Data from: A 3,000 year record of Caribbean reef urchin communities reveals causes and consequences of long-term decline in Diadema antillarum

Urchins are the last abundant grazers of macroalgae on most Caribbean reefs following the historical overexploitation of herbivorous fishes. The long-spined urchin Diadema antillarum was particularly effective at controlling macroalgae and facilitating coral dominance on Caribbean reefs until its ecological extinction from a catastrophic disease epidemic in the early 1980s. Despite their important role in the structure and functioning of Caribbean reef ecosystems, the natural dynamics of Caribbean reef urchin communities are poorly known due to the paucity of ecological survey data prior to large-scale human disturbances and the Diadema dieoff. To help resolve the baseline abundances and ecological roles of common urchin taxa, we track changes in urchin abundance and composition over the past 3,000 years from analysis of subfossil urchin spines preserved in reef matrix cores collected in Caribbean Panama. Echinometra consistently dominated the subfossil spine assemblage, while Diadema was consistently rare in the subfossil record in this region. Rather than increasing during a period of heightened human exploitation of their fish competitors and predators, Diadema began declining over a millennium ago. Convergent cross mapping (CCM) causality analyses reveal that Diadema abundance is causally related to coral community composition. Diadema is negatively affected by Acropora cervicornis dominance, likely due to the tight association between this coral and the threespot damselfish, an effective Diadema competitor. Conversely, Diadema positively affects the abundance of the coral Madracis mirabilis, possibly via its control of macroalgae. Causal relationships were not detected among abundances of individual urchin taxa, indicating that inter-specific echinoid competition is not a factor limiting Diadema recovery. Our detailed record of prehistorical and historical urchin community dynamics suggests that the failure of Diadema to recover over 30 years after its mass mortality event may be due in part to the prey release of damselfish following the long-term overfishing of piscivorous fishes.在草食性鱼类遭受历史过度捕捞之后，海胆已成为多数加勒比海珊瑚礁上现存最丰富的大型藻类牧食者。长棘海胆（Diadema antillarum）曾在调控大型藻类生长、维持加勒比海珊瑚礁的珊瑚主导状态中发挥了尤为关键的作用，直至20世纪80年代初因一场灾难性疾病流行引发生态灭绝。尽管海胆在加勒比海珊瑚礁生态系统的结构与功能中扮演着重要角色，但由于大规模人类扰动与长棘海胆大规模死亡事件发生前的生态调查数据极度匮乏，学界对加勒比海海胆群落的自然动态仍知之甚少。为厘清常见海胆分类群的基线丰度与生态功能，我们通过分析采自巴拿马加勒比海域礁基质岩芯中保存的亚化石海胆棘，重建了过去3000年中海胆丰度与群落组成的动态变化。研究发现，石笔海胆属（Echinometra）始终在亚化石棘组合中占据主导地位，而该区域的亚化石记录中长棘海胆始终较为稀少。值得注意的是，在其鱼类竞争者与捕食者被人类大规模捕捞的时期，长棘海胆的种群数量并未出现增长，反而在一千多年前就开始了下降。收敛交叉映射（Convergent Cross Mapping, CCM）因果分析结果显示，长棘海胆的丰度与珊瑚群落组成存在因果关联：长棘海胆的丰度会因鹿角轴孔珊瑚（Acropora cervicornis）的主导存在而受到负面影响，这可能与该种珊瑚与三斑雀鲷（threespot damselfish）的紧密共生关系有关——三斑雀鲷是长棘海胆的有力竞争者。反之，长棘海胆会对奇异杯珊瑚（Madracis mirabilis）的丰度产生正向影响，这一效应可能通过其对大型藻类的牧食控制实现。未检测到不同海胆分类群的丰度间存在因果关系，这表明种间海胆竞争并非限制长棘海胆种群恢复的因素。我们的史前与历史时期海胆群落动态详细记录显示，在大规模死亡事件发生后的30余年里，长棘海胆未能实现种群恢复，这一现象可能部分源于食鱼鱼类（piscivorous fishes）长期被过度捕捞后，雀鲷种群出现的猎物释放效应。