Hyperspectral Remote Sensing Of Wild Oyster Reefs

• Published in: Estuarine, Coastal and Shelf Science
• Main Authors: LE BRIS, Anthony, Rosa, Philippe, Lerouxel, Astrid, Cognie, Bruno, Gernez, Pierre, Launeau, P., Robin, Marc, Barillé, Laurent
• Other Authors: Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN), Mer, molécules et santé EA 2160 (MMS), Université de Nantes - UFR des Sciences Pharmaceutiques et Biologiques, Université de Nantes (UN)-Université de Nantes (UN)-Le Mans Université (UM)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Benthos; Crassostrea gigas; hyperspectral; oyster reefs; remote sensing; Tidal flats; geo; envir
• Online Access: https://doi.org/10.1016/j.ecss.2016.01.039; https://hal.archives-ouvertes.fr/hal-01270305

International audience The invasion of the wild oyster Crassostrea gigas along the western European Atlantic coast hasgenerated changes in the structure and functioning of intertidal ecosystems. Considered as an invasivespecies and a trophic competitor of the cultivated conspecific oyster, it is now seen as a resource byoyster farmers following recurrent mass summer mortalities of oyster spat since 2008. Spatialdistribution maps of wild oyster reefs are required by local authorities to help define managementstrategies. In this work, visible-near infrared (VNIR) hyperspectral and multispectral remote sensingwas investigated to map two contrasted intertidal reef structures: clusters of vertical oysters buildingthree-dimensional dense reefs in muddy areas and oysters growing horizontally creating large flat reefsin rocky areas. A spectral library, collected in situ for various conditions with an ASDspectroradiometer, was used to run Spectral Angle Mapper classifications on airborne data obtainedwith an HySpex sensor (160 spectral bands) and SPOT satellite HRG multispectral data (3 spectralbands). With HySpex spectral/spatial resolution, horizontal oysters in the rocky area were correctlyclassified but the detection was less efficient for vertical oysters in muddy areas. Poor results wereobtained with the multispectral image and from spatially or spectrally degraded HySpex data, it wasclear that the spectral resolution was more important than the spatial resolution. In fact, there was asystematic mud deposition on shells of vertical oyster reefs explaining the misclassification of 30% ofpixels recognized as mud or microphytobenthos. Spatial distribution maps of oyster reefs werecoupled with in situ biomass measurements to illustrate the interest of a remote sensing product toprovide stock estimations of wild oyster reefs to be exploited by oyster producers. This workhighlights the interest of developing remote sensing techniques for aquaculture applications in coastalareas.