Little is known about vertical patterns of leaf characteristics for submerged macrophytes in freshwater ecosystems. Here, after sampling Ceratophyllum demersum and Hydrilla verticillata in deep (3.8 m) and shallow areas (1.0 m) in a shallow subtropical lake, we cut the individuals into segments along the vertical direction, and measured leaf biofilm and physiology characteristics. In the deep area, leaf pigment concentrations showed declining trends with an increasing water depth, but the enzymatic specific activity of peroxidase (POD-ESA) was precisely the opposite. Moreover, the amount of attached biofilm matter and epiphyte biomass were greatest on leaves of upper middle segments, and lowest on bottom segments. In the shallow area, bottom leaves of C. demersum had more attached biofilm matter and epiphyte biomass, but the opposite was true for H. verticillata. Additionally, leaf chlorophyll-a concentration was higher on the bottom segments for H. verticillata, and C. demersum had a higher POD-ESA in bottom leaves. Our analysis found that vertical pattern of leaf physiology was closely related to light intensity, and biofilms played an auxiliary role. Our study highlighted vertical patterns of leaf biofilm and physiology for submerged macrophytes, and suggested that such patterns are generally species-specific, especially in shallow areas.

对于淡水生态系统中被淹没的大型植物的叶片特征的垂直模式知之甚少。在这里，在亚热带浅湖的深层（3.8 m）和浅层区域（1.0 m）中取样了杜鹃花（Ceratophyllum demersum）和褐藻（Hydrilla verticillata），然后沿垂直方向将其切成段，并测量了叶片的生物膜和生理特性。在深处，随着水深的增加，叶片色素的浓度呈下降趋势，但过氧化物酶（POD-ESA）的酶比活性恰好相反。此外，附着的生物膜物质和附生生物量在上部中段叶片上最大，而在下部段上最低。在浅水区，C。demersum的底部叶片有更多的附着生物膜的物质和真菌的生物量，但相反的是真实的黑藻。此外，叶受叶绿素一个浓度上的底部段更高黑藻，和金鱼藻有在底部叶片更高POD-ESA。我们的分析发现，叶片生理的垂直模式与光强度密切相关，而生物膜起着辅助作用。我们的研究强调了淹没水生植物的叶片生物膜和生理的垂直模式，并建议这种模式通常是特定于物种的，尤其是在浅水区。