Plankton biodiversity along a gradient of productivity and its mediation by macrophytes
Plankton biodiversity along a gradient of productivity and its mediation by macrophytes
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DOI：
10.1890/07-0048.1
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发表时间：
2007-09-01
期刊：
影响因子：
4.8
通讯作者：
de Meester, L.
中科院分区：
文献类型：
--
作者：
Declerck, S.;Vanderstukken, M.;de Meester, L.
我们研究了水生植被对浮游生物三个功能群（浮游植物、浮游动物和底栖浮游动物）沿着初级生产力梯度的物种分类和群落聚集过程的影响。我们进行了一个室外牛水槽实验（n = 60），使初级生产力梯度（四个营养添加水平：0，10，100，1000 μ g P/L; N/P比：16）与植被梯度（无水生植物，人工水生植物，和真实的伊乐藻）的正交组合。我们使用人工植物来评估植物物理结构的影响，而不考虑其他植物效应，如营养竞争或化感作用。浮游植物和浮游动物的种类丰富的混合物接种的坦克。生产力和水生植物影响群落结构和多样性的三个功能群。类群丰富度下降，增加浮游生物生产力在每个功能组根据嵌套的子集模式。我们没有发现单峰多样性与生产力关系的证据。水蚤和殖民地栅藻的比例丰富的生产力强烈增加。GLM分析表明，悬浮物饲养丰富度的下降是由于竞争性排斥的水蚤在高生产力。浮游植物丰富度的下降可能是由于水蚤的高放牧。然而，部分分析表明，这些解释并不能完全解释这些模式。可能，与高生产率相关的环境恶化（例如，高pH值）也是导致所观察到的丰富度下降的原因。水生植物对3个功能类群的组成和多样性都有积极的影响，并与初始生产力梯度相互作用决定其群落结构，水生植物通过其物理结构和其他机制影响3个功能类群的组成和多样性。部分大型植物效应可能是通过减少浮游植物产量间接产生的。我们的研究结果还间接表明，经常报道的单峰初级生产力和多样性之间的关系在性质上可能部分介导的倾向，沉水植物是最丰富的中间生产力水平。
We studied the effect of aquatic vegetation on the process of species sorting and community assembly of three functional groups of plankton organisms (phytoplankton, seston-feeding zooplankton, and substrate-dwelling zooplankton) along a primary productivity gradient. We performed an outdoor cattle tank experiment (n = 60) making an orthogonal combination of a primary productivity gradient (four nutrient addition levels: 0, 10, 100, and 1000 mu g P/L; N/P ratio: 16) with a vegetation gradient (no macrophytes, artificial macrophytes, and real Elodea nuttallii). We used artificial plants to evaluate the mere effects of plant physical structure independently from other plant effects, such as competition for nutrients or allelopathy. The tanks were inoculated with species-rich mixtures of phytoplankton and zooplankton.Both productivity and macrophytes affected community structure and diversity of the three functional groups. Taxon richness declined with increasing plankton productivity in each functional group according to a nested subset pattern. We found no evidence for unimodal diversity-productivity relationships. The proportional abundance of Daphnia and of colonial Scenedesmus increased strongly with productivity. GLM analyses suggest that the decline in richness of seston feeders was due to competitive exclusion by Daphnia at high productivity. The decline in richness of phytoplankton was probably caused by high Daphnia grazing. However, partial analyses indicate that these explanations do not entirely explain the patterns. Possibly, environmental deterioration associated with high productivity (e.g., high pH) was also responsible for the observed richness decline. Macrophytes had positive effects on the taxon richness of all three functional plankton groups and interacted with the initial productivity gradient in determining their communities.Macrophytes affected the composition and diversity of the three functional groups both by their physical structure and through other mechanisms. Part of the macrophyte effect may be indirect via a reduction of phytoplankton production. Our results also indirectly suggest that the often reported unimodal relationship between primary productivity and diversity in nature may be partially mediated by the tendency of submerged macrophytes to be most abundant at intermediate productivity levels.