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The team are working on the use of high-resolution imaging techniques to investigate the scale patterns of faunal dynamics at deep-sea vents and delineate the factors shaping those dynamics. They present case studies demonstrating how technological advances in underwater platforms and computer power have proved beneficial to using imaging techniques to expand knowledge on vent ecology. Indeed, our scientific perception of natural systems is highly constrained by technological limits. The methods we develop can be used to acquire insights on hydrothermal vent fauna ecology, hence expanding ecological characterisation across various spatial and temporal scales. Imaging techniques are non-destructive. This makes them ideal to characterise the deep-sea communities without disturbing them, since we do not know for sure the impact that repetitive long-term scientific sampling can have on them.
Yes! For example, the analyses of images acquired daily over 7 years with the TEMPO underwater camera connected to the deep-sea European Multidisciplinary Seafloor and water-column Observatory (EMSO)-Azores observatory revealed the high stability of the vent habitat and associated Bathymodiolus azoricus vent mussel assemblage (see Figure below). We further developed a baseline workflow that enabled to detect a short migration of the vent mussels of 2 decimetres over 2 years.
Moreover, the team shows the benefit of 3D reconstructions over several years to accurately unravel the dynamics of vent assemblages over a 450-m² hydrothermal edifice with a resolution of a few centimetres (Eiffel Tower edifice, -1,700 m, Lucky Strike, Mid-Atlantic Ridge) despite the complex topography of the sulphide edifice. This 5-year time series confirmed the high stability of the vent communities, despite local changes in the immediate vicinity of vent exits (see Figure below). Vent mussels appear to reposition over a few decimetres, but their overall population remained constant.
The team is also currently discussing the use of 3D high-resolution models retrieved from seafloor images to characterise the distribution of biological communities over the portion of hectares of seabed at the hydrothermal vent field of Lucky Strike, near the Azores Islands (see Figure below). The navigation, corrected by photogrammetric reconstruction, provides an accurate mapping of biological assemblages. Those spatial patterns provide detailed information on the drivers shaping their spatial distribution, for instance according to the seafloor terrain or the presence of other organisms.
Ecological investigation aims to characterise patterns of variability in faunal communities in order to better delineate the biological and environmental drivers affecting their distribution and dynamics in space, from centimetres to kilometres, and in time, from infra-daily to a decade. Understanding these patterns requires high-resolution and long-term monitoring over large areas of biological communities and their environment. With the improvement of underwater platforms and resolution of optical imagery, imaging the deep sea has become a powerful and increasingly cost-efficient method for characterising deep-seafloor habitats and associated communities across scales.
If you want more information, please contact Loïc Van Audenhaege (loic.vanaudenahege[at]gmail.com/ loic.van.audenhaege[at]ifremer.fr), but please also check the following:
Main contributors: Loïc Van Audenhaege, Jozée Sarrazin, Marjolaine Matabos, based at IFREMER (Brest, France)