Some embryogenic responses of mummichog, Fundulus heteroclitus (L.) (Cyprinodontidae), to continuous incubation in various combinations of temperature and salinity
Embryos of mummichog, Fundulus heteroclitus (L.), were incubated in various combinations of constant salinity (0, 10, 20, 30, 60‰ S) and temperature (15, 20, 25, 30C) from fertilization to completion of hatching. In all instances, the velocity of embryonal development was accelerated at higher temperatures. In salinities of 0, 10, 20, 30‰, higher temperature had a similar accelerating effect on developmental rate throughout the embryonal term. However, the highest salinity (60‰) retarded embryonal development particularly after neurulation. This retarding effect increased with the increasing temperature. The onset of hatching and 50% hatching time were also retarded in 60‰ S. Embryos hatched with difficulty in the lowest incubation combination, 0‰ S, 15C. This observation is discussed in the light of pertinent literature.Highest percentage total hatch and viable (normal) hatch were obtained at 20C in all test salinities. Response surface analysis showed that optimum conditions for survival for mummichog embryos appeared to be associated with salinities and temperature of 19–20‰ and 18C.Larval length was greatest in groups incubated at 15 and 20C and 0–30‰ S.