Thermal variability: how realistic temperature fluctuations alter physiological performance in intertidal mussels

Area of Science:

• Physiological ecology
• Climate change biology
• Comparative physiology

Background:

• Fluctuating temperatures critically impact ectotherm physiological performance.
• Predicting species' climate change responses requires understanding thermal performance.
• Laboratory thermal designs often oversimplify natural temperature fluctuations.

Purpose of the Study:

• To investigate the effects of simplified versus naturalistic fluctuating temperature regimes on mussel respiration.
• To determine if thermal performance curves (TPCs) differ based on temperature fluctuation patterns.
• To assess the ecological relevance of laboratory thermal simulation methods.

Main Methods:

• Mussels were exposed to two distinct temperature regimes: alternating daily min/max and field-derived continuous data.
• Oxygen consumption was measured in temperature-controlled chambers.
• Nonlinear thermal performance curves (TPCs) were fitted to estimate key physiological parameters (Topt, Rmax, CTmax).

Main Results:

• Mussel respiration patterns significantly differed between the two temperature treatments.
• TPC parameter estimates (Rmax, Topt, CTmax) exhibited non-overlapping confidence intervals between treatments.
• Heating rate and exposure duration were identified as key factors influencing thermal performance.

Conclusions:

• Ecologically realistic thermal regimes are crucial for accurate laboratory studies on ectotherm physiology.
• Simplified thermal designs may lead to inaccurate predictions of species' resilience to climate change.
• Findings highlight the importance of considering natural temperature variability in physiological research.