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Leaf size doesn’t matter: environment shapes eelgrass biodiversity more than a foundation species’ traits.
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  • Alexandre MULLER,
  • Stanislas Dubois,
  • Aurelien Boye,
  • Gabin Droual,
  • Mathieu Chevalier,
  • Marine Pasquier,
  • Loïg Roudaut,
  • Jerome Fournier,
  • Isabelle Auby,
  • Flavia Nunes
Alexandre MULLER
Ifremer Département Océanographie et Dynamique des Écosystèmes
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Stanislas Dubois
IFREMER DYNECO
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Aurelien Boye
Ifremer
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Gabin Droual
Ifremer Departement Oceanographie et Dynamique des Ecosystemes
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Mathieu Chevalier
Ifremer Département Océanographie et Dynamique des Écosystèmes
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Marine Pasquier
Ifremer Département Océanographie et Dynamique des Écosystèmes
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Loïg Roudaut
Ifremer Département Océanographie et Dynamique des Écosystèmes
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Jerome Fournier
Museum National d'Histoire Naturelle
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Isabelle Auby
Ifremer
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Flavia Nunes
Ifremer Département Océanographie et Dynamique des Écosystèmes
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Abstract

Aim: Understand the ecological processes that shape community composition in eelgrass meadows along the coast of France at local and regional scales. Location: Northeastern Atlantic. Methods: Combining taxonomic and trait-based approaches with structural equation modeling, we explored the mechanisms governing community assembly in five meadows located over a distance of 800 km along the French coast in the Northeast Atlantic. We assessed the spatial variability of eelgrass-associated invertebrate communities as affected by environmental parameters or morphological traits of the eelgrass and linked these mechanisms to their impacts at local and regional scales through analyses of the taxonomic and functional α and β diversities. We then quantified the direct and indirect effects of environmental factors on macrofaunal structure and composition. Results: Eelgrass meadows locally favored higher species abundance, diversity, and functional traits present in the community relative to nearby bare sediments. At the regional scale, eelgrass diversity was comparable between sites, with high species turnover observed among them, and each site being characterized by different species and different sets of traits. These differences were due in part to morphological traits of the meadows, but the explanatory variables that best explained the differences among the meadows were environmental conditions, including temperature, current velocity, and Δ water level. Main conclusions: Meadows appear to harbor subsets of species from the regional species pool, rather than harboring eelgrass-specific assemblages. The processes that maintain seagrass diversity appear to reflect a seascape-scale meta-community composed of many habitats connected by source-sink dynamics. Given that eelgrass enhances the diversity and abundance of species found in neighboring habitats, conservation programs should consider ecosystem-level protection spanning multiple habitats, including eelgrass, in order to maximize the protection of biodiversity.
25 May 2022Submitted to Ecology and Evolution
30 May 2022Assigned to Editor
30 May 2022Submission Checks Completed
01 Jun 2022Reviewer(s) Assigned