Salinity and temperature
tolerance of embryos and juveniles of the pearl oyster, Pinctada
imbricata Röding
W.A. O'Connor, N.F. Lawler-2004
Aquaculture, 229(1-4): 493-506
Abstract:
The responses of embryos and juveniles of the pearl
oyster, Pinctada imbricata, to variation in temperature and salinity
were investigated to assist hatchery production and farming. Embryos were
incubated at temperatures in the range 14–26 °C and salinities in the
range 11–35 ppt. Embryos did not develop to D-veliger stage at 14 °C and
at salinities of 26 ppt or less. Within the salinity range 29–35 ppt, the
percentage embryos developing to D-veliger stage increased significantly
with increasing salinity. Within the temperature range 18–26 °C,
increasing temperature increased the rate of development as well as the
number of embryos developing to D-veliger stage within 40 h. Juvenile P.
imbricata (17 mm shell height) held at temperatures in the range of
14–24 °C were exposed to salinities in the range of 11–35 ppt. Spat
formed byssal attachments most rapidly at salinities of 29 and 32 ppt,
irrespective of temperature. At these salinities, >70% of oysters formed
byssal attachments to the aquaria walls within 6 h. Outside this narrow
salinity range, the rate of byssal attachment decreased and ceased
altogether at salinities of 17 ppt or less. Temperature also affected byssal
attachment although the impacts were not as great as those of salinity.
Within the optimal salinity range (29–32 ppt), the rate of byssal
attachment was fastest at 18 °C, where up to 80% of oysters had attached
within 4 h. This rate was slightly greater than that observed at 22 °C,
which in turn exceeded those observed at 14 and 26 °C. Salinity and
temperature also affected survival. Irrespective of temperature, survival
was high at salinities of 32 and 35 ppt. By contrast, high rates of
mortality occurred within 7 days at salinities of 23 ppt or less. Onset of
mortality was most rapid and overall mortality highest at the two extremes
in temperature tested, 14 and 26 °C.
(NSW Fisheries, Port Stephens Fisheries Centre,
Taylors Beach, NSW 2316, Australia, e-mail: oconnorw@fisheries.nsw.gov.au)