Date:March 25, 2016
Source:American Society for Microbiology
Outbreaks of botulism killed large percentages of waterbirds inhabiting a wetland in Spain. During one season, more than 80 percent of gadwalls and black-winged stilts died. The botulinum toxin's spread may have been abetted by an invasive species of water snail which frequently carries the toxin-producing bacterium, Clostridium botulinum, and which is well adapted to wetlands polluted by sewage. Global warming will likely increase outbreaks, said corresponding author Rafael Mateo, PhD. The research was published March 25th in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.
Botulism is a major killer of waterbirds, including some endangered species. In earlier studies, some also published inApplied and Environmental Microbiology, these investigators had found that eutrophication of some of these wetlands, due to effluent from waste water treatment plants, was encouraging growth of C. botulinum and other bacterial pathogens of birds.
In the current study, the investigators surveyed mortality among the resident waterbirds, and investigated how the bacterium is spread. During two outbreaks, the investigators collected 43 dead white-headed ducks, representing seven percent and 17 percent of their maximum population on Navaseca lake during 2011 and 2012, respectively, said Mateo, who is Head of the Group of Wildlife Toxicology, at the Spanish Institute of Game and Wildlife Research, Cuidad Real, Spain. White-headed ducks are highly endangered, with only about ten thousand surviving individuals worldwide.