Bacteria in the Clear Lake Preservation Area near Minden, Ontario, Canada

As the bacterial count in the Clear Lake Conservation Area has increased since 2000 we wanted to compare the values for 2006 in early May and later after the long Victoria Day weekend, when boat traffic was intense, to find out if very big motor boats could be the cause of the increased bacterial count.

Bacteria in the Clear Lake Preservation Area near Minden, Ontario, Canada Dr Alicja Zobel, James Nigshwander As the bacterial count in the Clear Lake Conservation Area has increased since 2000 we wanted to compare the values for 2006 in early May and later after the long Victoria Day weekend, when boat traffic was intense, to find out if very big motor boats could be the cause of the increased bacterial count. On July 06, 2006, after long weekend, the number of counted bacteria was the highest it had been for the last 6 years. It was 70 times that of June 29th, May 23rd or May 3rd, 2006. In the winter of 2005 the coliform count was reduced, and then on May 3rd 2006 the values of E. coli were zero at all sites and the coliform count was 4-17 depending on the site. On May 23rd values were 14-47 for coliform and still no E.coli. But on June 29th the values of E.coli had increased, reaching 1-8, but still in the middle of the lake and at one of the campsites the values of E. coli were zero. However in July just after the intensive boat traffic of the Canada Day holiday the values increased dramatically. Two cottages showed 680 and 400 coliform bacteria and 4 and 1 E. coli, strongly supporting the theory that coliforms came from the sediment through water movement due to the power boats rather than from animal excrement, which would also increase the E. coli levels, but they were only 4 and 1. Two campsites showed 520 and 540 coliforms, and 10 and 1 E.coli. What is interesting is that the two cottages which used no motor boats showed only 11 and 25 coliforms, and 1 and zero E.coli, suggesting that their water movements, not produced by big motors, were too weak to roil the water and release bacteria. Middle-lake waters, taking east-west traffic of motorboats, showed 220 coliforms but no E.coli. We concluded that increased bacterial contamination, approaching the maximum level of 1000 coliforms allowed in Canada, was caused by stirring up the lake bottom sediments by intensive motor boat traffic. We shall continue collecting data after coming long weekends. Introduction E.coli’s great genomic plasticity allowed it to occupy new niches of the envi-ronment, both in the human body and the outside environment such as lakes. Scientists found that E. coli can live in animals and in lakes, surviving very low pH in our stomachs, as well as temperature shifts, heavy metal contamination and other microbes in the environment, waiting for the opportunity to re-enter the animal body, where the conditions are the best with the right proportions of minerals and food and stable temperature. The fresh water environment with changing tempera-ture is not optimal for E.coli, and for a long time scientists hoped that E. coli would die over the winter, but now we know that not only some strains survive but because they are exposed to harsh conditions they adjust by new mutations, become stronger and some strains can become more pathogenic for humans. Thus we should be now more concerned about water contamination with E. coli, especially of water we could drink or swallow, e.g., during swimming. For sure we do not want to convert the lake our cottage is on into a cesspool in which we could not even swim or allow to splash on body openings (e.g. eyes) and scares be exposed to water with E. coli. Infection causes production of toxins, very potent — surviving antibiotic treatment, and that way killing people. The purpose of the toxin is to let E. coli strain survive the competition from other microbes. The action of citizens to have E. coli counted in our lakes is a great idea. The contamination in big lakes is difficult to explain because of many inflows and for other reasons. The small headwater lakes are more easily isolated. Clear Lake near Minden, Ontario, Canada has been ideal for research on occasional E.coli contamin-ation, being isolated water of small area and having been studied by Trent University scientists since 1968. In view of the many people who died in the Walkerton disaster, the aim of this study was to evaluate the E.coli count in 2004 immediately after the Labour Day weekend after intense human activities at the lake, on 22 of September, three weeks after what could be recovery time, and on November 17 after human activities had ceased.

Alicja Zobel, James Nigshwander