What's causing a stink in Sydney harbour? The answer is unclear

People living around Sydney harbour may have caught a whiff of something foul in the last few days, but just what is causing the stench is anyone's guess.

Rod Beresford lives along Sydney harbour in Westmount, N.S., and is a biologist at Cape Breton University.

He believes the odour could be tied to high winds along with large swings between high and low tide levels over the last week or so.

"With these really low tides there's probably a lot of [harbour bottom] material being exposed," Beresford said.

"You also have rotting seaweed, things like that on the harbour that are always going to break down and give those kinds of smells."

'Sewer-type smell'

Beresford said similar odours have come and gone in the past, but he admits that the recent perfume may be stronger.

Along with rotting seaweed, he said, smells come from dead fish and other wildlife such as seal carcasses. 

One thing is for certain, the unpleasant aroma is causing a lot of chatter. 

"There's more people talking about it," Beresford said. "I guess there is a little more to it,… It certainly does have a sewer-type smell."

Bruce Hatcher is another Sydney biologist who suggests the stench is likely being caused by natural occurrences within the harbour. 

Hatcher suggests churning waters may have brought decaying material from the harbour bottom up to the surface.

"My best guess is that we had a great spring and the harbour woke up early, if you wish," said Hatcher. "The bacteria warmed up and then got busy — decomposed a lot of the organic material in the seabed — and produced the usual sort of smelly gases." 

Hatcher said it's typical for decomposing smells from the sea to mimic the smell of sewage or rotten eggs. 

Cape Breton Regional Municipality spokesperson Christina Lamey said she's aware people are complaining about the smell, and said they perform routine inspections of their wastewater facilities and solid waste facilities.

"We had operations staff check all sites in regards to the odour and found none to be the source," she said.

Norma MacAskill, who has been living in Westmount for 35 years, noticed a smell outside her home that comes and goes periodically. 

"To me it smells like stagnant pond water, like something that's very stagnant and stale, which possibly could be sewage. I don't know."

CBC News spoke to officials from the Department of Fisheries and Oceans who say they're not sure what's behind the occasional whiff of bad air. 

With files from Information Morning Cape Breton