莱州湾浮游植物群落结构与环境因子的时空变化特征研究

本文对莱州湾2014年5月和9月水文、化学和生物参数进行了综合分析，探讨了浮游植物群落结构与环境因子时空分布特征及相互关系。研究表明，两个月份的盐度、溶解性无机氮（DIN）与溶解性无机磷（DIP）均值差别较小，均值分别相差0.80，4.90 μmol/L，0.01 μmol/L；而平均温度在9月份较5月份升高了11.0℃，溶解性硅酸盐（DSi）平均浓度升高了6.02 μmol/L。营养盐结构分析表明，调查期间不存在氮限制，5月份仅1个站位存在DIP相对限制，但80%的站位存在硅限制；相反，9月份86.7%的站位存在DIP的相对限制，仅有1个站位存在硅限制。雨季降水的增多，尤其7月份黄河调水调沙带来的大量泥沙，可能是缓解莱州湾硅限制的重要因素。浮游植物群落结构响应了环境变化，物种多样性与生物量在9月份显著高于5月份。通过对浮游植物群落结构与环境因子的主成分分析，发现DSi浓度和海水温度升高是引起两个月份浮游植物群落结构差异的重要环境因子，其中，硅藻群落对温、盐变化的敏感性低于甲藻群落。

Temporal and spatial variations of phytoplankton community and environmental factors in Laizhou bay

An ecological survey was carried out in May and September 2014 in the Laizhou bay, with the aim of exploring temporal and spatial variations of phytoplankton community and their correlation with environmental factors. The results showed that differences of the average salinity, concentrations of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphate (DIP) in the two months were not obvious, with the differences of 0.80, 4.90 μmol/L and 0.01 μmol/L, respectively. Compared to the values in May, the average of temperature and dissolved silicate (DSi) concentrations increased 11.0℃ and 6.02 μmol/L, and declined gradually from the inshore to offshore waters in September, corresponding to the increased freshwater loading. The analysis of nutrient structure indicated that no sites appeared nitrogen limitation in two surveys. Up to 80% sites showed absolute and relative limitation in DSi, while DIP limitation only appeared in one sites in May. In contrast, 86.7% of the sites had DIP limitation but only one site had DSi limitation in September. The reason might be related to increased precipitation and silicate loadings during the water and sediment regulation of Yellow River in July. Phytoplankton responded to environmental changes and higher diversity and biomass of phytoplankton appeared in September. The results of Canonical Correspondence Analysis between phytoplankton assemblages and environmental factors indicated that increased temperature and concentrations of DSi were dominant factors related to the temporal and spatial variation of phytoplankton. Dinoflagellates had a higher sensitivity to changes of temperature and salinity than diatoms.