Relationships between carbon sources, trophic level and mercury exposure in generalist shorebirds revealed by stable isotope ratios in chicks

Tavares, P.C., McGill, R.A.R. , Newton, J. , Pereira, E., Duarte, A.C. and Furness, R.W. (2009) Relationships between carbon sources, trophic level and mercury exposure in generalist shorebirds revealed by stable isotope ratios in chicks. Waterbirds, 32(2), pp. 311-321. (doi: 10.1675/063.032.0211)

Abstract

Mercury exposure may he linked to several sources of variation related to habitat conditions and species ecology. In generalist birds, feeding habits may change quickly in response to environmental conditions, prey availability and individual requirements. Stable: nitrogen isotope ratios (δ^N15) were used as a marker of trophic level, and stable carbon isotope ratios (δ^C13) as a marker of carbon sources (terrestrial vs. marine) in food webs involving waterbirds, to infer the effect oil mercury exposure dice to differences in feeding ecology and the relative dependence em aquatic environments. Four generalist species occupying three different habitats were examined during the breeding season. Habitats: Brackish Water-saltwater (saltpans), brackish water-freshwater (ricefields anti some saltpans) and terrestrial environment (steppes). Species: Avocet (Recurvirostra avosetta), Black-winged Stilt (Himantopus himantopus), Kentish Plover (Charadrius alexandrinus) anti Cattle Egret (Bulbucus ibis). Chick feathers were collected at several locations between 2000 and 2003. Species used resources differently ill the environment, and distinct pathways were involved in the mobilization of mercury into food webs. The positive relationship between leather δ^N15 values and mercury levels indicated mercury bioaccumulation and biomagnification. Inter-specific variation in feather δ^C13 values revealed a different relative dependence among species on terrestrial vs. aquatic prey. Intra-specific variation in feather δ^C13 values also indicated differential use of marine inputs within each species, and within saltpans for Avocet chicks. Feather mercury levels and δ^C13 values suggested that the: relative use of marine-derived prey influences mercury levels in chicks

• Item Type: Articles
• Keywords: stable isotopes, trophic shift, carbon, nitrogen, mercury, birds, chicks
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Newton, Dr Jason and McGill, Dr Rona and Furness, Professor Robert
• Authors: Tavares, P.C., McGill, R.A.R., Newton, J., Pereira, E., Duarte, A.C., and Furness, R.W.
• Subjects: Q Science > QL Zoology; Q Science > QH Natural history > QH345 Biochemistry
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Waterbirds
• ISSN: 1524-4695
• ISSN (Online): 1938-5390