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A new scientific paper has revealed how fish communities change dramatically with depth in the Maldives. Conducted as part of the First Descent Nekton Maldives Mission, the study provides the first comprehensive view of reef fish diversity from shallow waters to the deep sea.
Researchers surveyed habitats at 2, 10, 30, 60, 120, 250, and 500 metres, covering shallow, mesophotic, and deep-sea habitats. The findings highlight the need to protect the full spectrum of reef habitats, not just the shallow zones. By understanding the unique ecological roles played at each depth, conservation strategies can better safeguard biodiversity in the face of climate change and other pressures.
We investigated the structure and diversity of fish communities in atolls in the Maldives from surface to 500m to understand how their vulnerability changes with depth.
The abundance and richness (number of species) decreased with depth. This means the community structure of fish is driven by depth, a trend seen globally.
We found distinct fish communities in the mescophotic coral ecosystems (MCEs) of the Maldives. In these habitats, many fish were the most functionally unique species (sharks and rays) and are threatened with extinction.
The functional roles filled by species in deeper habitats cannot be replaced by other species, meaning that once removed, the functional diversity is reduced and life history traits are lost.
MCEs and deep-sea habitats face several pressures, and this study shows that they are home to functionally specialised fish. Due to their vulnerability to disturbance, these habitats should be prioritised in marine spatial planning initiatives.
