title: Canopy interactions and physical stress gradients in subtidal communities.
abstract: Species interactions are integral drivers of community structure and can change from competitive to facilitative with increasing environmental stress. In subtidal marine ecosystems, however, interactions along physical stress gradients have seldom been tested. We observed seaweed canopy interactions across depth and latitudinal gradients to test whether light and temperature stress structured interaction patterns. We also quantified interspecific and intraspecific interactions among nine subtidal canopy seaweed species across three continents to examine the general nature of interactions in subtidal systems under low consumer pressure. We reveal that positive and neutral interactions are widespread throughout global seaweed communities and the nature of interactions can change from competitive to facilitative with increasing light stress in shallow marine systems. These findings provide support for the stress gradient hypothesis within subtidal seaweed communities and highlight the importance of canopy interactions for the maintenance of subtidal marine habitats experiencing environmental stress.
authors.affiliation: School of Plant Biology & UWA Oceans Institute, University of Western Australia, 39 Fairway, Crawley, 6009, WA, Australia.
authors.forename: Scott
authors.initials: S
authors.lastname: Bennett
authors.affiliation: School of Plant Biology & UWA Oceans Institute, University of Western Australia, 39 Fairway, Crawley, 6009, WA, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wernberg
authors.affiliation: School of Plant Biology & UWA Oceans Institute, University of Western Australia, 39 Fairway, Crawley, 6009, WA, Australia.
authors.forename: Thibaut
authors.initials: T
authors.lastname: de Bettignies
authors.affiliation: School of Plant Biology & UWA Oceans Institute, University of Western Australia, 39 Fairway, Crawley, 6009, WA, Australia.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Kendrick
authors.affiliation: Seaweed Research Unit, Department of Agriculture, forestry and Fisheries, Pvt Bag X2, Roggebaai, 8012, South Africa.|Department of Biological Sciences and Marine Research Institute, University of Cape Town, Rondebosch, 7701, South Africa.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Anderson
authors.affiliation: Department of Biological Sciences and Marine Research Institute, University of Cape Town, Rondebosch, 7701, South Africa.
authors.forename: John J
authors.initials: JJ
authors.lastname: Bolton
authors.affiliation: Leigh Marine Laboratory, Institute of Marine Science, University of Auckland, PO Box 349, Warkworth, 0941, New Zealand.
authors.forename: Kirsten L
authors.initials: KL
authors.lastname: Rodgers
authors.affiliation: Leigh Marine Laboratory, Institute of Marine Science, University of Auckland, PO Box 349, Warkworth, 0941, New Zealand.
authors.forename: Nick T
authors.initials: NT
authors.lastname: Shears
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 6, Station Biologique, Place Georges Teissier, Roscoff, 29680, France.|CNRS, Station Biologique, Place Georges Teissier, UMR 7144, Roscoff, 29680, France.
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Leclerc
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 6, Station Biologique, Place Georges Teissier, Roscoff, 29680, France.|CNRS, FR 2424, Station Biologique, Place Georges Teissier, Roscoff, 29680, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Lévêque
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 6, Station Biologique, Place Georges Teissier, Roscoff, 29680, France.|CNRS, Station Biologique, Place Georges Teissier, UMR 7144, Roscoff, 29680, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Davoult
authors.affiliation: Section for Marine Biology, Norwegian Institute for Water Research, Oslo, Norway.
authors.forename: Hartvig C
authors.initials: HC
authors.lastname: Christie
mesh_terms: D000064:Acclimatization; D001315:Australia; D017753:Ecosystem; D044423:Kelp / Q000145:classification / Q000502:physiology*; D008027:Light; D013312:Stress, Physiological; D013696:Temperature
keywords: Allee effects; competition; facilitation; kelp; seaweed; species interactions; stress gradient hypothesis