Institute of Earth Sciences - ICT, University of Évora, Rua Romão Ramalho n°. 59, 7000-671 Évora, Portugal; Water Laboratory, University of Évora, P.I.T.E. Rua da Barba Rala No. 1, 7005-345 Évora, Portugal.
Institute of Earth Sciences - ICT, University of Évora, Rua Romão Ramalho n°. 59, 7000-671 Évora, Portugal; Water Laboratory, University of Évora, P.I.T.E. Rua da Barba Rala No. 1, 7005-345 Évora, Portugal.
Sci Total Environ. 2019 Apr 1;659:1242-1255. doi: 10.1016/j.scitotenv.2018.12.251. Epub 2018 Dec 24.
Freshwater diatom communities are known to respond to a wide range of environmental factors, however, the depth gradient is usually neglected and few studies are available, especially in large reservoirs. During the ALqueva hydro-meteorological EXperiment (ALEX) field campaign, diatom communities were studied in the margins and in three platforms (from the surface to the bottom of the reservoir) located in the limnetic zone of the Alqueva reservoir, one of the largest artificial lakes in western Europe. A detailed meteorological and physico-chemical characterization of the reservoir was carried out from June to September in Summer 2014, when the reservoir was stratified, to relate these variables with diatom assemblages. Despite the large dimensions of the reservoir, no differences in the water physico-chemical characteristics and diatom descriptors were detected among platforms. Small changes in diatom assemblages, ecological guilds, taxa richness and Shannon diversity index were observed between sampling campaigns. Nevertheless, differences in diatoms were detected along a depth gradient, both in terms of diatom assemblages and ecological guilds. Taxa richness, Shannon diversity index, Pielou's evenness and Specific Pollution sensitivity Index (SPI) also differed with depth, with the lowest values of all indices detected at surface samples, increasing with depth, reaching the highest values at 20 m for taxa richness, Shannon diversity and Pielou's evenness indices.
淡水硅藻群落对广泛的环境因素有反应，但深度梯度通常被忽视，相关研究很少，特别是在大型水库中。在阿尔奎瓦 hydro-meteorological EXperiment (ALEX) 实地考察期间，对阿尔奎瓦水库（欧洲西部最大的人工湖之一）的湖沼带和三个平台（从水库表面到底部）的硅藻群落进行了研究。2014 年夏季 6 月至 9 月，在水库分层期间，对水库进行了详细的气象和物理化学特征描述，以便将这些变量与硅藻组合相关联。尽管水库的规模很大，但平台之间的水物理化学特性和硅藻描述符没有差异。在采样期间，硅藻组合、生态类群、分类丰富度和香农多样性指数观察到小的变化。然而，在深度梯度上，无论是在硅藻组合还是生态类群方面，都发现了硅藻的差异。在分类丰富度、香农多样性指数、皮埃罗均匀度和特定污染敏感指数 (SPI) 方面，深度也存在差异，所有指数的最低值都出现在表层样本中，随深度增加而增加，在 20m 处达到最高值。
