Brown, JamesWhiteley, NiaBailey, AllisonGraham, HelenHop, HaakonRastrick, Samuel2020-12-092020-12-092020-10-07Brown, J., Whiteley, N. M., Bailey, A. M., Graham, H., Hop, H., & Rastrick, S. P. (2020). Contrasting responses to salinity and future ocean acidification in arctic populations of the amphipod Gammarus setosus. Marine Environmental Research, 162, 105176. https://doi.org/10.1016/j.marenvres.2020.1051760141-113610.1016/j.marenvres.2020.105176http://hdl.handle.net/10034/624052Climate 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, MO2, and Cellular Energy Allocation, CEA). In the field, all populations had similar osmregulatory capacities and MO2, but lower-salinity populations had lower CEA. Reduced salinity (S = 23) and elevated pCO2 (~1000 μatm) in the laboratory for one month increased gill NKA activities and reduced CEA in all populations, but increased MO2 in the higher-salinity population. Elevated pCO2 did not interact with salinity and had no effect on NKA activities or CEA, but reduced MO2 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).https://creativecommons.org/licenses/by-nc-nd/4.0/Arcticamphipodscellular energy budgetsmetabolic ratesocean acidificationsalinityKongsfjordenSvalbardArticleMarine Environmental Research162