Microbial Infections Are Associated with Embryo Mortality in Arctic-Nesting Geese

Abstract

ABSTRACTTo address the role of bacterial infection in hatching failure of wild geese, we monitored embryo development in a breeding population of Greater white-fronted geese (Anser albifrons) on the Arctic Coastal Plain of Alaska. During 2013, we observed mortality of normally developing embryos and collected 36 addled eggs for analysis. We also collected 17 infertile eggs for comparison. Using standard culture methods and gene sequencing to identify bacteria within collected eggs, we identified a potentially novel species ofNeisseriain 33 eggs,Macrococcus caseolyticusin 6 eggs, andStreptococcus uberisandRothia nasimuriumin 4 eggs each. We detected seven other bacterial species at lower frequencies. Sequences of the 16S rRNA genes from theNeisseriaisolates most closely matched sequences fromN. animalorisandN. canis(96 to 97% identity), but phylogenetic analysis suggested substantial genetic differentiation between egg isolates and knownNeisseriaspecies. Although definitive sources of the bacteria remain unknown, we detectedNeisseriaDNA from swabs of eggshells, nest contents, and cloacae of nesting females. To assess the pathogenicity of bacteria identified in contents of addled eggs, we inoculated isolates ofNeisseria,Macrococcus,Streptococcus, andRothiaat various concentrations into developing chicken eggs. Seven-day mortality rates varied from 70 to 100%, depending on the bacterial species and inoculation dose. Our results suggest that bacterial infections are a source of embryo mortality in wild geese in the Arctic.