Associations between the morphology and biomechanical properties of submerged macrophytes: implications for its survival and distribution in Lake Erhai

Abstract

Submerged macrophytes mainly distribute in the wind-protected littoral zones, rather than continuously distribute around the lake due to mechanical damage by strong wave. However, it is unknown how the biomechanical properties, the key targets against mechanical stress, contribute to its survival and distribution in natural aquatic ecosystem. In this study, the distribution, plant growth, and leaf biomechanical and morphological traits of different segments of Vallisneria natans were examined at 25 sites with three wind strength [sites exposed to strong ES wind (HW), sites exposed to moderate ES wind (MW) and sites sheltered by lakeshore with weak wind disturbance], in Lake Erhai, of Yunnan Province, China. Results showed that V. natans mainly distributed in the wind-protected eastern and northern littoral zones within 5 m water depth. The smallest plant growth, strongest and least flexible leaves were at MW, indicating that V. natans is prone to dominate the littoral zones exposed to strong but short wave. Additionally, the high plant growth and relatively stronger and less flexible leaves at HW suggested that the maximization of photosynthesis was at the cost of reduced biomechanical properties and increased drag forces from similar waves, which were unfavourable to complete their life cycles and ultimately reduce the survival and distribution of V. natans under strong wave disturbance. The significant associations between the biomechanical and morphological traits may trigger trade-offs between the mechanical resistance and other plant functions, such as photosynthesis, ultimately determining survival and distribution of submerged macrophytes in natural aquatic ecosystems.

Hydrometeorological conditions drive long-term changes in the spatial distribution of Potamogeton crispus in a subtropical lake

“…Macrophytes in lakes are often affected by water flow resistance, which is frequently over 25 times more resistant compared to terrestrial vegetation under similar wind speeds ( Denny and Gaylord, 2002 ). Submerged macrophytes will also show different biomechanical characteristics subject to the wind and wave conditions ( Zhu et al., 2015 ). Consequently, most submerged macrophytes float to the water’s surface when strong winds and waves cause stems to break or entire plants to be uprooted.…”

Effects of water flow on submerged macrophyte-biofilm systems in constructed wetlands

“…Hydraulic forces generated by waves and flow strongly influence the growth, distribution and species diversity of submerged macrophytes in aquatic environments 14 . Meanwhile, hydraulic conditions modulate the bacterial density, community structure, spatial distribution, and activities (respiration, potential nitrification, denitrification and methanogenesis) of the microbes through adjusting the attachment and detachment of bacteria, the distribution of extracellular polymeric substances and the mass transfer at the biofilm-water interface 15 – 17 .…”

“…Unlike on rigid non-living materials, the surface properties of submerged macrophytes are flexible and animate. The flexibility reduces the physical damage of water flow to the submerged macrophytes by decreasing the water flow and shear force at the leaf-water interface to different extent depending on the degree of architecture complexity of submerged macrophytes 14 , 24 . The animate host would be growing and interacting with epiphytic biofilms throughout its lifetime through physiological activities (e.g.…”

Thematic issue: water of the Erhai and Dianchi Lakes

“…It systematically analysed the pollution process, stages characteristics and major biological group changes of Dianchi and Erhai Lakes (He et al 2015a). It also analysed the major problems such as the evolution of the basin's water environment, and its protection and treatment, in order to further promote and enhance the protection and treatment of Dianchi, Erhai and other lakes in China Zhang et al 2015a, b;Zhu et al 2015). …”