Ah yes, the ol’ otter–urchin–kelp relationship. Ever heard of it? It’s a classic example of a ‘top-down trophic cascade,’ where a keystone species shapes an entire ecosystem. Okay yes, this is a sea lion. But stick with us. Sea otters were hunted to near extinction during the fur trade and were wiped out along the West Coast of North America by the early 1900s. Without otters to eat them, urchin populations exploded, overgrazing kelp forests and leaving behind urchin barrens. Now, we’re seeing a similar story in Australia, but this time, climate change is the culprit. Warming waters are pushing urchins south into kelp forests around New South Wales and Tasmania. Their overgrazing is devastating both ecosystems and the livelihoods of those who depend on them. The good news is that urchins are surprisingly tasty — and culling efforts in both regions are trying to turn them into a sustainable seafood option! Would you try a sea urchin? Photo by mitty #OceanSchool #Otter #SeaUrchin ...