Otolith reliability is context-dependent for estimating warming and CO₂ acidification impacts on fish growth

Area of Science:

• Environmental science
• Aquatic ecology
• Climate change research

Background:

• Otoliths are crucial proxies for studying climate change effects on fish growth globally.
• However, varying otolith growth sensitivity to temperature and CO2, and inconsistencies with body growth, question their reliability.
• Understanding these factors is vital for accurate climate change impact assessments in aquatic ecosystems.

Purpose of the Study:

• To conduct a global meta-analysis on the effects of warming and CO2 acidification on fish otolith growth.
• To compare otolith growth responses with fish body growth responses under these climate change scenarios.
• To identify key factors influencing the reliability of otoliths as climate change impact proxies.

Main Methods:

• Global meta-analysis of 297 warming and 293 CO2 acidification experiments on fish.
• Utilized hierarchical models to assess overall effects and quantify influences of nine explanatory factors.
• Compared direct effects on otolith growth with fish body growth responses.

Main Results:

• Warming and acidification significantly increased otolith growth; warming's effect size (49.23%) was much larger than acidification's (7.51%).
• Factors like feeding habit, life stage, habitat, and experimental conditions influenced response heterogeneity.
• Otolith growth mirrored fish body growth under warming but not under acidification, where body growth was non-significant.

Conclusions:

• The reliability of using otoliths to assess climate change impacts on fish is context-dependent.
• Otolith growth is a more consistent proxy for warming impacts than for acidification.
• Further research is needed to refine the application of otoliths for climate change impact studies.