Oysters that had been cultured in low-temperature
fisheries were kept at a constant temperature of 25 °C
after the water temperature had been gradually raised.
The changes over time in the emergence rates of the four
coloration levels as observed visually are shown in
Fig. 4, organized according to the number of days
elapsed in the experiment or the cumulative water
temperature for days when it was over 19 °C (AT19). On
the seventh day of the laboratory experiment when the
water temperature was still low in the 16 °C to 17 °C
range (AT19=0), 20% to 50% of oysters in all groups
had a coloration level of 1 or above.