The desmids constitute a highly diverse group with potential as a bioindicator of the conservation status of freshwater environments. We evaluated the changes in the desmid community on macrophytes with different structural complexities within mixed stands in a floodplain shallow lake in the Brazilian semi-arid region. Our main question was whether the environmental variables that best predict desmid structure among macrophyte species in mixed stands. Samplings were performed at each two months at four fixed stations during one year in a shallow tropical lake. To assess the changes in community structure, we sampled the periphyton on three macrophytes species (Cabomba caroliniana, Nymphaea amazonum, and Utricularia foliosa) with different complexity levels, which were quantified by their fractal dimension. Multivariate analysis showed that the structure and composition of the periphytic desmids were influenced by fractal dimension, nutrient availability, and temperature. The richness, density, and diversity of desmids differed between macrophytes with complex structure (U. foliosa and C. caroliniana) and simple structure (N. amazonum). We also observed that more complex macrophytes have a greatest contribution of desmids with small cell (< 40 μm) in the community, suggesting that the substrate complexity affects the use of habitat. Our results suggest that the substantial fractal differences between host macrophytes are a major determining factor in the structure of periphytic desmid communities.

demids 构成了一个高度多样化的群体，具有作为淡水环境保护状况的生物指标的潜力。我们评估了巴西半干旱地区泛滥平原浅湖混合林分内具有不同结构复杂性的大型植物的desmid群落的变化。我们的主要问题是环境变量是否最能预测混合林分大型植物物种中的硬粒结构。在热带浅湖的一年中，每两个月在四个固定站进行采样。为了评估群落结构的变化，我们对三种大型植物（Cabomba caroliniana、Nymphaea amazonum和Utricularia foliosa) 具有不同的复杂性级别，这些级别通过其分形维数进行量化。多变量分析表明，附生藻的结构和组成受分形维数、养分有效性和温度的影响。结构复杂的大型植物（ U. foliosa和C. caroliniana）和结构简单的（N. amazonum ）的硬粒的丰富度、密度和多样性不同）。我们还观察到，更复杂的大型植物群落中具有小细胞（< 40 μm）的脱粒的贡献最大，这表明基质的复杂性会影响栖息地的利用。我们的研究结果表明，宿主大型植物之间的显着分形差异是附生植物群落结构的主要决定因素。