Sarah Stewart-Clark holds up a plastic cup to get a better look at the contents.  Suspended inside is a disgusting-looking blob.  It’s a relatively new invasive aquatic species to Prince Edward Island called a tunicate.

“The first tunicates showed up in our bays in 1998,” says Stewart-Cark.  “We now have four species living here.  It’s a big problem for our mussel industry.”

Stewart-Clark is one of UPEI’s eleven winners of the province’s Innovation PEI Graduate and Post-Doctoral Fellowships.  She begins work this fall on a project called “Development of molecular markers to evaluate the impact of tunicate mitigation treatments on mussel gene expression and health.”

“Prince Edward Island produces 80 per cent of the mussels consumed in North America,” explains Stewart-Clark.  “It’s an important industry for the Island, and these tunicates are a serious threat.  They grow right on the mussels and farming gear, and increase in population much quicker than the mussels do.”

Mussels grow on long strands of material hanging down from the surface of the water called socks.  Stewart-Clark says it usually takes just one person to lift a sock full of mussels from the water.

“A sock infected with tunicates can take up to four people to lift,” she explains.  “It’s that bad.  And until now, it’s been impossible to know if your farm is infected until it’s too late.”

Stewart-Clark’s doctoral research helped develop a test for larval and pre-larval stages of tunicate in the waste water of mussel processing plants.  Her next project focuses on the process of getting rid of the tunicates once they arrive – specifically, whether the techniques to remove them have a negative effect on the mussels.

“The current treatments for tunicates include blasting them with fresh water, or hauling the infected socks through troughs filled with lime -- neither of which is very effective.”

Other researchers at AVC are developing new, innovative techniques to remove or kill the tunicates.  Using a new piece of equipment called a mussel microarray, Stewart-Clark can monitor the gene activity within the mussel at the genome level during those tunicate treatments.

“We can ensure the mussels aren’t being overstressed by the treatments in a way that would compromise the quality of the mussels.  I think it’s very exciting to be involved in research that has an impact on the people who live and work on the Island.  It’s what drew me to it in the first place.”

Sarah Stewart-Clark’s supervisors in this project are Dr. Jeff Davidson and Dr. Spencer Greenwood.