Development of phytoplankton in Lake Pääjärvi (Finland) during under-ice convective mixing period
Development of phytoplankton in Lake Pääjärvi (Finland) during under-ice convective mixing period
复制标题
冰下对流混合期间帕雅尔维湖（芬兰）浮游植物的发育
DOI：
10.1007/s10452-009-9273-4
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发表时间：
2009
期刊：
影响因子：
1.8
通讯作者：
K. Salonen
中科院分区：
文献类型：
--
作者：
A. Vehmaa;K. Salonen
冬季浮游植物群落的发展进行了研究，在浅水区和深水区的Pääjärvi湖，芬兰南部，在冬季冰盖的最后2周。浮游植物主要由硅藻、隐藻和金藻组成。硅藻Aulacoseira和Rhizosolenia总是均匀分布的深度，最初可能是由于混合引起的热通量从沉积物，后来由于热对流。能动的Rhococcus cryptophytes和Chrysococcus chrysophytes是最丰富的附近的冰显示，尽管他们的小尺寸，他们部分能够抵抗对流混合。它们能够停留在更明亮的水层中，这反映在净增长率上，比湖中硅藻的净增长率高出一个数量级。鉴于低温和对流，所观察到的净增长率的运动类群是非常高的增长率相比，在文献中报道。冰融化后，光的可用性逐渐增加，导致主要浮游植物类群的丰度持续增加，而不管深对流环流。这表明，那些藻类最丰富的破冰时有竞争优势，在以下开放的水域条件时，营养物质丰富，但深水循环限制光的可用性。研究结果强调，在湖泊冷却低于最大密度的水冻结前，明显的微小差异，温度和光照条件可能会导致重要的变化，影响浮游植物的发展循环模式。
The development of winter phytoplankton communities was studied in both shallow and deep areas of Lake Pääjärvi, southern Finland, during the final 2 weeks of winter ice cover. Phytoplankton was mainly composed of diatoms, cryptophytes and chrysophytes. The diatoms Aulacoseira and Rhizosolenia were always uniformly distributed with depth, initially probably due to mixing induced by heat flux from the sediment and later due to thermal convection. Motile Rhodomonas cryptophytes and Chrysococcus chrysophytes were most abundant near the ice showing that, despite their small size, they were partly able to resist mixing by convection. Their ability to stay in more illuminated water layers was reflected in net rates of increase about an order of magnitude higher than those of diatoms in the middle of the lake. Given the low temperatures and convection, the observed net rates of increase of motile taxa were very high compared to growth rates reported in the literature. The gradual increase in light availability following melting of ice led to a consistent increase in the abundances of major phytoplankton taxa irrespective of deep convective circulation. It is suggested that those algae most abundant at the time of ice break have a competitive advantage in the following open water conditions when nutrients are abundant but deep water circulation limits light availability. The results emphasize that in lakes which cool below the maximum density of water before freezing, apparently small differences in temperature and light conditions can cause important changes in the circulation patterns that impact on phytoplankton development.