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PCR tests to counter invasive species


The testsDeoxyribonucleic acid allow rapid detection before an endemic presence, when it is still possible to act.

It is indeed the same technology as that of the tests carried out to detect the COVID-19 virus, confirms Nathalie Simard, biologist at the Maurice-Lamontagne Institute and responsible for the file of invasive aquatic species.

It is a very effective and very sensitive tool, underlines the biologist. It makes it possible to identify a very weak presence before the infestation.

This technique can be used everywhere and is set to become widespread. Given that we have a large territory, this allows us to choose the places where we will go to look more in depth for a particular species., explains the biologist.

For the moment, however, it is only in the Madelinot archipelago that the tests polymerase chain reaction assay are used. The reason is very simple: Quebec’s maritime sector has the greatest number of invasive species, ie seven species.

Nathalie Simard’s team used it for the first time in 2019 to verify the presence of green crabs. This species has been present for many years (2010-2012), in the marshes and on the rocky coasts of the archipelago.

The population fell around 2015-16 as a result of heavy fishing and several colder winters. Difficult to determine the cause of the fall in the population, notes the biologist, but the tool is now used to follow its evolution. In case the population starts to increase significantly, so that we have a signal with the DNA to say: “OK, something is happening, and we have to go back to intensive fishing to control the population” .

A green crab.

The green crab population remains under close surveillance.

Photo: Courtesy: Fisheries and Oceans Canada

The method saves time and effort. Go get two liters of water and filter them, it’s fast.

Fast intervention

Recently, biologists have also carried out tests forDeoxyribonucleic acid to control the presence of yellow sea squirt in the Magdalen Islands, a tunicate that filters plankton and thus competes with mollusks such as mussels and oysters. This is a problem that can cause a lot of damage to the mold industry., underlines Nathalie Simard.

Tests revealed the presence of sea squirt at the Havre-aux-Maisons marina last summer.

A team of divers was able to confirm the presence of the invader in low abundance. Clean-up was immediately undertaken to prevent the species from colonizing the area.

Nathalie Simard explains that tests were also carried out in certain places on the North Shore or in the Gaspé. All the tests were found to be inconclusive.

Algae from the seabed of the bay of Sept-Îles.

The tests carried out on the North Shore and in the Gaspé did not detect anything.

Photo: Filippo Ferrario

On the other hand, this does not mean that other invaders are not present since, for the moment, only the tests for the green crab and for the ascidian are carried out, because they are the two species of the most concern.

Possibly, the detection by Deoxyribonucleic acid environmental could extend to any species under surveillance.

Nearly twenty species are under surveillance, seven of which are now present in maritime Quebec.

Nathalie Simard is reluctant to give a precise figure. watch list, but we know that there are species that can arrive without passing through Nova Scotia or the east coast of the United States. “,” text “:” We have a watch list, but we know that ‘there are species that can arrive without passing through Nova Scotia or the east coast of the United States. “}}’>We have one watch list, but we know that there are species that can arrive without passing through Nova Scotia or the east coast of the United States.

The potential of the method is there, notes the biologist. These are monitoring tools that could be used to cover a lot more territory, adds the researcher.

A vast marine territory under close surveillance

Detection by Deoxyribonucleic acid environmental protection is always used in addition to other methods and adds to the arsenal of fight against invasive species.

The invasive species monitoring program covers nearly forty sampling sites spread between the Saguenay Fjord and the Magdalen Islands.

In the estuary, the species tracked by the program that could settle in the short term – they are already present in the Maritimes or on the US East Coast – have not been spotted so far.

Collectors, for example traps for invasive tunicates, have also been installed in aquaculture sites, particularly in the Lower North Shore. For the moment, they do not have invasive species in the Lower North Shore, but we want to be present on the ground, indicates the person in charge of the program.

To protect the algae culture

In the Baie des Chaleurs and in certain places on the North Shore, two invasive species, also present in the Islands, are closely monitored.

These are the Japanese caprelle, a small crustacean that infests buoys and ropes, and membranipora, which can invade fields of kelp.

Both on the North Shore and in Chaleur Bay, there are no very serious infestations except that of the membranipora when, in some years, the water is warmer, says Ms. Simard.

Membranipora on a kelp.

Membranipora is a bryozoan, an invertebrate which can colonize a kelp forest and which, for commercialization, will alter its appearance.

Photo: Courtesy: Fisheries and Oceans Canada

In Maine waters, Fisheries and Oceans reports that membranipora has already caused the destruction of entire kelp forests, which can cause severe habitat damage for many species.

Even if it is not toxic, membranipora can also represent a serious disadvantage for the culture of algae, emerging in the Bay of Chaleur.

A project for the rapid detection of the presence of membranipora is underway in collaboration with aquaculturists to enable them to harvest their algae before colonization.

Despite the important role the program plays in countering the spread of unwanted species, Nathalie Simard recalls that the main factor remains prevention. Once they’re established, there isn’t much you can do.

The responsible behavior of the population, especially during navigation, remains a key element in the fight.

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