Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers
Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers
复制标题
湖泊变暖导致深水周转突然停止：对藻类初级生产者造成严重后果
作者：
Yana Yankova;S. Neuenschwander;O. Köster;T. Posch
在20世纪的强力施肥之后，中欧的许多深湖由于长期恢复（再少营养化）而再次营养贫乏。随着磷和氮负荷的减少，总生物生产力下降，湖泊的养分和生物量浓度现在处于历史低位。这引起了人们的猜测，即恢复过度，需要有意施肥以确保生态功能。这里我们表明，最近的再贫营养化过程确实加速了，但这是由湖泊变暖引起的。上升的空气温度加强了水柱的热稳定性，从而防止了彻底的周转（完全混合）。还原混合物阻碍富氧（表层）水体的下移和富磷、富氮（深层）水体的上移。然而，营养物的输入对藻类的春季繁殖至关重要，因为它们促进了每年食物网的演替。我们发现，自1977年以来，不断缺乏（自2013年以来）完全停止（自2013年以来）的完全共生导致了苏黎世湖（瑞士）剧烈的海洋磷消耗和浮游植物春季华的缺乏。通过模拟实验，我们可以诱导大量的春季藻华，证实目前由于出口减少而积累的低交磷充足。因此，预期的受精是非常值得怀疑的，因为在未来的自然或人工更替中，低酶营养物质将变得可用。
After strong fertilization in the 20th century, many deep lakes in Central Europe are again nutrient poor due to long-lasting restoration (re-oligotrophication). In line with reduced phosphorus and nitrogen loadings, total organismic productivity decreased and lakes have now historically low nutrient and biomass concentrations. This caused speculations that restoration was overdone and intended fertilizations are needed to ensure ecological functionality. Here we show that recent re-oligotrophication processes indeed accelerated, however caused by lake warming. Rising air temperatures strengthen thermal stabilization of water columns which prevents thorough turnover (holomixis). Reduced mixis impedes down-welling of oxygen rich epilimnetic (surface) and up-welling of phosphorus and nitrogen rich hypolimnetic (deep) water. However, nutrient inputs are essential for algal spring blooms acting as boost for annual food web successions. We show that repeated lack (since 1977) and complete stop (since 2013) of holomixis caused drastic epilimnetic phosphorus depletions and an absence of phytoplankton spring blooms in Lake Zurich (Switzerland). By simulating holomixis in experiments, we could induce significant vernal algal blooms, confirming that there would be sufficient hypolimnetic phosphorus which presently accumulates due to reduced export. Thus, intended fertilizations are highly questionable, as hypolimnetic nutrients will become available during future natural or artificial turnovers.
影响因子：
2.7
作者：
D. Straile
通讯作者：
D. Straile
影响因子：
5.2
作者：
O'Reilly, Catherine M.;Sharma, Sapna;Zhang, Guoqing
通讯作者：
Zhang, Guoqing