Which Body Size Metrics Should Be Used for Assessing Temperature Impacts on Fish Growth and Size?

Area of Science:

• Zoology
• Ecology
• Climate Change Biology

Background:

• Temperature is a critical factor influencing ectotherm physiology and growth.
• Existing research shows varied impacts of temperature on animal body size, particularly in fish.
• Discrepancies in study findings are often linked to differing definitions of body size.

Purpose of the Study:

• To identify and clarify common confusions in defining body size metrics for ectotherms.
• To promote standardized terminology and methodologies in studies of temperature effects on body size.
• To ensure accurate interpretation and comparability of research on global warming impacts on fish.

Main Methods:

• Literature review and conceptual analysis of body size definitions in ectotherm research.
• Examination of six prevalent confusions in measuring body size.
• Synthesis of existing knowledge on temperature-size relationships.

Main Results:

• Multiple, non-equivalent definitions of body size exist (e.g., size-at-maturity, asymptotic size, maximum size).
• Temperature's impact likely differs across these various size metrics.
• Inconsistent use of size metrics, biological scales, and empirical contexts contributes to research discrepancies.

Conclusions:

• Standardized definitions and consistent methodologies are essential for robust research on temperature-size relationships.
• Clearer definitions will improve our understanding of how climate change affects fish body size.
• Accurate interpretation of temperature impacts requires precise measurement and reporting of body size.