Evaluation of species thermal sensitivity with individual-based physiological performance

Area of Science:

• Marine Biology
• Physiological Ecology
• Climate Change Biology

Background:

• Global warming poses a significant threat to marine ectotherms, necessitating accurate assessments of species' thermal sensitivity.
• Intraspecific variation in physiological performance is often overlooked, potentially leading to inaccurate predictions of species' responses to climate change.
• An individual-based, bottom-up approach can provide a more nuanced understanding of thermal sensitivity across different biological levels.

Purpose of the Study:

• To assess the thermal sensitivity of intertidal bivalves to global warming by incorporating intraspecific variations.
• To determine the relationship between individual physiological performance, intraspecific variation, and species' overall thermal sensitivity.
• To identify geographically sensitive regions based on bivalve thermal tolerance.

Main Methods:

• Measured cardiac performance in 1159 individuals from multiple populations across six intertidal bivalve species.
• Determined the upper thermal limit for each individual bivalve.
• Calculated the proportion of individuals experiencing sublethal or lethal heat stress and mapped thermal sensitive areas.

Main Results:

• Significant inter-individual variation in cardiac performance and heat tolerance was observed at both population and species levels.
• Species exhibiting higher intraspecific variation in heat tolerance demonstrated greater overall thermal sensitivity.
• Geographic mapping revealed specific regions highly sensitive to elevated temperatures.

Conclusions:

• Individual-based physiological performance is essential for accurately assessing species' thermal sensitivity to global warming.
• Incorporating intraspecific variation provides a more robust framework for evaluating and forecasting species' responses to climate change.
• This bottom-up approach enhances our understanding of thermal stress impacts across individual, population, and species levels.