Intensified coastal eutrophication can result in an overgrowth of seagrass leaves by epiphytes, which is a major threat to seagrass habitats worldwide, but little is known about how epiphytic biofilms affect the seagrass phyllosphere. The physico-chemical microenvironment of Zostera marina L. leaves with and without epiphytes was mapped with electrochemical, thermocouple and scalar irradiance microsensors as a function of four irradiance conditions (dark, low, saturating and high light) and two water flow velocities (approx. 0.5 and 5 cm s−1), which resemble field conditions. The presence of epiphytes led to the build up of a diffusive boundary layer and a thermal boundary layer which impeded O2 and heat transfer between the leaf surface and the surrounding water, resulting in a maximum increase of 0.8°C relative to leaves with no epiphytes. Epiphytes also reduced the quantity and quality of light reaching the leaf, decreasing plant photosynthesis. In darkness, epiphyte respiration exacerbated hypoxic conditions, which can lead to anoxia and the production of potential phytotoxic nitric oxide in the seagrass phyllosphere. Epiphytic biofilm affects the local phyllosphere physico-chemistry both because of its metabolic activity (i.e. photosynthesis/respiration) and its physical properties (i.e. thickness, roughness, density and back-scattering properties). Leaf tissue warming can lead to thermal stress in seagrasses living close to their thermal stress threshold, and thus potentially aggravate negative effects of global warming.

中文翻译：

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水流和附生植物生长对海草（Zostera marina）叶际热、光和化学微环境的影响

沿海富营养化加剧会导致附生植物过度生长海草叶，这是对全球海草栖息地的主要威胁，但人们对附生生物膜如何影响海草叶际知之甚少。带和不带附生植物的 Zostera marina L. 叶子的物理化学微环境用电化学、热电偶和标量辐照微传感器绘制，作为四种辐照条件（暗、低、饱和和高光）和两种水流速度（约0.5 和 5 cm s−1)，类似于野外条件。附生植物的存在导致扩散边界层和热边界层的形成，这阻碍了 O2 和叶表面与周围水之间的热传递，导致相对于没有附生植物的叶子最大升高 0.8°C。附生植物还减少了到达叶子的光的数量和质量，从而降低了植物的光合作用。在黑暗中，附生植物的呼吸会加剧缺氧条件，这会导致缺氧并在海草叶际产生潜在的植物毒性一氧化氮。附生生物膜因其代谢活动（即光合作用/呼吸作用）及其物理特性（即厚度、粗糙度、密度和反向散射特性）而影响局部叶际物理化学。叶片组织变暖会导致生活在接近其热应力阈值的海草中产生热应力，从而可能加剧全球变暖的负面影响。附生植物呼吸加剧了缺氧条件，这会导致缺氧并在海草叶际产生潜在的植物毒性一氧化氮。附生生物膜因其代谢活动（即光合作用/呼吸作用）及其物理特性（即厚度、粗糙度、密度和反向散射特性）而影响局部叶际物理化学。叶片组织变暖会导致生活在接近其热应力阈值的海草中产生热应力，从而可能加剧全球变暖的负面影响。附生植物呼吸加剧了缺氧条件，这会导致缺氧并在海草叶际产生潜在的植物毒性一氧化氮。附生生物膜因其代谢活动（即光合作用/呼吸作用）及其物理特性（即厚度、粗糙度、密度和反向散射特性）而影响局部叶际物理化学。叶片组织变暖会导致生活在接近其热应力阈值的海草中产生热应力，从而可能加剧全球变暖的负面影响。光合作用/呼吸作用）及其物理特性（即厚度、粗糙度、密度和背向散射特性）。叶片组织变暖会导致生活在接近其热应力阈值的海草中产生热应力，从而可能加剧全球变暖的负面影响。光合作用/呼吸作用）及其物理特性（即厚度、粗糙度、密度和背向散射特性）。叶片组织变暖会导致生活在接近其热应力阈值的海草中产生热应力，从而可能加剧全球变暖的负面影响。