Oxygen availability and body mass modulate ectotherm responses to ocean warming.

Area of Science:

• Marine Biology
• Physiological Ecology
• Climate Change Science

Background:

• Oceans are experiencing rapid warming and deoxygenation, posing significant threats to marine species.
• Accurate forecasting of species' responses requires understanding how environmental changes affect fundamental physiology.
• Existing models may not fully capture the combined effects of temperature, oxygen, and organismal mass on metabolic constraints.

Purpose of the Study:

• To develop a novel metric, the absolute metabolic index (ΦA), quantifying the interplay of temperature, dissolved oxygen, and organismal mass on aerobic metabolism.
• To calibrate and validate the ΦA framework using physiological data from key marine invertebrates.
• To forecast species' habitat viability under projected ocean conditions and identify species-specific vulnerabilities.

Main Methods:

• Development of the absolute metabolic index (ΦA) based on physiological principles of oxygen consumption and supply.
• Calibration of ΦA parameters using empirical physiological measurements from red abalone (Haliotis rufescens) and purple urchin (Strongylocentrotus purpuratus).
• Modeling of ΦA to predict shifts in optimal temperature ranges and assess habitat suitability under varying environmental scenarios.

Main Results:

• The ΦA framework successfully quantifies the combined influence of temperature, dissolved oxygen, and organismal mass on metabolic oxygen budgets.
• Models reveal that the optimal temperature for oxygen supply shifts to cooler conditions with decreasing oxygen levels or increasing organism size.
• Habitat viability forecasts indicate disproportionately negative impacts on red abalone compared to purple urchin, highlighting species-specific physiological sensitivities.

Conclusions:

• The absolute metabolic index (ΦA) provides a mechanistic explanation for observed thermal preference patterns in marine organisms.
• Species-specific physiological traits significantly modulate the impact of climate change stressors, necessitating tailored conservation and management strategies.
• The ΦA framework offers a powerful tool for predicting species' responses and forecasting viable habitats in a changing ocean.