Understanding which species and ecosystems will be most severely affected by warming as climate change advances is important for guiding conservation and management. Both marine and terrestrial fauna have been affected by warming1,2 but an explicit comparison of physiological sensitivity between the marine and terrestrial realms has been lacking. Assessing how close populations live to their upper thermal limits has been challenging, in part because extreme temperatures frequently drive demographic responses3,4 and yet fauna can use local thermal refugia to avoid extremes5-7. Here we show that marine ectotherms experience hourly body temperatures that are closer to their upper thermal limits than do terrestrial ectotherms across all latitudes-but that this is the case only if terrestrial species can access thermal refugia. Although not a direct prediction of population decline, this thermal safety margin provides an index of the physiological stress caused by warming. On land, the smallest thermal safety margins were found for species at mid-latitudes where the hottest hourly body temperatures occurred; by contrast, the marine species with the smallest thermal safety margins were found near the equator. We also found that local extirpations related to warming have been twice as common in the ocean as on land, which is consistent with the smaller thermal safety margins at sea. Our results suggest that different processes will exacerbate thermal vulnerability across these two realms. Higher sensitivities to warming and faster rates of colonization in the marine realm suggest that extirpations will be more frequent and species turnover faster in the ocean. By contrast, terrestrial species appear to be more vulnerable to loss of access to thermal refugia, which would make habitat fragmentation and changes in land use critical drivers of species loss on land.

Greater vulnerability to warming of marine versus terrestrial ectotherms.

Thermal biology of zebrafish (Danio rerio)

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.

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

Thermal preference, tolerance and oxygen consumption of adult white shrimp Litopenaeus vannamei (Boone) exposed to different acclimation temperatures

Thermal tolerance and oxygen consumption rates of the catfish Horabagrus brachysoma (Günther) acclimated to different temperatures

The behavioural and metabolic responses of the largemouth bass Micropterus salmoides (Lacepede) to temperature were determined to define optimal thermal conditions. The final preferendum of largemouth bass juveniles determined with acute and gravitation methods was independent of the method (29.0–28.1 °C). The displacement velocity in the horizontal thermal gradient of bass juveniles was 22.4 cm h−1 in the light phase and 22.6 cm h−1 in the dark phase. Oxygen consumption rates in the largemouth bass increased significantly (P<0.05) from 48.8 to 69.4 mg O2 Kg−1 h−1 with an increase in the acclimation temperature from 20 to 33 °C. The temperature quotient (Q10) in the juveniles was 1.37–2.00 in the range of acclimation temperatures of 26–29 and 29–32 °C. The optimum temperature range for growth calculated using Jobling's equation was 28.1–28.6 °C and for Q10 values 26–29 °C. The results are discussed in relation to the use of this information in aquaculture.

Temperature preference and oxygen consumption of the largemouth bass Micropterus salmoides (Lacépède) acclimated to different temperatures

The thermoregulatory behaviour of green abalone Haliotis fulgens and pink abalone H. corrugata was investigated. Haliotis fulgens juveniles ranging in wet weight from 3.0 to 3.3 g and from 28.7 to 30.5 mm shell length and of H. corrugata 2.0 g and 25.7 mm in shell length were exposed to 19°C for 30 days in a flow-through water system. Temperature preference was determined in a horizontal thermal gradient and was found to be 25.4°C for green abalone and 25.0°C for pink abalone. Displacement velocity was 4.3 cm h⁻¹ for H. fulgens and 12.8 cm h⁻¹ for H. corrugata. The optimum temperature for growth calculated for both abalone species was 24.6 and 24.5°C respectively. The critical thermal maxima (CTMax) of H. fulgens and H. corrugata were determined as a measure of thermal tolerance. Abalones were subjected to increasing water temperatures at a rate of 1°C on 30 min until they detached from the substrate. The CTMax at 50% were 33.6 and 32.0°C for green and pink abalone respectively. The results are discussed in relation to site selection and commercial rearing.

Francisco Valenzuela

Papers

Temperature preference and oxygen consumption of the largemouth bass Micropterus salmoides (Lacépède) acclimated to different temperatures

Thermal preference and tolerance of green abalone Haliotis fulgens (Philippi, 1845) and pink abalone Haliotis corrugata (Gray, 1828)

Preparação, a nível de laboratório, de algumas argilas esmectíticas organofílicas