Algal toxins?Initiators of avian botulism?

Abstract

An outbreak of avian botulism in Whitewater Lake, Manitoba, Canada was associated with reducing sediments. But any linkage between sediments and botulism was only indirect; Clostridium botulinum was not observed in the sediments. The source of the C. botulinum was unclear but carcasses that overwintered appeared to perpetuate the outbreak. The algal toxins anatoxin-a and ( ) microcystin-LR were present 17 ( mg/ L when many birds were moulting and unable to fly, likely making them more sensitive to botulism. The sediment anoxia released phosphorus into lakewater so that concentrations increased from about 73 to 470 mg/ L and enhanced growth of Microcystis and Aphanizomenon. Wind resuspension of sediments resulted in areas with more algal biomass and associated algal toxins. ᮊ

Environmental Factors Influencing the Prevalence of a Clostridium botulinum Type C/D Mosaic Strain in Nonpermanent Mediterranean Wetlands

“…These factors include temperature, salinity of the substrate, pH, redox potential (of the surface water and soil/sediment pore water), dissolved oxygen level, and sediment/soil organic matter content (24,45,46). Moreover, large epidemic outbreaks are favored by the presence of botulism intoxicated avian carcasses and the maggots that feed on them.…”

Influence of Limnological Conditions on Clostridium Botulinum Type E Presence in Eastern Lake Erie Sediments (Great Lakes, USA)

“…However, the lake conditions reported in this study indicate that physico-chemical and biological changes occurred through the sampling season, and we found that the significant correlations in the study were in agreement with other studies' environmental findings in relation to the ecology of C. botulinum (Huss et al, 1979;Rocke & Samuel, 1999;Murphy et al, 2000). The nearsediment conditions we studied have not been reported previously for Lake Erie in connection with a botulism outbreak-year.…”

Eutrophication and Bacterial Pathogens as Risk Factors for Avian Botulism Outbreaks in Wetlands Receiving Effluents from Urban Wastewater Treatment Plants

“…Other authors have also observed links between changes in environmental characteristics of wetlands that can be due to eutrophication and botulism. Murphy et al (40) found that a change in the water Eh in Whitewater Lake (Canada) might have been a significant factor in the development of C. botulinum type C in its sediments. Rocke et al (41) found that increasing temperature and biomass may influence the initial phase of botulism outbreaks and that these were more frequent in wetlands with lower Eh.…”