title: The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications.
abstract: Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m(-2)). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas.
authors.affiliation: National Geographic Society, Washington, DC, United States of America. esala@ngs.org
authors.forename: Enric
authors.initials: E
authors.lastname: Sala
authors.forename: Enric
authors.initials: E
authors.lastname: Ballesteros
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Dendrinos
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Franco
authors.forename: Francesco
authors.initials: F
authors.lastname: Ferretti
authors.forename: David
authors.initials: D
authors.lastname: Foley
authors.forename: Simonetta
authors.initials: S
authors.lastname: Fraschetti
authors.forename: Alan
authors.initials: A
authors.lastname: Friedlander
authors.forename: Joaquim
authors.initials: J
authors.lastname: Garrabou
authors.forename: Harun
authors.initials: H
authors.lastname: Güçlüsoy
authors.forename: Paolo
authors.initials: P
authors.lastname: Guidetti
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Halpern
authors.forename: Bernat
authors.initials: B
authors.lastname: Hereu
authors.forename: Alexandros A
authors.initials: AA
authors.lastname: Karamanlidis
authors.forename: Zafer
authors.initials: Z
authors.lastname: Kizilkaya
authors.forename: Enrique
authors.initials: E
authors.lastname: Macpherson
authors.forename: Luisa
authors.initials: L
authors.lastname: Mangialajo
authors.forename: Simone
authors.initials: S
authors.lastname: Mariani
authors.forename: Fiorenza
authors.initials: F
authors.lastname: Micheli
authors.forename: Antonio
authors.initials: A
authors.lastname: Pais
authors.forename: Kristin
authors.initials: K
authors.lastname: Riser
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Rosenberg
authors.forename: Marta
authors.initials: M
authors.lastname: Sales
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Selkoe
authors.forename: Rick
authors.initials: R
authors.lastname: Starr
authors.forename: Fiona
authors.initials: F
authors.lastname: Tomas
authors.forename: Mikel
authors.initials: M
authors.lastname: Zabala
mesh_terms: D000465:Algorithms; D000818:Animals; D018533:Biomass; D003247:Conservation of Natural Resources; D057894:Coral Reefs; D017753:Ecosystem; D004777:Environment; D005399:Fishes / Q000502:physiology*; D005843:Geography; D006801:Humans; D007448:Invertebrates / Q000502:physiology; D008522:Mediterranean Sea; D011157:Population Dynamics