Spawning of calanoid copepod Acartia tonsa at low temperature and high salinity improves hatch success for cold-stored egg production

When copepod Acartia tonsa is isolated from tropical populations, the produced eggs exhibit low hatching after long-term storage, a critical aspect that makes their use difficult in aquaculture. In three experiments, this study spawned adults of A. tonsa cultured at different salinities and temperatures. The eggs were collected to determine hatching success of fresh and cold-stored eggs (HS-C). Experiment 1: Adults spawned under four combinations of two temperatures (18 and 28 °C) and two salinities (18 and 30 PSU) to determine the HS-C from 0 (fresh eggs) to 4 weeks of storage. Experiment 2: Adults spawned under three combinations of temperatures (18, 23, and 29 °C) and 30 PSU to determine the HS-C (from 0 to 4 weeks of storage). Experiment 3: Adults spawned under 18 °C and 30 PSU to determine the HS-C (from 0 to 8 weeks of storage). All adults were distributed in triplicate in 2 L containers at 0.5 individual mL−1 and fed with the Rhodomonas salina microalgae at 2000 μg C L−1. In every experimental unit, the eggs were collected and stored at 3 ± 1 °C. In fresh eggs (0 weeks of storage), most of the treatments showed great hatching (> 90%). However, low salinity and high temperature resulted in a significantly (p