149 / 2023-08-24 12:27:50

Predicting the impacts of marine heatwaves on future mariculture production in east and southeast Asia

thermal performance, marine heatwaves, thermal variability, population growth, east Asia, mariculture

Extremes in temperature associated with the increasing occurrence of marine heatwaves may exert a more significant pressure on biological systems than changes in mean temperature. Individuals and populations respond to these events through physiological resistance, migration, or local extinction depending on species-specific functional traits and physiology. However, at present our knowledge of how the local thermal environment affects essential physiological processes such as growth is based on laboratory experiments carried out either at constant temperatures, or by quickly ramping temperatures to a critical maximum. Neither of these methods take into consideration natural thermal variability cycles, or variability because of extreme events, and is a substantial knowledge gap in how future MHWs will shape the distribution of marine populations. In this study, we incorporate thermal variability into predictions of temperature-dependent growth performance for 40 species of longer-lived marine ectotherms across 50 degrees of latitude from east and southeast Asia. This region shows large differences in mean temperature and temperature variability. We found that predictions from models using data from laboratory studies overestimated the growth performance and the thermal resilience of the species studied, compared to when natural thermal variability was incorporated into predictions. Incorporating variability into predictions of the thermal safety margin resulted in as much as a 10 °C decrease in thermal buffer between the top 5% of temperatures experienced in a location and the predicted CT_max of the species. This analysis provides the first spatially explicit, species-level, physiological assessment of the potential for MHWs to cause performance declines. This analysis can be incorporated into planning tools to manage, and perhaps mitigate, some of the effects of future MHWs for the region that provides >70% of the world’s aquaculture.

Extremes in temperature associated with the increasing occurrence of marine heatwaves may exert a more significant pressure on biological systems than changes in mean temperature. Individuals and populations respond to these events through physiological resistance, migration, or local extinction depending on species-specific functional traits and physiology. However, at present our knowledge of how the local thermal environment affects essential physiological processes such as growth is based on laboratory experiments carried out either at constant temperatures, or by quickly ramping temperatures to a critical maximum. Neither of these methods take into consideration natural thermal variability cycles, or variability because of extreme events, and is a substantial knowledge gap in how future MHWs will shape the distribution of marine populations. In this study, we incorporate thermal variability into predictions of temperature-dependent growth performance for 40 species of longer-lived marine ectotherms across 50 degrees of latitude from east and southeast Asia. This region shows large differences in mean temperature and temperature variability. We found that predictions from models using data from laboratory studies overestimated the growth performance and the thermal resilience of the species studied, compared to when natural thermal variability was incorporated into predictions. Incorporating variability into predictions of the thermal safety margin resulted in as much as a 10 °C decrease in thermal buffer between the top 5% of temperatures experienced in a location and the predicted CT_max of the species. This analysis provides the first spatially explicit, species-level, physiological assessment of the potential for MHWs to cause performance declines. This analysis can be incorporated into planning tools to manage, and perhaps mitigate, some of the effects of future MHWs for the region that provides >70% of the world’s aquaculture.

Extremes in temperature associated with the increasing occurrence of marine heatwaves may exert a more significant pressure on biological systems than changes in mean temperature. Individuals and populations respond to these events through physiological resistance, migration, or local extinction depending on species-specific functional traits and physiology. However, at present our knowledge of how the local thermal environment affects essential physiological processes such as growth is based on laboratory experiments carried out either at constant temperatures, or by quickly ramping temperatures to a critical maximum. Neither of these methods take into consideration natural thermal variability cycles, or variability because of extreme events, and is a substantial knowledge gap in how future MHWs will shape the distribution of marine populations. In this study, we incorporate thermal variability into predictions of temperature-dependent growth performance for 40 species of longer-lived marine ectotherms across 50 degrees of latitude from east and southeast Asia. This region shows large differences in mean temperature and temperature variability. We found that predictions from models using data from laboratory studies overestimated the growth performance and the thermal resilience of the species studied, compared to when natural thermal variability was incorporated into predictions. Incorporating variability into predictions of the thermal safety margin resulted in as much as a 10 °C decrease in thermal buffer between the top 5% of temperatures experienced in a location and the predicted CT_max of the species. This analysis provides the first spatially explicit, species-level, physiological assessment of the potential for MHWs to cause performance declines. This analysis can be incorporated into planning tools to manage, and perhaps mitigate, some of the effects of future MHWs for the region that provides >70% of the world’s aquaculture.