Toxins in Great Blue Herons Eggs an indicator of contaminants in the Georgia Basin

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Map of the Great Blue Heron Colonies in the Georgia Basin

Since the late 1970s, Environment Canada has measured toxin levels at 21 colonies in the Georgia Basin. Of these colonies, three areas were chosen for in-depth monitoring, reflecting urban (UBC), industrial (Crofton) and rural (Nicomekl) habitats.

UBC
A colony in the UBC Endowment Lands was chosen to represent non-point source urban influences. This site is in a 763 ha urban park near Greater Vancouver (which contains over 1.8 million people). Herons from the UBC colony forage primarily in the slower waters of the lower Fraser River and its estuary, as well as along the Spanish Banks shoreline. Thus, the toxin load experienced by these herons reflects industrial development throughout the Fraser Basin, including ten pulp and paper mills, as well as urban influences from the City of Vancouver.

Crofton
A heron colony at Crofton was the principal study population to examine the effects of toxins from the pulp and paper industry. This colony was located on a small island north of log-sorting grounds, about 1 km from a bleached kraft pulp and paper mill. Herons were routinely observed feeding in the intertidal area adjacent to the underwater effluent discharge pipeline.

Nicomekl
The Nicomekl River colony was chosen to reflect the rural environment, and as such is a reference population geographically removed from both urban environments and pulp and paper mills. It is located in a rural agricultural setting, but away from intensively managed croplands. Herons from Nicomekl fed in the eelgrass-dominated intertidal zone of Mud and Boundary Bays. Although near to the Fraser River, the waters of these feeding grounds are isolated from the estuary and river mixing zones by oceanographic processes.

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Map of the Fraser River Watershed and Georgia Basin

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Organochlorine pesticides in Great Blue Heron eggs

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Toxic Equivalents (TEQs) of industrial organochlorines in Great Blue Herons eggs

* denotes years where TEQ values for dioxins and furans were not measured.

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References used in the Toxins in Great Blue Heron Eggs indicator:

• Bellward, G.D., R.J. Norstrom, P.E. Whitehead, J.E. Elliott, S.M. Bandiera, C. Dworschak, T. Chang, S. Forbes, B. Cadario, L.E. Hart and K.M. Cheng. 1990. Comparison and polychlorinated dibenzodioxin levels with hepatic mixed-function oxidase induction in Great Blue Herons. Journal of Toxicology and Environmental Health. 30:33-52.
• Custer, T.W., G.L. Hensler and T.K. Kaiser. 1983. Clutch size, reproductive success, and organochlorine contaminants in Atlantic coast Black-crowned Night Herons. Auk 100:699-710.
• Elliott, J.E., R.W. Butler, R.J. Norstrom and P.E. Whitehead. 1989. Environmental contaminants and reproductive success of great blue herons (Ardea herodias) in British Columbia, 1986-1989. Environ. Pollut. 59:91-114.
• Elliott, J.E., R.J. Norstrom and J. Smith, 1996. Patterns, trends and toxicological significance of chlorinated hydrocarbon and mercury contaminants in Bald Eagle eggs from the Pacific coast of Canada. Archiv. Environ. Contam. Toxicol. 31:354-367.
• Elliott, J.E., M.L. Harris, L.K. Wilson, P.E. Whitehead and R.J. Norstrom. 2001. Monitoring temporal and spatial trends in polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in eggs of Great Blue Heron (Ardea herodias) on the coast of British Columbia, Canada, 1983-1998. Ambio Vol. 30 No. 7, 416-428 Nov. 2001.
• Elliott, J.E., P. Shaw and D. Muir. 2002. Factors influencing domestic and international sources of chlorinated hydrocarbons to fish and ospreys in British Columbia. Toxic Substance Research Initiative TSRI # 224. 64pp.
• Harris, M.L., J.E. Elliott, R.W. Butler and L.K. Wilson. 2002. Reproductive success and chlorinated hydrocarbon contamination of resident great blue herons (Ardea herodias) from Coastal British Columbia, Canada, 1977 to 2000. Environmental Pollution 121: 207-227.
• Hart, L.E., K.M. Cheng, P.E. Whitehead, K.M. Shah, R.J. Lewis, S.R. Rushkowski, R.W. Blair, D.C. Bennett, S.M. Bandiera, R.J. Norstrom and G.D. Bellward. 1991. Dioxin contamination and growth and development in Great Blue Heron embryos. Journal of Toxicology and Environmental Health. 32:331-344.
• Hoffman, D.J., B.A. Rattner, C.M. Bunck, A. Krynitsky, H.M. Ohlendorf and R.W. Loew. 1986. Association between PCBs and lower embryonic weight in Black-crowned Night Herons in San Francisco Bay. J. Toxicol. Environ. Health 19:383-391.
• Moul, I.E. 1990. Environmental contaminants, disturbance and breeding failure at a Great Blue Heron colony on Vancouver Island. M.Sc. thesis, University of British Columbia, Vancouver, BC. 59pp.
• Sanderson, J.T., J.E. Elliott, R.J. Norstrom, P.E. Whitehead, L.E. Hart, K.M. Cheng and G.D. Bellward. 1994. Monitoring biological effects of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls in Great Blue Heron chicks (Area herodias) in British Columbia. J. Toxicol. Environ. Health. 41:435-450.
  
• Wilson, L.K., J.E. Elliott and P.E. Whitehead. 1996. Chlorinated compounds in wildlife from the Fraser River Basin. Technical Report Series Number 251. Pacific and Yukon Region, Canadian Wildlife Service, Environmental Conservation Branch. 73pp.

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