Use of SPOT 5 for mapping seagrasses: An application to Posidonia oceanica
✍ Scribed by Vanina Pasqualini; Christine Pergent-Martini; Gérard Pergent; Magali Agreil; Georges Skoufas; Laurent Sourbes; Anastasia Tsirika
- Publisher
- Elsevier Science
- Year
- 2005
- Tongue
- English
- Weight
- 976 KB
- Volume
- 94
- Category
- Article
- ISSN
- 0034-4257
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✦ Synopsis
The SPOT 5 satellite was launched in May 2002; it provides multispectral imagery with a spatial resolution of 10 m and fused imagery with a spatial resolution of 2.5 m. These types of satellite imagery were used for mapping beds of Posidonia oceanica in the Mediterranean Sea, where it is a dominant species forming monospecific beds in a structurally simple environment (four classes: sand, photophilous algae on rock, patchy seagrass beds and continuous seagrass beds). Supervised classifications by depth range were made of both types of image. A direct comparison of overall accuracy between SPOT 2.5 m and SPOT 10 m revealed that this tool provided accurate mapping in both cases (between 73% and 96% accuracy). Although SPOT 2.5 m provides lower overall accuracy than SPOT 10 m, it is a very useful tool for the mapping of P. oceanica, as it allows the patchiness of the formations to be better taken into account. The opportunity to use a reliability scale, which takes into account the effects of extrinsic factors on the processing of the images, confirmed the usefulness of the option of using a reduced pixel size in order to obtain an improved match between the results from mapping and field observations.