USGS


Studies on the Use of Biomarkers of PCB Exposure and Effect in Tree Swallows (Tachycineta bicolor) in the Eastern Region of the Biological Resources Division (BRD) - USGS



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Photo of Tree Swallows

Photo of Study Site Area in Pennsylvania

Mark J. Melancon and Amy L. Yorks
Patuxent Wildlife Research Center, Biological Resources Division - USGS, Laurel, MD.

ABSTRACT

This study was developed in response to a request by the State of Pennsylvania and the BRD cooperative fish and wildlife research unit at Pennsylvania State University for an approach to evaluate possible harm to avian wildlife from Photo of PCB Warning SignPolychlorinated Biphenyls (PCBs) in contaminated habitats. Separate studies deal with aquatic organisms with mammalian species. Meetings and discussions leading to the development of this study included participation by several Pennsylvania state agencies, several BRD facilities, the Fish and Wildlife Service and the National Park Service.

The goals of this study are: 1 -To develop several biomarkers for PCB exposure in nestling Tree swallows; 2-To collect nestling Tree swallows from a number of sites with a range of PCB concentrations and assess biomarkers, PCB concentrations and reproductive and other health-related parameters; 3-To utilize these data to evaluate any detrimental effects of PCBs on reproduction and on the nestling Tree swallows, and to field validate the biomarkers for PCB exposure and effect in this species; and 4-To prepare a summary of these results that will be of value to game management staff in assessing possible harm to wildlife by PCB contamination.

Tree swallows were selected as the species to study because they can be attracted to nest boxes, have reasonably limited feeding areas, are found in Pennsylvania, and are likely to be exposed to PCB contamination by their feeding habits.

Control sites include the Patuxent Wildlife Research Center and Blue Marsh Lake, located approximately 5 miles northwest of Reading in Berks County, Pennsylvania. Five study sites in Pennsylvania were selected because of known or possible contamination. These study sites include two compressor sites, Bernville and Bechtelsville, located in Berks County, Pennsylvania. Another site is located west of Norristown, Pennsylvania in Valley Forge National Historical Park. Valley Forge National Historical Park is in both Montgomery and Chester Counties. There are two sites located near the Philadelphia International Airport in Pennsylvania. Fort Mifflin is situated at the confluence of the Schuylkill and Delaware Rivers and the Tinicum Marsh site is located along Darby Creek, south of the airport. Also, there are two superfund sites (in Indiana and New York).

Mark J. Melancon
Patuxent Wildlife Research Center
12011 Beech Forest Road
Laurel, Maryland 20708-4041
voice: 301-497-5710
fax 301-497-5675
internet: Mark_Melancon@usgs.gov

BACKGROUND

Although PCBs are not currently manufactured they are found in many places because of past use patterns. Most field studies of effects of PCBs on avian species have dealt with waterbirds that consume contaminated fish and predators such as eagles which prey upon both fish and other avian fisheaters. Little has been done to study the effects of PCBs on avian species that would be present at inland PCB contamination sites in quantities that would permit their use as a sentinel or biomarker species to evaluate possible harm at such sites. Photo of Nest Box near StreamThe ability of wildlife managers to evaluate possible or actual harm caused by PCBs in the environment would be improved by information linking environmental levels of PCBs, tissue levels of PCBs in wildlife, biomarker responses, and actual harm (death, reduced reproductiion, etc.) in other species.

In a joint project with the Pennsylvania Game Commission, the Pennsylvania Cooperative Fish and Wildlife Research Unit, National Park Service, and Fish and Wildlife Service we are studying these relationships in tree swallows. Another project will examine these relationships in shrews. These projects in turn are related to another project in which the Pennsylvania Fish and Boat Commission, the Pennsylvania Cooperative Fish and Wildlife Research Unit, BRD and others are studying similar relationships for aquatic organisms.

SPECIFIC OBJECTIVES

1. To develop several biomarkers for PCB exposure in nestling tree swallows (Cytochromes P450, developmental abnormalities, and indicators for sex hormone modifications).

2. To collect nestling tree swallows from sites with a range of PCB concentrations and to assess biomarkers, PCB concentrations and reproductive and other health-related parameters.

3. To evaluate any detrimental effects of PCBs on reproduction and on the nestling tree swallows, and to field validate the biomarkers for PCB exposure and effect in this species.

4. To prepare a summary of these results for use by game managers and others in assessing possible harm to wildlife by PCB contamination.

OVERALL APPROACH

Tree swallows were selected for study because they can be attracted to Photo of Nest Boxnest boxes, have limited feeding areas, are widespread, and are likely to be exposed to PCB contamination by their feeding habits. Eight locations ranging from essentially no PCB contamination to high contamination have been selected, with Patuxent serving as an additional control location.

Eggs and nestling tree swallows produced in nest boxes at Patuxent were administered PCBs and prototype inducers of cytochromes P450 to provide tissue for methods development and to provide estimates of the responsiveness of the biochemical and physiological parameters being studied.

It is important to distinguish between effects due to PCBs present in the egg, and due to PCBs that the nestlings obtain from their food at the site. PCB analysis of one egg from each of 6 nests at each site will provide initial body burdens for the nestlings. The body burdens of PCBs in the nestlings at the time of sacrifice can be compared to these values to assess whether there has been accumulation of PCBs at the site by the nestlings. (Crop contents will be examined for the types of invertebrates present.)

DATA & SAMPLE COLLECTION

The field data collected included clutch size, hatching rate and overall survival rate. General appearance (ie. presence of any gross abnormalities) was assessed and total body weight and tibia, culmen, and wing chord length measured. One nestling per nest was sacrificed and in the first field season the remaining nestlings were banded.

Gonads - gross and histological examination.

Heads - brain removal and measurement.

Livers - cytochrome P450 assay.

Skin and heart - cytochrome P450 immunohistochemistry.

Carcass (less stomach contents) - PCB analysis.

Carcasses re-examined in lab for gross abnormalities before chemical analysis.

Stomach contents - from each site pooled for PCB analysis.

Sediment samples - from selected sites for PCB analysis.

Study Areas

Bernville Pumping Station, Texas Eastern Transmission Corp., Berks Cty, PA

Bechtelsville Pumping Station, Texas Eastern Transmission Corp., Berks Cty, PA

Blue Marsh Lake, Berks County, PA

Valley Forge Natl. Historical Park, Montgomery & Chester Cties, PA

Fort Mifflin, Philadelphia, PA

John Heinz National Wildlife Refuge, Philadelphia, PA

Winston-Thomas Superfund Site, Bloomington , IN

Hudson River, Glens Falls, NY

Patuxent Wildlife Research Center, Laurel, MD

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