Rapid environmental responses to climate-induced hydrographic changes in the Baltic Sea entrance
Rapid environmental responses to climate-induced hydrographic changes in the Baltic Sea entrance
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DOI：
10.5194/bg-16-3835-2019
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发表时间：
2019-10-07
期刊：
影响因子：
4.9
通讯作者：
Filipsson, Helena L.
中科院分区：
文献类型：
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作者：
Charrieau, Laurie M.;Ljung, Karl;Filipsson, Helena L.
厄勒海峡是丹麦海峡的一部分，连接着北海和波罗的海。这是一个过渡区，生态系统在盐度、温度、碳酸盐化学和溶解氧浓度方面都有很大的梯度。除了高度多变的环境条件外，该地区还对人为干扰作出反应，例如，营养负荷，温度，和pH值。我们已经重建在厄勒海峡的环境变化，在过去的CA。200年，特别是溶解氧浓度，盐度，有机质含量和污染水平，使用底栖有孔虫和沉积物地球化学。确定了五个具有特征性有孔虫组合的区域，每个区域都反映了相应时期的环境条件。最大的变化发生在1950年左右，当有孔虫组合从一个低多样性的动物群占主导地位的物种的梭形刺向更高的多样性和丰度和优势的Elphidium物种。同时，粒度分布从粘土质沉积物转移到砂质沉积物。为了探索环境变化的原因，我们使用重建的风况加上大尺度气候变化的时间序列记录的北大西洋涛动（NAO）指数以及ECOSMO II模型的电流在厄勒地区。结果表明，在1950年代后，该地区的水循环朝着更强的电流增加的变化。有孔虫动物群反应迅速（
The Oresund (the Sound), which is a part of the Danish straits, is linking the marine North Sea and the brackish Baltic Sea. It is a transition zone where ecosystems are subjected to large gradients in terms of salinity, temperature, carbonate chemistry, and dissolved oxygen concentration. In addition to the highly variable environmental conditions, the area is responding to anthropogenic disturbances in, e.g., nutrient loading, temperature, and pH. We have reconstructed environmental changes in the Oresund during the last ca. 200 years, and especially dissolved oxygen concentration, salinity, organic matter content, and pollution levels, using benthic foraminifera and sediment geochemistry. Five zones with characteristic foraminiferal assemblages were identified, each reflecting the environmental conditions for the respective period. The largest changes occurred around 1950, when the foraminiferal assemblage shifted from a low diversity fauna dominated by the species Stainforthia fusiformis to higher diversity and abundance and dominance of the Elphidium species. Concurrently, the grainsize distribution shifted from clayey to sandier sediment. To explore the causes of the environmental changes, we used time series of reconstructed wind conditions coupled with large-scale climate variations as recorded by the North Atlantic Oscillation (NAO) index as well as the ECOSMO II model of currents in the Oresund area. The results indicate increased changes in the water circulation towards stronger currents in the area after the 1950s. The foraminiferal fauna responded quickly (