Anthropogenic climate change presents a major challenge to coastal ecosystems. Mass population declines or geographic shifts in species ranges are expected to occur, potentially leading to wide-scale ecosystem disruption or collapse. This is particularly important for habitat-forming species such as free-living non-geniculate coralline algae that aggregate to form large, structurally complex reef-life ecosystems with high associated biodiversity and carbon sequestration capability. Coralline algal beds have a worldwide distribution, but have recently experienced global declines due to anthropogenic pressures and changing environmental conditions. However, the environmental factors controlling coralline algal bed distribution remain poorly understood, limiting our ability to make adequate assessments of how populations may change in the future. We constructed the first species distribution model for non-geniculate coralline algae (focusing on maerl-forming species but including crustose coralline algae associated with coralline algal beds) and showed that bathymetry, temperature at the seabed and light availability are the primary environmental drivers of present-day non-geniculate coralline algae distribution. Our model also identifies suitable areas for species presence that currently lack records of occurrence. Large-scale spatial declines in coralline algal distribution were observed under all IPCC Representative Concentration Pathways (ranging from 38% decline under RCP 2.6 up to 84% decline under RCP 8.5), with the most rapid rate of decline up to 2050. Refuge populations that may persist under projected climate change were also identified – informing priority areas for future conservation efforts to maximize the long-term survival of this globally important ecosystem.

中文翻译：

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物种分布模型预测预测气候变化下珊瑚藻种群的显着下降，对保护政策有影响

人为气候变化对沿海生态系统提出了重大挑战。预计将发生大规模人口下降或物种范围的地理变化，可能导致大规模的生态系统破坏或崩溃。这对于形成栖息地的物种尤其重要，例如自由生活的非膝状珊瑚藻，它们聚集形成大型、结构复杂的珊瑚礁生命生态系统，具有高度相关的生物多样性和碳固存能力。珊瑚藻床在世界范围内分布，但由于人为压力和不断变化的环境条件，最近经历了全球衰退。然而，控制珊瑚藻床分布的环境因素仍然知之甚少，限制了我们对未来种群如何变化进行充分评估的能力。我们为非膝状珊瑚藻构建了第一个物种分布模型（专注于形成海藻的物种，但包括与珊瑚藻床相关的壳珊瑚藻），并表明水深、海床温度和光照可用性是目前的主要环境驱动因素。 -天非膝状珊瑚藻分布。我们的模型还确定了目前缺乏发生记录的物种存在的合适区域。在所有 IPCC 代表性浓度路径下都观察到珊瑚藻分布的大规模空间下降（从 RCP 2.6 下的 38% 下降到 RCP 8.5 下的 84% 下降），下降速度最快，直到 2050 年。