The transition of a coral reef to an algal reef as a result of bleaching and overfishing is one of the most readily identifiable examples of a local ecosystem collapse (Image Credit: Stop Adani, CC BY 2.0, Image Cropped)
It’s a bleak headline, and one which was plastered all over my Twitter and Facebook feeds at the start of this week. I’m used to grim news about the environment. It’s part of my job. So there’s nothing particularly surprising about this title.
What it does represent though, is another use of a somewhat sensational term that is ill-defined by scientists and poorly understood by the public. We’ve written about such terms in the past, biodiversity and functional extinction being two examples. Here, I’m referring to ‘ecosystem collapse‘. I get the draw to such a term: people need to be alarmed about climate change and the ongoing loss of biodiversity our planet faces. Ecosystem collapse sounds really alarming.
So I thought I’d swim around in the literature a bit and see if I could figure out what we mean when we talk about ecosystem collapse.
Animals of wildly different sizes may have different likelihoods of extinction, but it could all depend on their range sizes (Image Credit: Harvey Barrison, CC BY-SA 2.0, Image Cropped)
Constraints on vertebrate range size predict extinction risk (2019) Newsome et al., Global Ecology and Biogeography, http://doi/epdf/10.1111/geb.1309
To act to prevent a species going extinct, we have to know that it’s at risk of extinction. Ecologists and conservationists simply don’t have the time or resources to make sure that all species remain safe. So having reliable methods of predicting species extinction risk is crucial.
On a global scale, the relationship between a species size and the area that it is found in (geographical range) has been studied intensively since ecology’s inception, both in existing and prehistoric species. Initial research showed that in general, the larger a species is, the larger its range size needed to be, with large species that had relatively smaller range sizes more prone to extinction. However more recent work has shown (naturally) that there are exceptions to this, with mammals viable range size actually decreasing up to a certain ‘breakpoint’, after which the size grows again.
African forest elephants populations are declining rapidly due to local human pressures. But is it fair to expect other humans to live among potential threats to their livelihood? (Image Credit: US Fish and Wildlife Service Headquarters, Public Domain Mark 1.0, Image Cropped)
Some species of animal do a better job of capturing our attention than others. For many of us, the exotic nature of these animals is often the kicker. Think of the majesty of an elephant strolling across the savannah, or the romanticised stalk of the tiger through the jungle. Yet while the public ogles these creatures in the wild or at the local zoo and mourns the decline of their wild populations or the reported deaths of iconic individuals, we often ignore the harsh reality: that there are people who live in close proximity to these animals, to whom they represent a day-to-day threat. So how does our attitudes to charismatic species in places like Africa and Asia here need to shift, and where can we start?