Brittany’s infralittoral seabed: an objective partitioning into marine ecological units
Other titles | Fonds infralittoraux de la Bretagne : partitionnement objective en paysages écologiques marins | ||||||||||||
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Type | Scientific report | ||||||||||||
Date | 2019 | ||||||||||||
Language | English | ||||||||||||
Ref. | RBE/STH/LBH 2019-2 | ||||||||||||
Author(s) | Tempera Fernando1, Vasquez Mickael1, Caillaud Matthieu1 | ||||||||||||
Publisher | Ifremer | ||||||||||||
Version | 1.0 | ||||||||||||
Mot-Clé(s) | écorégionalisation, paysages écologiques benthiques, partitionnement statistique, Bretagne, infralittoral | ||||||||||||
French abstract | Les patrons de distribution des espèces et communautés marines sont largement régulés par les propriétés physico-chimiques des eaux environnantes. La mise à disposition de nouvelles couches environnementales à résolution sub-kilométrique s’avère, par conséquent, d’une grande utilité pour cartographier de façon objective les paysages écologiques marins en vue d’interpréter des patrons biogéographiques, optimiser les campagnes à la mer ou planifier de manière adéquate les expérimentations in situ. |
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Keyword(s) | ecoregionalisation, benthic ecological units, statistical partitioning, Brittany, infralittoral | ||||||||||||
Abstract | Marine biological distribution patterns are largely regulated by the physico-chemical properties of the overlying waters. The availability of new environmental layers with sub-kilometric resolution is therefore of great use to map marine in objective ways and therefrom interpret biogeographic patterns, optimize region-wide field surveys or plan in situ experiments. This report presents a data-driven high-resolution partitioning of Brittany’s infralittoral seabed environment areas with comparable environmental conditions. Six major abiotic drivers of shallow-water biological communities are used to compose its environmental space, notably: temperature, salinity, oxygen, light, wave-induced kinetic energy and baroclinic currents kinetic energy. Each parameter is represented in the analysis by a climatologic raster corresponding to average conditions at seabed computed from multiannual series extracted from latest generation oceanographic models and satellite imagery. A k-means unsupervised partitioning, assisted by an optimal cluster number estimation, is used to statistically partition the points representing the environmental space, which are exclusively described by their environmental attributes. Mapping of the clustered data depicts spatially-coherent areas that match ecological divisions traditionally-recognised in Brittany by experts but which previously lacked a fine and objective spatial delimitation. The divide between northern and southern Brittany is successfully demarcated as well as specific ecological conditions associated to (i) bays, (ii) areas influenced by freshwater outflows, (iii) swell-exposed coastal stretches and (iv) current-exposed sectors. The analysis further highlights small ecological enclaves geographically isolated from their larger analogues. By representing conditions at seabed in great detail, the result permits a better understanding of the benthic compartment than previous analyses based on surface and/or vertically-integrated conditions. The approaches success demonstrates the capacity to analyse and exploit Ifremer wealth of novel environmental datasets to objectively map marine ecological units. |
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