摘要
人们是否能够对波罗的海各亚区营养状况的变化作出可靠的结论还存在着疑问,其主要原因是显示出较高自然变化性的生产力参数是以稀疏采样为基础的,这就突显了长期数据集的重要性。我们在此提供了一个30年期的芬兰湾西部叶绿素α的数据集。该研究区域的营养状况显示,20世纪七八十年代营养盐含量存在着上升的趋势,主要表现为春季水华加强的趋势。这一趋势在20世纪90年代没有继续出现,并且自此浮游植物的季节性最大值也开始表现出一些向夏末的偏移。浮游植物水华的季节性最大值的变化可能会反映出如下几个方面的信息:①氮的可获得性降低抑制了春季水华,这提高了夏季时磷的储备量;②磷的内部沉积量增加,从而能够进一步提高夏季时磷的储备量。
Drawing reliable conclusions on changes in the trophic state of various subareas of the Baltic Sea is problematic, in large part because the monitoring of productivity parameters exhibiting high natural variability is based on sparse sampling. This emphasizes the importance of long-term data sets. Here we present a 30-year chlorophyll a data set from the western Gulf of Finland. The trophic state of the study area showed an increasing trend in the 1970s and 1980s manifested mainly as strengthened vernal blooms. This trend did not continue in the 1990s, and the seasonal phytoplankton biomass maxima since then has begun to show some bias toward the late summer. The changes in seasonal maxima of phytoplankton blooms probably reflect i) decreased availability of N suppressing the magnitude of the vernal bloom, which increases the P reserves for the summer, and ii) enhanced internal P loading, which further increases the summer P reserves.
