Abstract:

Avian and fish botulism outbreaks have been recorded since 1999 in eastern Lake Erie. These outbreaks are caused by Clostridium Botulinum type E, a toxin-producing bacteria that is found in anoxic substrates rich in organic material. We studied the environmental conditions present in eastern Lake Erie during 2002, a year when several botulism outbreaks were observed. We also tested for the presence of C. botulinum type E in lake sediments. Samples were taken at six stations from two sites of different depths in the Dunkirk (New York, USA) area. The depth of the sampling sites influenced physico-chemical and biological processes in the sediments. We used the quantitative polymerase chain reaction (Q-PCR) to quantify the levels of C. botulinum type E in the samples. Sediment samples contained a patchy distribution of type E spore concentrations (from not detectable to 5520 DNA copies/mg). Samples of benthic invertebrates tested positive for C. botulinum type E spores in tissues (Gammarus 2028 DNA copies/mg, oligochaetes 428 DNA copies/mg, chironomids 148 DNA copies/mg and dreissenid mussels 715 DNA copies/mg). Principal components analysis (PCA) from inshore stations indicated that a decrease in dissolved oxygen, pH and redox potential near the sediment was associated to an increase in specific conductance and the type E toxin gene in sediments. We also found that C. botulinum type E spores are present in sediments at different depths and at different times through the ice-free season.

Keywords: botulism; Lake Erie; dissolved oxygen; temperature; conductivity; bontE gene

Document Type: Research article

DOI: 10.1007/s10750-005-0011-1

Affiliations: 1: Email: fuenteap@fredonia.edu