Hormetic effect of 60Co gamma radiation on tolerance to salinity and temperature stress in Haliotis discus discus

Low levels of radiation increase productivity and environmental resistance in a variety of organisms by hormesis. Here, we investigated the effects of different dose levels of 60Co gamma radiation (GR) on tolerance to high temperature (HT) and low salinity (LS) stress and immunological responses in the commercially consumed abalone, Haliotis discus discus. Although H. discus discus exhibited a significantly lower survival rate (SR) at a high level of GR (25Gy) than the control (0Gy), an increased SR and higher cardiovascular hemocyte counts were exhibited at 20Gy. Furthermore, enhanced tolerance to HT (30°C) and LS (25psu) stress, and increased lysozyme activity, were exhibited by the GR-treated H. discus discus groups. Although similar respiratory burst activity after 24h of stress exposure was exhibited by all of the groups, significantly enhanced superoxide dismutase activity was exhibited in the GR-treated abalone groups under LS stress. Our results indicate that GR-treated H. discus discus exhibit hormetic responses to 60CO gamma radiation against environmental stressors because of increased innate immune responses. It is considered that our study will provide beneficial information about potential use of gamma-radiation techniques for the environmentally-strong abalone production in aquaculture industry. •Most effective 60CO gamma radiation level for increasing hemocytes was 20Gy.•Enhanced stress tolerance was observed in 60CO gamma-irradiated H. discus discus.•Higher lysozyme activity was observed in 60CO gamma-irradiated H. discus discus.•Antioxidant enzyme responses differed with temperature and salinity stress.