Egg hatching rate and fatty acid composition of Acartia bilobata (Calanoida, Copepoda) across cold storage durations

Abstract

To investigate egg storage capacity of the copepod Acartia bilobata for aquaculture interest, we tested hatching success rate (HSR) of inclusive eggs (mixture of all egg types) after 4 degrees C storage. The HSR peaked after 14 days storage when incubating at 28 degrees C for 48 hr (85.8 +/- 1.6%) and 72 hr (87.6 +/- 0.9%), then gradually declined until 1 year (48 hr: 7 +/- 0.6%; 72 hr: 19.4 +/- 3.9%). Reallocation of fatty acid profile suggests that docosahexaenoic acid (DHA) is correlated with the HSR of A. bilobata eggs. Additionally, we investigated the HSR of diapausing eggs (unhatched eggs after 72 hr incubation of the inclusive eggs) after 4 degrees C storage. Their HSR peaked after 14 days storage (48 hr:75.3 +/- 3.5%; 72 hr:78.2 +/- 2.1%), then gradually declined until 60 days (48 hr HSR:42.1 +/- 2.3%; 72 hr HSR:53.0 +/- 3.2%). Overall, we illustrated the hatchability of diapausing and quiescent eggs of A. bilobata after 4 degrees C storage. The cold storage capacities were low (HSR after 60 days), and it could be limited by the egg DHA content. Our findings provide implications for future studies aiming to improve cold storage techniques of tropical copepod eggs for aquaculture applications.