Ship time is expensive, and a remotely operated vehicle can only look at so much seafloor in a day. That is the problem facing anyone trying to find deep-sea corals across the Pacific Islands, where the animals sit hundreds to thousands of meters down, often on steep slopes, seamounts and ridges. Those habitats give fishes and invertebrates a three-dimensional place to live. Surveys by ship and ROV, though, cover only a small slice of the region, so what imaging alone has shown about where the corals are remains thin.
Scientists at NOAA Fisheries’ Pacific Islands Fisheries Science Center are using species distribution models to fill the gaps. Kisei Tanaka and Beth Lumsden describe the work, which falls under the Pacific Islands Deep-Sea Ecosystems of Sponges and Corals: Exploration, Investigation and Technology Initiative, known as DESCENT. One of its central goals is broad-scale distribution and habitat-suitability models that sharpen the picture of coral and sponge communities and support ecosystem-based management.
How the models are built
The team starts with decades of observations pulled from several places: NOAA’s national deep-sea coral and sponge records, the Global Biodiversity Information Facility, the Ocean Biodiversity Information System and the University of Hawaiʻi’s Deep-sea Animal Research Center. For roughly 30 coral species, they pair each known sighting with the conditions at that spot, including depth, temperature, salinity, dissolved oxygen, nutrients, chlorophyll and ocean currents.
The model hunts for patterns in that data and estimates where each species is most likely to live. Stack the species together and the maps show expected coral richness and potential biodiversity hotspots. NOAA is plain about the limits. The maps are predictions, not inventories of the seabed, and they are meant to work alongside field observations.
What it shows around Hawaiʻi
Preliminary results show clear spatial patterns for the Main Hawaiian Islands. Higher modeled richness tracks many of the slopes, banks and deep features around the islands, and a few smaller areas rank as the top hotspots. Cells with the highest values are marked on the map, and the most concentrated are labeled “core” hotspots. NOAA calls them precise target zones for upcoming expeditions.
That link to fieldwork is the point. Researchers with limited ROV time can use the maps to choose where to look, find under-sampled areas and test how environment shapes where corals grow. A second map covers American Samoa, and data from the 2026 American Samoa ROV + Mapping Exploration expedition will go back into the models. As more records and validation data arrive, the models will be refined.
