Development of larvae of the golden king crab Lithodes aequispinus (Anomura: Lithodidae) reared at different temperatures

Abstract

Unfed lecithotrophic larvae of the golden king crab Lithodes aequispinus were reared at 3, 6, and 9°C in darkness and 33-34 ppt salinity. This study was done to improve our understanding of larval development time and the ability of the larvae to survive under different seasonal thermal conditions. The survival rates and intermolt duration was observed for the first zoeal molt (ZI), second molt (ZII), third molt (ZIII), and glaucothoe (G). The duration from hatching to the start of the first nonlarval stage (crab I) averaged 148, 94, and 75 days at 3, 6, and 9°C, respectively. Development rate for ZI to Crab I versus the rearing temperature was described by the equation: Development period (days) = -35.82 (Rearing Temperature °C) + 1.96 (°C2) + 238.6; r2 = 0.99. Regardless of stage, every degree increase in temperature reduced the length of the development period by approximately 9%. Survival rates of ZI larvae were typically ≥97% regardless of temperature. By the completion of the ZII molt 83-87% were still surviving. Survival rates to the end of the ZIII molt at 3°and 6°C were 77% and 75%, but only 65% at 9°C. Within stages there was no significant difference in survival rates for ZI, ZII, or ZIII at the 3 test temperatures. The survival rate through the glaucothoe stage was 47% and 51% for larvae reared at 3°and 6°C, respectively, while only 16% of those at 9°C survived to Crab I. There was no significant difference in the percentage of glaucothoe surviving at 3, 6, and 9°C.