Effects of environmental and farm stress on abalone physiology: perspectives for abalone aquaculture in the face of global climate change

Many abalone farms are reliant on coastal water inputs which are subject to fluctuations in environmental variables such as temperature, oxygen, CO2 and salinity. Near future climate change scenarios predict that there will be more frequent extreme weather events which can exacerbate these fluctuations and potentially be deleterious to farmed abalone where these variables remain largely uncontrolled. In this review, we have taken an in depth examination of current literature on the effects of environmental stress on abalone physiology and metabolism and how this affects their health and growth. In conjunction, we have also reviewed the effects of farm-specific stressors such as ammonia, stocking density, handling, nutrition and disease and the synergistic effects of these and environmental stressors on abalone physiology. We have identified currents gaps in our knowledge of this under-studied species and have made predictions on the effects of climate change on future abalone production with suggestions for future research. In summary, it is expected that abalone will show reduced growth rates as more energy is invested in combating stresses rather than growth. Furthermore, disease outbreaks may become more frequent with greater fluctuations in temperature and salinity, both of which have large-scale effects on immunity. The current body of knowledge is mainly on whole animal effects of stresses, but we know very little of their mechanistic foundation. Research in this area as well as investments in infrastructure will be pivotal in identifying and implementing strategic interventions to maintain a sustainable abalone industry in Australia.