Université Bordeaux 1, UMR 5805 EPOC, Environnements et Paléoenvironnements Océaniques et Continentaux, Station marine d'Arcachon, Arcachon, France ; CNRS, UMR 5805 EPOC, Environnements et Paléoenvironnements Océaniques et Continentaux, Arcachon, France.
PLoS One. 2013 Sep 30;8(9):e74531. doi: 10.1371/journal.pone.0074531. eCollection 2013.
Global change has become a major driving force of both terrestrial and marine systems. Located at the interface between these two realms, estuarine ecosystems are probably the place where both direct and indirect effects of human activities conspire together to affect biodiversity from phytoplankton to top predators. Among European estuarine systems, the Gironde is the largest estuary of Western Europe and many studies have provided evidence that it has been affected by a variety of anthropogenic stressors such as thermal and chemical pollution, physical alterations and exploitation, especially for maritime traffic. In such a context, species introduction is also a current major issue with the establishment of strong competitive species that could lead to ecosystem reorganization with potential decrease or even disappearance of native species. In the Gironde estuary, this hypothesis was proposed for the invasive shrimp species Palaemon macrodactylus as a decrease in the native species abundance was observed at the same time. Although species introduction often takes place via ballast water, the influence of climate-driven changes on the establishment of new species remains a key issue. The calanoid copepod Acartia tonsa, observed in the Gironde estuary for the first time in 1983, have since colonized most part of the estuary, reaching a level of abundance comparable to the dominant native species Eurytemora affinis. In this study, using both the concept of the ecological niche sensu Hutchinson (fundamental and realized niches) and statistical models, we reveal that the dynamics of the colonization of A. tonsa was facilitated by environmental conditions that have become closer to its environmental optimum with respect to temperature and salinity.
全球变化已成为陆地和海洋系统的主要驱动力。位于这两个领域的交界处，河口生态系统可能是人类活动的直接和间接影响共同作用于生物多样性的地方，从浮游植物到顶级捕食者。在欧洲河口系统中，吉伦特河口是西欧最大的河口，许多研究已经证明，它受到了各种人为胁迫的影响，如热污染和化学污染、物理改变和开发，尤其是海上交通。在这种情况下，物种引进也是一个当前的主要问题，因为引入的竞争物种可能导致生态系统重组，本地物种的数量减少甚至消失。在吉伦特河口，这个假设被提出是针对入侵的对虾物种 Palaemon macrodactylus，因为同时观察到本地物种的数量减少。尽管物种引进通常是通过压载水进行的，但气候驱动的变化对新物种建立的影响仍然是一个关键问题。在 1983 年首次在吉伦特河口观察到的哲水蚤属桡足类动物 Acartia tonsa 此后已经在河口的大部分地区定居，其丰度达到了与优势本地物种 Eurytemora affinis 相当的水平。在这项研究中，我们使用 Hutchinson 的生态位概念（基础生态位和实现生态位）和统计模型，揭示了 A. tonsa 的定居动态是由环境条件促进的，这些条件在温度和盐度方面更接近其环境最佳值。
