2010年夏季雷州半岛海岸带浮游植物群落结构特征及其与主要环境因子的关系

2010年夏季对雷州半岛海岸带的浮游植物群落结构及相关环境因子进行了调查,结果共检出浮游植物211种(含变种、变型),隶属于7门76属;优势种13种,以广温、广盐沿岸性种和温带沿岸性种为主,群落结构具有亚热带和沿岸性特征。半岛海岸带浮游植物平均种类数和细胞丰度的平面分布,均由近岸往远岸逐渐减少,此外种类数是西南部>西北部>南部>东南部>东北部,细胞丰度则东北部>南部>西南部>西北部>东南部。除了东北部海岸带,多样性指数和均匀度平均值分别低于3及0.7外,其他海岸带均高于此值,物种非常丰富。相关分析表明:浮游植物种类数与水温、Si/P呈极显著的正相关,与SiO23--Si、Si/N呈显著的正相关,与NO-2-N、PO34--P呈极显著的负相关,与盐度、pH值等不存在统计学意义上的相关性;浮游植物细胞丰度与pH值、叶绿素a、DO、NO-2-N呈极显著的正相关,与盐度呈极显著的负相关,与水温、NO-3-N等不存在统计学意义上的相关性;浮游植物种类数与细胞丰度之间也不存在统计学意义上的相关性。根据浮游植物生物学指标对雷州半岛海岸带的富营养化程度进行现状评价表明:雷州半岛海岸带水质营养类型属于中-贫营养型,而根据营养盐指标评价雷州半岛海岸带水质则总体上为氮限制中度营养或氮限制潜在性富营养化水平。

Community characteristics of phytoplankton in the coastal area of Leizhou Peninsula and their relationships with primary environmental factors in the summer of 2010

Phytoplankton are the most important primary producers in marine ecosystems and their distribution is influenced by environmental factors such as light, temperature, salinity, and nutrient availability, among others. The community structure and the spatial and temporal distribution of phytoplankton can reflect the characteristics of the environment. Leizhou Peninsula is located along the southern border of mainland China and is characterized by a winding coastline, numerous bays and islands, a wealth of marine biological resources and characteristic ecosystems such as coral reefs, mangroves, and seaweed beds, and so on. Interference from human activity has contributed to increased pollution levels in Leizhou Peninsula. To provide basic data for sustainable development of the economy and use of biological resources in the peninsula, the community structure of phytoplankton and the associated environmental factors were investigated in the coastal area of Leizhou Peninsula of Guangdong in the summer of 2010. Of the total 211 species (including distinct varieties and forms) from 76 genera of 7 phyla identified, 143 species from 45 genera were Bacillariophyta, 49 species from 15 genera were Pyrrophyta, 13 species from 10 genera were Chlorophyta, 3 species from 3 genera were Cyanophyta, and 1 species each was identified as Euglenophyta, Chrysophyta, or Raphidophyceae. Diatoms were predominant in the phytoplankton community in terms of species and biomass and 13 dominant diatom species were analyzed. Most of the dominant species were eurythermic and euryhaline, which is characteristic of a sub-tropical community structure along the seashore. Skeletonema costatum was the only dominant species that spread throughout the coastal area of Leizhou Peninsula. Phytoplankton species richness ranged from 10 to 59, and cell abundance varied from 1.25 to 1503.50 × 10⁴ cells/L (averaging 131.76 × 10⁴cells/L). Both phytoplankton species richness and cell abundance decreased from landward zone to seaward zone. In addition, the greatest abundance of species was observed in the southwest area, followed by the northwest area, south area, southeast area, and northeast area; however, the highest cell densities occurred in the northeast area, followed by the south area, southwest area, northwest area, and southeast area. The average diversity index and evenness of species exceeded 3.0 and 0.7, respectively, in the whole coastal area with the exception of the northeastern coastal area. Correlation analysis indicated that species richness of the phytoplankton was positively correlated with water temperature, Si/P, SiO₃^2--Si, and Si/N, negatively correlated with NO₂^--N and PO₄^3--P, and not correlated with salinity, pH, surface chlorophyll a, DO, NO₃^--N, NH₄⁺-N, DIN, and N/P. Phytoplankton cell abundance was positively correlated to pH, surface chlorophyll a, DO, and NO₂^--N, negatively correlated to salinity, and was not correlated to water temperature, NO₃^--N, NH₄⁺-N, DIN, PO₄^3--P, SiO₃^2--Si, N/P, Si/P, and Si/N. Furthermore, no correlation was found between phytoplankton species richness and cell abundance. Assessment of water quality according to the biological indicators of phytoplankton revealed that the quality was of middle-poor trophic type; however, according to nutrient indicators, the coastal area of Leizhou Peninsula was designated as nitrogen-limited mesotrophic or nitrogen-limited potential eutrophication.