title: Macroalgae blooms and delta 15N in subtropical coastal lagoons from the Southeastern Gulf of California: discrimination among agricultural, shrimp farm and sewage effluents.
abstract: Macroalgae blooms of Gracilaria vermiculophylla, Hypnea spinella and Spyridia filamentosa have been found in coastal lagoons in the SE Gulf of California. Agriculture, livestock, shrimp and poultry farms and sewage contribute anthropogenic nitrogen to the systems. The delta(15)N of these sources, water column and macroalgae were studied in order to identify the N supply for macroalgae blooms. delta(15)N of three species of macroalgae (4.3-13.6 per thousand) were enriched compared to the water column (delta(15)N-NO(3)(-) 3.7-6.8 per thousand), probably because of fractioning from the macroalgae. delta(15)N of POM (1.4-10.3 per thousand) was similar to the water column but the relationship was unclear. Depending on the site, macroalgae showed different delta(15)N values since some sites receive more or less influence from one given source of the associated watershed, which is reflected in the different delta(15)N values of the macroalgae of the same system and in the relative contributions of the sources.
authors.affiliation: Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Unidad Académica Mazatlán, Apdo. Postal 811, Mazatlán, Sinaloa 82040, Mexico.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Piñón-Gimate
authors.affiliation: Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Unidad Académica Mazatlán, Apdo. Postal 811, Mazatlán, Sinaloa 82040, Mexico. Electronic address: martin@ola.icmyl.unam.mx.
authors.forename: Martín F
authors.initials: MF
authors.lastname: Soto-Jiménez
authors.affiliation: Facultad de Ciencias del Mar, Universidad Nacional Autónoma de Sinaloa, Paseo Claussen s/n, Mazatlán, Sinaloa 82000, Mexico.
authors.forename: María Julia
authors.initials: MJ
authors.lastname: Ochoa-Izaguirre
authors.affiliation: Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Unidad Académica Mazatlán, Apdo. Postal 811, Mazatlán, Sinaloa 82040, Mexico.
authors.forename: Eynar
authors.initials: E
authors.lastname: García-Pagés
authors.affiliation: Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Unidad Académica Mazatlán, Apdo. Postal 811, Mazatlán, Sinaloa 82040, Mexico.
authors.forename: Federico
authors.initials: F
authors.lastname: Páez-Osuna
mesh_terms: D000383:Agriculture; D017756:Aquaculture; D056890:Eukaryota / Q000737:chemistry* / Q000254:growth & development*; D005068:Eutrophication / Q000502:physiology*; D008800:Mexico; D009587:Nitrogen Isotopes / Q000032:analysis*; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry; D012722:Sewage
chemical_list: D009587:Nitrogen Isotopes; D012722:Sewage