Responses of invertebrates to temperature and water stress: A polar perspective

Abstract

16As small bodied poikilothermic ectotherms, invertebrates, more so than any other animal 17 group, are susceptible to extremes of temperature and low water availability. In few places is 18 this more apparent than in the Arctic and Antarctic, where low temperatures predominate and 19 water is unusable during winter and unavailable for parts of summer. Polar terrestrial 20invertebrates express a suite of physiological, biochemical and genomic features in response to 21 these stressors. However, the situation is not as simple as responding to each stressor in 22 isolation, as they are often faced in combination. We consider how polar terrestrial 23 invertebrates manage this scenario in light of their physiology and ecology. Climate change is 24 also leading to warmer summers in parts of the polar regions, concomitantly increasing the 25 potential for drought. The interaction between high temperature and low water availability, and 26 the invertebrates' response to them, are therefore also explored. 27 28

Survival of rapidly fluctuating natural low winter temperatures by High Arctic soil invertebrates

“…The large majority of polar Acari and Collembola are known to employ the freeze avoidance tactic (Sinclair et al, 2003;Everatt et al 2014). The use of the alternative cryoprotective dehydration strategy by the springtail Megaphorura arctica, a distinctive species not present in the current study, has also been documented (Worland et al, 1998).…”

“…Resistance to environmental stresses, in particular cold and desiccation, is generally thought to be well developed, although the majority of detailed studies have focused on a limited number of groups and species. Two cold tolerance strategies are utilised by many polar invertebrates (Everatt et al, 2014). Freeze avoidance involves the organism maintaining its body contents in the liquid state below the freezing point of water, while freeze tolerance involves the use of ice nucleating agents to encourage controlled ice formation in extracellular compartments, leading to concentration and lowering of the freezing point of intracellular fluids (see Block, 1990;Danks, 2007;Thomas et al, 2008;Denlinger and Lee, 2010;Ávila-Jiménez et al, 2010;Coulson et al, 2014;Everatt et al, 2014).…”

“…Two cold tolerance strategies are utilised by many polar invertebrates (Everatt et al, 2014). Freeze avoidance involves the organism maintaining its body contents in the liquid state below the freezing point of water, while freeze tolerance involves the use of ice nucleating agents to encourage controlled ice formation in extracellular compartments, leading to concentration and lowering of the freezing point of intracellular fluids (see Block, 1990;Danks, 2007;Thomas et al, 2008;Denlinger and Lee, 2010;Ávila-Jiménez et al, 2010;Coulson et al, 2014;Everatt et al, 2014). However, detailed specific studies of the cold tolerance and survival characteristics of High Arctic arthropods have focussed on relatively few groups, in particular the Hemiptera, Acari and Collembola (Block et al, 1994;Strathdee et al, 1995;Hayward et al, 2000;Holmstrup et al, 2002;Søvik and Leinaas 2003;Hodkinson and Bird 2004;Bahrndorff et al, 2007;Clark et al, 2009;Sørensen and Holmstrup, 2011), with a very limited amount of work on other groups such as nematodes (Carlsson et al, 2013).…”

Observed trends of soil fauna in the Antarctic Dry Valleys: early signs of shifts predicted under climate change

“…Although terrestrial Antarctic invertebrates are well adapted to survive extreme and fluctuating abiotic conditions (Treonis and Wall , Everatt et al. ), they are also particularly exposed to rapid change and intense events, abiotic conditions being near thresholds of physiological tolerance. For example, increased summer temperatures in the region will initiate more frequent freeze‐thaw cycles in dry soils, increasing mortality of the dominant invertebrate (Knox et al.…”

When water interacts with temperature: Ecological and evolutionary implications of thermo‐hydroregulation in terrestrial ectotherms

“…Change in the posture according to the daytime in frogs (Pough et al, 1983) Hydroregulation: Change in water availability selects for different body postures between day and night to reduce the rate of evaporative water loss Posture changes though time are explained by the need of optimizing heat transfers and at the same time minimizing water losses for some insects' species with unusually strong resistance to evaporative water loss (Chown et al, 2011), strong tolerance to dehydration (Everatt, Convey, Bale, Worland, & Hayward, 2015;Kleynhans & Terblanche, 2011), or strong tolerance to hyperthermia (Everatt et al, 2015;Hoffmann, Chown, & Clusella-Trullas, 2013;Hoffmann, Sørensen, & Loeschcke, 2003).…”