title: Inputs of anthropogenic nitrogen influence isotopic composition and trophic structure in SE Australian estuaries.
abstract: Urban development in coastal settings has increased the input of nitrogen into estuaries globally, in many cases changing the composition of estuarine ecosystems. By focussing on three adjacent estuaries with a gradient of anthropogenic N loadings, we used stable isotopes of N and C to test for changes due to increased anthropogenic N input on the structure of some key trophic linkages in estuaries. We found a consistent enrichment in δ(15)N corresponding to increased anthropogenic N at the three ecosystem levels studied: fine benthic organic matter, grazing invertebrate, and planktivorous fish. The degree of enrichment in δ(15)N between fine benthic organic matter and the grapsid crab Parasesarma erythrodactyla was identical across the three sites. The glassfish Ambassis jacksoniensis showed lower levels of enrichment compared to basal food sources at the higher N-loaded sites, suggesting a possible effect of anthropogenic N in decreasing food-chain length in these estuaries.
authors.affiliation: Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232, Australia. Electronic address: debashish.mazumder@ansto.gov.au.
authors.forename: Debashish
authors.initials: D
authors.lastname: Mazumder
authors.affiliation: Department of Environmental Sciences, Macquarie University, Sydney, NSW 2109, Australia.
authors.forename: Neil
authors.initials: N
authors.lastname: Saintilan
authors.affiliation: Cardno, PO Box 19, St Leonards, NSW 1590, Australia.
authors.forename: Brendan
authors.initials: B
authors.lastname: Alderson
authors.affiliation: Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232, Australia.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Hollins
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D001315:Australia; D003386:Brachyura; D002247:Carbon Isotopes / Q000032:analysis; D017753:Ecosystem; D063366:Estuaries; D005399:Fishes; D020387:Food Chain; D060434:Herbivory; D007448:Invertebrates; D009584:Nitrogen / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis; D010473:Perciformes
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D009584:Nitrogen
keywords: Anthropogenic N; Estuaries; Stable isotopes; Trophic linkages