Macrozooplankton and the persistence of the deep chlorophyll maximum in a stratified lake
Macrozooplankton and the persistence of the deep chlorophyll maximum in a stratified lake
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DOI：
10.1111/fwb.12604
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发表时间：
2015-08
影响因子：
2.7
通讯作者：
A. Pannard;D. Planas;B. Beisner
中科院分区：
文献类型：
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作者：
A. Pannard;D. Planas;B. Beisner
1.深叶绿素最大值（DCM）是常见的深，贫营养分层湖泊。DCM指的是在深度发现的最大叶绿素a浓度，而不是在湖面。虽然DCM的控制被认为是通过在许多湖泊的物理化学因素，浮游动物在epilimnetic沃茨放牧的作用仍然是一种可能性。在较小的湖泊中，DCM的发生和动态记录很少，其中浮游动物的摄食可能会产生更强的结构效应。在小而浅的分层湖泊中，由于垂直梯度短和整体水温较高，放牧的生物控制可能会被放大。2.研究了小型分层湖泊中几个物理、化学和生物学参数对浮游植物生物量垂直分布的贡献。浮游植物的深度分布和温度，光照和营养盐的垂直梯度和草食性浮游动物的密度之间的关联建立通过回归和广义线性模型。3.检测到DCM通过来自上方的光和来自下方的营养物的共刺激。在3%的入射光（100 lmol光子m 2 s-1），低于DCM消失的阈值检测。沼泽生物量与养分有效性有关，阈值浓度为4 lg P L 1，低于该浓度时，DCM占主导地位。4.更大的稳定性的水团和更多的浮游动物与更高的浮游植物生物量在DCM。稳定性可能有控制的垂直营养盐通量，这是被拦截的metalimnetic浮游植物。浮游动物放牧的epilimnetic生物量可以增加入射光到达顶部的metalimonion，从而有利于光合生物量在DCM的增殖。5.风混合事件，检测减少湖数（LN，风强迫垂直结构的影响的措施），诱导垂直侵入metalimnetic水，富含营养物质和浮游植物，进入上层。我们可以推断，浮游植物的优势在上层水层会发生在夏季早些时候，如果浮游动物放牧没有删除epilimnetic浮游植物。我们的研究结果表明，虽然稳定的分层是必要的初始DCM的形成，浮游动物放牧可能会促进持续的DCM。
1. Deep chlorophyll maxima (DCM) are common in deep, oligotrophic stratified lakes. The DCM refer to the maximal chlorophyll a concentration found at depth, and not at the lake surface. While control of the DCM is thought to be via physicochemical factors in many lakes, a role for zooplankton grazing in epilimnetic waters remains a possibility. The occurrence and dynamics of DCM are poorly documented in smaller lakes, where zooplankton grazing is likely to have a stronger structuring effect. In small, shallow stratified lakes, biological control by grazing may be magnified by the short vertical gradient and overall higher water temperature. 2. The respective contributions of several physical, chemical and biological parameters to the vertical distribution of phytoplankton biomass in a small stratified lake were examined. Associations between phytoplankton depth distribution and vertical gradients in temperature, light and nutrients and the density of herbivorous zooplankton were established through regressions and generalised linear models. 3. Colimitation of the DCM by light from above and nutrients from below was detected. A threshold was detected at 3% incident light (100 lmol photon m 2 s 1), below which the DCM disappeared. Epilimnetic biomass was related to nutrient availability, with a threshold concentration at 4 lg P L 1, below which the DCM dominated. 4. Greater stability of the water mass and more zooplankton were associated with higher phytoplankton biomass in the DCM. Stability is likely to have controlled vertical nutrient fluxes, which were intercepted by the metalimnetic phytoplankton. Zooplankton grazing of epilimnetic biomass could have increased incident light reaching the top of the metalimnion, thereby favouring proliferation of photosynthetic biomass in the DCM. 5. Wind mixing events, as detected by a reduction in Lake number (LN, a measure of the influence of wind forcing on vertical structure), induced vertical intrusions of metalimnetic water, rich in nutrients and phytoplankton, into the epilimnion. We can infer that dominance of phytoplankton in the epilimnion would have occurred earlier during the summer if grazing by zooplankton had not removed epilimnetic phytoplankton. Our results suggest that, while stable stratification is necessary for initial DCM formation, zooplankton grazing may promote the persistence of a DCM.