Search

Climate change is leading to alterations in salinity and carbonate chemistry in arctic/sub-arctic marine ecosystems. We examined three nominal populations of the circumpolar arctic/subarctic amphipod, Gammarus setosus, along a salinity gradient in the Kongsfjorden-Krossfjorden area of Svalbard. Field and laboratory experiments assessed physiological (haemolymph osmolality and gill Na + /K + -ATPase activity, NKA) and energetic responses (metabolic rates, MO 2 , and Cellular Energy Allocation, CEA). In the field, all populations had similar osmregulatory capacities and MO 2 , but lower-salinity populations had lower CEA. Reduced salinity (S = 23) and elevated pCO 2 (~1000 μatm) in the laboratory for one month increased gill NKA activities and reduced CEA in all populations, but increased MO 2 in the higher-salinity population. Elevated pCO 2 did not interact with salinity and had no effect on NKA activities or CEA, but reduced MO 2 in all populations. Reduced CEA in lower-rather than higher-salinity populations may have longer term effects on other energy demanding processes (growth and reproduction)., (Copyright © 2020 Elsevier Ltd. All rights reserved.)