Dinoflagellate cysts analyses from sediment cores of the Po River discharge plume over the last two centuries

To obtain insight into the natural and/or human-induced changes in the trophic state of the distal portion of the Po River discharge plume over the last two centuries, high temporal resolution dinoflagellate cyst records were established at three sites. Cyst production rates appear to reflect the natural variability in the river's discharge, whereas cyst associations reflect the trophic state of the upper waters, which in turn can be related to agricultural development. The increased abundances of Lingulodinium machaerophorum and Stelladinium stellatum found as early as 1890 and 1920 correspond to the beginning of the industrial revolution in Italy and the first chemical production and dispersion of ammonia throughout Europe. After 1955, the increased abundances of these species and of Polykrikos schwartzii, Brigantedinium spp. and Pentapharsodinium dalei correspond to agriculturally induced alterations of the hypertrophic conditions. A slight improvement in water quality can be observed from 1987 onward.

为深入了解过去两个世纪波河（Po River）排放羽流远端部分营养状态（trophic state）的自然和/或人为变化，研究人员在三个站点建立了高时间分辨率的甲藻孢囊（dinoflagellate cyst）记录。孢囊生产率似乎反映了河流排放的自然变异性，而孢囊组合则反映了上层水体的营养状态——这一状态又与农业发展密切相关。早在1890年和1920年便观测到的马氏鳞甲藻（Lingulodinium machaerophorum）与星状星甲藻（Stelladinium stellatum）丰度上升，对应着意大利工业革命的开端以及欧洲范围内首次化学合成氨的生产与扩散。1955年后，上述物种以及施瓦茨多甲藻（Polykrikos schwartzii）、Brigantedinium属（Brigantedinium spp.）、戴尔五盾藻（Pentapharsodinium dalei）的丰度增加，则与农业活动引发的超富营养状态改变相关。1987年起，水体质量呈现轻微改善的趋势。