Phytoplankton community structure in Lake Buchanan, TX, during an extended drought, Central Texas, USA (2010-2015)

This study investigated the impacts of an extended, severe drought in Central Texas, USA, from 2010-2015 by assessing the potential for cyanobacterial harmful algal blooms (CyanoHABs) related to drought conditions. Water samples were collected from 2013 to 2017 to evaluate water quality and preserved microalgae were used to estimate cellular biovolume of major taxa; live samples were collected in the summer of 2017 and individual microalgal cells/filaments were isolated for DNA barcoding. rDNA sequencing confirmed the presence of bloom-forming cyanobacteria, most notably those with the potential of producing saxitoxins, microcystins, and anatoxins. Based on cell counts and sequencing results, Planktothrix, Chrysosporum, and Raphidiopsis thrived in drought conditions whereas Limnothrix and Pseudanabaena were dominant post-drought. Following the drought period, Chrysosporum ovalisporum, Phormidium tenue, and Planktothrix sp. were still present, however the community had shifted to predominantly diatoms, e.g., Fragilaria and Lindavia. These observations suggest drought conditions may promote the success of potentially toxic cyanobacteria. This dataset includes consensus sequences for CyanoITS, ITS2, 23S, and 18S aligned using Geneious and cellular biovolumes using protocols described in Gamez et al. 2022.