Province says there have been 16 anoxic events so far this year
A sea lettuce harvester removes some of the algae from the bay in Stanhope in this Guardian file photo.
A study is being carried out this week to see if sea lettuce can be harvested by a major corporation on P.E.I.
If it can, it could address the ongoing problem of estuaries in the province being rendered anoxic because sea lettuce is choking off the oxygen supply in the water.
Brenda Campbell, president of the P.E.I. Shellfish Associaition, said Monday that ADI Lands in Oromocto, N.B., will harvest a small quantity in its lab.
The test will determine if sea lettuce can be used in the biodigester at Cavendish Farms in New Annan. Many species of sea lettuce serve as a food source for humans in Scandinavia, Great Britain, Ireland, China and Japan.
“If this sea lettuce has value to the biodigester process this may enable the association to develop a business plan to harvest sea lettuce or at least waive tippage fees on the disposal of sea lettuce,’’ Campbell said, noting that shellfishers hope that it leads to expanding their fishing areas, many of which have been shut down because of anoxic rivers.
“In my opinion, it’s dire straits here,’’ she said, referring to anoxic waters in P.E.I. “There’s only so many times that people can gasp in horror. It’s getting worse.’’
According to provincial government biologist Cindy Crane, it isn’t getting worse but it isn’t getting better either.
Crane says there have been 16 anoxic events this year, so far, nine of them in different systems. They are mostly found on the north shore but the province is investigating one in the Brudenell area right now. There was also an event on the Boughton River.
“As of right now, it’s definitely on par with previous years,’’ Crane said of the number of events this year. “The only thing that may be different with this year is the onset of anoxic events was a bit later in the season than we’ve been seeing in the last two to three years.’’
That said, those events are occurring in the same problem areas they did before.
And sea lettuce is usually the culprit in the vast majority of cases, Crane said.
“We did see a couple of small localized ones in some marshes that were due to some very high tides pushing salt water into a normally fresh water area.’’
Salt water will kill aquatic plants.
Campbell said shellfishers see the problems most pronounced on the north shore and on the western side of the province.
Runoff from fields gets into the water and tends to cause sea lettuce to grow alarmingly quick. And when sea lettuce rots, it causes quite the foul odour.
Crane explains that the north shore has a lower tidal range, thus less flushing occurs.
“That means these areas (such as the north shore) are susceptible to nutrient loading.’’
Crane said people often ask her department to fix the problem but she says it’s not that easy. Campbell said shellfishers don’t want to get into a fishermen-vs.-farmers debate but wonders whether larger buffer zones around waterways is one answer.
Crane said the solution is a long-term one.
“The solution is to deal with excess nutrients we have. Unfortunately, over the short term, there’s not anything that can be done to stop it or make it shorter.’’
Crane said the public has been instrumental in reporting anoxic events. Anyone who notices an anoxic event is asked to call 368-5044.