Cryoprotective dehydration is widespread in Arctic springtails

Cryoprotective dehydration (CPD) is a cold tolerance strategy employed by small invertebrates that readily lose water by evaporation when subjected to sub-zero temperatures in the presence of ice. Until now, relatively few species have been investigated using methods by which CPD can be shown. In the present study we investigated the cold tolerance strategy of seven soil arthropod species from the high Arctic Spitzbergen, and compared water content and water loss, body fluid melting points (MP) and survival under cold and desiccating conditions. We tested the hypothesis that CPD is a commonly occurring cold hardiness strategy among soil arthropods. We found that four springtail species (Hypogastrura viatica, Folsomia quadrioculata, Oligaphorura groenlandica and Megaphorura arctica; Collembola) went through severe dehydration and MP equilibration with ambient temperature, and thus overwinter by employing CPD, whereas a beetle (Atheta graminicola) and one of the springtails (Isotoma anglicana) were typical freeze avoiding species over-wintering by supercooling. Desiccation tolerance of the red velvet mite (Neomolgus littoralis) was also investigated; very low water loss rates of this species indicated that it does not survive winter by use of CPD. All in all, the results of the present study confirm the hypothesis that CPD is an effective over-wintering strategy which is widespread within soil arthropods.

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► Cryoprotective dehydration (CPD) is a cold tolerance strategy employed by small permeable invertebrates.
► Out of seven tested species we found that four species belonging to Collembola employed CPD as an effective cold tolerance strategy.
► Species using CPD lost practically all of their osmotically active water when exposed to −12 ̊C for several weeks and had melting points equal to the exposure temperature.
► The results show that CPD is a widespread and effective over-wintering strategy among soil arthropods.