Influence of free-floating plants on the structure of a natural phytoplankton assemblage: an experimental approach
Influence of free-floating plants on the structure of a natural phytoplankton assemblage: an experimental approach
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DOI：
10.1093/plankt/fb1056
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发表时间：
2007-01-01
影响因子：
2.1
通讯作者：
O'Farrell, Ines
中科院分区：
文献类型：
--
作者：
de Tezanos Pinto, Paula;Allende, Luz;O'Farrell, Ines
利用野外中生态系统评价了自由漂浮植物对天然浮游植物结构的影响。恶劣的水下光照气候（天然大型植物覆盖和暗网处理）决定了适应阴影、生长缓慢的丝状和群体蓝藻的优势[S和L-o官能团]；Reynolds, c.s, Huszar， V., Kruk， C.等（2002）淡水浮游植物的功能分类。[j].水生生物学报，2004,24(4):417-428。生物体积和叶绿素a （Chl a）保持较低，缺氧条件普遍存在，pH为环中性，营养水平差异不显著。相反，去除漂浮植物提高光有效性，浮游植物和物理化学环境发生了重大变化：S-L-o组合被快速生长的单细胞绿藻（X1和X2）和真核浮游植物（X3）取代，缺氧恢复，铵和磷酸盐浓度显著降低。我们认为，在营养丰富的温暖湿地中，浮游植物的遮阳作用是形成浮游植物的驱动力，并决定了一种新描述的替代状态。然而，如果遮阳限制被解除，浮游植物会发生强烈的增强，氮变得有限。这种实验方法证实了在自然界中所描述的优势官能团的行为，从而加强了这种新的浮游植物控制方案的有效性，并加深了对这种新方案的理解。
The influence of free-floating plants on the structure of natural phytoplankton was assessed using field mesocosms. Poor underwater light climate (natural macrophyte cover and dark mesh treatments) determined the dominance of shade-adapted, slow-growing filamentous and colonial cyanobacteria [S and L-o functional groups; Reynolds, C. S., Huszar, V., Kruk, C. et al. (2002) Towards a functional classification of the freshwater phytoplankton. J. Plankton Res., 24, 417-428]. Biovolume and chlorophyll a (Chl a) remained low, anoxic conditions prevailed, pH was circumneutral and nutrient levels did not differ significantly. Conversely, the improvement in light availability by removal of floating plants brought about major changes on the phytoplankton and in the physicochemical environment: the S-L-o assemblage was replaced by fast-growing unicellular green algae (X1 and X2) and eukaryotic picophytoplankton (X3) increased, anoxia was reverted and ammonium and phosphate concentrations decreased significantly. We propose that in warm nutrient-rich wetlands, the shading effect posed by floating plants is the driving force in shaping the phytoplankton and in determining a newly described alternative state. Notwithstanding, if the shading constraint is released, a strong phytoplankton enhancement occurs and nitrogen becomes limiting. This experimental approach confirms the behaviour of dominant functional groups as described in nature and thus reinforces the validity and deepens the comprehension of this novel scheme for phytoplankton control.