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Sci Total Environ. 2019 Apr 1;659:1242-1255. doi: 10.1016/j.scitotenv.2018.12.251. Epub 2018 Dec 24.

Vertical distribution of benthic diatoms in a large reservoir (Alqueva, Southern Portugal) during thermal stratification.

Author information

1
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. Electronic address: hnovais@uevora.pt.
2
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.
3
Institute of Earth Sciences - ICT, University of Évora, Rua Romão Ramalho n°. 59, 7000-671 Évora, Portugal.
4
Institute of Earth Sciences - ICT, University of Évora, Rua Romão Ramalho n°. 59, 7000-671 Évora, Portugal; Department of Physics, ECT, University of Évora, Rua Romão Ramalho n° 59, 7000-671 Évora, Portugal.

Abstract

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.

KEYWORDS:

Benthic diatoms; Depth-gradient; Ecological guilds; Physico-chemical characterization

PMID:
31096337
DOI:
10.1016/j.scitotenv.2018.12.251
[Indexed for MEDLINE]

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