Weckström Kaarina, Korhola Atte, Weckström Jan
Department of Biological and Environmental Sciences, Division of Aquatic Sciences, University of Helsinki, Finland.
Ambio. 2007 Apr;36(2-3):155-60. doi: 10.1579/0044-7447(2007)36[155:ioeodl]2.0.co;2.
Increased nutrient and sediment loading can affect the functioning and biodiversity of coastal ecosystems. Lacking long-term monitoring data, paleolimnological techniques enable the estimation of habitat and diversity change through time. Using these methods we assessed the effects of eutrophication on diatom community structure and species richness over the past ca. 200 years in coastal waters of the Gulf of Finland. The abundance of planktonic diatoms has increased markedly because of increased eutrophication and turbidity. The loss of benthic habitats resulted in a clear decrease in diatom species richness after a threshold of 400-600 microg L(-1) total dissolved nitrogen; no unimodal pattern between diversity and productivity was observed in our data. The urban sites displayed a marked decrease in species richness starting in the late 19th century with increased urbanization. A clear recovery was visible after the cessation of point source loading by the mid-1980s at two sites, whereas at the third site no recovery was detected because of diffuse loading from the large catchment. Changes in the rural sites were minor and did not start until the 1940s.
营养物质和沉积物负荷增加会影响沿海生态系统的功能和生物多样性。由于缺乏长期监测数据，古湖沼学技术能够估算生境和多样性随时间的变化。我们运用这些方法评估了过去约200年富营养化对芬兰湾沿海水域硅藻群落结构和物种丰富度的影响。由于富营养化加剧和浊度增加，浮游硅藻的丰度显著上升。底栖生境的丧失导致在总溶解氮达到400 - 600微克/升的阈值后，硅藻物种丰富度明显下降；我们的数据中未观察到多样性与生产力之间的单峰模式。随着城市化进程加快，从19世纪后期开始，城市区域的物种丰富度显著下降。到20世纪80年代中期，两个地点在点源污染负荷停止后出现了明显的恢复，而第三个地点由于来自大型集水区的面源污染，未检测到恢复情况。农村地区的变化较小，直到20世纪40年代才开始。
