River invertebrate. Photo credit: LIAM MARSH WWW.LIAMMARSH.COM

Invertebrates. These creepy crawlers make up over 95% of all non-plant species on the planet, and yet we pay almost no attention to them. And when we do it’s to swat them away from our face or squash them as they run for their lives. Sure, there are a select few that get a bit more love, like butterflies and bees, but the vast majority of the invertebrates, the worms, beetles, spiders and flies, are largely ignored. But, here’s the thing: we should probably be paying a bit more attention. Invertebrates are the foundation of many of the planet’s food webs, facilitating the transfer of nutrients all the way up to us.

Thankfully there are plenty of scientists that have been keeping tabs on invertebrates for quite some time, investigating how these critters are faring amid climate change. Generally, the takeaways aren’t good: a study last October found that insects had declined by 75% in nature reserves across Germany, and research has shown that bees are declining at alarming rates worldwide. One of the biggest challenges when it comes to figuring out how to help invertebrates is that there’s a lot that we just don’t know about the health of their populations; it can be pretty difficult to investigate this class of tiny creatures. But now, a new study published in Nature Ecology & Evolution helps tackle this problem, giving scientists and policymakers a shortcut to understanding how climate change impacts a whole range of bugs. By combining years of data provided by different institutions, the study found some important trends about the impact of melting glaciers on river invertebrates—namely that river invertebrates, which includes things like river flies, worms and beetles, tend to react similarly to decreasing glacier cover all across the globe.

“For the first time, we’re able to show that you can sort of predict what will happen to these river invertebrates, no matter where you are in the world,” said the paper’s lead author, Professor Lee Brown from the University of Leeds. The study was largely focused on analyzing how glacial retreat impacts things like body size, movement, longevity and eating habits in invertebrates. But the investigation also gave us a view into the overall health of invertebrate species living in these ecosystems. “Because traits determine how species respond to changes in the environment, we can chart the effect of environmental change on functional traits and thus understand the impact on river invertebrate communities worldwide,” explained Brown. “What we find across nine different geographic zones is that as glaciers retreat, we lose the species that are more adaptive to really cold conditions,”

Why Should We Care About Bugs?

There are a few reasons to care how invertebrates are doing. First, and most important to our egocentric view of the world, we should care because invertebrates are critical for the stability of the entire pyramid of life. We’ve all heard the example of what happens if the bees die (summary: lots of natural systems stop functioning, and it’s very, very bad for us). But it’s not just the bees and pollination that are necessary. “These critters act as major conduits from the bottom of the food web, from algae and the detritus and the plant matter, transferring that energy up to fish, birds and amphibians,” said Brown. Warms, flies and other crawlers are critical in breaking down waste into useful nutrients, providing links in the food chain.


And there’s more: some invertebrates deserve to be protected simply because they’re the last of their species; they only live in a very small geographic area, and if they disappear it would mean the extinction of a species. Examples include things like some cold-water invertebrates that are specifically adapted to areas of the French Pyrenees, or a type of stonefly that is only found in a mountain range in Alabama. “As glaciers retreat and disappear, then there’s a good chance that some of these species will be lost for good, because they’re not found anywhere else,” said Brown. So there’s that.

So, how can we protect the worms, flies and bees? While there are some specific policy prescriptions for a few invertebrates (like banning certain pesticides to protect bee populations) there doesn’t seem to be a solid catch-all response to protecting the bugs of our planet. The one thing we can do that will almost certainly help is reduce our greenhouse gas emissions, which would help halt global warming and give millions of species more time to adapt to the new global conditions.

Another thing that’s critically important is understanding how invertebrates are impacted by human activity, which is precisely what this new paper aims to do. “This study allows us to see how functional traits influence species adaption to the changing environment. For example, as glaciers shrink we see that invertebrate responses are strongly influenced by whether they can easily migrate to and thrive in a new location,” explained the paper’s co-author Dr Martin Wilkes, from Coventry University, in a press release. “Under scenarios of rapid future environmental change such as global glacier retreat, organisms which are only able to migrate short-distances might not keep pace with habitat shifts — leading to major changes in these aquatic ecosystems.”


It’s a start. Brown and his colleagues are hopeful that this study will lead to further investigation and awareness about the importance of invertebrate communities worldwide.

“I think in general terms, a call to policy makers to start looking at invertebrate communities and trying to make sure their protected is really important, that’s what we need to do,” explained Brown. “We tend to focus on the big charismatic species, the big cuddly ones, rather than the creepy crawly invertebrates, even though the invertebrates are probably more important in running the world.”