Survival of freezing by hydrated tardigrades inhabiting terrestrial and freshwater habitats

Will the Antarctic tardigrade Acutuncus antarcticus be able to withstand environmental stresses due to global climate change?

“…et al, 2013). Because anhydrobiotic tardigrades have very low water content with consequently undetectable metabolism and high levels of bioprotectants and antioxidant molecules (Mali et al, 2010;Rizzo et al, 2010;Guidetti et al, 2011a;Bonifacio et al, 2012;Horikawa et al, 2013;Rebecchi, 2013;Boothby et al, 2017), they were expected to be less damaged than hydrated tardigrades after UV radiation. The UV radiation per se should not represent a limiting factor for the survivorship of A. antarcticus, as the decline in survival of animals in both physiological states occurred when specimens were exposed to the highest tested UV doses, which should not be reached in the natural environment (unfortunately, data on UV radiation at ground level of Victoria Land are not available).…”

“…Tardigrades survive dehydration or freezing of their habitat by temporally suspending their metabolism through entering anhydrobiosis or cryobiosis, respectively (for reviews, see Wełnicz et al, 2011;Guidetti et al, 2011b;Møbjerg et al, 2011). These animals are known to tolerate, both in the dormant and hydrated state, a number of extreme chemical and physical stressors, including very high and low temperatures and high doses of UV radiation (Li and Wang, 2005;Rebecchi et al, , 2009bAltiero et al, 2011;Guidetti et al, 2011a;Horikawa et al, 2006Horikawa et al, , 2013.…”

Distribution and diversity of Tardigrada along altitudinal gradients in the Hornsund, Spitsbergen (Arctic)

“…They are distributed across all continents, inhabiting a great majority of terrestrial, freshwater and marine ecosystems, from the highest mountain peaks and polar deserts to the deep ocean floors. They are famous for their impressive cryptobiotic properties that allow them to withstand extreme conditions, including these of the outer space (Ramazzotti & Maucci 1983;Bertolani et al 2004;Guil 2008;Guidetti et al 2011;Wełnicz et al 2011). In extreme environments on Earth, such as those of the polar regions, tardigrades usually live alongside bdelloid rotifers and nematodes (e.g., Sohlenius & Boströ m 2008;Smykla et al 2010), but in some cases they may constitute the only metazoan element present in an ecosystem (e.g., Convey & McInnes 2005).…”

Phylum Tardigrada

“…As the environmental water surrounding the animal evaporates, the terrestrial tardigrade contracts, retracting the head and legs and becoming the characteristic immobile barrel-shaped tun ( Figure 17.19(a) and (b)). Only one true limnic species (D. parthenogeneticus) and a few other species (A. scoticum and H. dujardini) have been tested for anhydrobiotic capability, but they did not survive experimental desiccation (Guidetti et al, 2011a). The rate of desiccation must be slow to ensure survival and return to active life with the addition of water.…”