Thursday, October 1, 2020
Home Lead Story Invasive Species May Not Be All Bad: Scientists

Invasive Species May Not Be All Bad: Scientists

An active debate among biologists about the role of invasive species in a changing world is going on

Off the shores of Newfoundland, Canada, an ecosystem is unraveling at the hands (or pincers) of an invasive crab.

Some 1,500 kilometers (930 miles) to the south, the same invasive crab — the European green crab — is helping New England marshes rebuild.

Both cases are featured in a new study that shows how the impacts of these alien invaders are not always straightforward.

Around the world, invasive species are a major threat to many coastal ecosystems and the benefits they provide, from food to clean water. Attitudes among scientists are evolving, however, as more research demonstrates that they occasionally carry a hidden upside.

“It’s complicated,” said Christina Simkanin, a biologist at the Smithsonian Environmental Research Center, “which isn’t a super-satisfying answer if you want a direct, should we keep it or should we not? But it’s the reality.”

Simkanin co-authored a new study showing that on the whole, coastal ecosystems store more carbon when they are overrun by invasive species.

Good news, crab news

Take the contradictory case of the European green crab. These invaders were first spotted in Newfoundland in 2007. Since then, they have devastated eelgrass habitats, digging up native vegetation as they burrow for shelter or dig for prey. Eelgrass is down 50 percent in places the crabs have moved into. Some sites have suffered total collapse.

That’s been devastating for fish that spend their juvenile days among the seagrass. Where the invasive crabs have moved in, the total weight of fish is down tenfold.

The loss of eelgrass also means these underwater meadows soak up less planet-warming carbon dioxide from the atmosphere.

In Cape Cod, Massachusetts, the same crab is having the opposite impact.

Off the coast of New England, fishermen have caught too many striped bass and blue crabs. These species used to keep native crab populations in check. Without predators to hold them back, native crabs are devouring the marshes.

But the invasive European green crab pushes native crabs out of their burrows. Under pressure from the invader, native crabs are eating less marsh grass. Marshes are recovering, and their carbon storage capacity is growing with them.

Invasive species
In this May 8, 2016 photo, eelgrass grows in sediment at Lowell’s Cove in Harpswell, Maine. VOA

Carbon repositories

Simkanin and colleagues compiled these studies and more than 100 others to see whether the net impact on carbon storage has been positive or negative.

They found that the ones overtaken by invasive species held about 40 percent more carbon than intact habitats.

They were taken by surprise, she said, because “non-native species are thought of as being negative so often. And they do have detrimental impacts. But in this case, they seem to be storing carbon quicker.”

At the Smithsonian Environmental Research Center where she works, the invasive reed Phragmites has been steadily overtaking a marsh scientists are studying.

Phragmites grows much taller, denser and with deeper roots than the native marsh grass it overruns.

But those same traits that make it a powerful invader also mean it stores more carbon than native species.

“Phragmites has been referred to as a Jekyll and Hyde species,” she said.

Not all invaded ecosystems stored more carbon. Invaded seagrass habitats generally lost carbon, and mangroves were basically unchanged. But on balance, gains from marsh invaders outweighed the others.

Invasive species
Phragmites plants growing on Staten Island draft in a breeze in the Oakwood Beach neighborhood of Staten Island. VOA

Not a lot of generalities

To be clear, Simkanin said the study is not suggesting it’s always better to let the invaders take over; but, it reflects an active debate among biologists about the role of invasive species in a changing world.

“One of the difficult things in the field of invasion biology is, there aren’t a lot of generalities,” said Brown University conservation biologist Dov Sax, who was not involved with the research. “There’s a lot of nuance.”

The prevailing view among biologists is that non-native species should be presumed to be destructive unless proven otherwise.

When 19 biologists wrote an article in 2011 challenging that view, titled, “Don’t judge species on their origins,” it drew a forceful rebuke from 141 other experts.

Sax said the argument is likely to become more complicated in the future.

Also Read: Climate Change Not A Hoax: Trump

“In a changing world, with a rapidly changing climate, we do expect there to be lots of cases where natives will no longer be as successful in a region. And some of the non-natives might actually step in and play some of those ecosystem services roles that we might want,” he said.

“In that context, what do we do? I definitely don’t have all the answers.” (VOA)

STAY CONNECTED

19,134FansLike
362FollowersFollow
1,779FollowersFollow

Most Popular

Indian Travellers Discover Simple Pleasures Next Door Amid Pandemic: Booking. com

While the pandemic has led to seismic shifts in travel behaviours and destination choices, many Indian travellers have discovered simple pleasures next door, leading...

Cardiac Arrest Common in Critically ill Covid-19 Patients: Study

Cardiac arrest is common in critically ill patients with Covid-19 and is associated with poor survival, particularly among patients aged 80 or older, say...

IISc Researchers Identify Cancer Cells Using a 3D Tumour Model, Nanomotors

By N. B. Hombal An interdisciplinary team of researchers from the Indian Institute of Science (IISc) has made a breakthrough in the field of identifying...

International Coffee Day: Celebrate it With These Easy Recipes

By Puja Gupta Coffee is one of the most loved beverages in the world and theres no denying that! In India, the love for barista-style...

Here’s Semi-Permanent Make-Up for Attractive Eyebrows and Lips

By Puja Gupta The youth these days are not only concerned about pigmentation, acne or dark circles, but also look for that perfect shaped Eyebrows....

It’s Time to Create Vibrant Cocktails with Simplest of Ingredients!

The white spirits have often been unanimously hailed as one of the most popular when it comes to cocktail making. With the colourless, distilled...

Why Does Automobile Industry Use Instagram?

The automobile industry is known for its constant initiatives in visual communications and marketing for over a decade! Earlier the standard rule for vehicle...

How to Create a Workout Routine That Helps the Planet

Many of us are looking for more eco-friendly ways for just about everything: from making our food to our clothes. You can make some simple...

Recent Comments