects of pressure apparently
resulted from direct influences. Similar effects occurred in still noninnervated hearts of young embryos and in de-innervated hearts of
older embryos.
High pressure effects on intact fishes have received very little attention since Cattell’s review (1936). The author knows of only one brief,
entirely behavioral paper ( Nishiyama, 1965). Cattell himself cites only
three substantial papers ( Regnard, 1891; Fontaine, 1930; Ebbecke,
1935b). The papers by Regnard and Fontaine both completely summarize previously published series of shorter papers by the same authors.
Nishiyama (1965) observed the behavior of rainbow trout, goldfish,
bitterling, and loach during exposures of up to 5 days’ duration to
pressures up to about 25 atm. Abnormal behavior patterns were observed
in all species (e.g., unusual swimming postures or cessation of swimming,
irregular respiratory rhythms, and “convulsions” during pressure
changes ) . Paling of body color because of melanophore contraction also
occurred in the trout.
A brief description of the major features of the results previously
reviewed by Cattell seems useful here as well. Regnard, Fontaine, and
Ebbecke each observed behavioral changes and tolerances for high
pressures (to lo00 atm for Regnard, about 700 atm for Fontaine, and
500 atm for Ebbecke) in a variety of both freshwater and marine shallow
water fishes, including forms with and without swim bladders. Details
varied somewhat between species, but the basic pattern of response to
quickly applied and released pressures, usually over durations of a few
minutes to at most a few hours, was an increase in physical activity
under moderate pressures, then depression of activity, ultimately leading
to cessation at higher pressures. The region of stimulation extended to