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Auteur Houngnandan, F.; Kéfi, S.; Deter, J.
Titre Identifying key-conservation areas for Posidonia oceanica seagrass beds Type Article scientifique
Année 2020 Publication Revue Abrégée Biological Conservation
Volume 247 Numéro Pages 108546
Mots-Clés Human activities; Landscape indices; Random Forest; Submerged aquatic vegetation (SAV)
Résumé The configuration of a habitat often reflects its conservation status and, to be effective, the conservation actions to be implemented must be adapted to local environmental conditions and human activities. Here, we take advantage of a fine resolution map (1:10000) of marine habitats to study the spatial configuration of Posidonia oceanica seagrass beds, a marine habitat of great ecological and economic importance. Six different composition and landscape descriptors were calculated at different resolutions (grid cells of 400 m × 400 m, 200 m × 200 m and 100 m × 100 m) between 0 and 40 m deep along 1700 km of French Mediterranean coastline (mainland and Corsica). A Random Forest approach was applied to relate these landscape descriptors to anthropogenic and environmental factors and to assess their relative importance. The best predictive power of the Random Forests models was obtained for 100 m × 100 m grid cells with models explaining 87% of the variance of the decline index and 70% of the variance of the cohesion index. The identification of threshold points for all environmental variables allowed to localize seagrass beds in either good or bad environmental conditions. We also identified sites whose spatial configuration is degraded despite good environmental conditions. These are sites with greater influence from human activities that could benefit from proactive conservation measures.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue en Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0006-3207 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2800
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Auteur Le Fur, I.; De Wit, R.; Plus, M.; Oheix, J.; Simier, M.; Ouisse, V.
Titre Submerged benthic macrophytes in Mediterranean lagoons: distribution patterns in relation to water chemistry and depth Type Article scientifique
Année 2018 Publication Revue Abrégée Hydrobiologia
Volume 808 Numéro 1 Pages 175-200
Mots-Clés southern france; eutrophication; coastal lagoon; Eutrophication; Depth; Salinity; environmental-factors; seagrass; aquatic vegetation; Canonical correspondence analysis (CCA); canonical correspondence-analysis; French coastal lagoons; potamogeton-pectinatus; spatiotemporal dynamics; Submerged aquatic vegetation (SAV); thau-lagoon
Résumé A large spectrum of coastal lagoon types with a wide range of environmental conditions is observed along the French Mediterranean coast. These comprise wide trophic and salinity gradients, ranging from oligotrophic to hypertrophic status, and from nearly freshwater to slightly above marine Mediterranean Sea water salinities, respectively. The statistical analysis of a long-term dataset, including water column variables and observations of macrophyte genera, showed that salinity, depth, and then trophic status, were important factors explaining the distribution of benthic macrophytes for the soft-bottom sediments in the 34 studied French Mediterranean lagoons. Based on this, we assumed that the vegetation succession along the eutrophication gradient was different according to the lagoon salinity ranges. Euhaline and polyhaline lagoons follow the well-known Schramm schematic model, where aquatic angiosperm such as seagrasses dominate under oligotrophic conditions, and opportunistic macroalgae and phytoplankton dominate under eutrophic and hypertrophic conditions. In oligohaline and mesohaline lagoons, the succession is probably an intermediate scheme between the successions observed in small temperate lakes and in marine coastal ecosystems due to the presence of both brackish and freshwater species. We thus propose a conceptual scheme for the oligohaline and mesohaline lagoons.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0018-8158 ISBN Médium
Région Expédition Conférence
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Numéro d'Appel MARBEC @ alain.herve @ collection 2280
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