Le Bas Tim

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Last Name
Le Bas
First Name
Tim
ORCID
0000-0002-2545-782X

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Hydrothermal vent fields and chemosynthetic biota on the world's deepest seafloor spreading centre

2012-01-10 , Connelly, Douglas P. , Copley, Jonathan T. , Murton, Bramley J. , Stansfield, Kate , Tyler, Paul A. , German, Christopher R. , Van Dover, Cindy L. , Amon, Diva , Furlong, Maaten , Grindlay, Nancy , Hayman, Nicholas W. , Huhnerbach, Veit , Judge, Maria , Le Bas, Tim , McPhail, Stephen , Meier, Alexandra , Nakamura, Ko-ichi , Nye, Verity , Pebody, Miles , Pedersen, Rolf B. , Plouviez, Sophie , Sands, Carla M. , Searle, Roger C. , Stevenson, Peter , Taws, Sarah , Wilcox, Sally

The Mid-Cayman spreading centre is an ultraslow-spreading ridge in the Caribbean Sea. Its extreme depth and geographic isolation from other mid-ocean ridges offer insights into the effects of pressure on hydrothermal venting, and the biogeography of vent fauna. Here we report the discovery of two hydrothermal vent fields on the Mid-Cayman spreading centre. The Von Damm Vent Field is located on the upper slopes of an oceanic core complex at a depth of 2,300 m. High-temperature venting in this off-axis setting suggests that the global incidence of vent fields may be underestimated. At a depth of 4,960 m on the Mid-Cayman spreading centre axis, the Beebe Vent Field emits copper-enriched fluids and a buoyant plume that rises 1,100 m, consistent with > 400 °C venting from the world’s deepest known hydrothermal system. At both sites, a new morphospecies of alvinocaridid shrimp dominates faunal assemblages, which exhibit similarities to those of Mid-Atlantic vents.

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Benthic habitat map of the southern Adriatic Sea (Mediterranean Sea) from object-based image analysis of multi-source acoustic backscatter data

2021-07-24 , Prampolini, Mariacristina , Angeletti, Lorenzo , Castellan, Giorgio , Grande, Valentina , Le Bas, Tim , Taviani, Marco , Foglini, Federica

A huge amount of seabed acoustic reflectivity data has been acquired from the east to the west side of the southern Adriatic Sea (Mediterranean Sea) in the last 18 years by CNR-ISMAR. These data have been used for geological, biological and habitat mapping purposes, but a single and consistent interpretation of them has never been carried out. Here, we aimed at coherently interpreting acoustic data images of the seafloor to produce a benthic habitat map of the southern Adriatic Sea showing the spatial distribution of substrates and biological communities within the basin. The methodology here applied consists of a semi-automated classification of acoustic reflectivity, bathymetry and bathymetric derivatives images through object-based image analysis (OBIA) performed by using the ArcGIS tool RSOBIA (Remote Sensing OBIA). This unsupervised image segmentation was carried out on each cruise dataset separately, then classified and validated through comparison with bottom samples, images, and prior knowledge of the study areas.