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

Unfed lecithotrophic larvae of the golden king crab Lithodes aequispinus we re reared at 3, 6, and 9 degrees 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 cond itions. The survival rates and intermolt duration was observed for the firs t zoeal molt (ZI), second molt (ZII), third molt (ZIII), and glaucothoe (G) . The duration from hatching to the start of the first nonlarval stage (cra b I) averaged 148, 94, and 75 days at 3, 6, and 9 degrees C, respectively. Development rate for ZI to Crab I versus the rearing temperature was descri bed by the equation: Development period (days) = -35.82 (Rearing Temperatur e degrees C) + 1.96 (degrees C-2) + 238.6; r(2) = 0.99. Regardless of stage , every degree increase in temperature reduced the length of the developmen t 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 rat es to the end of the ZIII molt at 3 degrees and 6 degrees C were 77% and 75 %, but only 65% at 9 degrees C. Within stages there was no significant diff erence in survival rates for ZI, ZII, or ZIII at the 3 test temperatures. T he survival rate through the glaucothoe stage was 47% and 51% for larvae re ared at 3 degrees and 6 degrees C, respectively, while only 16% of those at 9 degrees C survived to Crab I. There was no significant difference in the percentage of glaucothoe surviving at 3, 6, and 9 degrees C.