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Learning in a living classroom

Students at Marystown Central High School traded their textbooks and the warmth of the classroom for a more hands-on approach to the study of science Tuesday.

Marystown Central High student Chelsea Riggs and her schoolmates enjoyed finding green crab and other sea life while visiting the beach in Spanish Room Tuesday. The excursion was lead by researchers with the Department of Fisheries and Oceans and Marine Institute.

“I think it’s really fun,” Courtney Labour told The Southern Gazette while on the beach in Spanish Room. “I love doing this kind of stuff, it is one of my passions, so I really enjoyed this.”

Labour said both of her parents are involved in the fishery but this the first time she’s had such a first-hand experience.

Approximately 120 Grade 10 students joined researchers from the Department of Fisheries and Oceans (DFO) on the beach to conduct studies on the green crab population in the area.

The European green crab was first discovered in Newfoundland waters in 2007, and DFO has been keeping a close eye on its movements.

Cynthia McKenzie, a research scientist for DFO, said the crab could pose threats on a couple of fronts.

“One is the direct impact it has on other species. It preys on whatever’s there — it will eat clams, scallops, mussels, and in few of them we have found juvenile lobster in their gut.”

McKenzie said the crab can also interfere with lobster pots by entering them and eating the bait before it attracts lobsters or by eating the lobster once it is trapped inside.

She also said they have a number of indirect effects on the ecosystem.

“They dig up eel grass, because they’re digging around trying to bury and look for food, and when they get rid of eel grass … that is the habitat for juvenile fish such as cod and haddock.”

Greg Pittman, a science teacher from MCHS, said for the students who are taking Science 1206, it provides a learning experience they can’t get inside the classroom.

“It is an opportunity to see what real research is like in the field. This particular group happens to be looking at invasive species, which is one of the topics (students) cover.”

The students were involved in a number of activities at the beach. McKenzie said it was nice to see them take an interest in the work.

“You couldn’t get them off the beach — they found lots of small (juvenile) green crab, and (mature) green crab, and lots of other things.”

She said the importance of finding the juveniles is that it allows them to do genetic studies in the hopes of finding out where the crab have come from.

“We think that they (may) have different origins, from Placentia Bay, Fortune Bay or even in Stephenville, so we are going to do some sampling to see if we can determine how they are related to each other,” she said, adding that if they know how it is getting here, they have a better chance of stopping it.  

McKenzie said because green crab reacts differently when threatened than the native rock crab, it has few natural predators.

She explained that instead of hiding like the native species, the green crab presents a defensive front, which until recently has driven away the animals that would feed upon them.

“We are finding more birds are eating them then they used to. It’s taken a while to figure it out.”

Kiley Best, a fisheries technologist with the Centre for Fisheries Ecosystems Research at the Marine Institute, explained another factor that has led to the growth of the green crab population.

“They can hold off (reproducing) — that’s why they are so successful. They can hold off on a bad year and wait for conditions to be better and spawn when they know their larva will survive.”

Some samples found at the beach showed signs that the crabs have not started to reproduce yet, but Best said there’s not enough data to tell if something has delayed the cycle.

McKenzie said that DFO officials are looking into ways to control the green crab population.

“We are working with five fish harvesters on either side of Placentia Bay, and they fished for 10 days each and they got about 70,000 pounds of green crab.”

She added that a discovery Best made while completing her master’s of science in aquaculture, in the area of invasive species, may also help in controlling the growth of the population.

 “She has found that they don’t start to be reproductive until they are above 30 (millimetres in size), so we are trying to take out everything above 30 mm so that they won’t be reproductive.”

McKenzie added that this mitigation will help to balance things out.

“We’re trying to bring it down it down to (where) only the small ones are left. That way other things, like lobster (and) rock crab, can (use) them as food themselves.”


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