BackgroundThe invasive diatom Didymosphenia geminata (Lyngbye) M. Schmidt has received considerable attention in recent years due to its rapid geographic expansion and massive proliferation, which have altered habitat availability for benthic species and triggered negative effects on stream ecosystems. We evaluated the changes in the community structure of phytobenthos caused by the temporal variation in D. geminata coverage, in addition to the environmental variables correlated with the temporal variation of this invasive microalga in the Andean sector of the Biobio River basin, Chile.MethodsEnvironmental parameters were measured during the austral summer of 2014–2015, when phytobenthos samples were collected and used to develop a relative abundance matrix of taxa by calculating species richness and Shannon diversity. Multivariate techniques were used to establish the relationships among environmental variables, including D. geminata coverage, and the phytobenthic community.ResultsMassive proliferation of D. geminata occurs during summer (December–January). According to multiple regression analysis, electrical conductivity, temperature and total phosphorus were the variables that best explained the variation in D. geminata coverage. When D. geminata coverage was over 50%, phytobenthic species richness was significantly higher than at the uninvaded site, without a significant change in Shannon diversity. In addition, the % coverage of this invasive microalga and total phosphorus concentration were variables that differentiated phytobenthic communities among the study sites.ConclusionsEnvironmental factors such as conductivity, temperature and total phosphorus concentration influenced the temporal variability of D. geminata mats. In addition, the massive growth of this invasive diatom caused a higher species richness without altering Shannon diversity. Our results suggest that the spatio-temporal variability of D. geminata correlated with environmental variables will help predict the habitat suitability of this alga in other Andean rivers and allow a better understanding of ecological habitat alterations.

中文翻译：

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Didymosphenia geminata 覆盖率对智利安第斯盆地底栖植物群落的影响

背景入侵硅藻Didymosphenia geminata (Lyngbye) M. Schmidt 近年来因其快速的地理扩张和大规模增殖而受到广泛关注，这改变了底栖物种的栖息地可用性并引发了对河流生态系统的负面影响。除了与智利比奥比奥河流域安第斯地区的这种入侵微藻的时间变化相关的环境变量外，我们还评估了由 D. geminata 覆盖率的时间变化引起的底栖植物群落结构的变化。 方法环境参数在 2014 年至 2015 年的南方夏季期间测量了底栖植物样本，并通过计算物种丰富度和香农多样性来开发类群的相对丰度矩阵。多变量技术用于建立环境变量之间的关系，包括 D. geminata 覆盖率和底栖植物群落。结果 D. geminata 的大规模增殖发生在夏季（12 月至 1 月）。根据多元回归分析，电导率、温度和总磷是最能解释 D. geminata 覆盖率变化的变量。当 D. geminata 覆盖率超过 50% 时，底栖植物物种丰富度显着高于未入侵地点，而香农多样性没有显着变化。此外，这种侵入性微藻的覆盖率百分比和总磷浓度是区分研究地点底栖植物群落的变量。结论环境因素如电导率、温度和总磷浓度影响 D. geminata 垫子的时间变异性。此外，这种入侵硅藻的大量生长在不改变香农多样性的情况下导致了更高的物种丰富度。我们的结果表明，与环境变量相关的 D. geminata 的时空变异将有助于预测这种藻类在其他安第斯河流中的栖息地适宜性，并有助于更好地了解生态栖息地的变化。