Enhanced reproduction in mallards fed a low level of methylmercury: An apparent case of hormesis

  title={Enhanced reproduction in mallards fed a low level of methylmercury: An apparent case of hormesis},
  author={Gary H. Heinz and David J. Hoffman and Jon D. Klimstra and Katherine R. Stebbins},
  journal={Environmental Toxicology and Chemistry},
Breeding pairs of mallards (Anas platyrhynchos) were fed a control diet or a diet containing 0.5 µg/g mercury (Hg) in the form of methylmercury chloride. There were no effects of Hg on adult weights and no overt signs of Hg poisoning in adults. The Hg‐containing diet had no effect on fertility of eggs, but hatching success of eggs was significantly higher for females fed 0.5 µg/g Hg (71.8%) than for controls (57.5%). Survival of ducklings through 6 d of age was the same (97.8%) for controls and… 

Reproduction in mallards exposed to dietary concentrations of methylmercury

It is concluded that mallard reproduction does not appear to be particularly sensitive to methylmercury, and the mercury concentrations in eggs may be more useful in extrapolating to possible harmful effects in nature than are the dietary levels the authors fed.

Hormesis Associated with a Low Dose of Methylmercury Injected into Mallard Eggs

The finding of hormesis when a low dose of methylmercury was injected into eggs agrees with a similar observation in a study in which a group of female mallards was fed a low dietary concentration of methylMERcury and hatching of their eggs was significantly better than that of controls.

Survival of White Ibises (Eudocimus albus) in response to chronic experimental methylmercury exposure

Results suggest many survival studies have been confounded by seasonal depuration through molt, and variation in exposure rates, and future studies concentrate on evaluating survival effects during nonmolting periods in species for which methylmercury exposure is relatively constant.

Toxicity reference values for methylmercury effects on avian reproduction: Critical review and analysis

A comprehensive review of methylmercury (MeHg) effects on bird reproduction, evaluating laboratory and field studies in which observed effects could be attributed primarily to Hg, concludes that species not yet tested for MeHg toxicity should be evaluated using toxicity data from tested species with similar body weights.

Interactions between methylmercury and selenomethionine injected into mallard eggs

Selenomethionine appeared to be more embryotoxic than equivalent doses of methylcury when injected into eggs, and both injected methylmercury and selenometHionine were more toxic to mallard embryos than when deposited naturally in the egg by the mother.


Effects of mercury (Hg) on birds have been studied extensively and with increasing frequency in recent years. The authors conducted a comprehensive review of methylmercury (MeHg) effects on bird

Tissue Mercury Concentrations and Survival of Tree Swallow Embryos, Nestlings and Young Adult Females on a Contaminated Site

Tree swallows nesting on mercury-contaminated sites along the South River in Virginia, USA were monitored for reproductive success and mercury had its greatest effect on these songbirds during the nestling stage, whereas for embryos or first-time breeding females, other factors likely played larger roles in mortality.

To breed or not to breed: endocrine response to mercury contamination by an Arctic seabird

High mercury concentration could affect the ability of long-lived birds to modulate their reproductive effort according to ongoing environmental changes in the Arctic, thereby impacting population dynamics.

Impact of Mercury Exposure on Birds and the Effect of Molt on Mercury Depuration in Songbirds

The first investigation of the depuration of mercury from songbird tissues and the impact of molt on the speed with which mercury is eliminated from tissues is attempted, confirming that molting expedites depuration, and suggesting that migration/dispersal behavior and molt timing must be taken into consideration during risk assessment.



Methylmercury: Reproductive and behavioral effects on three generations of mallard ducks

Ducks from parents fed methylmercury were less responsive than controls to tape-recorded maternal calls, but were hyper-responsive to a frightening stimulus in avoidance tests; there were no significant differences in locomotor activity in an open-field test.

Effects of methylmercury on reproduction in American kestrels

The estimated decline in fledged young per pair for kestrels consuming 0.7 mg/kg dry weight of mercury (Hg) raises concerns about population maintenance in areas subject to high inputs of anthropogenic Hg.

Embryotoxic Thresholds of Mercury: Estimates from Individual Mallard Eggs

  • G. HeinzD. Hoffman
  • Environmental Science
    Archives of environmental contamination and toxicology
  • 2003
Although embryo mortality was seen in eggs estimated to contain as little as 0.74 μg/g mercury, there were considerable differences in the sensitivity of mallard embryos, especially from different parents, with some embryos surviving as much as 30 or more μg/G mercury in the egg.

Patterns of common loon (Gavia immer) mercury exposure, reproduction, and survival in wisconsin, USA

No relationship was observed between levels of adult Hg exposure and reproductive performance or annual adult return rates (an index of survival); however, chick production was lower at lakes where chick blood Hg concentrations were elevated.


Males of two breeds of chickens, Single Comb White Leghorns (SCWL) and broiler-type, were fed rations containing eight levels of added mercury from methyl mercury dicyandiamide (0.0, 0.33, 0.66,

Methylmercury exposure associated with reduced productivity in common loons

Lake pH, mercury (Hg) concentrations in small fish, blood Hg levels in adult male, female and juvenile common loons, and loon productivity from 120 lakes in Wisconsin, USA and New Brunswick and Nova Scotia, Canada (Maritimes) were measured.

Effects of methylmercury and spatial complexity on foraging behavior and foraging efficiency in juvenile white ibises (Eudocimus albus).

A nonlinear dose-response relationship at low levels of methylmercury exposure is suggested, and this appears to be the first experimental demonstration of the effects of habitat complexity on foraging efficiency in long-legged wading birds.

Mercury, Methylmercury, and Selenium Concentrations in Eggs of Common Loons (Gavia immer) from Canada

A weak but significant positive correlation was observed between egg-Hg and -Se concentrations and this relationship was unexpected and was contrary to relationships established for organic and inorganic Hg vs. Se in adult loon liver and kidney tissue.

Adverse effects from environmental mercury loads on breeding common loons

The common loon is used as an upper trophic level bioindicator of aquatic Hg toxicity in freshwater lakes to measure significant changes related to elevated MeHg body burdens, including aberrant incubation behavior, lethargy, and wing area asymmetry.

Effects of Environmental Methylmercury on the Health of Wild Birds, Mammals, and Fish

Abstract Wild piscivorous fish, mammals, and birds may be at risk for elevated dietary methylmercury intake and toxicity. In controlled feeding studies, the consumption of diets that contained Hg (as