title: Relationship between anthropogenic sewage discharge, marsh structure and bird assemblages in an SW Atlantic saltmarsh.
abstract: One of the main effects of urbanization on coastal areas is through the discharge of sewage, which increases nutrient concentrations in the receiving environment. Salt marshes, like other coastal marine environments, are limited by nutrients, mainly nitrogen, and thus increasing nutrient loadings to a marsh may have consequences on marsh characteristics. We evaluated how the effects of nutrient enrichment in the form of sewage input, affected the vegetation structure and bird assemblages in a Spartina alterniflora salt marsh system near Bahía Blanca, Argentina (39° 01' S - 56° 25' W). Surveys of nutrient concentration, vegetation and birds were made at three different distances from the sewage discharge source. The concentration of ammonium, phosphate, and nitrate and the percent organic matter was higher in marshes nearest to the sewage discharge source. Bird composition and abundance, and vegetation physiognomy changed along a gradient of nutrient concentration. The increased habitat complexity found near the areas of higher nutrient concentration was exploited by birds that use neighboring interior and coastal habitats, including Spartina densiflora marshes, freshwater marshes and upland shrubby habitats. Our results show that local increases of nutrient inputs directly changed the vegetation physiognomy, and indirectly the composition and abundance of bird assemblages.
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina, Funes 3250, 7600 Mar del Plata, Argentina. acardoni@mdp.edu.ar
authors.forename: D A
authors.initials: DA
authors.lastname: Cardoni
authors.forename: J P
authors.initials: JP
authors.lastname: Isacch
authors.forename: M E
authors.initials: ME
authors.lastname: Fanjul
authors.forename: M
authors.initials: M
authors.lastname: Escapa
authors.forename: O O
authors.initials: OO
authors.lastname: Iribarne
mesh_terms: D000818:Animals; D001118:Argentina; D001267:Atlantic Ocean; D044822:Biodiversity; D001717:Birds / Q000502:physiology*; D019015:Geologic Sediments / Q000737:chemistry; D009566:Nitrates / Q000032:analysis; D010710:Phosphates / Q000032:analysis; D011156:Population Density; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012722:Sewage; D053833:Wetlands
chemical_list: D009566:Nitrates; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D012722:Sewage