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A marine plant called sea lettuce is the reason some P.E.I. waterways change colour and smell like rotten eggs, says an expert in water biology.
Sea lettuce is a type of algae, and it occurs naturally in marine environments, said Kyle Knysh, a provincial surface water biologist.
“It thrives under high-nutrient conditions, and when it begins to rot, much of the organic material from all the decomposers sucks up a lot of oxygen in those waterways,” Knysh said.
That lack of oxygen in a waterway creates what’s known as an anoxic event.
Knysh said there are a handful of discoloured waterways that have been reported to the province so far this year, including an estuary in the Oyster Bed, P.E.I., area.
It was reported on July 9 for having discoloured green, grey-white water, said a statement from the province’s Department of Land and Environment.
“This type of colour change is associated with low dissolved oxygen conditions,” the statement said.
The province said it monitors oxygen levels in that waterway on a yearly basis, along with other waterways across the Island.
It said the department, in collaboration with Fisheries and Oceans Canada, plans to review oxygen data trends from all monitored estuaries over the last decade.
Knysh said those who suspect a body of water might be anoxic should take precautions and avoid coming into contact with it.
“Your hands or feet will probably smell like rotten eggs for quite a while. It’s always good to avoid areas you’re unfamiliar with or unsure of conditions,” he said.
As for wildlife, Knysh said some animals have developed adaptations, but many species of marine life don’t have mechanisms to deal with low oxygen levels.
“Most things really like breathing oxygen that swim in the water. So when these low oxygen periods occur, they either have to move away from the area or they get trapped,” he said.
“If they can’t move away, they don’t persist there much longer.”
Anyone with concerns about a waterway on P.E.I. can call the Land and Environment Department to investigate.
