Small-scale effects of hydrodynamics on the structure of intertidal macroalgal communities: A novel approach

Type Article
Date 2019-10
Language English
Author(s) Burel Thomas1, Schaal Gauthier1, Grall Jacques2, Le Duff Michel2, Chapalain Georges3, Schmitt Blondie1, Gemin Maxence1, Boucher Olivier3, Ar Gall Erwan1
Affiliation(s) 1 : Laboratoire des Sciences de l’Environnement Marin, UMR 6539 UBO/CNRS/IRD/IFREMER, Rue Dumont d’Urville, 29280, Plouzané, Brittany, France
2 : Institut Universitaire Européen de la Mer. Observatoire du Domaine Côtier, UMS 3113. Université de Bretagne Occidentale, Rue Dumont d’Urville, 29280, Plouzané, Brittany, France
3 : Laboratoire de Génie Côtier et Environnement (LGCE), Cerema, 155 rue Pierre Bouguer, Technopôle Brest-Iroise BP 5, 29280, Plouzané, Brittany, France
Source Estuarine Coastal And Shelf Science (0272-7714) (Elsevier BV), 2019-10 , Vol. 226 , P. 106290 (10p.)
DOI 10.1016/j.ecss.2019.106290
WOS© Times Cited 3
Keyword(s) Macroalgal communities, Intertidal zone, Rocky shores, Wave heights, Hydrodynamics, Mini-diver, Brittany
Abstract

Wave height was used as a proxy to assess the effect of hydrodynamics on the development and structure of intertidal North-East Atlantic rocky macroalgal communities (Brittany). The characterization of hydrodynamics at small-scale (about 10 m) was performed through wave height in situ monitoring using pressure sensors. Both the diversity and the cover of the macroalgal communities were sampled in parallel. Wave heights exhibit large variations with values ranging from ca. 5 cm to 1.60 m. We show that wave height directly controls the cover of macroalgal canopies (Pearson's r between −0.62 and −0.39). In all communities, most of the fucoid covers regressed with increasing wave height values. By contrast, positive correlations were found at low shore levels between wave heights and the cover of the kelp Laminaria digitata and also of several species of Rhodophyta. Redundancy analysis points out the significant effect of wave height on the inner variability of macroalgal communities, explaining up to 19% of their upright structure and more than 15% of the distribution of canopy-forming groups. In assemblages dominated by either Pelvetia canaliculata or Fucus serratus, a significant negative correlation was also evidenced with the index of community structure (Ics), which gives an appraisal of both the structure and the development of macroalgal communities. In conclusion, this study provides a novel experimental approach helping to quantify the effects of hydrodynamics on the structure of macroalgal communities using a small-scale in situ quantification of wave heights, revealing hydrodynamics as the main environmental driver of inner structural variations in seaweed assemblages.

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Burel Thomas, Schaal Gauthier, Grall Jacques, Le Duff Michel, Chapalain Georges, Schmitt Blondie, Gemin Maxence, Boucher Olivier, Ar Gall Erwan (2019). Small-scale effects of hydrodynamics on the structure of intertidal macroalgal communities: A novel approach. Estuarine Coastal And Shelf Science, 226, 106290 (10p.). Publisher's official version : https://doi.org/10.1016/j.ecss.2019.106290 , Open Access version : https://archimer.ifremer.fr/doc/00506/61769/