Establishing larval feeding regimens for the decorator crab Camposcia retusa : Effects of live prey types and density on larval survival and development

Abstract

Decorator crab Camposcia retusa is a popular marine ornamental species; however, it has never been bred previously. To establish a feeding regime for C. retusa larvae, which include two zoeal and a megalopal stage, three experiments were conducted. In all experiments, ≥60% of unfed 1st zoeal (Z1) larvae survived to the next stage, combined with the orange guts observed in larvae fed Artemia, suggesting Z1 larvae are facultative lecithotrophic. Experiment 1 evaluated the suitability of ss‐type rotifer Brachionus rotundiformis as prey. Z1 larvae were fed rotifer at a density from 0 to 90 ind./ml. There was no significant difference in Z1 survival among treatments (56.7–68.3%, p > 0.05); therefore, ss‐type rotifer is considered an unsuitable prey for the larvae. Experiment 2 examined the suitability and optimal density of Artemia nauplii, and co‐feeding copepod Pavocalanus crassirostris with Artemia, for larval rearing. The larvae fed 10 Artemia/ml had the highest survival to megalopae (91.3 ± 3.1%, p < 0.05). However, high mortality occurred in megalopae, resulting in poor survival to the 1st crab stage (1.3%–12.5%) in all treatments (p > 0.05). Meanwhile, co‐feeding copepods with Artemia showed significantly inferior survival and development to megalopae when compared to that of 10 Artemia/ml treatment. Experiment 3 evaluated the effects of Artemia enrichment on larval performance. The results suggested that Artemia enrichment did not improve larval survival or development. Based on our results, Artemia nauplii fed at 10 ind./ml throughout larval development appears to be appropriate for C. retusa.