title: Isotopic studies in Pacific Panama mangrove estuaries reveal lack of effect of watershed deforestation on food webs.
abstract: Stable isotopic N, C, and S in food webs of 8 mangrove estuaries on the Pacific coast of Panama were measured to 1) determine whether the degree of deforestation of tropical forests on the contributing watersheds was detectable within the estuarine food web, and 2) define external sources of the food webs within the mangrove estuaries. Even though terrestrial rain forest cover on the contributing watersheds differed between 23 and 92%, the effect of deforestation was not detectable on stable isotopic values in food webs present at the mouth of the receiving estuaries. We used stable isotopic measures to identify producers or organic sources that supported the estuarine food web. N isotopic values of consumers spanned a broad range, from about 2.7 to 12.3‰. Mean δ(15)N of primary producers and organic matter varied from 3.3 for macroalgae to 4.7‰ for suspended particulate matter and large particulate matter. The δ(13)C consumer data varied between -26 and -9‰, but isotopic values of the major apparent producers or organic matter sampled could not account for this range variability. The structure of the food web was clarified when we added literature isotopic values of microphytobenthos and coralline algae, suggesting that these, or other producers with similar isotopic signature, may be part of the food webs.
authors.affiliation: The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02534, USA; Instituto Español de Oceanografía, Centro Oceanográfico de La Coruña, Apdo. 130, 15080 La Coruña, Spain.
authors.forename: Inés G
authors.initials: IG
authors.lastname: Viana
authors.affiliation: The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02534, USA. Electronic address: ivaliela@mbl.edu.
authors.forename: Ivan
authors.initials: I
authors.lastname: Valiela
authors.affiliation: Instituto de Investigaciones Marinas y Costeras, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Mar del Plata, CC573 Mar del Plata, Argentina.
authors.forename: Paulina
authors.initials: P
authors.lastname: Martinetto
authors.affiliation: The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02534, USA.
authors.forename: Rita
authors.initials: R
authors.lastname: Monteiro Pierce
authors.affiliation: Cape Cod National Seashore, National Park Service, 99 Marconi Site Road, Wellfleet, MA 02667, USA.
authors.forename: Sophia E
authors.initials: SE
authors.lastname: Fox
mesh_terms: D002247:Carbon Isotopes / Q000032:analysis; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D063366:Estuaries; D020387:Food Chain; D009587:Nitrogen Isotopes / Q000032:analysis; D010176:Panama; D013460:Sulfur Isotopes / Q000032:analysis; D053833:Wetlands
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D013460:Sulfur Isotopes
keywords: Carbon; Food webs; Mixing models; Nitrogen; Sulfur