Herbivores play an essential role in the health and recovery of a coral reef ecosystem. The lack of recovery of the keystone herbivore Diadema antillarum has had long-lasting effects, evidenced with many reefs persisting in algal dominance. This study restocked 756 lab-reared D. antillarum to four coral reefs on the east and south coast of Puerto Rico. Sea urchins were placed in experimental plots (“corrals”) for 2 months, and the change in benthic composition was measured. Significant changes in the benthic structure were observed during the first week after the restocking. Significant reductions of fleshy macroalgae (Dictyota spp.) and thick turf algal/sediment mats (TAS), both unsuitable substrates (e.g. coral settlement), contributed to this change. Also, restocked D. antillarum significantly reduced the cover of encrusting red algae, Ramicrusta spp. By the end of the study, the abundance of fleshy macroalgae decreased by a mean of 77% (max of 100%) and Ramicrusta and TAS by 53% (max 71%) and 56% (max 100%), respectively. Clean substrate (“pavement”), crustose coralline algae (CCA), and filamentous turf algae increased between one to two orders of magnitude. The restoration of native sea urchins is a non-invasive and useful approach to aid in the mitigation of algae, especially potentially dangerous alga like Ramicrusta. The results of this study highlight the importance of herbivores in improving the conditions on coral reefs.

中文翻译：

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通过重新引入基石食草动物长刺海胆 Diadema antillarum，减少加勒比珊瑚礁上的有害藻类

草食动物在珊瑚礁生态系统的健康和恢复中发挥着重要作用。基石食草动物Diadema antillarum缺乏恢复产生了长期影响，许多珊瑚礁持续保持藻类优势就证明了这一点。这项研究将 756 只实验室饲养的D. antillarum补充到波多黎各东海岸和南海岸的四个珊瑚礁中。海胆被放置在试验区（“畜栏”）中 2 个月，并测量底栖成分的变化。在放养后的第一周观察到底栖结构的显着变化。肉质大型藻类（ Dictyota）的显着减少spp.) 和厚草皮藻/沉积垫 (TAS)，这两种不适合的基质（例如珊瑚沉降）促成了这种变化。此外，补充的D. antillarum显着减少了结壳红藻Ramicrusta spp。到研究结束时，肉质大型藻类的丰度平均减少了 77%（最大 100%），枝壳藻和 TAS 分别减少了 53%（最大 71%）和 56%（最大 100%）。清洁基质（“路面”）、甲壳珊瑚藻（CCA）和丝状草皮藻类增加了一到两个数量级。恢复原生海胆是一种非侵入性且有用的方法，可帮助减轻藻类，尤其是像拉米克拉斯塔这样具有潜在危险的藻类. 这项研究的结果强调了食草动物在改善珊瑚礁条件方面的重要性。