Abstract
The effect of controlled flushing on natural phytoplankton communities in brackish estuarine water ponds of Donana Natural Park (Guadalquivir marshes, SW Spain) was evaluated throughout a year cycle by 16S chloroplast rDNA metagenome analysis. Multivariate analysis of phytoplankton assemblages based on the abundance of 30 main identified microalgae included in seven different phyla revealed pond flushing accounted for 19.6% of total data variation, a value far below the 42.5% variability explained by seasonality. Microalgae species biovolume was a better descriptor explaining phytoplankton assemblages in comparison to species relative abundance. Increasing pond flushing led to augmented phytoplankton diversity in spring, summer and autumn, but not in winter. Diatoms were more abundant under high water flushing, a situation that favoured the tychopelagic behaviour of some species. Cyanobacteria and dinophytes were more abundant under low flushing. Haptophytes and cryptophytes relative biomass was also enhanced by low water flushing, but only during winter and spring. Two main haptophytes that seasonally succeeded each other exhibited opposed response to hydrology with Isochrysis sp. showing negative response to increased flushing and Diacronema vlkianum showing a positive reaction. Both species represented a permanent and relevant haptophytes contribution to phytoplankton assemblages in marsh ponds previously undescribed in the area.
Published Version
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