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.海胆（Urchin）是当前多数加勒比珊瑚礁上仅剩的优势大型藻类牧食类群，这一现状源于草食性鱼类（herbivorous fishes）曾遭受的历史过度捕捞。长棘海胆（Diadema antillarum）曾在加勒比珊瑚礁的大型藻类管控与珊瑚群落优势地位维持中发挥了至关重要的作用，直至20世纪80年代初因一场灾难性疫病流行而发生生态灭绝。尽管海胆在加勒比珊瑚礁生态系统的结构与功能中扮演着核心角色，但由于大规模人类干扰发生前的生态调查数据匮乏，加之长棘海胆的大规模死亡事件，学界对加勒比海胆群落的自然动态仍缺乏系统认知。为明确常见海胆类群的基线丰度与生态功能，本研究通过分析采自巴拿马加勒比海域珊瑚礁基质岩芯（reef matrix cores）中保存的亚化石（subfossil）海胆棘刺，重建了过去3000年的海胆丰度与群落组成变化序列。该区域的亚化石棘刺组合始终以棘海胆属（Echinometra）占主导，而长棘海胆的亚化石记录则始终较为稀少。在其鱼类竞争者与捕食者遭到人类高强度捕捞的时期，长棘海胆的种群数量非但没有上升，反而在千余年前便已开始下降。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柱形鹿角珊瑚（Acropora cervicornis）的优势地位上升而降低，这可能与该珊瑚与三斑豆娘鱼（threespot damselfish）的紧密共生关系有关——后者是长棘海胆的有力竞争者。反之，长棘海胆则会对奇妙迷枝珊瑚（Madracis mirabilis）的丰度产生正向影响，这一效应可能源于其对大型藻类的牧食管控作用。研究未检测到不同海胆类群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精细记录显示，长棘海胆在大规模死亡事件发生后的30余年里未能实现种群恢复，这一现象可能部分源于长期过度捕捞食鱼鱼类（piscivorous fishes）后引发的豆娘鱼猎物释放效应。