(Table 1) Ion concentrations in the haemolymph of Apherusa glacialis after incubation at different medium salinities

• Main Authors: Kiko, Rainer, Werner, Iris, Wittmann, Astrid C
• Format: Dataset
• Language: English
• Published: PANGAEA 2009
• Subjects: Arctic Ocean; ARK-XXII/2; Calcium ion; Chloride ion; Experimental treatment; Haemolymph; magnesium ion; potassium ion; sodium ion; sulfate ion; ICE; Ice station; Polarstern; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; PS70/328-1; PS70 SPACE DAMOCLES; Sample type; SPP1158; Sum; Arctic; Antarctic; Damocles; Antarc*; Polar Biology; Sea ice
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.858995; https://doi.org/10.1594/PANGAEA.858995

Amphipods living at the underside of Arctic sea ice are exposed to varying salinities due to freezing and melting, and have to cope with the resulting osmotic stress. Extracellular osmotic and ionic regulation at different salinities, thermal hysteresis, and supercooling points (SCPs) were studied in the under-ice amphipod Apherusa glacialis. The species is euryhaline, capable to regulate hyperosmotically at salinities S(R) < 30 g/kg, and osmoconforms at salinities S(R) >= 30 g/kg. Hyperosmotic regulation is an adaptation to thrive in low-salinity meltwater below the ice. Conforming to the ambient salinity during freezing reduces the risk of internal ice formation. Thermal hysteresis was not observed in the haemolymph of A. glacialis. The SCP of the species was -7.8 ± 1.9°C. Several ions were specifically downregulated ([Mg2+], [SO4]2-), or upregulated ([K+], [Ca2+]) in comparison to the medium. Strong downregulation of [Mg2+], is probably necessary to avoid an anaesthetic effect at low temperatures.