Effect of thermal injury on embryos of banded coral shrimp (Stenopus hispidus) under hypothermal conditions

Abstract

Cryopreservation technology regarding banded coral shrimp (Stenopus hispidus) embryos is important as it could improve cultivation and preservation of the species. The development of this technology is to reduce collections of this species from the wild, thus preventing damage to coral reefs. This study investigated the tolerance of different developmental stages of S. hispidus embryos in response to low temperature in the presence or absence of cryoprotectant. Embryos undergoing three stages of embryonic development (eye-formation, heart beat and pre-hatch stage) were selected and exposed to 5, 0 and -5°C in cryoprotectant solutions of 1 or 2M methanol for 1, 2, 4, 6, 8, 16 and 32h. Embryo survival was evaluated based on their hatching percentage. In experiments on the effect of different concentrations of methanol on chilling sensitivity of embryos, it was determined that methanol at 1M methanol reduced the chilling sensitivities of embryos most effectively when compared to the other tested concentrations. Experiments regarding the chilling sensitivity of embryos in different developmental stages indicated that pre-hatch stage embryos were more resistant to subzero temperatures than early stage embryos; they tolerated the 32h exposure at 5 and 0°C without a loss in survival. The study also indicated that late stage embryos are considered to be resistant to chilling, and that pre-late stage embryos are better candidate for cryopreservation.