Keynote lecture: Drs. Oliver Klokman

Since 2019, we have been working to restore the long-spined sea urchin Diadema antillarum to Caribbean coral reefs. We have made real progress in culturing and restocking on Saba and learned a great deal about these animals. However, every step forward seems to raise as many questions as it answers. Large scale cultivation appears possible, but requires specific optimization, and post-release survival remains stubbornly variable. Every restock attempt reveals new aspects that need to be considered in order to be successful. Physiology and behavioral ecology have added yet another layer: how urchins are conditioned before release appears to influence how they cope on the reef, raising its own questions about what laboratory-reared animals are actually prepared for.

The honest takeaway is that restoring Diadema is not simply a production problem. The biology is complex, the system keeps surprising us, and there is still plenty we don't fully understand. That uncertainty isn't a reason for pessimism, but it is something worth keeping in mind when planning restoration work. Our experience on Saba is not unique, and we hope to offer useful insights for practitioners working across other systems.