Category Archives: Invasive Species

Between a Dam and a Hard Place

Dams like this change the flow regimes of rivers, and prevent some species from accessing their spawning grounds, lowering population viability. But is removing them completely danger-free? (Image Credit: Notorious4Life, CC0 1.0, Image Cropped)

Anybody who has ever studied freshwater ecosystems will end up having to study dams at some point. And they’ll no doubt learn that dams are the enemy. They fragment ecosystems. They cut fish off from their spawning grounds. They change flow regimes. So it makes sense that the recent trend of dam removal across Europe and the world in general would please ecologists. But there’s a problem with dam removal, and it comes in the form of invasive species.

Read more

The Pacific Oyster

The Pacific oyster could make its way further north as the Arctic and sub-Arctic regions warm

Image Credit: Hans, Pixabay licence, Image Cropped

Last Monday, I wrote about how climate change can facilitate the spread of non-native and invasive species. Today, we look at a species that whilst problematic now, could spread further throughout Norwegian waters as temperatures rise.

The last time we looked at an ocean-dweller in this series, we saw that while some species may not be great for ecosystems, they can provide an obvious benefit to other aspects of the region, in this case the fishing industry. The Pacific oyster (Crassostrea gigas) was also introduced intentionally for cultivation and is now on the verge of becoming a major problem in Norwegian waters.

Read more

Invasive Species and Climate Change

The next 50 years will see parts of the planet warm significantly. So how does this impact invasive species?

Image Credit: TheDigitalArtist, Pixabay licence, Image Cropped

In this series, we’ve looked mostly at species that have been introduced at defined points in time. The Pink Salmon and the Red King Crab were introduced into Russian waters near Norway in the 50s, the Canada Goose was brought to Europe in the 30s, the Sitka Spruce in the late 1800s. But with the onset of climate change, warmer conditions in the Arctic and sub-Arctic mean that the doors will open for more gradual arrivals. So let’s look at how climate change will facilitate the arrival of these newcomers.

Read more

In Defense of Aliens

It's important to remember that not all alien species are harmful, and we shouldn't treat them all as such

Image Credit: Lou133lou133, CC BY-SA 4.0, Image Cropped

Building on last week’s article on defining invasive and alien species as well as the work of Professor Mark Davis, I am going to do the unimaginable for an ecologist and argue that maybe alien species aren’t always a bad thing. I want to emphasize that maintaining biodiversity is essential, but maybe we should focus on the role of species in their environment rather than their place of origin.

Read more

The Sitka Spruce

The Sitka Spruce was introduced by the timber industry, and now covers almost 5 million hectares in Norway (Image Credit: James Brooks, CC BY 2.0, Image Cropped)

Once again, let us talk about trees. Do not be fooled by their innocent appearance – that is exactly what they want! In reality, they can be just as problematic as any animal species. This week I takes a closer look at the Sitka spruce (Picea sitchensis).

Read more

Defining an Invader

The Northern Pike. Although it's native to Norway, it has been moved around since and is now classified as 'regionally invasive'.

The Northern Pike. Although it’s native to Norway, it has been moved around since and is now classified as ‘regionally invasive’. (Image Credit: Jik jik, CC BY-SA 2.0)

Two weeks ago, Norwegian Science Institute Artsdatabanken (ADB) announced that they would be changing the name of their invasive and alien species index. Formerly known as the Black List, the institute decided to use a name with less negative connotations, “Fremmedartslista“, loosely translated, the Alien Species list. Given this series’ focus on species from that list, it seems like an appropriate time to look at how we define the terms ‘alien’ or ‘invasive’ species.

Read more

The Red King Crab

The Red King Crab has been invading Norwegian waters over the last 50 years

Image Credit: Michelle Pemberton, The Children’s Museum of Indianapolis, CC BY-SA 3.0, Image Cropped

“… a red army of monster crustaceans – marshaled by Soviet-era leaders – is threatening to invade Western Europe …”

– James Owen, National Geographic, 2004

Ominous. That’s the thing, isn’t it. Some invasive species look harmless. You can’t be scared of a baby Canada Goose, can you? Or a nice purple garden flower. Such florescence. You can, however, be scared of a spiny, alien-looking 10 kilo mass of spines and pincers that has been shuffling its way into Norwegian waters over the last half-century.

Read more

Bringing Back Carnivores

Image Credit: Per Harald Olsen, NTNU, CC BY 2.0, Image Cropped

In my previous posts on rewilding and wild boar, I talked about the effects of reintroducing species that were previously found in Norway. Now, I want to talk more about the large carnivores in Scandinavia which serve as protection against invasive species. This opinion piece is coming from an ecologist and a foreigner, so treat this like a Scandic breakfast buffet and take what you want.

Read more

The Common Ragweed

The common ragweed, set to become a nightmare for hayfever sufferers

Image Credit: Sue Sweeney, CC BY-SA 3.0, Image Cropped.

In this series, we’ve already learnt about the impacts of alien trees and garden plants in Norway, but others are invading too, including some that are easier to overlook. And some of them can not only out-compete native species, but also pose health problems for humans. In today’s guest post by Vanessa Bieker, we look at Ambrosia artemisiifolia (common ragweed), which produces highly allergenic pollen and is one of the main causes of hay fever.

Read more

« Older Entries Recent Entries »