生物和非生物因子对东海南麂岛海域表层沉积物甲藻孢囊分布的影响

本文首次对东海南麂岛海域的甲藻孢囊群落进行了为期一年（2014-2015）的定量分析研究。在南麂岛近岸8个采样点中，鉴定并定量了6个种群，34种形态的甲藻孢囊，其中包括14%的潜在产毒物种。自养型孢囊占总孢囊数量的74%。通过与邻近海域的研究结果比较，南麂海域总孢囊数量（2-33个孢囊/毫升沉积物）相对较低。Scrippsiella trochoidea和Protoperidinium avellana分别是丰度最高的自养和异养型孢囊。我们采用多元统计方法评估了甲藻孢囊分布同非生物或生物变量之间的关系。在DCA排序图中，发现季节之间有明显的分化。尽管采样点之间的水动力条件有所不同，甲藻孢囊的空间分布差异并不显著。可溶性活性磷酸盐，氮磷比和米氏凯伦藻（Karenia mikimotoi）藻华是通过CCA确定的与表层沉积物孢囊分布相关的三个重要因素（P<0.05），这表明该区域营养盐状况对甲藻孢囊分布影响较大。虽然本研究未能明确近年来南麂岛海域有害赤潮的源头，但对于进一步了解南麂岛的甲藻孢囊动态和潜在的毒素威胁具有重要的参考意义。

The impact of biotic and abiotic factors on the distribution of surface sediment dinoflagellate cyst assemblages on the Nanji Island in the East China Sea

The dinoflagellate cyst assemblages on the Nanji Island in the East China Sea, are documented at the first time to construct a quantitative overview of the cyst bank from 2014 to 2015. Thirty-four morphotypes from six groups are identified and quantified at eight sampling sites around the island, including a high proportion of potentially toxigenic species (14%). Autotrophic dinocysts constitute 74% of the total cyst counts, which is relatively low (two to thirty-three per millilitre sediment) compared with previous studies in adjacent areas. Scrippsiella trochoidea and Protoperidinium avellana are the most abundant autotrophic and heterotrophic species, respectively. A multivariate analysis is performed to assess associations between dinocysts and abiotic or biotic variables. Differentiation among seasons is evident in the detrended correspondence analysis (DCA) ordination plot, while a spatial pattern is not clearly revealed despite heterogeneity of the hydrodynamic conditions between sampling sites. Soluble reactive phosphate, the ratio of nitrogen to phosphorus concentrations and Karenia mikimotoi bloom are the three factors significantly (P<0.05) related to surface sediment cyst assemblage defined by the canonical correspondence analysis (CCA), highlighting the importance of nutrient regime to a dinocyst distribution in this area. Although attempts to address the origin of HAB events in recent years using seed banks have failed, knowledge can be valuable for further investigation of dinocyst dynamics and potential toxin threats on the Nanji Island.