The Culture of Eggs and Embryos of Amphipod Crustaceans: Implications For Brood Pouch Physiology

Abstract

A technique is described for thein vitroculture of the eggs and embryos of amphipod crustaceans. The technique was used, with mixed success, to culture the eggs of four species of amphipod (Gammarus duebeni, Orchestia gammarellus, Gammarus pulexandEchinogammarus pirloti) through to hatching. Eggs of the brackish waterG. duebenishowed good hatching success in culture (70–75%) over a wide range of experimental salinities (75–1250 mOsm kg¹). The eggs ofO. gammarellusshowed higher mortality rates in culture (compared withG. duebeni), especially in more dilute salinities (300 mOsm kg¹) in which they swelled greatly prior to disintegration. Survival and true growth (as distinct from osmotic swelling) ofO. gammarellusembryos in dilute salinities were significantly im-proved by introducing embryos into culture at a later stage of development. Antibiotic treatment had no demonstrable effect on embryo survival or growth. Whilst difficult to culture using this method, the eggs of the fresh water G.pulexshowed best hatching success on a very dilute saline medium (~40 mOsm kg¹). The results are discussed in relation to the development of embryonic osmoregulation, the implications for brood pouch function and the potential for female control of the embryonic environment, especially in semi-terrestrial species.