Contaminant Concentrations and Biomarker Response in Great Blue Heron Eggs From 10 Colonies on the Upper Mississippi River, Usa

Abstract

In 1993, great blue heron (Ardea herodias; GBH) eggs were collected from 10 colonies on the upper Mississippi River (UMR). They were then artificially incubated until pipping and analyzed for mercury, selenium, and organochlorines. Livers of embryos were analyzed for hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity and four measures of oxidative stress. Brains were measured for asymmetry and blood was measured for the coefficient of variation of DNA (DNA CV). Organochlorine concentrations were generally low (geometric mean DDE ϭ 1.3 g/g wet weight; polychlorinated biphenyl [PCB] ϭ 3.0 g/g; 2,3,7,8-tetrachlorodibenzo-p-dioxin [TCDD] ϭ 11.5 pg/g). Eggshell thickness was negatively correlated with DDE concentrations. Mercury (geometric mean ϭ 0.8 g/g dry weight) and selenium (3.1 g/g dry weight) concentrations in GBH eggs were within background levels. EROD activity was not correlated with total PCBs, TCDD, or toxic equivalents (TEQs), based on the relative contribution of individual PCB congeners, dibenzodioxins (PCDDs), and dibenzofurans (PCDFs) to total calculated TEQs. Three of the four measures of oxidative stress were correlated with mercury concentrations. Twenty of 43 (47%) embryo brains were asymmetrical and the embryos with asymmetrical brains had higher EROD concentrations in the liver and higher DNA CV in the blood than embryos with symmetrical brains.

Contamination and Biomarkers in the Great Blue Heron, an Indicator of the State of the St. Lawrence River

“…Sampling of various types of feathers in these studies could explain part of these differences. PCBs and OC levels in heron eggs from the St. Lawrence River were comparable to those from other studies and lower than levels at which reproductive effects have been documented (Elliott et al, 1989;Blus, 1996;Hoffman et al, 1996;Custer et al, 1997;Thomas and Anthony, 1999). Levels of PCBs and most OCs in heron eggs declined by about one third since 1979 (Laporte, 1982), although levels of dieldrin and p,p¢-DDE from Ile du Bic appear unchanged.…”

“…Mean (standard deviation * ) concentrations of mercury in feathers (lg/g dry weight) and mercury (lg/g wet weight), total PCBs and selected organochlorines (lg/kg wet weight) in whole blood of great blue heron fledglings collected in [1996][1997] observed in blood and feather mercury levels or in PCB levels in eggs and blood (Champoux et al, 2002). Despite this decline, Hg levels in eggs were still higher or comparable to other published levels for great blue heron eggs from various locations in North America (Elliott et al, 1989;Custer et al, 1997;Thomas and Anthony, 1999). Mercury levels in blood were also high compared to other published data for nestlings of various piscivorous species (Sepuvelda et al, 1999).…”

“…The great blue heron (Ardea herodias) has been widely used as an indicator species (DesGranges, 1979;Elliott et al, 1989Elliott et al, , 2001aCuster et al, 1997;Thomas and Anthony, 1999) because of its distribution in both marine and freshwater environments, the accessibility of its colonies and its strategic position at the top of the food chain. Between 1991 and 1993, we conducted studies to select indicators of exposure and effects of sublethal concentrations of contaminants in the St. Lawrence River in order to develop a biomarker-based biomonitoring program.…”

An evaluation of the effects of persistent environmental contaminants on the reproductive success of Great Blue Herons (Ardea herodias) in Indiana

“…Colony means of total PCBs ranged from 577 to 9,169 ppb in the current study; these values are consistent with those reported to have no observed impact on reproductive success (Custer et al 1997;Halbrook et al 1999;Harris et al 2003;Nosek and Faber 1984;Sample and Suter 1999). The dominant PCB congeners measured in the current study are similar to those reported in GBH eggs studied elsewhere (Custer et al 1997(Custer et al , 1998Harris et al 2003;Mora 1996).…”

Trace Element Concentrations and Bioindicator Responses in Tree Swallows from Northwestern Minnesota

“…In both laboratory and field studies of birds, oxidative stress measures have been associated with Hg and selenium (Se) contamination (Custer et al, 1997(Custer et al, , 20002003a, b, 2005Hoffman and Heinz, 1998;. Chromosomal damage in birds has been associated with industrialized urban sites (Yauk and Quinn, 1996) as well as Cd exposure related to mining (Custer et al, 2003a).…”