Abstract
Ongoing climate change has led to an increase in sea surface temperatures of 2–4°C on the west coast of Greenland. Since fish are ectothermic, metabolic rate increases with ambient temperature. This makes these animals particularly sensitive to changes in temperature; subsequently any change may influence their metabolic scope, i.e. the physiological capacity to undertake aerobically challenging activities. Any temperature increase may thus disrupt species-specific temperature adaptations, at both the molecular level as well as in behavior, and concomitant species differences in the temperature sensitivity may shift the competitive balance among coexisting species. We investigated the influence of temperature on metabolic scope and competitive ability in three species of marine sculpin that coexist in Greenland coastal waters. Since these species have different distribution ranges, we hypothesized that there should be a difference in their physiological response to temperature; hence we compared their metabolic scope at three temperatures (4, 9 and 14°C). Their competitive ability at the ambient temperature of 9°C was also tested in an attempt to link physiological capacity with behaviour. The Arctic staghorn sculpin, the species with the northernmost distribution range, had a lower metabolic scope in the higher temperature range compared to the other two species, which had similar metabolic scope at the three temperatures. The Arctic staghorn sculpin also had reduced competitive ability at 9°C and may thus already be negatively affected by the current ocean warming. Our results suggest that climate change can have effects on fish physiology and interspecific competition, which may alter the species composition of the Arctic fish fauna.
Highlights
Over the last decade sea surface temperatures on the west coast of Greenland have increased by 2–4uC and the glaciers are decreasing in size at an unprecedented rate [1,2]
Both resting and maximal metabolic rate increased with temperature (4 to 14uC), with the increase in resting metabolic rate being more pronounced for all three species, i.e. 171%, 135% and 205% for the shorthorn, Arctic and Arctic staghorn sculpins, respectively (Fig. 3)
Maximal metabolic scopes for shorthorn and Arctic scuplins were reached at 9uC (91613 and 9567 mg O2 kg21 h21, respectively) (Fig. 4), which was the recorded sea surface temperature (SST) at the time of the experiment
Summary
Over the last decade sea surface temperatures on the west coast of Greenland have increased by 2–4uC and the glaciers are decreasing in size at an unprecedented rate [1,2]. This increase in temperature is believed to have severe physiological, behavioural and ecological implications for ectothermic animals, such as fishes, inhabiting these waters because metabolic rate [3,4] and aerobic metabolic scope [5,6,7,8] may change with temperature.
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