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Tag Archives: invasive

Invasive Snails and Their Hippo Victims

Posted on September 21, 2022 by Adam Hasik Leave a comment

Image credit: Muhammad Mahdi Karim, CC BY-SA 4.0, Image Cropped

Invasive snails, parasite spillback, and potential parasite spillover drive parasitic diseases of Hippopotamus amphibius in artificial lakes of Zimbabwe (2021) Schols et al., BMC Biology, https://doi.org/10.1186/s12915-021-01093-2

The Crux

Artificial lakes can be a huge plus for the regions where they are constructed. People come to hang out at them, they can serve as habitat for local or migrating species, and they can also improve water accessibility. In fact, the majority of the research that I did for my PhD took place in artificial, human-made lakes (see here and here). Yet, these artificial lakes can also wreak havoc by destroying local ecosystems and introducing invasive species. Furthermore, because humans build communities around these lakes there is a risk of increased transmission of parasites to livestock and humans alike.

One group of common invasive species in these artificial lakes are snails, which serve as intermediate hosts for many parasites (see Did You Know?). Introduced water plants (like hyacinth) often harbor invasive species like the snails, and dams built to make artificial lakes often block snail predators from accessing the lakes, which means that the snails increase in number due to the release from predation pressure. Today’s authors wanted to understand how invasive snails modified parasite transmission within an artificial lake.

Paper of the Week

After The Hare Comes The Tortoise: Monitoring The Effect Of A Deliberately Introduced Reptile

Posted on September 12, 2022 by Sam Perrin Leave a comment

Image Credit: Yulia Kolosova, CC BY 4.0, Image Cropped

Impacts of herbivory by ecological replacements on an island ecosystem (2022) Moorhouse-Gann et al., Journal of Applied Ecology, https://doi.org/10.1111/1365-2664.14096

The Crux

Turning an ecosystem that has been ruined by humans back into a thriving natural world is a long, difficult task, but it is possible. One method for making it easier is re-introducing species that we’ve wiped out. Often the reintroduction of the functions that these species perform helps restore many other species, and helps the ecosystem returns to a more ‘natural’ state.

But what happens when a really key species has gone extinct? One way of solving this conundrum is introducing a similar species that performs the same function. This sounds like a good workaround, but introducing a non-native species might have unexpected ecological repercussions.

This week’s researchers were based on Round Island, in Mauritius, where two species of giant tortoise (the saddle-backed and the domed Mauritius giant tortoise) had gone extinct. A third species, the Aldabra giant tortoise, was introduced in 2007. The main point of concern on the island is that the tortoise diet may overlap with that of a vulnerable species, the Telfair’s skink. This week’s team wanted to find out whether the tortoise was helping or hindering the island.

Paper of the Week

When Is A Fish Really Native?

Posted on October 18, 2021 by Sam Perrin One comment

Image Credit: Alexandre Roux, CC BY-NC-SA 2.0, Image Cropped

In the summer of 2019 I spent a week driving around south-east Norway with my Master’s student Bastian. The plan was to speak to local freshwater managers and get their take on invasive fish species in Norway. I’d never conducted this sort of research before, but I thought I knew what I was in for. Invasive bad, native good, right? More nuanced approaches are for those who are disconnected from the problem, academics like me who could watch from a distance and comment airily.

First interview. What does the term “invasive species” mean to you?

Obviously I expected some combination of “alien to the region”, “brandishes halberds and horned helmets” and “outcompetes the native trout” (trout and its fellow salmonids are really quite popular here). What I got instead (abridged) was a contemplative shrug and a reminder that there are almost no native populations of trout left anywhere in Norway.

Insert confused ecologist.

The Species On The Globe Go Round And Round

Posted on September 2, 2021 by Sabhrina Gita Aninta Leave a comment

Today we associate lions with Africa, but they used to be widespread around the northern hemisphere (Image Credit: MLbay, Pixabay licence, Image Cropped)

While I continuously hear my little one’s nursery rhyme about a certain stuff going round and round, I think, what else moves round and round in my field? Species!

They move around as they are looking for a mate, food, to avoid cold weather, the list goes on. They occupy a reasonable range that can be handled by their bodily functions, and either stay in that range or move when the environment changes. A species’ historical movement is one of the most important aspects of its natural history.

Opinions

Investigating the Financial Costs of Invasive Species

Posted on September 1, 2021 by Sam Perrin One comment

Economic costs of biological invasions in the United Kingdom (2021) Cuthbert et al., NeoBiota, https://doi.org/10.3897/neobiota.67.59743

The Crux

I write near constantly about non-native species on Ecology for the Masses, but I mainly focus on the negative impacts that many of them have on native ecosystems. Yet often if we want to really kick off initiatives to manage invasive non-native species, we need to point out the financial burden that many of them bring.

Yet obtaining a simple monetary estimate for invasive species is not easy. A few particularly notorious invasives tend to take up a lot of research focus, which mean that there are many species out there for which our cost estimates could be unreliable. Likewise, we’re likely to have a better picture of the impact of non-native species which have been established longer than ones who have just arrived, and haven’t been sufficiently studied or haven’t spread far enough to have had a measurable impact.

But non-native species aren’t slowing down in their spread anytime soon, so it’s important to figure out what the costs of invasive non-native have been and will be, as well as where there are holes in our knowledge that need to be filled. That’s what today’s study set out to do, by looking at invasive species in the United Kingdom.

Polly Want A City? Population Boom Sparks Call For Cull Of London’s Invasive Parakeets

Posted on March 2, 2021 by Charlie Woodrow 2 comments

When someone imagines London, they probably visualise Big Ben, Buckingham palace, and an overly patriotic use of the Union Jack. What they probably don’t picture is flocks of bright green parrots occupying every tree branch and streetlamp in view. However, urban populations of invasive parrot species are becoming more readily observed globally, and in London, there are fears the population may be growing too fast!

Earlier this year, the UK saw headlines announcing that the government has been advised to cull the iconic birds following a recent increase in numbers. But with their bright colours making them a unique addition to the fauna of the city, and their nonchalant nature towards locals and tourists, many are opposed to the cull. So what is the right thing to do when we get attached to an invasive species? And are parrots on their way to becoming the next globally distributed ‘pest’?

Opinions

Crossing the River Between Fishers and Fish Science

Posted on January 12, 2021 by Sam Perrin One comment

"We need the next generation of scientists to be at the coalface, communicating good scientific information."

This article was first published in late 2018 (Image Credit: Mallee Catchment Management Authority, CC BY-SA 4.0, Image Cropped)

When a food source provides almost half a planet with protein, you can expect the people who deliver that food source to play an important role in society. Fishing is no exception. Any country that has a marine or freshwater ecosystem in close proximity will have a fishing community, and that community can play a variety of roles, from something as simple as putting food on people’s tables to campaigning heavily to keep your country from joining the EU.

So it makes sense that fishers should have access to good fish science, at every level. If you’re a multi-million-dollar corporation, you need to know how fish stocks will respond to certain catch levels over a sustained period. If you’re a local or specialised fishing community, you need to know how available your catch will be in five years given temperature increases. And if you’re one person on a boat in a river, you might want to know how best to treat an over- or under-sized fish to ensure it survives being released.

It follows, then, that there should be open communication between fish scientists and fishers. At this year’s Australian Society of Fish Biology conference, I asked a variety of delegates a simple question: Is there open communication?

Opinions

Incompetent Invaders Dilute Parasites and Alter Disease Dynamics

Posted on April 29, 2020 by Sam Perrin One comment

Guest post by Paula Tierney

Invasive freshwater fish (Leuciscus leuciscus) acts as a sink for a parasite of native brown trout Salmo trutta (2020) Tierney et al. Biological Invasions. https://doi.org/10.1007/s10530-020-02253-1

The Crux

From house cats to cane toads, invasive species are one of the biggest threats worldwide to native plants and wildlife, second only to habitat destruction. There are a few different definitions of an invasive species, but two consistent tenets are a) that they are a living organism spreading and forming new populations outside of their native range and b) causing some kind of damage to the native ecosystem, economy or human health. As humans move around the globe with increasing ease (these last two months aside), the spreading of invasive species is increasingly common in our globalised world.

The spread of invasive species creates new ecological interactions between native and invasive species that can impact how our native ecosystems function, including disease dynamics. One key set of interactions that can be completely changed by the introduction of the invader are that of parasites and their hosts. If development and transmission of native parasites is different in invasive hosts compared to their usual native hosts, the parasite dynamics of the whole system can be altered.

Paper of the Week

Introduced Species Might Restore Ecological Functions Lost During The Ice Age

Posted on April 15, 2020 by Julia Ramsauer One comment

Image Credit: hbieser, Pixabay Licence, Image Cropped

Introduced herbivores restore Late Pleistocene ecological functions (2020) Lundgren et al., PNAS, https://doi.org/10.1073/pnas.1915769117

The Crux

The fauna of the Pleistocene (also known as the Ice Age) was not that dissimilar to the communities of animals which inhabit our planet now. However, many more large land mammals inhabited all kinds of ecosystems. By the end of the Pleistocene, many of them were extinct, mainly due to climate change impacts (glaciers got larger and restricted their ragne) and prehistoric human impacts like over-hunting, habitat alteration, and introduction of new diseases. The decline of large-bodied herbivores in the Late Pleistocene (LP from here on) led to many ecological changes including reduced nutrient cycling and dispersal, reduced primary productivity, increased wildfire frequency and intensity, and altered vegetation structure. These changes have become our norm.

Scientists usually study species introduction under the premise that they are ecologically novel. However, the introduction of large herbivores has been found to drive changes in the environment, potentially restoring or introducing novel ecological functions similar to pre-extinction Late Pleistocene conditions. This week’s researchers wanted to investigate what sort of role introduced mammals played in restoring ecological interactions by investigating their functional similarity with LP species.