The effect of temperature on circulating levels of methyl farnesoate and ecdysteroid hormones in female snow crab Chionoecetes opilio, from the Bering Sea

Abstract

Methyl farnesoate, a reproductive hormone in crustaceans, was detected for the first time in the hemolymph of female Chionoecetes opilio. Ovigerous crabs were maintained at -1,0, 1, and 3° C to represent near bottom temperatures of the Bering Sea, throughout a reproductive cycle to assess changes, and temperature effects, in hormone levels associated with ovarian maturation, hatching and subsequent extrusion of the next clutch. Methyl farnesoate (MF) levels did not change significantly in any treatment throughout the duration of egg incubation. Levels of MF significantly decreased in crabs exposed to -1 and 0° C when initial versus post extrusion levels were compared. Ecdysteroid levels remained low throughout the egg incubation period but increased significantly after extrusion in all treatments except the 0° C treatment. Decrease in temperature significantly prolonged time to extrusion between all temperature groups except 3 and 1 ° C. Extrusion was delayed in the 0 and -1 ° C treatments when compared to the 3 and 1 ° C treatments. The duration of extrusion increased by as much as 77% (between -1 and 0° C) as temperature decreased, suggesting changes in temperature can have a significant effect on the reproductive timing in C. opilio.