HR: 14:00h
AN: NB23D-03    [Abstracts]
TI: Tracing Fluxes Of Aquatic Production And Contaminants Into Terrestrial Food Webs With Nitrogen Stable Isotopes
AU: Rivard, A
EM: alexandre_rivard@uqtr.ca
AF: Dept. Chimie-Biologie, Universite du Quebec … Trois-Rivieres, CP 500, Trois-Rivieres, QC G9A 5H7 Canada
AU: * Cabana, G
EM: gilbert_cabana@uqtr.ca
AF: Dept. Chimie-Biologie, Universite du Quebec … Trois-Rivieres, CP 500, Trois-Rivieres, QC G9A 5H7 Canada
AU: Rainey, W
EM: rainey@socrates.berkeley.edu
AF: Dept. of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720-3140 United States
AU: Power, M
EM: mepower@socrates.Berkeley.EDU
AF: Dept. of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720-3140 United States
AB: Biomagnifying contaminants such as mercury can be transported and redistributed across the watershed by streams and rivers. Their fate and effects on consumers depend on food web transfer both within and between aquatic and terrestrial ecosystems. The Truckee River (Ca/Ne) is heavily contaminated by Hg originating from century-old upstream mining operations. We used nitrogen stable isotope analysis to trace the incorporation of Hg transported by the Truckee and transferred by emerging aquatic insects into the riparian food web. N-isotope ratios and Hg of aquatic primary consumers were significantly elevated compared to that of terrestrial arthropods (13.3 vs 5.6 % and 110 vs 17 ngg-1). Estimates of dependence on aquatics in 16 riparian passerine bird species based on blood delta 15N ranged between 0.0 and 0.95 and were significantly related to Hg in blood. Similar correlations between Hg and delta 15N measured in tail tips of western fence lizard (Sceloporus occidentalis) collected at increasing distances from the river were observed. High inter-individual variation in bird Hg was highly correlated with delta 15N. These results show how stable isotopes and contaminant fluxes can reveal important food web linkages across aquatic/terrestrial ecotones.
DE: 0400 Biogeosciences
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly