The National Field Station of Freshwater Ecosystem in Liangzi Lake, College of Life Sciences, Wuhan University, Wuhan 430072, PR China.
Chemosphere. 2013 Oct;93(7):1301-8. doi: 10.1016/j.chemosphere.2013.07.008. Epub 2013 Aug 16.
Nutrient and dissolved inorganic carbon are two important factors that influence the development and species composition of submerged macrophyte communities in shallow lake ecosystems. Yet little is known about their potential interactive effects on the submerged macrophytes and competition outcome of macrophyte-phytoplankton. We performed a mesocosm experiment to investigate the growth and photosynthetic performance of three submerged macrophytes in relation to phytoplankton/epiphyton with nutrient and bicarbonate enrichment. During the experimental period (42 d), increase in nutrient loading in water column resulted in a substantial burst of phytoplankton and epiphyton growth and increased light attenuation. When combined with nutrient loading, bicarbonate enrichment also resulted in a heavily phytoplankton- and epiphyton-dominated state, although bicarbonate enrichment per se does not cause the phytoplankton and epiphyton growth. However, increase in nutrient loading in water column had significant negative impact on individual performances (growth and photosynthesis) of the three submerged macrophytes and bicarbonate enrichment increased the effect of eutrophication on two dissected-leaf macrophytes (M. spicatum and E. nuttallii). Furthermore, our results also suggest that species-specific photosynthetic performances occurred when submerged macrophytes in an environment with high abundance of phytoplankton/epiphyton. This study highlighted that increase in nutrient loading and bicarbonate in water column is likely to interactively impact both abiotic and biotic properties of a freshwater ecosystem. The interactions of these two factors could select macrophyte species that are able to resist the shading from phytoplankton/epiphyton, making these species more dominant in natural freshwater ecosystems.
营养物质和溶解无机碳是影响浅水湖泊生态系统中沉水植物群落发育和物种组成的两个重要因素。然而，人们对它们对沉水植物的潜在相互作用以及植物-浮游植物竞争结果知之甚少。我们进行了一个中观实验，以研究三种沉水植物的生长和光合作用性能与浮游植物/附生植物的关系，同时考虑了营养物质和碳酸氢盐的富化作用。在实验期间（42 天），水柱中营养物质的增加导致浮游植物和附生植物的大量生长和光衰减增加。当与营养物质负荷结合时，碳酸氢盐富化也导致了以浮游植物和附生植物为主的状态，尽管碳酸氢盐富化本身不会导致浮游植物和附生植物的生长。然而，水柱中营养物质的增加对三种沉水植物的个体表现（生长和光合作用）有显著的负面影响，而碳酸氢盐富化增加了富营养化对两种解剖叶沉水植物（M. spicatum 和 E. nuttallii）的影响。此外，我们的结果还表明，当环境中浮游植物/附生植物丰富时，沉水植物会出现特定的光合作用性能。本研究强调，水柱中营养物质和碳酸氢盐的增加很可能会相互作用，影响淡水生态系统的非生物和生物特性。这两个因素的相互作用可以选择能够抵抗浮游植物/附生植物遮荫的植物物种，使这些物种在自然淡水生态系统中更加占优势。
