Hatching rate of the egg-carrying estuarine copepod Eurytemora affinis

The egg-carrying copepod Eurytemora affinis is often a characteristic and dominant component in the carbon cycles of freshwater influenced marine ecosystems in the Northern Hemisphere. In egg-carrying copepods the specific egg production rate in the field can be calculated from the egg hatching rate at in situ temperatures, the egg/female ratio and the carbon content of the eggs and females. To determine the temperature dependent egg hatching time (HT) of 2 populations of E. affinis, hatching experiments were conducted at 6 different temperatures (T). Hatching times ranged from 14.1 to 1.6 d at 5 and 22 degrees C, respectively. Results from the 2 populations were pooled and fitted to a power function: HT = 187 T-1.54 (r(2) = 0.97; p < 0.001). There is a large range in the hatching times versus temperature reported in the Literature, and our results reveal longer hatching times than previously reported. To overcome this pronounced variation in hatching times, we present a significant relationship (r(2) = 0.87; p < 0.001) based on all available data: HT = 36.8 T-1.04.