Hidden hormone–habitat relationship revealed in reef fish

This article reveals a hidden hormone–habitat relationship in reef fish, highlighting how environmental factors influence developmental adaptability. Conducted by researchers at the International Research Laboratory 2028 (IRL EARLY) in collaboration with Dr. David Lecchini and the Marine-Eco-Evo-Devo Unit at OIST, the multiyear study sheds light on the mechanisms behind the physical and environmental relationship in animal development.

Using a common reef fish as a model, the researchers explored how environmental differences affected thyroid hormone signaling, which is essential for developmental regulation. Through transcriptomics, metabolomics, and other physiological analytical approaches, they revealed that the development of these fish changed significantly across various ecosystems.

The study found that environment and development are far more closely linked than previously assumed, raising questions about the flexibility that animals have when their environments change. This is particularly important in light of climate change and habitat degradation, which threaten many animal populations.

The researchers examined convict surgeonfish (Acanthurus triostegus), which are found along both beaches and mangroves. Despite the starkly different conditions, these fish undergo dramatic physical changes during their transition from open ocean to coastal nurseries. During the first day after entering the reef, 90% of juveniles are eaten by predators, and those that survive often lose 20% of their weight during their first week.

The study reveals that thyroid hormone levels and gene expression vary significantly between different habitats, such as beaches, rock reefs, and mangrove ecosystems. These variations in thyroid hormone signaling produce habitat-specific developmental outcomes, which can be crucial for the survival of reef fish in the face of environmental challenges.