title: Abundance and Diversity of Crypto- and Necto-Benthic Coastal Fish Are Higher in Marine Forests than in Structurally Less Complex Macroalgal Assemblages.
abstract: In Mediterranean subtidal rocky reefs, Cystoseira spp. (Phaeophyceae) form dense canopies up to 1 m high. Such habitats, called 'Cystoseira forests', are regressing across the entire Mediterranean Sea due to multiple anthropogenic stressors, as are other large brown algae forests worldwide. Cystoseira forests are being replaced by structurally less complex habitats, but little information is available regarding the potential difference in the structure and composition of fish assemblages between these habitats. To fill this void, we compared necto-benthic (NB) and crypto-benthic (CB) fish assemblage structures between Cystoseira forests and two habitats usually replacing the forests (turf and barren), in two sampling regions (Corsica and Menorca). We sampled NB fish using Underwater Visual Census (UVC) and CB fish using Enclosed Anaesthetic Station Vacuuming (EASV), since UVC is known to underestimate the diversity and density of the 'hard to spot' CB fish. We found that both taxonomic diversity and total density of NB and CB fish were highest in Cystoseira forests and lowest in barrens, while turfs, that could be sampled only at Menorca, showed intermediate values. Conversely, total biomass of NB and CB fish did not differ between habitats because the larger average size of fish in barrens (and turfs) compensated for their lower densities. The NB families Labridae and Serranidae, and the CB families Blenniidae, Cliniidae, Gobiidae, Trypterigiidae and Scorpaenidae, were more abundant in forests. The NB taxa Diplodus spp. and Thalassoma pavo were more abundant in barrens. Our study highlights the importance of using EASV for sampling CB fish, and shows that Cystoseira forests support rich and diversified fish assemblages. This evidence suggests that the ongoing loss of Cystoseira forests may impair coastal fish assemblages and related goods and services to humans, and stresses the need to implement strategies for the successful conservation and/or recovery of marine forests.
authors.affiliation: Université Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, France.|Muséum National d'Histoire Naturelle, UMR 7208 BOREA, Station Marine de Dinard-CRESCO, Dinard, France.
authors.forename: Pierre D
authors.initials: PD
authors.lastname: Thiriet
authors.affiliation: Université Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, France.|CRIOBE, USR 3278 CNRS-EPHE-UPVD, Perpignan, France.
authors.forename: Antonio
authors.identifier: http://orcid.org/0000-0003-3411-7015
authors.initials: A
authors.lastname: Di Franco
authors.affiliation: Université Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, France.|UMR 5110 CNRS/UPVD-CEFREM, Université de Perpignan Via Domitia, Perpignan, France.
authors.forename: Adrien
authors.initials: A
authors.lastname: Cheminée
authors.affiliation: Université Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, France.
authors.forename: Paolo
authors.initials: P
authors.lastname: Guidetti
authors.affiliation: Septentrion Environnement, Marseille, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Bianchimani
authors.affiliation: Septentrion Environnement, Marseille, France.
authors.forename: Solène
authors.initials: S
authors.lastname: Basthard-Bogain
authors.affiliation: Université Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Cottalorda
authors.affiliation: Université Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, France.|Marine Science Institute, University of the Philippines, Diliman, Quezon City, Philippines.
authors.forename: Hazel
authors.initials: H
authors.lastname: Arceo
authors.affiliation: Estación de Investigación Jaume Ferrer, Maó, Menorca, Illes Balears, España.|Instituto Español de Ocenografía (IEO), Centre Oceanogràfic de les Balears, Moll de Ponent s/n, Palma de Mallorca, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Moranta
authors.affiliation: STARESO, Station de Recherches Océanographiques et Sous-Marines, Calvi, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Lejeune
authors.affiliation: Université Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Francour
authors.affiliation: Université Nice Sophia Antipolis, CNRS, FRE 3729 ECOMERS, Parc Valrose 28, Nice, France.|Sorbonne Universités, UPMC Univ. Paris 06, INSU-CNRS, UMR 7093, Laboratoire d'Océanographie de Villefranche, Villefranche sur mer, France.
authors.forename: Luisa
authors.initials: L
authors.lastname: Mangialajo
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D005399:Fishes / Q000145:classification*; D015999:Multivariate Analysis; D000459:Phaeophyceae / Q000254:growth & development; D012624:Seaweed / Q000254:growth & development*