Climate Change Is Making Spiders Bigger Study Says

July 25th, 2018

You might be creeped out by spiders, but science tells us that their presence is a good thing.

National Geographic explorer and ecologist, Amanda Koltz, has spent the last two years studying the effects of climate warming on arctic wolf spiders.

WHY, you might ask? Because of their ecological status, of course!

Fun-fact: Di you know that in the Arctic Tundra, wolf spiders are top predators?

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National Geographic/Kiki Contreras Source: National Geographic/Kiki Contreras

Being a top, or apex-predator is a big deal.

Apex predators represent species that are at the top of their food chain and who don’t have any natural predators.

These are also known as keystone species, as the size of their population greatly determines the health of the entire ecosystem.

This includes which plants will thrive in an environment, and soil health and composition.

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National Geographic/Amanda Koltz Source: National Geographic/Amanda Koltz

Due to their predatory status, and the chain-reaction their population increase or decrease has on ecosystem function, the arctic wolf spider can be seen and studied as an indicator species.

According to the Encyclopedia of Life, an indicator species is important for helping us understand biological changes within the ecosystem around us.

Indicator species can signal a change in the biological condition of a particular ecosystem, and thus may be used as a proxy to diagnose the health of an ecosystem.

This is why Koltz chose to take on the task of understanding the wolf spiders response to climate changes.

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National Geographic/Amanda Koltz Source: National Geographic/Amanda Koltz

We know (those of us paying attention to the science) that climate change is without-a-doubt REAL, and is most definitely accelerated by modern-day human activities.

That being said, Koltz thought it important to set up a controlled experiment to test how significant rises in temperature affect the population density in wolf spiders and impact surrounding ecosystem functions.

To do this, she and her team created 3 plots acting as biodomes; one maintained an ambient temperature as the control, and two were heated for the experiment.

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Wikimedia Commons/Sarefo Source: Wikimedia Commons/Sarefo

The intention was to see how their dietary habits changed, specifically in terms of preying on Collembola, commonly called springtails.

These are tiny invertebrates that thrive on fungus and live anywhere there’s soil and humidity.

In years where the Arctic is warmer for longer, wolf spiders tend to get larger as food becomes more abundant. In turn, they breed more frequently and therefore consume more of the springtails.

Koltz hypothesized that as the Arctic warms up, the spider colonies will increase and eat more springtails, inadvertently causing an abundance of fungus in the soil.

This would drastically speed up the decomposition of permafrost, releasing even more heat-trapping gases like CO2 and methane into the air.

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Flickr/Sean McCann Source: Flickr/Sean McCann

Contrary to her hypothesis, Koltz found the ecological reaction to her heated pods to be something quite different altogether.

What Koltz observed is when wolf spiders increased, they ate less of the springtails, not more.

The spiders actually changed their dietary habits in response to the warmer temperatures. As a result, the springtail population increased and more of the decomposing fungus was consumed.

Koltz’s experiment has successfully proven the domino effect that ripples through an ecosystem in response to climate change. Koltz told National Geographic,

“We tend to forget about the tiny animals because they’re not as visible as the bigger mammals, but I think it’s really neat to think about how these small animals have important impacts on the ecosystem as well.”

Indeed, Koltz’s findings are significant in helping us understand the ramifications of rising temperatures and how we will be impacted, from the smallest life to the largest.

H/T: National Geographic