Highlights
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Climate change is leading to changes in salinity and pCO2 in arctic/sub-arctic coastal ecosystems.
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We examined Gammarus setosus at 3 sites along a salinity gradient in the field and laboratory.
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Reduced salinity had more of an effect than elevated pCO2 by reducing energy budgets.
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Lower salinities increased ion transporting capacities in the laboratory but not in the field.
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G. setosus at lower salinity sites have lower energy budgets suggesting impacts on performance.
Abstract
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, 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).
Brown J., Whiteley N. M., Bailey A. M., Graham H., Hop H. & Rastrick S. P. S., in press. Contrasting responses to salinity and future ocean acidification in arctic populations of the amphipod Gammarus setosus. Marine Environmental Research. Article (subscription required).
