Induced quiescence in eggs of the tropical calanoid copepod Acartia tropica : Effect of different storage conditions

Abstract

Copepods of genus Acartia are considered as efficient live feeds for marine fish larviculture. A few reports are already there on production and storage for eggs of few temperate species of Acartia. Present study evaluated the storage potential of eggs of a tropical calanoid copepod, A. tropica. Different conditions examined were higher salinity storage (40–200 ppt) at room temperature, cold storage (4ºC) at different salinities (15–200 ppt), cryoprotectant solutions (methanol, glycerol) and antibiotic solutions (kanamycin, oxytetracycline). Results showed that higher salinity storage (50–200 ppt) could not retain egg viability under cold storage, as well as normal temperature conditions. The eggs exposed to cold storage and lower salinities (15–40 ppt) for 24 h survived with highest egg-hatching success (EHS, %) recorded at 15 ppt (69.44 ± 8.12). The condition was not efficient to retain egg viability beyond 24 h. The addition of certain cryoprotectants and antibiotics to the storage media significantly improved the survival of A. tropica eggs after 48 h storage. In the cryoprotectant treatments highest EHS after 48 h storage was recorded at 1M Glycerol (41.27 ± 6.34). Amongst the antibiotic treatments highest EHS after 48 and 72 h of storage were recorded at 100 ppm Kanamycin (46.79 ± 10.33, 2.67 ± 0.35) and 50ppm Kanamycin (43.86 ± 12.81, 1.73 ± 0.27), respectively. A drastic reduction in egg viability was recorded after 48 h and the antibiotics and cryoprotectants examined were not efficient to retain egg viability beyond 72 h. Hence the conditions examined in the present study could retain the viability of A. tropica eggs maximum up to 72 h and were not sufficient to induce long term quiescence in A. tropica eggs.