水產動物淡海水適應之生理機制─魚類對鹽度之能量代謝反應及調節機制之研究

The physiological responses of the
groupers, Epinephelus coioides under acute
salinity shock were monitored. The study is
focused on hematological responses, osmoregulation
and carbohydrate metabolism.
The acclimated groupers at the salinity of
25 ppt were directly transferred to varying
salinities of 5, 15, 25, 35 and 45 ppt, and the
osmoregulation of the groupers under the
salinity shock was monitored. The parameters
monitored included hematocrit,
hemoglobin, plasma osmolarity and ion
composition, and Na+-K+ -activated ATPase
activity in the gills.
Under hypoosomotic environment (5 and
15 ppt), hypoosmorality was characteristic
responses in the initial phase of salinity
shock, but the plasma osmolarity recovered
to the normal level after 6hr. A temporary
hyperosmorality was noted under
hyperosmotic environments in the initial
period up to 12 hr. Furthermore, Na+-K+
ATPase activity was elevated under
hyperosmotic conditions, and vice versa. The
physiological responses and regulation were
demonstrated in these parameters monitored.
Hyperglycemia was found to be a common
indicator for stress response in the groupers
exposed to varying salinities. Plasma glucose
was elevated within 48 hr under hight salinity
condition, and only in a short initial phase of
low salinity conditions. The observation not
only implied the occurrence of stress
responses, but also increased demands for
energy for physiological regulation and
compensation. Hyperlactocemia was another
indicator of the stress responses, and
significant increase in the plasma lactate was
detectable within 1 hr after the shock in all
cases, followed by gradual declines thereafter.
This suggested that the groupers rely heavily
on the energy supplies through anaerobic
pathway in the initial phase of physiological
compensation.