Data from: Contrasts in the marine ecosystem of two Macaronesian islands: a comparison between the remote Selvagens Reserve and Madeira Island

The islands of Madeira and Selvagens are less than 300 km apart but offer a clear contrast between a densely populated and highly developed island (Madeira), and a largely uninhabited and remote archipelago (Selvagens) within Macaronesia in the eastern Atlantic. The Madeira Archipelago has ~260,000 inhabitants and receives over six million visitor days annually. The Selvagens Islands Reserve is one of the oldest nature reserves in Portugal and comprises two islands and several islets, including the surrounding shelf to a depth of 200 m. Only reserve rangers and a small unit of the maritime police inhabit these islands. The benthic community around Selvagens was dominated by erect and turf algae, while the community at Madeira was comprised of crustose coralline and turf algae, sessile invertebrates, and sea urchin barrens. The sea urchin Diadema africanum was 65% more abundant at Madeira than at Selvagens. Total fish biomass was 3.2 times larger at Selvagens than at Madeira, and biomass of top predators was more than 10 times larger at Selvagens. Several commercially important species (e.g., groupers, jacks), which have been overfished throughout the region, were more common and of larger size at Selvagens than at Madeira. Important sea urchin predators (e.g., hogfishes, triggerfishes) were also in higher abundance at Selvagens compared to Madeira. The effects of fishing and other anthropogenic influences are evident around Madeira. This is in stark contrast to Selvagens, which harbors healthy benthic communities with diverse algal assemblages and high fish biomass, including an abundance of large commercially important species. The clear differences between these two island groups highlights the importance of expanding and strengthening the protection around Selvagens, which harbors one of the last intact marine ecosystems in the North Atlantic, and the need to increase management and protection around Madeira.

马德拉（Madeira）与塞尔瓦任斯（Selvagens）群岛相距不足300公里，却呈现出鲜明的开发与生态差异：前者是大西洋东部马卡罗尼西亚（Macaronesia）区域内人口稠密、开发程度极高的岛屿，后者则是基本无人居住的偏远群岛。马德拉群岛总人口约26万，年接待游客停留总天数超600万天。塞尔瓦任斯群岛保护区是葡萄牙最古老的自然保护区之一，由两座主岛及若干附属小岛组成，保护范围覆盖周边水深200米以内的大陆架海域。该群岛仅常驻保护区护林员与少量海事警察分队。塞尔瓦任斯周边的底栖（benthic）群落以直立藻类与垫状藻类（turf algae）为优势类群；而马德拉群岛的底栖群落则由壳状珊瑚藻（crustose coralline algae）、垫状藻类、固着无脊椎动物以及海胆荒漠（sea urchin barrens）构成。非洲长棘海胆（Diadema africanum）在马德拉群岛的种群丰度较塞尔瓦任斯高出65%。塞尔瓦任斯的鱼类总生物量为马德拉群岛的3.2倍，顶级捕食者的生物量更是超过马德拉的10倍。该区域多种具有商业价值的鱼类（例如石斑鱼（groupers）、鲹科鱼类（jacks））均遭到过度捕捞，而在塞尔瓦任斯，这些物种的分布更为广泛、个体体型普遍更大。重要的海胆捕食者（例如尖猪鱼（hogfishes）、扳机鲀（triggerfishes））的种群丰度也显著高于马德拉群岛。马德拉群岛周边已显现出明显的捕捞活动与其他人为干扰影响。这与塞尔瓦任斯形成强烈反差：后者拥有健康的底栖群落，兼具多样的藻类组合与极高的鱼类生物量，其中包含大量体型庞大的商业重要物种。这两类群岛群落间的显著差异，凸显了加强塞尔瓦任斯群岛保护工作的重要性——该区域拥有北大西洋最后一批完整的海洋生态系统之一，同时也证明了强化马德拉群岛海洋管理与保护的必要性。