Basin Head's unique Irish moss disappearing

A unique strain of Irish Moss is disappearing from the lagoon at Basin Head in eastern P.E.I. , and an invasive species may be to blame.

Giant moss only grows in a lagoon at Basin Head, P.E.I.

Fragments of the moss are being preserved in case it disappears from the lagoon. (Nancy Russell - CBC)

A unique strain of Irish moss is disappearing from the lagoon at Basin Head in eastern P.E.I.

Scientists and the local watershed group say invasive green crab could mean the end for the marine plant known as giant moss. 

"In the day there was probably a few ton of Irish moss here," said Fred Cheverie of the Souris and Area Branch of the Wildlife Federation. 

"Now you could probably gather it all up and put it in a five-gallon bucket."

Irish moss is a valuable sea plant, a rich source of carrageenan, which is a thickening agent used in food processing.

What makes the moss unique

  • It is free floating and stays in the lagoon by attaching itself to the blue mussel. Other Irish moss strains are anchored.
  • It yields 75 per cent pure carrageenan versus 45 to 50 per cent found in the common form,
  • The plant is much larger - 800 grams - than the common strain of Irish moss - 50 grams,
  • It maintains its red-brown color throughout the year while the common form exhibits color changes from red to yellow to green throughout the summer. 

The Souris and Area Branch of the P.E.I. Wildlife Federation has been setting a large net trying to trap the rare strain as it floats across the lagoon looking to attach itself to a new home. In the past that home was mussels. That was before green crab moved into the lagoon and began eating the mussels. 

"The reason it seems to have disappeared, the number one reason, is green crab moved into the area in the late 1990s. And it has decimated it," said Cheverie.

"We also have a nitrate problem.  And we've got a fair bit of silt moving in [the] particular upper reaches of this here basin."

The researchers will take the fragments to an area where mussels grow in hopes the moss will find a home quickly ahead of the green crab.

Fisheries and Oceans has also gathered up the rare moss and is keeping it in a lab in case it disappears from the lagoon altogether.

It has also placed the moss in mussel socks hanging from buoys above the basin floor out of the reach of the green crab, and is protecting other plants inside of cages in the lagoon.      


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