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Antarctic emerald rockcod have the capacity to compensate for warming when uncoupled from CO 2 ‐acidification
Author(s) -
Davis Brittany E.,
Flynn Erin E.,
Miller Nathan A.,
Nelson Frederick A.,
Fangue Nann A.,
Todgham Anne E.
Publication year - 2018
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.13987
Subject(s) - ocean acidification , acclimatization , juvenile , effects of global warming on oceans , pco2 , biology , climate change , ecology , ecosystem , global warming , environmental science , medicine
Increases in atmospheric CO 2 levels and associated ocean changes are expected to have dramatic impacts on marine ecosystems. Although the Southern Ocean is experiencing some of the fastest rates of change, few studies have explored how Antarctic fishes may be affected by co‐occurring ocean changes, and even fewer have examined early life stages. To date, no studies have characterized potential trade‐offs in physiology and behavior in response to projected multiple climate change stressors (ocean acidification and warming) on Antarctic fishes. We exposed juvenile emerald rockcod Trematomus bernacchii to three P CO 2 treatments (~450, ~850, and ~1,200 μatm P CO 2 ) at two temperatures (−1 or 2°C). After 2, 7, 14, and 28 days, metrics of physiological performance including cardiorespiratory function (heart rate [ f H ] and ventilation rate [ f V ]), metabolic rate ( M ˙ O 2 ), and cellular enzyme activity were measured. Behavioral responses, including scototaxis, activity, exploration, and escape response were assessed after 7 and 14 days. Elevated P CO 2 independently had little impact on either physiology or behavior in juvenile rockcod, whereas warming resulted in significant changes across acclimation time. After 14 days, f H , f V andM ˙ O 2significantly increased with warming, but not with elevated P CO 2 . Increased physiological costs were accompanied by behavioral alterations including increased dark zone preference up to 14%, reduced activity by 12%, as well as reduced escape time suggesting potential trade‐offs in energetics. After 28 days, juvenile rockcod demonstrated a degree of temperature compensation as f V ,M ˙ O 2 , and cellular metabolism significantly decreased following the peak at 14 days; however, temperature compensation was only evident in the absence of elevated P CO 2 . Sustained increases in f V andM ˙ O 2after 28 days exposure to elevated P CO 2 indicate additive ( f V ) and synergistic ( M ˙ O 2 ) interactions occurred in combination with warming. Stressor‐induced energetic trade‐offs in physiology and behavior may be an important mechanism leading to vulnerability of Antarctic fishes to future ocean change.