Shallow lake restoration by nutrient loading reduction - some recent findings and challenges ahead
Shallow lake restoration by nutrient loading reduction - some recent findings and challenges ahead
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DOI：
10.1007/s10750-007-0596-7
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发表时间：
2007-06-01
期刊：
影响因子：
2.6
通讯作者：
Jensen, Jens Peder
中科院分区：
文献类型：
--
作者：
Jeppesen, Erik;Sondergaard, Martin;Jensen, Jens Peder
浅水湖泊对营养负荷减少的反应。最近对长时间序列湖泊数据进行的多湖比较的主要结果表明：磷（P）通常在10-15年后达到新的平衡状态，氮（N）在< 5-10年后达到新的平衡状态，湖中总N：总P和无机N：P比值增加，浮游植物和鱼类生物量往往减少;食鱼动物的百分比经常增加，浮游动物：浮游植物生物量的比例，水蚤对浮游动物生物量的贡献，以及枝藻的大小。这表明，加强资源和捕食者控制往往相互作用，从富营养化的恢复。到目前为止，重点一直是针对减少外部负载的P.然而，一项实验研究和跨系统分析的数据，从许多湖泊在北温带湖泊表明，氮可能发挥更重要的作用，丰富和物种丰富度的沉水植物比通常预期的总磷是中等偏高。根据替代状态假设，我们应该预期生态阻力养分负荷减少和P滞后。我们目前的结果表明，这两种替代状态是不稳定的，比原来预期的。全球变暖如何影响浅水湖泊的水质是有争议的。我们认为，水的清晰度往往会减少，由于无论是增强浮游植物的生长，或者，如果沉水植物的刺激，这些植物的能力降低，以保持清澈的水条件。后者得到了佛罗里达和丹麦湖泊的跨系统比较的支持。小鱼的比例可能会增加，我们可能会看到更多的鱼类聚集在植被中（导致浮游动物避难所的损失），更多的年度鱼类群体，更多的鱼类杂食性喂养和更少的专业食鱼性。此外，湖泊的生长季节可能会延长，藻类长时间大量繁殖的风险更高，而且在漂浮植物群落密集的地方。湖泊管理者在制定未来临界负荷目标时，需要考虑到全球变暖的影响，因为这些目标在未来很可能需要调整。最后，我们强调了一些未来的挑战，我们看到在湖泊恢复研究。
Shallow lakes respond to nutrient loading reductions. Major findings in a recent multi-lake comparison of data from lakes with long time series revealed: that a new state of equilibrium was typically reached for phosphorus (P) after 10-15 years and for nitrogen (N) after < 5-10 years; that the in-lake Total N:Total P and inorganic N:P ratios increased; that the phytoplankton and fish biomass often decreased; that the percentage of piscivores often increased as did the zooplankton:phytoplankton biomass ratio, the contribution of Daphnia to zooplankton biomass, and cladoceran size. This indicates that enhanced resource and predator control often interact during recovery from eutrophication. So far, focus has been directed at reducing external loading of P. However, one experimental study and cross-system analyses of data from many lakes in north temperate lakes indicate that nitrogen may play a more significant role for abundance and species richness of submerged plants than usually anticipated when total phosphorus is moderate high. According to the alternative states hypothesis we should expect ecological resistance to nutrient loading reduction and P hysteresis. We present results suggesting that the two alternative states are less stable than originally anticipated. How global warming affects the water clarity of shallow lakes is debatable. We suggest that water clarity often will decrease due to either enhanced growth of phytoplankton or, if submerged macrophytes are stimulated, by reduced capacity of these plants to maintain clear-water conditions. The latter is supported by a cross-system comparison of lakes in Florida and Denmark. The proportion of small fish might increase and we might see higher aggregation of fish within the vegetation (leading to loss of zooplankton refuges), more annual fish cohorts, more omnivorous feeding by fish and less specialist piscivory. Moreover, lakes may have prolonged growth seasons with a higher risk of long-lasting algal blooms and at places dense floating plant communities. The effects of global warming need to be taken into consideration by lake managers when setting future targets for critical loading, as these may well have to be adjusted in the future. Finally, we highlight some of the future challenges we see in lake restoration research.