Forecasting the future establishment of invasive alien freshwater fish species (2021) Perrin et al., Journal of Applied Ecology, https://doi.org/10.1111/1365-2664.13993
I know I write a lot about whether or not we should jump to conclusions about non-native species, but the fact is that there are lots of situations in which invasive species need to GO. Giving them the boot, however, can be a right pain, and more often than not it’s impossible.
But an ounce of prevention is worth a pound of cure (I don’t know the imperial system well so I assume that makes sense), and figuring out where an invader is likely to turn up means you can take measures to stop it happening in the first place. This saves a lot of hassle (and money) down the road.
So how do we figure out where invasives are likely to show up? That’s what this paper, which made up the first chapter of my thesis, aimed to find out, by looking at where invasive freshwater fish species have been popping up in Norway over the last 100 years.
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.
Biotic interactions are more often important at species’ warm versus cool range edges, Paquette & Hargreaves, 2021 Ecology. https://doi.org/10.1111/ele.13864
Image credit: Trey Ratcliff, CC BY-NC-SA 2.0
In nature, we usually refer to the given area in which a species is found as a species range. The size of these vary, even between species that are very similar in appearance. For example, many of the dragonflies and damselflies I worked with during my PhD research could be found all over the state of Arkansas, but others had more limited ranges, and could only be found in the more southern lakes that I visited. Often, species are limited to these areas because the environmental conditions, such as temperature, are favorable to them, and the change in those conditions beyond the boundaries of their range will lead to them suffering. Knowing which factors limit the range of a given species is important for management policies, as knowing the temperature limits can inform predictions about the effects of climate change, while knowledge of natural enemies (like predators) can help with the containment of invasive species.
Previous work on the constraints experienced by species at their range limits tend to focus on abiotic factors (temperature, precipitation, etc.), as these data are easily quantified and there are very extensive records available. However, biotic factors (interactions with predators/competitors, the availability of prey) can also limit the range of a species. Though biotic factors are important, they are more difficult to quantify than abiotic factors, and are often species-specific. That is, the effect of a competitor on limiting the range of one species won’t be the same on another species. Interestingly, biotic interactions may be more important in warmer range limits, while the abiotic may be more important in the cooler range limits. Today’s authors used data from a number of studies to test just that idea.
Image Credit: Amy-Jo, Pixabay licence, Image Cropped
Let’s get the humblebragging out of the way – this week a paper that I wrote was published in the Journal of Applied Ecology. It was a paper that I genuinely enjoyed writing, and it gives a tangible outcome – the forecasting of the establishment of invasive species within a region. The applications are obvious. Knowing where an invasive species is likely to pop up lets us detect it early and take action quickly.
Yet that very tangibility of the outcome has resulted in it being the paper of which I most fear the consequences. So in an exorcism of my general nerves (and as a soft disclaimer), I wanted to talk about why forecasting or predicting anything can be such a complicated undertaking for an ecologist.
Image Credit: flowcomm, CC BY 2.0, Image Cropped
Public health and economic benefits of spotted hyenas Crocuta crocuta in a peri-urban system (2021) Sonawane et al., Journal of Applied Ecology, https://doi.org/10.1111/1365-2664.14024
The natural world provides as with a laundry list of health services, from cleaning the water we drink to providing blueprints for cutting edge medicine. Yet on this list of ecosystem services, carnivores often get left by the wayside. One such carnivore is the spotted hyena, which can be found roaming the outskirts of many towns in eastern Africa. The hyenas are adept scavengers, and clear away massive amounts of discarded meat every year, potentially preventing the spread of carcass-borne diseases like anthrax and tuberculosis.
Yet as with many predators, hyenas have often been feared, whether as a result of their historical association with evil spirits or more recent unfavourable portrayals. In a world where carnivores like wolves, dingoes and bears are often feared and driven off, providing proof of the benefits they bring is crucial. So that’s what today’s researchers set out to do.
Image Credit: Wade Tregaskis, CC BY-NC 2.0, Image Cropped.
If there’s one film that I could perhaps credit for sparking my fascination with the natural world, the it’s The Land Before Time. BUT if we’re going with films that do not feature the most gangly Pachycephalosaurids you ever did see, then it has to be The Lion King. The sweeping landscapes, the (at times literal) fountains of species, the Shakespearian drama, the poor understanding of trophic cascades – it’s got it all.