Biomechanical properties and morphological characteristics of lake and river plants: implications for adaptations to flow conditions

Biomechanical properties and morphological characteristics of stems of eight species of submerged aquatic plants were studied to analyse (1) differences between river and lake specimens, (2) seasonal differences between winter/spring and summer/autumn specimens, and (3) change of biomechanical properties and morphological characteristics along the stems. The data show that river macrophytes display not only characteristic biomechanical traits and morphological characteristics specific to their hydraulic habitats, but also distinctive temporal changes due to seasonally varying water temperature, flow velocity, and growth phase. Furthermore, the data reveal differences between lake and river specimens that could be explained by wind exposure of the lake sampling sites and the species-specific flow requirements of the river macrophytes. Biomechanical properties and morphological characteristics varied along the stem with larger cross-sections and a higher resistance against tension and bending forces at the bottom compared to the top parts, being similar for both lake and river specimens. The acquired and analysed stem biomechanical and morphological data contribute to the plant biomechanics database to underpin a wide range of studies in aquatic ecology, river and wetland management.