Category Archives: Invasive Species

Our Responsibility Regarding Invasive Species (A Counterpoint to Mark Davis)

The Eastern Oyster, a species which has a high potential to spread throughout Norwegian waters, but little known ecological effect

The Eastern Oyster, a species which has a high potential to spread throughout Norwegian waters, but little known ecological effect (Image Credit: Chesapeake Bay Program, CC BY-NC 2.0)

Last week I posted an interview with Mark Davis, an invasion ecologist who has urged caution when rushing to eliminate invasive species from an ecosystem. Whilst I didn’t agree with absolutely everything Mark said, he makes some very important points about the language around invasive species and our understanding of them.

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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? (

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: pxhere, CC0)

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.

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Invasive Species and Climate Change

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

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.

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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

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.

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Defining an Invader

With the rebranding of Nrwaoys' Black List as the Alien Species List, we look at what makes a species alien and/or invasive (Pictured: The invasive Yellow Sweet Clover)

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.

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Alien Trees & Filling the Knowledge Gap

recent report jointly published by WWF, Sabima, Friends of the Earth Norway and the Norwegian Botanical Society showed that alien tree species are one of the largest threats to native tree species, even inside protected areas. The news even reached Norwegian news outlet NRK. But why are alien trees a problem? Isn’t a tree, well, just a tree? As guest blogger Tanja Petersen explains, not quite.

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