Tag Archives: Invasive Species

Wild Horses Couldn’t Drag Me Away (From The Fact That They’re Invasive)

A mob of feral horses at Yarangobilly, Australia (Image Credit: Ian Sanderson, CC BY-NC 2.0, Image Cropped)

This is a guest post by Danielle Crowley.

Horses are, without a doubt, a hugely significant part of human culture and history. Worldwide, they’ve played the role of food source, beast of burden, war steed, postal service, transport, and in modern times pet and sports star. Horses were and in many places still are are an omnipresent part of life. People have a lot of feelings about them.

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Introducing New Dung Beetles to Australia: Battling the Cane Toad’s Legacy

Image Credit: Dr Mary Gillham Archive Project, CC BY 2.0, Image Cropped

Last week, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) announced that they were going to import Moroccan dung beetles into Australia. The purpose being ostensibly to combat the fact that local Australian dung beetles have not evolved in step with marsupials instead of cattle, and are therefore pretty ineffective when it comes to breaking down the dung of sheep and cows. The introduction of the new beetles (specifically the Moroccan dung beetle, Gymnopleurus sturmi) is therefore intended to aid in the breakdown of cattle dung, returning nutrients to the soil, reducing the populations of the flies which follow cattle around and just generally cleaning the joint up. Sounds great. We’ve never had problems with species introduced to clean up our own mess before.

Read More: Dung Beetles with Benefits

Ok but didn’t you introduce the cane toads to sort out your problems and now they’re everywhere?

YES YOU’RE DAMN RIGHT WE DID. For those less familiar with the poster child for biological controls gone wrong, the cane toad (Bufo marinus) was introduced to Australia mid last century to deal with the cane beetle, which was destroying sugar crops. Australian species, having no experience which a poisonous frog of this type, have been heavily affected ever since, and the toads spread like lightning.

So this is a bad idea?

Well not exactly. While many people are comparing this directly to Australia’s previous mistakes, there are some marked differences. Exotic dung beetles have actually already been in Australia for decades. We do have 500 native species of dung beetle (accounting for about 10% of discovered species worldwide), yet scientists from the CSIRO introduced new species in the mid 60s to combat the same problem they’re trying to combat now.

This initial project is not exactly a great look for the CSIRO. In a paper from 2018, Bernard Doube of Dung Beetle Solutions International and formerly of CSIRO pointed out that of the 53 species that scientists attempted to introduce, ten were never introduced and 20 never successfully established. Doube attributed some of this to poor understanding of dung beetle breeding biology, which is worrying, given that we should really know as much as possible about a species before we go dropping it into a new ecosystem. The remaining 23 have spread to varying degrees throughout what was thought would be their natural range in a country like Australia. So far, they don’t appear to have posed a problem for native species, and have done their job in some areas.

So why will these new ones make a difference?

According to the CSIRO, the dung beetles that they have introduced don’t seem to get much work done during the spring. That’s why they’re introducing the new species. They’re not hyperfunctional crazy shitrolling juiced up beetle monsters, they just work a different shift.

This seems… fine?

Yeah ok, BUT IT’S NOT. I don’t actually have a problem with the science, it SEEMS pretty solid and anything that sequesters carbon needs to be given a look-in these days. But the way the CSIRO seems to have ignored the obvious questions that come with this irritates me. Even without reading into this too much, it is perfectly natural for anyone with a passing knowledge of the cane toad debacle to question it. The CSIRO needs to, right off the bat, acknowledge that this might sound like a bad decision, and then be abundantly clear about why it’s not.

This whole thing brings to mind the recent decision to introduce genetically modified mosquitoes into Florida to deal with the Zika virus. The science appears sound, but goddamn the concept of human-made super mosquitoes suddenly being released sounds like the start of a horror film we don’t want right now. As an example of how this sort of communication SHOULD be handled, mosquito ecologist Kara Fikrig posted a fantastic explanation of why the mosquito introduction should work, linked below.

I genuinely believe that science communication is getting better all the time. And I think this project sounds promising. I just wish that in articles like this one, and the one linked below (both of which do a pretty good job of communicating the science behind the project), both the media and the scientists would do a better job of addressing people’s valid concerns about the use of exotic species as biological invaders.

Read More: New dung beetle species set to help farmers reap benefits of turning poo into free fertiliser all year round


Sam Perrin is a freshwater ecologist who completed his PhD at the Norwegian University of Science and Technology who didn’t make a single poo joke for this entire article and deserves your respect because of it. You can read more about his research and the rest of the Ecology for the Masses writers here, see more of his work at Ecology for the Masses here, or follow him on Twitter here.

Ass-ets

Non-native species are often portrayed as villains – although not without reason as they can often cause more harm than good. The wild horses and donkeys in America’s west are no exception – both having a bad rep amongst landowners for trampling vegetation and competing with livestock and native species. But they do do some good as well – and I say this after putting my love for ponies aside.

Research has shown that these equids are actually very good diggers – specifically digging wells to tap into underground water sources. These wells create artificial oases across the arid landscape – meaning that other (native) species don’t have to travel as far to water sources, competition at water points is rdduced (no Lion King-esque waterhole dance numbers ’round here) as well as providing water to plant species.

While the fact that equids are providing water sources doesn’t erase the more detrimental effects that invasive species can have on the environment, it does show that they can help promote biodiversity in some cases. Maybe its a case of giving credit to the good that comes with the bad.

The original article can be found here:  https://doi.org/10.1126/science.abd6775

Do Disturbances Promote Biodiversity in the Presence of an Invasive Species?

Image Credit: Paresh Poriya, CC BY 4.0, Image Cropped (also not featuring tunicates)

Testing ecological theories in the Anthropocene: alteration of succession by an invasive marine species (2021) Christianson et al., Ecosphere, https://doi.org/10.1002/ecs2.3471

The Crux

Ecological disturbances, such as fire, floods, or storms, might seem like a catastrophe at first glance, but often they open up space for new species to take the place of dominant ones, creating a more diverse ecosystem. When a disturbance occurs matters as well – if a storm hits right before a particular species starts to reproduce, that species could take advantage of the extra space and become dominant in a short time.

In the 1970s, John Sutherland and Ronald Karlson tested this theory, looking at the invertebrate community of a coastal dock in North Carolina, USA. They found that which species dominated depended on when the community began to grow (a proxy for when disturbance opened up new space).

The area has since seen the introduction of an invasive species of tunicate, Clavelina oblonga. This week’s authors wanted to test whether the original patterns seen in the 1970s still showed up in the presence of the invader.

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Can Wind Farms Slow the Growth of Shorebird Populations?

Vulnerability of northern gannets to offshore wind farms; seasonal and sex-specific collision risk and demographic consequences (2020) Lane et al., Marine Environmental Research, https://doi.org/10.1016/j.marenvres.2020.105196

The Crux

A green on green conflict is what occurs when forms of renewable energy can have a potentially negative effect on the local environment. We see it in hydropower disrupting freshwater fish populations, or in the case of today’s paper, wind farms causing bird deaths. Marine shorebirds are often killed by wind turbines, yet it’s not totally clear to what extent population numbers are impacted by these deaths.

Additionally, whether wind farms are more dangerous to male or female, old or young birds could have a big impact on whether these bird deaths affect population numbers in the future. Today’s authors wanted to investigate this question, using a population of northern gannets off the coast of Scotland.

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When Beaver Introduction Backfires

A reintroduced ecosystem engineer species may exacerbate ongoing biological invasion: selective foraging of the Eurasian beaver in floodplains (2020) Juhasz et al., Global Ecology and Conservation, https://doi.org/10.1016/j.gecco.2020.e01383

The Crux

The reintroduction of species to an area from which they have been wiped out can have benefits which extend beyond that one species. Often they can restore ecological functions that have since been lost, which can result in everything from an increase in biodiversity to restructuring of an entire landscape.

That last example might seem a bit far-fetched, but beavers (Castor fiber) are capable of just that. Their damming activities can change river flows and restore healthy floodplains, and as such beavers are the target of a large reintroduction campaign now occurring throughout much of Europe.

But what happens when a species like the beaver is reintroduced to an ecosystem that has seen significant changes since it has been gone, like the introduction of invasive species? Today’s authors wanted to find out whether or not the presence of the beaver benefited native plants, or whether it made things easier for the invasive species.

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Forecasting Worldwide Alien Invasions

Image Credit: Bernard Dupont, CC BY-SA 2.0, Image Cropped

Projecting the continental accumulation of alien species through to 2050 (2020) Seebens at al., Global Change Biology, DOI: 10.1111/gcb.15333

The Crux

A by-product of globalisation is that over the coming decades, no matter how many episodes of Border Patrol get recorded, new species are going to find their way into new habitats and potentially become invasive alien species, exerting negative effects on the locals. We’ve seen this in the past, and I’ve beaten many a dead horse writing about these species on this site.

What this paper set out to find is whether or not we can predict at what scale this trend will increase.

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Assessing the Impact of the Newly Introduced European Flounder

Image Credit: Tiit Hunt, CC BY-SA 3.0, Image Cropped

Guest Post by Theresa Henke

First record of niche overlap of native European plaice (Pleuronectes platessa) and non-indigenous European flounder (Platichthys flesus) on nursery grounds in Iceland (2020) Henke et al., Aquatic Invasions, In Press

The Crux

Determining whether or not an introduced species is invasive is important, as it determines whether or not management steps need to be taken to slow or eliminate any negative impacts it might have on the local ecosystem. In Iceland, 15 introduced species have been recorded over the past decades but only six of them are currently classified as invasive or potentially invasive. One of these potentially invasive species is the European flounder (Platichthys flesus), a flatfish commonly found in coastal waters of Europe. The flounder is a catadromous fish, meaning it spawns in marine habitats but has the ability to survive in freshwater streams as well.

In 1999, the flounder was firstly identified in Icelandic waters in the southwest of the country. Since then it has rapidly spread clockwise around the country. Currently, it can be found in every part of Iceland, mostly in estuaries but also up in rivers and lakes. Juvenile flounder can be found on nursery grounds in shallow, brackish waters where they overlap with juvenile European plaice (Pleuronectes platessa). Plaice is a commercially important flatfish species native to Iceland. Despite the knowledge of the flounder’s arrival in Iceland in 1999, not much research has been conducted on the impact of this potentially invasive species.

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Here Kitty: Our Love-Hate Relationship With Feral Cats

Image Credit: Alexey Komarov, CC BY-SA 4.0, Image Cropped

While outdoor and feral cats are pretty universally accepted by scientists these days to be environmental hazards of the most destructive kind, the fact remains that they’re… well, cats. They’ve been companion animals for millenia, and often the general public react strongly against proposed measures for feral cats (or even to being told to keep their own cats indoors).

So why is it that despite a wealth of science making the case for feral cat management, many people simply can’t get on board with keeping them in check? And why do ecologists even need the public onside in the first place?

To dig a bit deeper, I spoke to Brooke Deak, a socioecologist based at the University of Adelaide. Brooke has spent the last three years studying the feral cat management debate, trying to better understand the relationship between feral cats and the general public.

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Forecasting Europe’s (Very Specific) Rodent Problem

Image Credit: Birgit, Pixabay Licence, Image Cropped

The potential current distribution of the coypu (Myocastor coypus) in Europe and climate change induced shifts in the near future (2020) Schertler et al., NeoBiota, https://doi.org/10.3897/neobiota.58.33118

The Crux

For all my talk on not immediately demonising alien species, there are a plethora of annoying little critters who the label ‘invasive’ was made for. This is the case with the Coypu, an annoying beaver-like rodent initially from South America who has since spread through other parts of the world, including large swathes of Europe.

The Coypu is a textbook invader – it reproduces quickly, and though individuals don’t stray far from rivers, as a species they are capable of expanding their range very quickly. They destabilise riverbanks through their burrowing, which can lead to severe ecological and economical damage.

They are, however, quite sensitive to temperature, and as such it’s important to know what the effects of climate change will have on their distribution. Today’s authors set out to come up with a habitat suitability map for the Coypu in light of the rise in temperature we’re expecting in the coming decades.

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