The Mediterranean Sea is one of the most vulnerable ecosystems in the world due to the variety and severity of cumulative impacts faced, including high climate risk. Species distributions are expected to track climate niches in response to warming, with meridionalization (i.e. northern spread of native warm-water species) as a common documented response. However, the Mediterranean environment is also highly heterogeneous and structured at regional scales, constraining generalized species responses. Based on long-term monitoring data of demersal communities in the Western Mediterranean (1994–2019), we calculated seven indicators characterizing the space–time patterns of multiple species distributions and their temporal rates of change. Simultaneously, we computed climate velocity based on the space–time variation of sea surface temperature. Subsequently, we modeled the space–time patterns of species distributions as response to climate velocity, taking into account the species’ temperature and depth preferences. Contrary to the generalized northward expectation as a consequence of communities’ meridionalization, a large number of species have shifted their distributions toward the south and southwest to higher and medium r climate velocity values and averaged warmer conditions. In general, cold-water species with an affinity for low and moderate mean temperature and wide and narrow temperature ranges were better at tracking climate velocity. Furthermore, species distributed over the continental shelf shifted towards shallower and inshore waters in response to high climate velocity, as opposed to shallower waters further away and contrary to expectations of shifts towards deeper waters, following the bathymetric gradient. The ranges of dispersion and the spatial heterogeneity of these species expanded, although not explicitly in response to climate velocity, suggesting additional synergistic drivers. Our results confirm the importance of climate velocity as a useful metric for predicting species responses at sub-regional levels and provide information on expected species responses at the scales required for embracing regional to local management measures.

中文翻译：

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气候速度推动了西地中海物种转移的意外南移模式

由于面临的累积影响的多样性和严重性（包括高气候风险），地中海是世界上最脆弱的生态系统之一。预计物种分布将跟踪气候生态位以应对变暖，其中经向化（即本地暖水物种向北扩散）是常见的有记录的响应。然而，地中海环境也具有高度异质性，并且在区域尺度上具有结构性，限制了普遍的物种反应。基于西地中海底层群落的长期监测数据（1994-2019），我们计算了表征多个物种分布的时空格局及其时间变化率的七个指标。同时，我们根据海面温度的时空变化计算了气候速度。随后，我们考虑了物种的温度和深度偏好，对物种分布的时空模式作为对气候速度的响应进行了建模。与由于群落经向化而普遍向北的预期相反，大量物种已将其分布向南部和西南部转移，以达到较高和中等的气候速度值和平均较温暖的条件。一般来说，对低和中等平均温度以及宽和窄温度范围有亲和力的冷水物种更能跟踪气候速度。此外，分布在大陆架上的物种响应高气候速度而向较浅和近海水域转移，而不是更远的较浅水域，并且与根据测深梯度向较深水域转移的预期相反。这些物种的分散范围和空间异质性扩大了，尽管没有明确地响应气候速度，这表明存在额外的协同驱动因素。我们的结果证实了气候速度作为预测次区域层面物种反应的有用指标的重要性，并提供了采用区域到地方管理措施所需规模的预期物种反应信息。