An experimental study on the effects of polymorphiasis in common eider ducklings

Eight common eider (Somateria mollissima) ducklings were experimentally inf ected from 1 lune through 13 June, 1995 with acanthocephalans (Polymorphus minutus) by allowing the birds to feed on Gammarus spp. (Gammarus oceanicus , G. salinus, G. zaddachi, and G. lacustris) containing acanthocephalan cys tacanths. Uninfected Gammarus spp, were fed to a control group of seven duc klings. No mortality of ducklings occurred during the experiment. However, the infected ducklings gained weight more slowly than the control birds. Af ter the 2 wk study period, the mean serum concentrations of total protein, albumin, beta-globulin, gamma-globulin, fructosamine and creatine kinase we re lower in the infected group than in the controls. The mean (+/-SE) numbe r of acanthocephalans in the intestine of the infected ducklings was 21 (+/ -4). The parasites were attached to the mucosa of the posterior small intes tine of the infected ducklings with a mixed inflammatory reaction consistin g of heterophils and mononuclear lymphocytes surrounding the attachment sit es.