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.本研究针对美国德克萨斯州中部2010至2015年的持续性严重干旱展开调查，评估了与干旱条件相关的蓝藻有害藻华（CyanoHABs）发生潜力。研究于2013至2017年采集水样以评估水质，并通过保存的微藻样本估算主要类群的细胞生物体积；2017年夏季采集鲜活样本，分离单个微藻细胞/丝状体用于DNA条形码分析。rDNA测序证实了产毒蓝藻的存在，其中尤以可产生石房蛤毒素、微囊藻毒素和鱼腥藻毒素的类群最为显著。基于细胞计数与测序结果，浮游蓝丝藻属（Planktothrix）、柱孢藻属（Chrysosporum）和尖头藻属（Raphidiopsis）在干旱条件下大量增殖，而湖丝藻属（Limnothrix）和假鱼腥藻属（Pseudanabaena）则在干旱后期成为优势类群。干旱结束后，卵形柱孢藻（Chrysosporum ovalisporum）、纤细席藻（Phormidium tenue）和浮游蓝丝藻未定种（Planktothrix sp.）仍有存在，但群落结构已转变为以硅藻为主，例如脆杆藻属（Fragilaria）和林多藻属（Lindavia）。这些观测结果表明，干旱环境可能会促进产毒蓝藻的繁盛。本数据集包含使用Geneious软件比对得到的CyanoITS、ITS2、23S及18S序列的一致序列，以及采用Gamez等人2022年发表的实验方法测定的细胞生物体积数据。