Assessment of the thermal tolerance of abalone based on cardiac performance in Haliotis discus hannai, H. gigantea and their interspecific hybrid

Temperature stress is one of the major threats to the economic and ecological sustainability of marine fisheries and aquaculture. The abalone aquaculture in China has been in development for more than twenty years, while summer mortality for Pacific abalone (Haliotis discus hannai) is still the most serious issue for its aquaculture in southern China. Therefore, an effective and accurate measurement for evaluating the abalone's thermal tolerance is crucial for both scientific researchers and farmers. In this study, we evaluate the thermal tolerance of two abalone species: H. discus hannai (DD), H. gigantea (GG) and their offspring H. gigantea female x H. discus hannai male (GD) using Arrhenius break temperatures (ABT) of cardiac performance. These three groups possessed different thermal limits, as indicated by ABT, GD (32.50 +/- 0.71 degrees C) > GG (31.30 +/- 1.52 degrees C) > DD (30.00 +/- 1.23 degrees C). The results were similar to further assessments of lethal temperature, Kaplan-Meier cumulative survival curves and critical thermal maximum. These results indicate that cardiac performance is an effective method to assess heat tolerance and can represent the different physiological statuses of abalones. Moreover, the results also suggested that global warming may have a profound influence on abalone aquaculture in China in the near future. Statement of relevance: The results of the present study may facilitate in better understanding the difference on the thermal tolerance ability of H. discus hannai, H. gigantea and their offspring H. gigantea. x H. discus hannai. using Arrhenius break temperatures (ABT) of cardiac performance. The results were similar to further assessments of lethal temperature, Kaplan-Meier cumulative survival curves and critical thermal maximum. These findings indicate that cardiac performance is an effective method to assess heat tolerance and can represent the different physiological statuses of abalone. The ABT of cardiac performance could afford an efficient method to predict abalone thermal performance, which would be greatly beneficial in aquaculture and breeding projects. Moreover, it may have potentially broad application in the study of thermal tolerance of abalone and other commercially aquaculture species. (C) 2016 Elsevier B.V. All rights reserved.