Sediment at Murray and Parlee beaches suggested as source of bacteria spike

Accumulated contamination in the sediment of Murray and Parlee beaches might be the source of high levels of E. coli and enterococcus bacteria in water samples taken for testing, a Mount Allison University biology professor says.

Some test results this summer have shown bacteria counts at both beaches exceeding the acceptable limit, leading the government to post no-swimming advisories.

Murray Beach reopened to the public on Wednesday, while an advisory remained up at Parlee Beach after high bacteria counts closed both beaches on Monday. 

No new samples have been taken since July 24, according to the government website.  ​

A spike in bacteria does not usually occur at different beaches at the same time, Doug Campbell told Information Morning Moncton.

This has made the Canada Research Chair on phytoplankton ecophysiology "increasingly wonder what's going on in the sediment."

"It's similar to what we have been seeing for years now at Murray Corner and at Parlee," Campbell said. "Counts going along at low levels and then a sudden sharp spike, although this Murray Corner spike is as high as we have ever seen."

Bacteria are not growing or originating from the sediment, he said, but it could be a reservoir for them since bacteria can survive in the sediment for longer than in water and lead to high counts when stirred up.

Human bacteria, not animal

Genetic testing on samples has not been done, but Campbell suspects the source of the bacteria found at the two beaches on the Northumberland Strait is human, not animal.

"The level of enterococcus relative to E. coli is quite high and that is characteristic of human sources rather than animal sources," he said.

According to Campbell, the acceptable water quality threshold is set on a one per cent risk of infection. At this level, if 1,000 people go swimming, 10 will get a waterborne illness.

"When we're looking at counts that are many times higher than the regulatory threshold there's a significant risk of waterborne illness based on swimming so I wouldn't swim and I wouldn't take my family swimming with counts that high."

A spokesperson for Serge Rousselle, the minister of environment and local government, told the CBC work to upgrade Murray Beach sewage lagoon has begun with the installation of a nutrient infuser.

The next step will be to install an ultra-violet purifier.

At Parlee Beach, a rain gauge and a real time data logger have been installed and an education campaign is underway on the responsible dog ownership, with waste bins and bag dispensers at the beaches as well.