title: The degree of urbanization across the globe is not reflected in the δ(15)N of seagrass leaves.
abstract: Many studies show that seagrass δ(15)N ratios increase with the amount of urbanization in coastal watersheds. However, there is little information on the relationship between urbanization and seagrass δ(15)N ratios on a global scale. We performed a meta-analysis on seagrass samples from 79 independent locations to test if seagrass δ(15)N ratios correlate with patterns of population density and fertilizer use within a radius of 10-200 km around the sample locations. Our results show that seagrass δ(15)N ratios are more influenced by intergeneric and latitudinal differences than the degree of urbanization or the amount of fertilizer used in nearby watersheds. The positive correlation between seagrass δ(15)N ratios and latitude hints at an underlying pattern in discrimination or a latitudinal gradient in the (15)N isotopic signature of nitrogen assimilated by the plants. The actual mechanisms responsible for the correlation between δ(15)N and latitude remain unknown.
authors.affiliation: The University of South Alabama, Department of Marine Sciences, Mobile, AL 36688, USA; The Dauphin Island Sea Lab 101 Bienville Blvd., Dauphin Island, AL 36528, USA. Electronic address: bchristiaen@disl.org.
authors.forename: Bart
authors.initials: B
authors.lastname: Christiaen
authors.affiliation: The University of Alabama, Department of Biological Sciences, Tuscaloosa, AL 35487, USA; The Dauphin Island Sea Lab 101 Bienville Blvd., Dauphin Island, AL 36528, USA. Electronic address: rjbernard@ua.edu.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Bernard
authors.affiliation: The University of Alabama, Department of Biological Sciences, Tuscaloosa, AL 35487, USA; The Dauphin Island Sea Lab 101 Bienville Blvd., Dauphin Island, AL 36528, USA. Electronic address: bmortazavi@ua.edu.
authors.forename: Behzad
authors.initials: B
authors.lastname: Mortazavi
authors.affiliation: The University of South Alabama, Department of Marine Sciences, Mobile, AL 36688, USA; The Dauphin Island Sea Lab 101 Bienville Blvd., Dauphin Island, AL 36528, USA. Electronic address: jcebrian@disl.org.
authors.forename: Just
authors.initials: J
authors.lastname: Cebrian
authors.affiliation: The University of South Alabama, Department of Marine Sciences, Mobile, AL 36688, USA; The Dauphin Island Sea Lab 101 Bienville Blvd., Dauphin Island, AL 36528, USA. Electronic address: aortmann@disl.org.
authors.forename: Alice C
authors.initials: AC
authors.lastname: Ortmann
mesh_terms: D035961:Alismatales / Q000737:chemistry* / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D009587:Nitrogen Isotopes / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry*; D011156:Population Density; D014507:Urbanization
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D009584:Nitrogen
keywords: Isotope; Nitrogen; Nutrients; Pollution; Seagrass; Urbanization