Search

Variation in water temperature can have important effects on the energetics underlying metabolism, growth, and reproduction of many organisms. In order to anticipate how a species' allocation of energy may change in a warming ocean, we need to know the degree to which processes such as metabolic rate change with temperature (i.e., the thermal sensitivity of metabolism, Q10 ). In the context of long-term climate change, it will also be helpful to know whether local populations that experience different thermal regimes exhibit differences in thermal sensitivity. If so, it would indicate that thermal sensitivities of populations may adjust via acclimation or adaptation. We measured metabolic rates of Woolly Sculpin collected from two distant populations (Santa Cruz (SC) and Los Angeles (LA) counties, California, USA) and housed in a common environment. Using respirometry, we estimated resting mass-specific oxygen consumption ( MO2) and calculated metabolic rates (MR) at temperatures of 12 °C, 16 °C, and 20 °C for 59 fish. The Q10 value across this range of temperatures was 2.92. Populations did not differ with respect to overall MO2, nor did they vary in their degree of thermal sensitivity. However, the LA population had greater variation in MO2 among individuals when compared to the SC population. Larger variation in overall MO2 among individuals within specific populations may reflect greater genetic diversity , and this may buffer some populations against the effect of future increases in water temperature.

As climate continues to change, many marine species will experience both an increase in average temperature and more extreme diel and seasonal fluctuations. Understanding how these variations in ocean temperature affect processes such as metabolism and energy consumption is important for many species, and may be particularly important for sedentary species that cannot make large-scale movements in response to changes in environmental conditions. We examined how metabolic rates and energetic demands responded to temperature in a temperate reef fish, the bluebanded goby ( Lythrypnus dalli ). Using respirometry, we estimated resting oxygen consumption (VO2) for 42 L. dalli individuals of varying sizes and calculated metabolic rates (MR) at three different temperatures (13 °C, 16 °C, and 20 °C). As predicted, VO2 and MR increased significantly with temperature and mass, but the rate of temperature-dependent increase in metabolism indicated a very high degree of thermal sensitivity for L. dalli (Q10 value for VO2 was 5.21 across the range of experimental temperatures). The mass-scaling exponent (b ) was estimated to be 0.95 and aligned closely with other benthic species. Our results suggest that changes in temperature – especially those that occur over weeks and seasons – likely play a significant role in the ecology of these gobies. Long-term increases in seawater temperature will either necessitate an increase in foraging and consumption, or drive costly trade-offs between metabolism and processes such as growth and reproduction.