Larger zooplankton in Danish lakes after cold winters: are winter fish kills of importance?
Larger zooplankton in Danish lakes after cold winters: are winter fish kills of importance?
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DOI：
10.1007/s10750-010-0164-4
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发表时间：
2010-06-01
期刊：
影响因子：
2.6
通讯作者：
Jeppesen, E.
中科院分区：
文献类型：
--
作者：
Balayla, D.;Lauridsen, T. L.;Jeppesen, E.
冬季鱼类死亡可能是激烈的冰下浅湖，并对食物网，并最终对湖水的透明度级联影响。在西欧沿海地区，冬季通常温和，但偶尔较冷的时期也可能对湖泊鱼类群落产生强烈影响。全球变暖可能通过延迟冻结和缩短冰层覆盖期而产生不成比例的影响。我们研究了浮游动物（枝角类，桡足类和轮虫）的差异：浮游植物生物量，浮游动物群落结构，和个体大小之间的37个丹麦湖泊的不同深度，化学特性，和奖杯，通过比较四个不同的严重程度的冬天（平均冬季温度范围从-1.19A摄氏度在1996年至+2.9A摄氏度在1995年）。我们发现，甲壳类动物的平均身体尺寸显着较大，在夏季后，一个非常寒冷的冬天。浮游动物群落在一个寒冷的冬季后的夏季有一个显着较大的比例较大的物种和类群。浮游植物生物量，表示为叶绿素a（叶绿素a），较低，浮游动物草食性（叶绿素a：TP指数），较高，在1995/1996年的严重寒冷的冬季后的夏天。所有这些影响在浅水湖泊中比在深水湖泊中更强。与其他年份相比，1996年夏季浮游动物的变化可能是由于1995-1996年严冬期间冰下鱼类死亡造成的。在浅水湖泊较短的水柱中，由于冰下氧气耗尽而导致的鱼类死亡预计会发生得更早，而且会更彻底。随着气候变化，预计严冬将变得不那么频繁，冬天将变得更温和和更短。一般来说，这可能导致冬季鱼类存活率提高，次年夏季浮游动物对浮游植物的摄食减少，沃茨更加浑浊，特别是在富营养化的浅水湖泊中。
Winter fish kills can be intense under ice in shallow lakes, and have cascading effects on the food web and ultimately on lake water clarity. In maritime Western Europe, winters are usually mild, but occasional colder periods may also have strong effects on lake fish communities. Global warming may have disproportionate effects by delaying freezing and shortening the period of ice coverage. We studied differences in zooplankton (cladocerans, copepods, and rotifers): phytoplankton biomass, zooplankton community structure, and individual body size among 37 Danish lakes of various depths, chemical characteristics, and trophy, by comparing four winters of different severity (mean winter temperatures ranging from -1.19A degrees C in 1996 to +2.9A degrees C in 1995). We found that crustacean mean body sizes were significantly larger in the summer following a severely cold winter. The zooplankton communities in the summer after a cold winter had a significantly larger proportion of larger-bodied species and taxa. Phytoplankton biomass, expressed as chlorophyll-a (chl-a), was lower and zooplankton herbivory (chl-a:TP index), higher, in the summer after the severely cold winter of 1995/1996. All these effects were stronger in shallow lakes than in deep lakes. Changes in zooplankton during summer 1996, compared with other years, were likely caused by fish kills under ice during the preceding severe winter of 1995-1996. Fish kills due to under ice oxygen depletion would be expected to occur earlier and be more complete in the shorter water columns of shallow lakes. With climate change, severe winters are predicted to become less frequent and the winters to be milder and shorter. In general, this is likely to lead to higher winter survival of fish, lower zooplankton grazing of phytoplankton the following summer and more turbid waters, particularly in shallow eutrophic lakes.