Nogueira M G, Ferrareze M, Moreira M L, Gouvêa R M
Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista – UNESP, Campus de Rubião Júnior, CP 510, CEP 18610-000, Botucatu, SP, Brazil.
Braz J Biol. 2010 Oct;70(3 Suppl):781-93. doi: 10.1590/s1519-69842010000400009.
The phytoplankton assemblages from eight reservoirs of the Paranapanema River were studied during two consecutive years. Chlorophyceae and Bacillaryophyceae dominated in richness. The observed high number of taxa, 234, reflects the extensive sampling programme and evidences the necessity of considering the whole hydrograph basin to assess the biodiversity status of inland water ecosystems. The dams had a negative effect on phytoplankton richness, with higher number of taxa associate to riverine (non-regulated) stretches. The tributary rivers also exhibited high species richness, showing the importance of considering the lateral dimension, in addition to the longitudinal one, for aquatic biota inventories in large river basins/reservoirs. Richness and diversity were also positively influenced by the connectivity with lateral wetlands (macrophyte-dominated lakes) due to the periphyton influence. The phytoplankton abundance/biomass was not influenced by higher water retention time. Higher values occurred in the middle basin stretches (river-passage reservoirs) due to the increase in the trophic conditions. There was a positive correlation with phosphorus. Poorer light conditions in the cascade do not limit the phytoplankton biomass, with assemblages dominated by species tolerant to turbulent conditions and high mineral turbidity. Bacillariophyceae and Cryptophyceae dominated numerically. The first group (unicellular forms) was prominent in the large and oligotrophic upstream reservoirs. The second was highly abundant in the river-passage (low retention time), and more eutrophic, reservoirs. Cyanophyceae growth is probably controlled by advection processes (wash-out effect). The zooplankton does not control the phytoplankton biomass and the diversity of both groups is positively associated in the cascade. The structure of the phytoplankton assemblages showed to be a good indicator of the operationally distinct reservoirs of the Paranapanema cascade and also reflected the changes in the trophic conditions along the basin.
连续两年对巴拉那帕内马河八个水库中的浮游植物群落进行了研究。绿藻门和硅藻门在种类丰富度上占主导地位。观察到的234个分类单元数量众多，这反映了广泛的采样计划，并证明有必要考虑整个水文流域来评估内陆水生态系统的生物多样性状况。水坝对浮游植物丰富度有负面影响，与河流（未调节）河段相关的分类单元数量更多。支流河流也表现出较高的物种丰富度，这表明除了纵向维度外，考虑横向维度对于大型流域/水库中水生生物群落清查的重要性。由于周丛生物的影响，与侧向湿地（以大型植物为主的湖泊）的连通性也对丰富度和多样性产生了积极影响。浮游植物的丰度/生物量不受较长的水滞留时间影响。由于营养条件的增加，较高的值出现在流域中部河段（河道型水库）。与磷呈正相关。梯级水库中较差的光照条件并不限制浮游植物生物量，群落以耐湍流条件和高矿物浊度的物种为主。硅藻门和隐藻门在数量上占主导地位。第一组（单细胞形式）在大型贫营养上游水库中占主导。第二组在河道型（滞留时间短）且营养程度更高的水库中大量存在。蓝藻门的生长可能受平流过程（冲刷效应）控制。浮游动物并不控制浮游植物生物量，且两组的多样性在梯级水库中呈正相关。浮游植物群落结构显示是巴拉那帕内马河梯级不同运行水库的良好指标，也反映了沿流域营养条件的变化。
