Effects of light and short-term temperature elevation on the 48-h hatching success of cold-stored Acartia tonsa Dana eggs

The effects of light and short-term temperature elevation on the 48-h egg hatching success (HS) of cold-stored (2 °C) Acartia tonsa Dana (Copepoda: Calanoida) eggs were examined in the present study. The eggs can be stored for up to 7.5 months and maintain their high hatching rate under optimal conditions. Intensively produced eggs from the copepod A. tonsa may be hatched and used as an inoculum for producing copepod nauplii as live feed for fish larvae. The HS for eggs that were directly exposed to LED light declined rapidly after 1 month of storage (from 91 to 25 %), and these eggs did not hatch at all after 3 months of storage. The highest HS found was for eggs stored in complete darkness. The HS for eggs stored in normoxic (≥7 mg DO L−1) and anoxic (≤0.03 mg DO L−1) seawater was not affected by short-term temperature transitions from 2 °C up to 9 or 17 °C for a period of 12 or 24 h, when hatched 1 week post-exposure. The global mean HS for eggs stored in normoxic seawater was 85.9 % and significantly lower compared to eggs stored under anoxic conditions after 3 weeks of storage (91.8 %) (P = 0.001; SNK).