中文摘要：

采用Fluor Cam便携式叶绿素荧光成像仪测定鄱阳湖南矶山国家级自然保护区白沙湖和常湖冬季沉水植物的光合荧光特性,包括QY-max（即Fv/Fm,PSⅡ的最大光量子产量）、ΦPSⅡ（PSⅡ实际量子效率）、q P（光化学淬灭系数）等参数及其相应的荧光成像;应用频度法统计估测沉水植物的频度,并测定水环境的营养水平。结果表明：白沙湖优势沉水植物黑藻（Hydrilla verticillata）和苦草（Vallisneria natans）的PSⅡ的最大量子产量分别为0.48-0.68和0.52-0.71,PSⅡ实际量子效率分别为0.32-0.58和0.20-0.46,表明白沙湖的黑藻和苦草具有相似的光合作用效率;而常湖优势沉水植物莕菜（Nymphoides peltatum）和苦草的PSⅡ最大光量子产量分别为0.66-0.77和0.19-0.68,PSⅡ实际量子效率分别为0.26-0.48和0.22-0.43,表明莕菜有较高的光合作用效率,容易形成优势物种。调查中发现,白沙湖黑藻的频度为90%,苦草为93.3%,小茨藻（Najas minor）为26.7%,眼子菜（Potamogeton franchetii）为10%;常湖中莕菜的频度为86.7%,苦草为16.7%,小茨藻为56.7%。白沙湖中沉水植物的频度值总体高于常湖,优势物种也存在差异性。综合分析白沙湖和常湖水体的营养水平、沉水植物多样性和光合荧光特性,结果表明：白沙湖的富营养化水平高于常湖,黑藻和苦草同为沉水植物中的优势种,光合活性相似;常湖中莕菜和苦草为优势种,但莕菜的光合活性显著高于苦草,这与湖泊水体透明度和南矶山湿地不同水体的富营养化差异及不同沉水植物的生态位有着密不可分的关系。

英文摘要：

We used a FluorCam portable chlorophyll fluorescence imaging system to measure QY-max （the maximum light quantum yield, Fv/Fm, the largest light quantum efficiency of PS Ⅱ） of submerged plants in wetlands of Baisha Lake and Changhu Lake, Jiangxi Nanjishan Wetland National Nature Reserve, in winter 2013. Specifically, we measuredΦPS Ⅱ （PS Ⅱ actual quantum efficiency）, qP （photochemical quenching） and corresponding fluorescence images. Using the visual method and sampling sites method to obtain coverage, richness and abundance of submerged plants, and determined nutrient levels in water. The results show that the QY-max ofHydrilla verticillata andVallisneria natans in Baisha Lake ranged from 0.48 to 0.68 and 0.52 to 0.71, respectively; theΦPS Ⅱ of these two species ranged from 0.32 to 0.58 and 0.20 to 0.46, respectively. The two plants had similar photosynthetic efifciency. The QY-max ofNymphoides peltatum andV. natans in Changhu Lake ranged from 0.66 to 0.77 and 0.19 to 0.68, respectively; theΦPS Ⅱ of these two species ranged from 0.26 to 0.48 and 0.22 to 0.43, respectively. The observed higher photosynthetic efifciency of N peltatum suggests it is more likely to become the dominant species. In Baisha Lake, the frequency of occurrence of plants was：H. verticilata, 90%;V. natans, 93.3%;Najas minor26.7%, andPotamogeton francheti10%. In Changhu Lake, the frequency of N. pel-tatum was 86.7%,V. natans was 16.7%, andN. minor was 56.7%. The overal frequency of submerged plants living in Baisha Lake was much higher than that of submerged plants living in Changhu Lake, with different species dominating the two lakes. According to comprehensive analysis and comparison of trophic levels, biodiversity and photosynthetic fluorescence characteristics in the two lakes, eutrophication of Baisha Lake was higher than for Changhu Lake; andH. verticillata andV. natans were the dominant species, with similar photosynthetic activity. Conversely, in Changhu Lake,N. peltatum andV. natans were the dominant speci