The Effects of Temperature, Body Size, and Oxygen Variation on the Future Habitable Range of Pacific Red Abalone (Haliotis rufescens)

Red abalone (Haliotis rufescens) is an ecologically, culturally, and economically important species along the Pacific Coast of North America, and understanding how its future habitable range is likely to change as a response to climatic stimuli is essential for preemptive management. Currently, red abalone populations are being negatively impacted by many factors, including overfishing, competition from purple sea urchins, and kelp forest degradation. The Metabolic Index is a physiological tool that integrates temperature, oxygen, and body size in order to predict the viable aerobic habitat of a given species. While this technique has been applied to describe aerobic limitations in several marine organisms, it has yet to be used to describe red abalone with conditions mimicking those predicted for the year 2100. Laboratory respirometry experiments of red abalone show body mass does not have a significant effect on the critical oxygen threshold, or Pcrit. Pcrit also does not increase significantly in experiments from 14 to 22 degrees Celsius (i.e., near-zero Eo in the Metabolic Index framework), indicating that the species is not significantly aerobically limited by increasing temperature. This suggests that the species is not expected to experience temperature-driven hypoxia during future predicted warming. Because of this, management of the species and maintenance of its current range should rely less on the mitigation of oceanic temperature and oxygen changes and more on the protection of their natural habitat from overharvesting and regime shifts. Using this information, managers are better able to make more informed decisions and ultimately help to protect red abalone populations in the Northeast Pacific.