title: A continental scale evaluation of the role of limpet grazing on rocky shores.
abstract: It is critical for our knowledge of biodiversity and ecosystem processes to understand how individual species contribute to ecosystem processes and how these contributions vary in space and time. We used a manipulative field experiment in five locations over 17 degrees of latitude [from southern Portugal to the Isle of Man (British Isles)] to determine the relative response of rocky intertidal algal assemblages released from control by the grazing of limpets. Response ratios showed that when limpets were removed there was a trend of effects from north to south. In the north, grazing had a strong effect on algal assemblages, but removing grazers reduced spatial variability in assemblages. In the south, the effect of limpet grazing was far weaker and removal of grazers had a much reduced impact on spatial variability. Here we show a clear trophic control of an ecosystem in that grazing by limpets not only determines macroalgal abundance overall but also modifies ecosystem stability via variability in cover of algae.
authors.affiliation: School of Biological Sciences, University of Southampton, SO16 7PX, Southampton, UK. rcoleman@usyd.edu.au
authors.forename: Ross A
authors.initials: RA
authors.lastname: Coleman
authors.forename: Antony J
authors.initials: AJ
authors.lastname: Underwood
authors.forename: Lisandro
authors.initials: L
authors.lastname: Benedetti-Cecchi
authors.forename: Per
authors.initials: P
authors.lastname: Aberg
authors.forename: Francisco
authors.initials: F
authors.lastname: Arenas
authors.forename: Julio
authors.initials: J
authors.lastname: Arrontes
authors.forename: João
authors.initials: J
authors.lastname: Castro
authors.forename: Richard G
authors.initials: RG
authors.lastname: Hartnoll
authors.forename: Stuart R
authors.initials: SR
authors.lastname: Jenkins
authors.forename: José
authors.initials: J
authors.lastname: Paula
authors.forename: Paolo
authors.initials: P
authors.lastname: Della Santina
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Hawkins
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D005247:Feeding Behavior; D008974:Mollusca / Q000502:physiology*