Effects of white phosphorus on mallard reproduction

Extensive waterfowl mortality involving thousands of ducks, geese, and swan s has occurred annually at Eagle River Flats, Alaska, USA, since at least 1 982. The primary agent for this mortality has been identified as white phos phorus. Although acute and subacute lethality have been described, subletha l effects are less well known. This study reports on the effects of white p hosphorus on reproductive function in the mallard (Anas platyrhynchos)in ca ptivity. Fertility, hatching success, teratogenicity, and egg laying freque ncy were examined in 70 adult female mallards who received up to seven dail y doses of 0, 0.5, 1.0, and 2.0 mg/kg of white phosphorus. Measurements of fertility and hatchability were reduced by the white phosphorus. Teratogeni c effects were observed in embryos from hens dosed at all treatment levels. Egg laying frequency was reduced even at the lowest treatment level; treat ed hens required a greater number of days to lay a clutch of 12 eggs than c ontrol hens. After two doses at 2.0 mg/kg, all females stopped laying compl etely for a minimum of 10 d, and laying frequency was depressed for at leas t 45 d. Fertility of 10 adult male mallards dosed with 1.0 mg/kg of white p hosphorus did not differ from 10 controls, but plasma testosterone levels w ere significantly (p < 0.05) reduced in the treated males 1 d after dosing ended. These results provide evidence that productivity of free-ranging mal lards may be impaired if they are exposed to white phosphorus at typical fi eld levels.