Sea Urchin Guts Shift Gears to Survive Warming Waters

Sub-Antarctic marine ecosystems are facing rapid changes as oceans warm, putting resident species at risk. Scientists previously feared that Abatus cordatus, a sea urchin endemic to the Kerguelen Islands, was particularly vulnerable due to its limited ability to move and specific temperature needs. However, new research reveals this spiny creature is far tougher than expected.

When exposed to near-future warming scenarios, the urchins showed remarkably low mortality rates. The secret to their survival appears to lie within their digestive systems. While the bacterial communities in the surrounding sediment remained rigid and stable, the urchins’ gut microbiomes—the complex ecosystem of microorganisms living inside them—underwent significant changes.

The study found that as temperatures rose, the gut bacteria shifted composition, specifically increasing fermentative types while depleting sulphate-reducing ones. This biological flexibility, or plasticity, suggests the microbiome acts as a dynamic buffer, adjusting its functions to help the host resiliently weather environmental stress.