Empirical evidence of temperature variability as a concurrent limiting factor for abalone distribution

Abstract

Understanding how the performance, fitness, and distribution of species are impacted by changes in temperature is crucial for forecasting the ecological effects of climate change. Increasing mean sea surface temperature may alter the distribution of abalone species in the northeastern Pacific, although no apparent pattern has yet emerged. Ecophysiological observations (energy budget and the temperature performance curve based on scope for growth), satellite-derived daily sea surface temperature data, and observations of the population density distribution of wild abalones were integrated. The highest temperature-dependent scope for growth (physiological optimum) was discovered between 20.5 and 28.5 °C, peaking at 24 °C, with the upper thermal limit about 30 °C. Off the west coast of Baja California, the distribution of abalone appears to be dictated by the tradeoff between a mean temperature close to the physiological optimum and exposure to a highly variable environment (i.e., more stress and the risk of reaching suboptimal and lethal warm temperatures at the daily scale). The findings suggest that future models of the distribution of marine species in relation to thermal habitat should contain time-domain variability in addition to spatial-domain variability.