TEMPERATURE-DEPENDENT DEVELOPMENT OF PARTHENOGENETIC EMBRYOS IN DAPHNIA-PULEX DE GEER

An in vitro study of the embryonic stages of Daphnia pulex de Geer was carried out by way of removing and isolating eggs from the females. The temperature-dependent development rates and the developmental features were recorded photographically. The total development time was 351 h at 5°C, 161 h at 10°C and 87 h at 15°C. The relative times of development of embryonic 'stages' also showed significant variation between temperatures. The observed variations in relative development time of D.pulex embryos at different temperatures will question the accuracy of previously used methods for estimations of population birth rates using egg age determinations. © 1990 Oxford University Press.