水东湾海域浮游植物潮汐分布特征及其与环境因子的关系

2014年秋、冬两季,每个季节在大潮期和小潮期对水东湾海域浮游植物群落结构和环境因子进行了调查,共鉴定出4门57属134种。其中硅藻门42属106种,占浮游植物种类数的79.1%;甲藻门13属26种,占浮游植物种类数的19.4%;蓝藻门1属1种,占浮游植物种类数的0.8%;针胞藻纲1属1种,占浮游植物种类数的0.8%。优势种15种,主要为尖布纹藻Gyrosigma aluminatum、圆海链藻Thalassiosira rotula、中肋骨条藻Skeletonema costatum、丹麦细柱藻Leptocylindrus danicus和舟形鞍链藻Campylosira cymbelliformis等。4个航次共有种类数在18—40种,Jaccard种类相似性指数范围在0.200—0.404,多样性指数和均匀度平均值分别为2.60和0.60。秋季大、小潮期多样性指数差异较显著(P0.05),冬季细胞丰度、多样性指数和均匀度大、小潮期均无明显差异。浮游植物细胞丰度变化范围为0.95×10~4个/L—28.0×10~4个/L,平均为6.86×10~4个/L,平均丰度冬季小潮期(9.46×10~4个/L)秋季小潮期(7.56×10~4个/L)冬季大潮期(5.97×10~4个/L)秋季大潮期(4.44×10~4个/L)。主成分分析(PCA)表明:盐度和营养盐可能是影响水东湾海域生态环境的主导因子。对水东湾海域浮游植物群落结构与主要环境因子进行Spearman相关性分析,细胞丰度与盐度在秋季大、小潮期为负相关,在冬季大、小潮期呈显著正相关;与无机氮和磷酸盐在冬季大、小潮期呈极显著负相关,在秋季大、小潮期均无相关性。冬季小潮期水温与多样性指数、均匀度和细胞丰度均呈正相关;从测定结果来看浮游植物细胞丰度、多样性指数和均匀度与叶绿素a含量均无统计学意义上的相关性。

Effect of tidal changes and major environmental factors on the distribution of phytoplankton in Shuidong Bay

Phytoplankton is the most important primary producer in marine ecosystems. Its growth and reproduction are affected by the biological characteristics of the different speciesas well as by environmental factors. Owing to the inflow of land-sourced material and mariculture activities, Maoming (Guangdong province), Shuidong Bay, a natural harbor and an important fishery production center, has become heavily polluted.In order to reveal the effect of tidal changes and major environmental factors on the distribution of phytoplankton in Shuidong Bay, the structure of the phytoplankton community and environmental factors were investigated during both high and low tides during the autumn and winter in 2014. As a result, 4 phyla, 57 genera and 134 species of phytoplankton were identified, including 42 genera and 106 species of diatoms, 13 genera and 26 species of dinoflagellates, and 1 species of cyanobacteria, accounted for 79.1%, 19.4% and 0.8% of the phytoplankton respectively. There were 15 dominant species, the major ones were Gyrosigma aluminatum, Thalassiosira rotula, Skeletonema costatum, Leptocylindrus danicus, and Campylosira cymbelliformis.18-40 species were identified at each sampling, and the Jaccard species similarity index ranged from 0.200-0.404, with a diversity index and average uniformity of 2.60 and 0.60respectively.The diversity index, cell abundance, and evenness of the phytoplankton sampled during the high and low tides were significantly different (P < 0.05) in the autumn but were not significantly different during the other seasons. Cell abundance, which ranged from 0.95×10⁴ to 28.0×10⁴ cells/L (mean=6.86×10⁴ cells/L), varied by season and tide: winter low tides (9.46×10⁴ cells/L) > autumn low tides (7.56×10⁴ cells/L) > winter high tides (5.97×10⁴ cells/L) > autumn high tides (4.44×10⁴ cells/L). Principal component analysis indicated that both salinity and nutrient content were likely the dominant environmental factors affecting the phytoplankton in Shuidong Bay. Meanwhile, correlation analysis indicated that cell abundance was negatively and positively correlated with salinity during the high and low tides of autumn and winter respectively, and negatively correlated with inorganic nitrogen and phosphate during the both the low and high tides of winter. In addition, water temperature was positively correlated with the diversity index, evenness, and cell abundance of phytoplankton sampled during the low tides of winter. However, none of the parameters was correlated with the content of chlorophyll a.