The deep ocean was once thought to be a barren place, too dark and hostile to be home to any significant marine life. But as our exploration of the ocean depths has expanded, the huge diversity, richness and complexity of deep-sea life has been revealed.
The distribution of life on the deep seafloor is controlled by many factors: seafloor topography, water depth, substrate, temperature, salinity and oxygen, food availability, and many more physiochemical factors. As global change accelerates, changes in the physical environment may trigger changes in ecosystem distribution as different parts of the ocean become more or less optimal for different species to thrive – or simply survive.
Mapping the Atlantic seafloor and the distribution of its ecosystems has been ongoing since the Challenger Expedition set sail in 1872, enabled through a multitude of schemes, projects and initiatives – most which have focused on particular regions or specific taxa. This collective effort has generated a huge volume of data but has resulted in a patchwork of knowledge at varying scales and resolutions, with significant gaps and an imbalance of information between the North and South Atlantic.
To truly advance our knowledge of the status and resilience of Atlantic ecosystems, we need to map their geomorphology, ecology and biology at a range of scales. But with an area of over 100 million km2 and an average water depth of around 3600 m, the challenge of mapping Atlantic ecosystems at multiple scales is vast.
However, recent advances in mapping technology and automated sampling techniques can help address this challenge. Marine autonomous and robotic vehicles, coupled with new sensor technology, now give us the ability to survey and image large areas of the deep-sea without the need for labour-intensive manual sampling. Whilst iAtlantic cannot map the entire Atlantic Ocean basin and every ecosystem within it, we have compiled large-scale mapping data with new data from these robotic technologies to map ecosystems and habitats across basin-wide, regional and local scales.
In September 2021, the iAtlantic mapping team completed a basin-wide Atlantic marine landscape map (Deliverable 2.1) based on 8 global datasets, which identified 9 clearly-defined seabed areas through the Atlantic basin.
Through its extensive expedition programme, iAtlantic has deployed state-of-the-art autonomous equipment and instrumentation to map key deep-ocean ecosystems in selected study regions in the South and North Atlantic to address some of the critical data gaps. This flood of new data has been processed using new imaging and analysis approaches for marine species detection and classification (Deliverable 2.4), and combined with existing datasets to extend the overall mapping coverage of the Atlantic. Predictive habitat modelling techniques have then been applied to extrapolate species and biodiversity observations up to regional and global scales, enabling us to expand our understanding of ecosystem distribution, status and resilience from local scale to full Atlantic scale.
New image mapping techniques have been used to generate 3D habitat maps (Deliverable 2.3) and models of ecosystems such as hydrothermal vents, once considered to be highly dynamic and unstable. But the new 3D imagery, compiled to show ecosystem change over time, reveals the vent assemblage to be surprisingly stable.
At a regional scale, habitat maps have been developed for each of the 12 iAtlantic study areas. In selected areas, this has been complemented by extensive water column sampling, high-resolution 3D seafloor mapping, and seafloor image surveys. Genetic material from plankton and sediment samples has provide the source material for eDNA mapping – a new technique that has promising potential for biodiversity mapping. iAtlantic has tested this technique to understand the differences between eDNA-based biodiversity measures relative to image-based biodiversity measures over the same regions.
Key objectives:
Map, at nested scales, the present ecosystem status of deep and open-ocean ecosystems in the Atlantic:
- Evaluate and expand our current knowledge on ecosystem distribution and the physical environment across the Atlantic;
- Describe the 3D structure of key ecosystems at regional and local scale;
- Identify the main environmental drivers behind the spatial distribution of ecosystems.
iAtlantic’s work on ecosystem mapping was led by Dr Veerle Huvenne at the National Oceanography Centre UK, supported by Prof. Dr. Colin Devey at GEOMAR.
