New seabed geology maps to enable long term conservation around Ascension Island

The Ascension Island Marine Protected Area (MPA) is one of the largest areas of protected ocean in the world and safeguards a unique ecosystem in the South Atlantic Ocean. It supports many species that are found nowhere else on earth, a mixture of deep sea and open ocean habitats that remain largely untouched and unexplored, whilst the island itself is home to thousands of nesting turtles and seabirds.

The British Geological Survey (BGS) recently completed a programme of high-resolution bathymetry surveys and drop-camera sampling within the nearshore areas of the Island. The survey team even managed to collect data where no other survey had ever been undertaken, which in addition to supporting conservation efforts, will also enable safer navigation in future.

The project was funded by the UK Government and utilised both BGS and Royal Navy bathymetry (depth), backscatter (seabed composition), ground-truth sampling (underwater video footage) and many other derived data layers to create the suite of bespoke geological outputs.  

The maps, which include seabed geology (substrate and geomorphology) and habitat, are the first to be created for the Island and determine the character, distribution and extent of the nearshore habitats of the MPA.

The geomorphological map revealed a collection of previously unmapped volcanic, erosion-depositional and coastal features including seamounts, submerged lava flows, ridges, submarine landslides and channels. Whilst the substrate map focused on the nearshore areas, composed of sandy sediments and rocky outcrops which are fundamental habitats for the marine communities. Both maps have enhanced the understanding of seabed processes and geological processes occurring around Ascension Island and enabled the creation of seabed habitat maps which provide unprecedented insight into the diverse ecosystems present in the surrounding waters.

As part of the project, the BGS Marine team provided training to the Ascension Island Government (AIG) in how to effectively use GIS software to view, edit, query and manipulate the data. The intention is for AIG to modify these maps as new data and knowledge becomes available and the management requirements of the protected area changes. Although the region is rich in biodiversity it is one of the habitats most at risk from anthropogenic development and climate change. The maps and data will be a vital resource for the AIG Conservation team as they continue to manage and safeguard the region.

“Collecting data in such a remote and exposed location was a challenge, but an absolute privilege and pleasure. BGS had to adapt existing technology to work with the available survey platform within the limits of Ascension’s wonderfully varied and unpredictable operating environment.”

Rhys Cooper, BGS Project Manager and Senior Surveyor

“The collection of new high-resolution datasets around Ascension Island allowed us to map the seafloor geology in unprecedented detail, uncovering critical geological features and habitats that support a rich diversity of marine life, and marks a significant milestone in our understanding of Ascension Island’s marine environment.”

Catriona Macdonald, BGS Marine Geoscientist

“AIG are excited to have access to such high-quality bathymetry and habitat maps. They will be transformative in our nearshore research and monitoring and allow for much more evidence based conservation management.”

Tiffany Simpson, Director of Conservation and Fisheries, Ascension Island Government

The final maps were delivered by BGS to the Ascension Island Government’s Department of Conservation in February 2025 and will be used by the team to manage the marine environment for future generations.

Further information

Ascension Island Marine Protected Area Website

BGS completes first mapping expedition to Ascension Island

In photos: Marine surveying a remote volcanic island

Mapping of geomorphology, seabed substrate and nearshore habitats within the Ascension Island Marine Protected Area

Report of survey : Ascension Island multibeam & video transects

This project is funded by the UK Government through Darwin Plus.