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Research article - Peer-reviewed, 2021

Energetic savings and cardiovascular dynamics of a marine euryhaline fish (Myoxocephalus scorpius) in reduced salinity

Sundell, Erika; Morgenroth, Daniel; Ekstrom, Andreas; Brijs, Jeroen; Axelsson, Michael; Grans, Albin; Sandblom, Erik


Few studies have addressed how reduced water salinity affects cardiovascular and metabolic function in marine euryhaline fishes, despite its relevance for predicting impacts of natural salinity variations and ongoing climate change on marine fish populations. Here, shorthorn sculpin (Myoxocephalus scorpius) were subjected to different durations of reduced water salinity from 33 to 15 ppt. Routine metabolic rate decreased after short-term acclimation (4-9 days) to 15 ppt, which corresponded with similar reductions in cardiac output. Likewise, standard metabolic rate decreased after acute transition (3 h) from 33 to 15 ppt, suggesting a reduced energetic cost of osmoregulation at 15 ppt. Interestingly, gut blood flow remained unchanged across salinities, which contrasts with previous findings in freshwater euryhaline teleosts (e.g., rainbow trout) exposed to different salinities. Although plasma osmolality, [Na+], [Cl-] and [Ca2+] decreased in 15 ppt, there were no signs of cellular osmotic stress as plasma [K+], [hemoglobin] and hematocrit remained unchanged. Taken together, our data suggest that shorthorn sculpin are relatively weak plasma osmoregulators that apply a strategy whereby epithelial ion transport mechanisms are partially maintained across salinities, while plasma composition is allowed to fluctuate within certain ranges. This may have energetic benefits in environments where salinity naturally fluctuates, and could provide shorthorn sculpin with competitive advantages if salinity fluctuations intensify with climate change in the future.


Cardiovascular; Metabolic rate; Marine; Euryhaline; Salinity variability

Published in

Journal of Comparative Physiology B
2021, Volume: 191, number: 2, pages: 301–311

    Sustainable Development Goals

    SDG14 Life below water
    SDG13 Climate action

    UKÄ Subject classification

    Fish and Aquacultural Science

    Publication identifier


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