Abstract：
Marine species are widely shifting their distributions in response to global changes and it is commonly expected they will move northward and to greater depths to reach cooler, less disturbed habitats. However, local manifestations of global changes, anthropogenic pressures, and species characteristics may lead to unanticipated and varied responses by individual species. In this regard, the Celtic-Biscay Shelf is a particularly interesting study system because it has historically been heavily fished and occurs at the interface between two distinct biogeographic provinces, its community thus comprised of species with diverse thermal preferenda. In the context of rapidly warming temperatures and intense fishery exploitation, we investigated the distribution shifts of 93 taxa (65 Actinopteri, 10 Elasmobranchii, 11 Cephalopoda, 5 Malacostraca, and 2 Bivalvia), which were sampled annually from 1997 to 2020 during a scientific bottom trawl survey. We used a set of 11 complementary spatial indices to quantify taxon distribution shifts over time. Then, we explored the relative effect of taxon abundance, fishing pressure, and climatic conditions on taxon\'s distribution shift when a significant shift was detected. We observed that 56% of the taxa significantly shifted. Not all taxa will necessarily shift northward and to deeper areas, as it is often expected. Two opposite patterns were identified: taxa either moving deeper and to the southeast, or moving closer to the surface and to the northwest. The main explanatory factors were climate change (short- and long-term temperatures) and taxon abundance. Fishing pressure was the third, but still significant, explanatory factor of taxa of greater commercial importance. Our research highlights that taxa are displaying complex distribution shifts in response to the combined anthropogenic disturbances and underscores the need to conduct regional studies to better understand these responses at the ecosystem scale to develop more suitable management plans and policies.
摘要：
海洋物种正在广泛改变其分布，以响应全球变化，通常预计它们将向北移动并到达更大的深度以达到更低的温度，不受干扰的栖息地。然而,全球变化的局部表现，人为压力，和物种特征可能导致单个物种的意外和变化的反应。在这方面,凯尔特-比斯开大陆架是一个特别有趣的研究系统，因为它在历史上被大量捕捞，发生在两个不同的生物地理省份之间的界面，因此，它的群落由具有不同热偏好的物种组成。在气温迅速变暖和渔业开发密集的背景下，我们调查了93个分类单元(65个Actinopteri，10Elasmobranchii,11头足类,5Malacostraca,和2Bivalvia），从1997年到2020年，每年在一次科学的底拖网调查中进行采样。我们使用了一组11个互补的空间指数来量化分类单元随时间的分布变化。然后，我们探索了分类单元丰度的相对影响，钓鱼压力，当检测到显著的变化时，气候条件对分类单元的分布变化的影响。我们观察到56％的分类单元发生了显着变化。并非所有的类群都会向北转移到更深的地区，正如人们经常期望的那样。确定了两种相反的模式：类群要么向东南方向移动，或者靠近地面和西北。主要解释因素是气候变化（短期和长期温度）和分类单元丰度。捕鱼压力是第三个，但仍然很重要，具有更大商业重要性的分类单元的解释因素。我们的研究强调，分类单元在应对人为干扰的综合作用下表现出复杂的分布变化，并强调需要进行区域研究，以更好地了解生态系统规模的这些响应，以制定更合适的管理计划和政策。
