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

Abstract

Many abalone farms are reliant on coastal water inputs which are subject to fluctuations in environmental variables such as temperature, oxygen, CO 2 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.

Effects of salinity on the growth and mucous cells of the abalone Haliotis diversicolor Reeve, 1846

“…Further, suboptimal low salinity causes added stress to the abalone Haliotis varia Linnaeus when exposed to toxic substances (Lasut 1999). As in other marine mollusks, cell volume is regulated during variation in external salinity using intracellular free amino acids as osmotic solutes (Baginski and Pierce 1975;Amende and Pierce 1980) causing changes in water content and weight of abalone (Morash and Alter 2016). In our study, the lowest salinity (20 ppt) is the least favorable to the growth of H. diversicolor.…”

“…Greater growth of some mollusks at lower salinities is due to the lower energetic cost of ionic and osmotic regulation, high food intake, efficient food conversion ratio, high retention of nutrients, low excretion of metabolites and low oxygen consumption (Ghiretti 1966). On the other hand, at higher salinities abalone spends more energy in counteracting stress rather than investing in growth, thus resulting in reduced growth rate (Morash and Alter 2016). It has been implicated that during seasonal salinity fluctuations the chemical balance between the environment and the body fluids is disrupted and efforts to regain homeostatic balance is an energetically costly process for abalone (Martello et al 1998;Morash and Alter 2016).…”

“…On the other hand, at higher salinities abalone spends more energy in counteracting stress rather than investing in growth, thus resulting in reduced growth rate (Morash and Alter 2016). It has been implicated that during seasonal salinity fluctuations the chemical balance between the environment and the body fluids is disrupted and efforts to regain homeostatic balance is an energetically costly process for abalone (Martello et al 1998;Morash and Alter 2016). Further, suboptimal low salinity causes added stress to the abalone Haliotis varia Linnaeus when exposed to toxic substances (Lasut 1999).…”

Non-Lethal Method for the Preparation of Metaphase Spreads Using Cultured Mantle Tissue From Live Adult Abalone

“…Owing to its protrusive structure [10], removing small pieces of tissue from it does not influence the survival and growth of abalone and the impaired epithelium in incision sites can recover in 2 months even though the sites are not filled with granulation tissue [11]. Indeed, all abalone that provided small pieces of mantle in our study survived and did not show any abnormal sign in their growth during the 6-month observation period after tissue sampling.…”

Epipodial Tentacle Gene Expression and Predetermined Resilience to Summer Mortality in the Commercially Important Greenlip Abalone, Haliotis laevigata

“…The value (e.g., growth and quality) of surviving animals can also be impaired (Morash and Alter 2015). Age is known to be an important factor for mollusks when investigating their reaction to stressors brought on by climate change (Clark et al 2013).…”