title: Fish-seastar facilitation leads to algal forest restoration on protected rocky reefs.
abstract: Although protected areas can lead to recovery of overharvested species, it is much less clear whether the return of certain predator species or a diversity of predator species can lead to re-establishment of important top-down forces that regulate whole ecosystems. Here we report that the algal recovery in a Mediterranean Marine Protected Area did not derive from the increase in the traditional strong predators, but rather from the establishment of a previously unknown interaction between the thermophilic fish Thalassoma pavo and the seastar Marthasterias glacialis. The interaction resulted in elevated predation rates on sea urchins responsible for algal overgrazing. Manipulative experiments and field observations revealed that the proximity of the seastars triggered an escape response in sea urchins, extending their tube feet. Fishes exploited this behavior by feeding on the exposed tube feet, thus impairing urchin movement, and making them vulnerable to predation by the seastars. These findings suggest that predator diversity generated by MPA establishment can activate positive interactions among predators, with subsequent restoration of the ecosystem structure and function through cascading consumer impacts.
authors.affiliation: CNR-IAMC, via Giovanni da Verrazzano 17, 91014 Castellammare del Golfo, Italy.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Galasso
authors.affiliation: Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Via Archirafi 22, I-90123 Palermo, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Bonaviri
authors.affiliation: Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Via Archirafi 22, I-90123 Palermo, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Trapani
authors.affiliation: Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Via Archirafi 22, I-90123 Palermo, Italy.
authors.forename: Mariagrazia
authors.initials: M
authors.lastname: Picciotto
authors.affiliation: Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Via Archirafi 22, I-90123 Palermo, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Gianguzza
authors.affiliation: CNR-IAMC, via Giovanni da Verrazzano 17, 91014 Castellammare del Golfo, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Agnetta
authors.affiliation: CNR-IAMC, via Giovanni da Verrazzano 17, 91014 Castellammare del Golfo, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Badalamenti
mesh_terms: D000818:Animals; D000460:Chlorophyta / Q000502:physiology*; D017753:Ecosystem; D005399:Fishes / Q000502:physiology*; D011157:Population Dynamics; D011235:Predatory Behavior / Q000502:physiology; D012617:Sea Urchins / Q000502:physiology