title: Lack of Impact of Posidonia oceanica Leaf Nutrient Enrichment on Sarpa salpa Herbivory: Additional Evidence for the Generalist Consumer Behavior of This Cornerstone Mediterranean Herbivore.
abstract: The fish Sarpa salpa (L.) is one of the main macroherbivores in the western Mediterranean. Through direct and indirect mechanisms, this herbivore can exert significant control on the structure and functional dynamics of seagrass beds and macroalgae. Past research has suggested nutritional quality of their diet influences S. salpa herbivory, with the fish feeding more intensively and exerting greater top down control on macrophytes with higher internal nutrient contents. However recent findings have questioned this notion and shown that herbivores do not preferentially feed on macrophytes with higher nutrient contents, but rather feed on a wide variety of them with no apparent selectivity. To contribute to this debate, we conducted a field fertilization experiment where we enriched leaves of the seagrass Posidonia oceanica, a staple diet for S. salpa, and examined the response by the herbivore. These responses included quantification of leaf consumption in fertilized and non-fertilized/control plots within the bed, and food choice assays where fertilized and non-fertilized/control leaves were simultaneously offered to the herbivore. Despite the duration of leaf exposure to herbivores (30 days) and abundant schools of S. salpa observed around the plots, leaf consumption was generally low in the plots examined. Consumption was not higher on fertilized than on non-fertilized leaves. Food choice experiments did not show strong evidence for selectivity of enriched leaves. These results add to a recent body of work reporting a broad generalist feeding behavior by S. salpa with no clear selectivity for seagrass with higher nutrient content. In concert, this and other studies suggest S. salpa is often generalist consumers not only dictated by diet nutrient content but by complex interactions between other traits of nutritional quality, habitat heterogeneity within their ample foraging area, and responses to predation risk.
authors.affiliation: Department of Marine Science and Applied Biology, University of Alicante, San Vicente del Raspeig, Alicante, Spain.|Marine Research Centre of Santa Pola (CIMAR), Santa Pola City Council, Alicante, Spain.
authors.forename: Candela
authors.initials: C
authors.lastname: Marco-Méndez
authors.affiliation: Dauphin Island Sea Lab, Dauphin Island, Alabama, United States of America.|Department of Marine Sciences, University of South Alabama, Mobile, Alabama, United States of America.
authors.forename: Caitlin
authors.initials: C
authors.lastname: Wessel
authors.affiliation: Dauphin Island Sea Lab, Dauphin Island, Alabama, United States of America.|Department of Marine Sciences, University of South Alabama, Mobile, Alabama, United States of America.
authors.forename: Whitney
authors.initials: W
authors.lastname: Scheffel
authors.affiliation: Department of Marine Science and Applied Biology, University of Alicante, San Vicente del Raspeig, Alicante, Spain.|Marine Research Centre of Santa Pola (CIMAR), Santa Pola City Council, Alicante, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Ferrero-Vicente
authors.affiliation: Department of Marine Science and Applied Biology, University of Alicante, San Vicente del Raspeig, Alicante, Spain.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Fernández-Torquemada
authors.affiliation: Dauphin Island Sea Lab, Dauphin Island, Alabama, United States of America.|Department of Marine Sciences, University of South Alabama, Mobile, Alabama, United States of America.
authors.forename: Just
authors.initials: J
authors.lastname: Cebrián
authors.affiliation: Dauphin Island Sea Lab, Dauphin Island, Alabama, United States of America.|Department of Marine Sciences, University of South Alabama, Mobile, Alabama, United States of America.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Heck
authors.affiliation: Department of Marine Science and Applied Biology, University of Alicante, San Vicente del Raspeig, Alicante, Spain.
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Sánchez-Lizaso
mesh_terms: D035961:Alismatales / Q000737:chemistry*; D000818:Animals; D060434:Herbivory / Q000502:physiology*; D009753:Nutritive Value; D010473:Perciformes / Q000502:physiology*; D018515:Plant Leaves / Q000737:chemistry; D011235:Predatory Behavior