With the scourge of tunicates wreaking havoc on mussel socks in Prince Edward Island for at least one decade, a mobile laboratory set up at Georgetown Wharf offers the opportunity to take a closer look at the problem.

It is suspected that some of these aquatic invasive species (AIS) have been transplanted via the ballast waters or attached to slow-moving, large Trans-Atlantic ships and transplanted into Canadian waters. With several species of tunicates to contend with, mussel growers struggle with extra labor costs and losses on product prices when the tunicates attach to the socks and mussels.

It’s labor-intensive work to pull them off.

All this puts undue pressure on the $125 million-dollar-a-year industry that sees PEI supplying 70 per cent of the United States market for mussels.

Christine Paetzold, an aquaculture researcher employed under the direction of Dr. Jeff Davidson, a veterinarian at the Atlantic Veterinary College in Charlottetown, has been doing some work at this portable aquatic laboratory (PAL) to try and alleviate some of the stress on the mussel industry.

“Our focus here is the Atlantic Innovation Fund Project that is divided into three modules … we are the third module looking at the mitigation of tunicates,” says Paetzold.

Funding for the project comes from the Atlantic Innovation Fund, sponsored through the PEI Aquaculture Alliance.

Paetzold points out that her duty this summer is to do trials with new “treatments” that can reduce tunicate levels. To do this, the researcher is working with a total of 30 small tanks that each holds 20 liters of water. There are also five large tanks that have a flow-through system, so it is able to use water straight from the harbor.

Both Paetzold and Davidson agree that this “natural” system gives a better view of just how tunicates function, as opposed to the artificial saltwater trials that were being carried out at the college. “At the vet college if we do trials, we use artificial sea water made up of fresh water and salt. So we get into problems of feeding the animals regularly and cleaning up an accumulation of waste.”

These natural condition trials at Georgetown Wharf will add a better insight into what really happens with tunicates in relation to the mussel population.

With four different species in island waters, Paetzold is focusing on the vase tunicate that is the biggest problem in the eastern shore areas. “They are there in vast numbers,” says Paetzold. Others species of tunicate include the clubbed tunicate, violet, and golden star.

To give a view of just what damage the tunicates do, Paetzold says just doing the maintenance on gear takes up considerable time. “The extra weight they add to the mussel socks takes considerable time to remove or just lift them from the water.

“Where one person could do the lifting now you have to have two or three.”

For the mussel grower, this means hiring more labor and adding extra hours to the workday-all at a high cost.

There are more financial losses when tunicates are left intact until they arrive at plants.

With a shortage of labor for this type of work, growers are forced to harvest and ship mussels to plants with tunicates attached. “They don’t get as much mussel product for their efforts,” says Paetzold.

She and Davidson both stress that although the tunicate is a mass of trouble for growers, they do not in any way affect the quality of the mussels.

However, this obviously “sticky” situation makes it a bigger challenge for the aquatic researcher to come up with a treatment that works. “We are aiming to disrupt the tissue of the tunicates so they can’t cling [to the mussel socks].”

Trying a disinfectant that is commonly used in labs when going from one area to another, Paetzold says this (disinfectant) could be used to dislodge the connective tissue of the Vase tunicate. “This is one issue we are focusing on. Tunicates grow in such big clumps and they grow together. If we can loosen the bond a bit, maybe the other treatments [already in use] will be more effective.

She explains that growers have used specially-built machinery spraying high-pressured water to blast off the tunicates.  “It is fairly effective in washing them off.”

Growers have used their ingenuity in trying different acidic agents, such as vinegar, or pelting them with salt. “We try all these natural treatments. It’s no good to find some highly toxic agent to treat them. It would just kill mussels and destroy the whole eco system,” explains Paetzold.

Talking about how the tunicates spread to the point of taking over mussel socks, Paetzold says they can be carried on the bottom of pleasure boats from one harbor to another, and the same for fishing boats

Davidson echoes that and also points out that the college has always worked with the Department of Fisheries and Oceans in the mitigation of tunicates. At this point both agree they may or may not have a break through treatment, but could get to a point where the tunicates is at a more manageable level.

“We can try treatments and Christine can look at those treatments over a series of time, and see if this is killing them, and we can put that treatment into action,” states Dr. Davidson.

The bonus of this portable lab is that it can be moved. “It’s rather unique (in comparison to artificial trials at the college) in that where tunicates is affecting many different areas of the province, we can just unhook this lab and take it to another location,” says Dr. Davidson.