Multiple stressors, allostasis and metabolic scaling in developing zebrafish

Area of Science:

• Environmental Science
• Aquatic Ecology
• Fish Physiology

Background:

• Rising global temperatures and deoxygenation pose threats to aquatic ecosystems.
• The physiological impacts of these stressors on sensitive developing fish stages remain understudied.

Purpose of the Study:

• To investigate the chronic and acute effects of high temperature and hypoxia on yolk-sac zebrafish energetics.
• To quantify impacts on oxygen consumption, growth, and energy conversion efficiency.

Main Methods:

• Yolk-sac zebrafish larvae were exposed to four chronic conditions: control, high temperature, hypoxia, and combined stressors.
• Larvae underwent acute respirometry tests under the same stressor combinations.
• Key energetic parameters including oxygen consumption, growth rates, and net conversion efficiency were measured.

Main Results:

• Larvae exposed to high temperatures were initially larger but exhibited increased metabolic demands.
• By the yolk-sac stage, energy was diverted from growth, reducing net conversion efficiency.
• Metabolic scaling relationships were altered under acute hypoxia and combined stressors, with high temperature being the dominant factor.

Conclusions:

• High temperature and hypoxia synergistically increase energetic costs for developing zebrafish.
• These combined stressors impair allostasis in larval stages more severely than in adult fish.
• Understanding these impacts is crucial for predicting fish population resilience in changing aquatic environments.