T7 PM Metals and Bioaccumulation
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 327-329

(GAL-1117-863133) Tree Swallows nesting in Calumet, IL as an indicator of contaminant transfer from aquatic to terrestrial systems.

Gallo, S^{1, 2}, Levengood, J¹, Soucek, D¹, Hill, W¹, Talbot, J³, Bordson, G³, ¹ Illinois Natural History Survey, Champaign, IL, USA² University of Illinois at Urbana-Champaign, Champaign, IL, USA³ Illinois Waste Management and Research Center, Champaign, IL, USA

ABSTRACT- Tree Swallows (Tachycineta bicolor) nesting near wetlands are widely recognized as useful biomonitors of sediment contaminants due to their tolerance of contaminants and their tendency to feed on emergent aquatic insects. We studied Tree Swallows nesting at two contaminated wetlands and one reference site in the highly industrialized Calumet region of Chicago, Illinois, to evaluate potential impacts from trophic transfer of contaminants from sediments and emergent aquatic insects. Total mean mercury levels in Tree Swallow eggs varied significantly by site ranging from 112 to 232 ppb dry weight, with similar levels in nestlings. Egg mercury levels were positively correlated with nest initiation date (r = 0.73861, p<0.0001) and negatively correlated with brood size (r =-0.54446, p=0.0009) across all sites. Generally, mean aquatic insect metal concentrations at the sites are much higher than the mean metal concentrations in both the swallow nestlings and eggs, with lead, manganese and iron being an order of magnitude higher. Copper levels in the emergent aquatic insects were 2 to 5 times higher than eggs and nestlings, with values between 19 to 30 ppm dry weight. Isotope analysis and additional diet analysis will be employed to quantify the difference between expected and observed concentrations in trophic levels.

Key words: trophic transfer, tree swallows, aquatic insects, metals