title: Spatial relationships between polychaete assemblages and environmental variables over broad geographical scales.
abstract: This study examined spatial relationships between rocky shore polychaete assemblages and environmental variables over broad geographical scales, using a database compiled within the Census of Marine Life NaGISA (Natural Geography In Shore Areas) research program. The database consisted of abundance measures of polychaetes classified at the genus and family levels for 74 and 93 sites, respectively, from nine geographic regions. We tested the general hypothesis that the set of environmental variables emerging as potentially important drivers of variation in polychaete assemblages depend on the spatial scale considered. Through Moran's eigenvector maps we indentified three submodels reflecting spatial relationships among sampling sites at intercontinental (>10,000 km), continental (1000-5000 km) and regional (20-500 km) scales. Using redundancy analysis we found that most environmental variables contributed to explain a large and significant proportion of variation of the intercontinental submodel both for genera and families (54% and 53%, respectively). A subset of these variables, organic pollution, inorganic pollution, primary productivity and nutrient contamination was also significantly related to spatial variation at the continental scale, explaining 25% and 32% of the variance at the genus and family levels, respectively. These variables should therefore be preferably considered when forecasting large-scale spatial patterns of polychaete assemblages in relation to ongoing or predicted changes in environmental conditions. None of the variables considered in this study were significantly related to the regional submodel.
authors.affiliation: Department of Biology, University of Pisa, CoNISMa (National Interuniversity Consortium of Marine Sciences), Pisa, Italy. lbenedetti@biologia.unipi.it
authors.forename: Lisandro
authors.initials: L
authors.lastname: Benedetti-Cecchi
authors.forename: Katrin
authors.initials: K
authors.lastname: Iken
authors.forename: Brenda
authors.initials: B
authors.lastname: Konar
authors.forename: Juan
authors.initials: J
authors.lastname: Cruz-Motta
authors.forename: Ann
authors.initials: A
authors.lastname: Knowlton
authors.forename: Gerhard
authors.initials: G
authors.lastname: Pohle
authors.forename: Alberto
authors.initials: A
authors.lastname: Castelli
authors.forename: Laura
authors.initials: L
authors.lastname: Tamburello
authors.forename: Angela
authors.initials: A
authors.lastname: Mead
authors.forename: Tom
authors.initials: T
authors.lastname: Trott
authors.forename: Patricia
authors.initials: P
authors.lastname: Miloslavich
authors.forename: Melisa
authors.initials: M
authors.lastname: Wong
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Shirayama
authors.forename: Claudio
authors.initials: C
authors.lastname: Lardicci
authors.forename: Gabriela
authors.initials: G
authors.lastname: Palomo
authors.forename: Elena
authors.initials: E
authors.lastname: Maggi
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D004777:Environment; D005843:Geography; D011077:Polychaeta / Q000145:classification*