Review of effects of water pollution on the breeding success of waterbirds, with particular reference to ardeids in Hong Kong.

Predatory waterbirds, such as ardeids, are susceptible to bioaccumulation of pollutants through the ingestion of contaminated food sources. High body burdens of contaminants, including PCBs, PAHs, cadmium, mercury, lead, copper, zinc and arsenic have been detected in many bird species worldwide. There is a paucity of literature, however, linking contaminant body burden and effects on reproductive success in waterbirds. This review is a synthesis of pertinent literature on this topic, with specific reference to contaminant residues in various tissue types, relationship between body burden and reproductive success, and the use of biomarkers to predict more serious adverse affects. The impetus for this review was the development of a conservation strategy and management plan (commissioned by the Agriculture, Fisheries and Conservation Department of Hong Kong Special Administrative Region (SAR)) for an important wetland in Hong Kong that supports many threatened waterbirds, including ardeids.

Disrupted patterns of behavior in natural populations as an index of ecotoxicity.

This paper examines behavioral changes in natural populations of wildlife associated with pollution. Although some changes such as lack of nest attentiveness and decreased nest defense have been noted, the results have not been consistent and have been difficult to relate to specific pollutants. Experimental studies involving lead, mercury, and organochlorine and organophosphate insecticides are described. Although changes in behavior have been observed, they are generally more difficult to quantify and are less reproducible than biochemical changes. To date, there is no clear evidence in wildlife that behavioral changes caused by pollutants are a serious threat to populations.

Do PCBs cause eggshell thinning?

The evidence that PCBs are involved in eggshell thinning is examined. In experiments in which both PCBs and DDE were used, it was found that DDE, but not PCBs, caused eggshell thinning of mallard and American kestrel. For two other species, bobwhite and Japanese quail, no thinning was observed with either agent. Numerous other studies with DDE alone have demonstrated that this agent can cause eggshell thinning in many, but not all, species. It is concluded that DDE is the only compound that has caused significant eggshell thinning at environmentally realistic doses.

The role of biomarkers in environmental assessment (1). Introduction.

A series of four papers, commissioned by the European Science Foundation, are presented on the state-of-the-art of the use of biomarkers in environmental assessment. These papers are phylogenetically based and cover invertebrates, vertebrates, plants and invertebrate populations and communities.

The role of biomarkers in environmental assessment (3). Vertebrates.

The most compelling reason for using biomarkers is that they can give information on the effect of pollutants rather than mere quantification of the levels present. The most critical aspect of environmental assessment is for society to decide how much damage it is prepared to tolerate. Once this is decided it is possible to devise tests to enforce these decisions. Suites of biomarkers have the potential to play an important role in environmental assessment.

Arctic marine ecosystem contamination.

The current state of knowledge of levels, spatial and temporal trends of contaminants in the Arctic marine ecosystem varies greatly among pollutants and among environmental compartments. Levels of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and some heavy metals such as mercury and lead, in Arctic marine mammals and fish are relatively well documented because of the need for comparisons with biota in more polluted environments and interest in the contamination of native diets. Levels of heavy metals, alkanes, polyaromatic hydrocarbons (PAH) and OCs in the Arctic Ocean are comparable to uncontaminated ocean waters in the mid-latitudes. But concentrations of alpha- and gamma-hexachlorocyclohexane (HCHs) are higher in northern waters far removed from local sources, possibly because lower water temperature reduces transfer to the atmosphere. Bioaccumulation of OCs and heavy metals in Arctic marine food chains begins with epontic ice algae or phytoplankton in surface waters. Polychlorinated camphenes (PCC), PCBs, DDT- and chlordane-related compounds are the major OCs in marine fish, mammals and seabirds. Mean concentrations of most PCBs and OC pesticides in ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic are quite similar indicating a uniform geographic distribution of contamination, although alpha-HCH showed a distinct latitudinal gradient in bears due to higher levels in zones influenced by continental runoff. Ringed seals from Spitzbergen have higher levels of PCBs, total DDT and polychlorinated dioxins/furans (PCDD/PCDFs). In contrast to other OCs, PCDD/PCDFs in Canadian Arctic ringed seals and polar bears were higher in the east/central Arctic than at more southerly locations. Remarkably high cadmium levels are found in kidney and liver of narwhal (Monodons monoceros) from western Baffin Bay (mean of 63.5 micrograms g-1) and western Greenland waters (median of 39.5 micrograms g-1). Mercury concentrations in muscle of ringed seal and cetaceans frequently exceed 0.5 microgram g-1 especially in older animals. Cadmium concentrations in polar bear liver increased from west to east, while mercury levels were higher in ringed seals from the western Canadian Arctic, which suggests that natural sources of these metals predominate. Studies of temporal trends in OCs in ringed seals and seabirds in the Canadian Arctic indicate PCB and DDT levels declined significantly from the early 1970s to the 1980s. There is a lack of temporal trend data for other OC pesticides as well as for heavy metals and hydrocarbons.(ABSTRACT TRUNCATED AT 400 WORDS)

Organochlorine contaminants in eggs of seabirds in the Northwest Atlantic, 1968-1984.

Eggs of three seabird species, double-crested cormorant (Phalacrocorax auritus). Leach's storm-petrel (Oceanodroma leucorhoa), and Atlantic puffin (Fratercula arctica) were collected at four-year intervals from 1968 to 1984, from colonies in eastern Canada and analyzed for organochlorines. This monitoring study was established to provide data on contamination of the marine environment and possible implications for seabird health. Long-term trend data are presented for PCBs, DDE, dieldrin, HCB, oxychlordane, heptachlor epoxide, HCH and mirex. DDE and PCBs declined significantly in all species from the Bay of Fundy. DDE declined significantly in puffins and petrels while PCBs declined only in petrels from the Atlantic coast of Newfoundland. Generally DDE declined more than PCBs. Dieldrin, oxychlordane, HCH and mirex levels decreased at some locations but were stable at others. Hexachlorobenzene and heptachlor epoxide levels remained steady or increased significantly, depending on the species and location. Organochlorine levels in cormorants from the St. Lawrence River estuary showed no significant trends.

Toxicological investigations of pollutant-related effects in Great Lakes gulls.

Reproductive failure of a number of fish-eating birds was observed on the Great Lakes in the mid-1960s to mid-1970s. The herring gull (Larus argentatus) has been used as the primary monitoring species. The low hatching success observed in this species on Lake Ontario in the mid-1970s was due to loss of eggs and failure of eggs to hatch. Egg exchange experiments demonstrated that this was due both to the incubation behavior of adults and to direct embryotoxic effects. Decrease of nest attentiveness was demonstrated using telemetered eggs, but attempts to reproduce the embryonic effects by injection of pollutant mixtures into eggs were not successful. Reproductive success improved rapidly during the late 1970s and was normal by the end of the decade. Recent studies have focused on cytogenetic and biochemical changes and detailed analytical chemistry of residues. No changes in the rate of sister chromatid exchange over values determined in coastal colonies were observed. Elevation of hepatic aryl hydrocarbon hydroxylase activity, levels of highly carboxylated porphyrins, and changes of thyroid function have been found. The geographic pattern of these changes indicates that they are caused by xenobiotics, but it has not been possible to relate the changes to a specific chemical.

Mixed-function oxidase activity in seabirds and its relationship to oil pollution.

1. The hepatic activity of epoxide hydrolase, aldrin epoxidase, aminopyrine N-demethylase, 7-ethoxyresorufin O-deethylase, benzo(a)pyrene 3-hydroxylase and UDP glucuronyl transferase was determined in adult herring gulls (Larus argentatus) at various stages of the breeding season. 2. MFO activity was measured for adult Leach's storm-petrels (Oceanodroma leucorhoa), guillemot (Uria aalge) and Atlantic puffins (Fratercula arctica). For most assays the values were highest for the puffin. 3. MFO activity in both nestling and adult Atlantic puffins was determined. The degree of induction caused by a single internal dose of Prudhoe Bay crude oil in adult puffins and that caused by multiple internal doses in nestling puffins was measured.

Biochemical and functional disturbances in red blood cells of herring gulls ingesting Prudhoe Bay crude oil.

Heinz body hemolytic anemia developed in Herring Gull (Larus argentatus) nestlings given oral doses of 10 ml of Prudhoe Bay crude oil per kilogram of body weight per day for 5 days. Associated disturbances in red blood cells were increased amounts of reduced glutathione (GSH), peroxidation of membrane lipids, an increase in membrane permeability, and a decrease in the oxygen-carrying capacity of cyanomethemoglobin-convertible hemoglobin. Among groups of gulls given different cumulative doses of oil over a 6-day period, significant covariance with dose and dependence on dose was demonstrated for packed cell volume, hemoglobin, and red cell GSH. Rapid defecation of oil by gulls indicated that the effective dose was substantially less than the administered dose. Pronounced damage to red cells occurred in some birds administered oil for only 2 days. These data imply that the toxic effects of ingested oil may contribute significantly to the morbidity and mortality of oil-contaminated birds.

Effects of ingestion of hibernia and Prudhoe Bay crude oils on hepatic and renal mixed function oxidase in nestling herring gulls (Larus argentatus).

Oral administration of Prudhoe Bay crude or Hibernia crude to nestling herring gulls increased the hepatic cytochrome P-450 content 4-fold. Concomitantly, there was an increase in various mixed-function oxidase and phase II enzyme activities. 7-Ethoxyresorufin O-deethylase was elevated 19-fold, benzo(a)pyrene 3-hydroxylase 6-fold, aniline hydroxylase 3-fold, and aminopyrine N-demethylase and uridine diphosphate glucuronyl transferase 2-fold. There was no change in reduced glutathione S-transferase activity. Renal mixed-function oxidase activities were also elevated. Herring gull livers contained very low levels of DT-diaphorase activity which was inducible 3- to 5-fold by oil administration.

Blood chemistry changes in food-deprived herring gulls.

Blood chemistry changes caused by food-stress was measured in fledgling herring gulls (Larus argentatus). Increases of corticosterone, T3, free fatty acids, glucose, cholesterol and alpha-amino n-butyric acid were observed. Significant decreases were found in the concentrations of 14 of the 26 free amino acids studied.

Heinz-body hemolytic anemia from the ingestion of crude oil: a primary toxic effect in marine birds.

Hemolytic anemia developed in young herring gulls and Atlantic puffins given daily oral doses of a Prudhoe Bay crude oil. Anemia developed 4 to 5 days after the initiation of oil ingestion and was accompanied by Heinz-body formation and a strong regenerative response. The data evince a toxic effect on circulating red blood cells involving an oxidative biochemical mechanism and the first clear evidence of a primary mechanism of toxicity from the ingestion of crude oil by birds.