ABSTRACT: 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 temperaturedependent 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°C, respectively. Results from the 2 populations were pooled and fitted to a power function: HT = 187T^-1.54 (r² = 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 (r² = 0.87; p < 0.001) based on all available data: HT = 36.8T^-1.04.

KEY WORDS: Eurytemora affinis · Egg production · Hatching rate

Published in MEPS Vol. 160 (1997) on December 15
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997