海洋工程建设对连云港近海环境因子和浮游植物的影响

为了明确海洋工程建设对连云港近海环境因子和浮游植物的影响，于2009年5月（海洋工程建设前）和2016年同期（海洋工程建成后）前后两次对连云港近海叶绿素a（Chl a）含量、浮游植物群落结构和环境因子的空间分布特征进行了综合调查.结果显示，海洋工程建成后，调查海域水环境发生明显变化，近岸海域出现一个明显的高温区，与离岸海域温差达3℃；营养盐浓度明显降低，尤其是可溶性硅（DSi），平均浓度降低了70%.Chl a浓度和浮游植物生物量显著升高，群落结构变化明显，由硅藻占优势转变为硅、甲藻共同占优势.海洋工程建设前优势度较高的星脐圆筛藻（Coscinodiscus asteromphalus）和夜光藻（Noctiluca scientillans）占比明显降低，中肋骨条藻（Skeletonema costatum）优势度明显升高.冗余分析（RDA）分析显示，海洋工程建设前化学需氧量（COD）、可溶性无机氮（DIN）和盐度（负相关）是影响浮游植物群落结构的主要因素；海洋工程建设后温度的影响明显升高；温度、BOD₅和DO的增加可能是促使春季浮游植物增加的主要因素.

Effects of marine engineering construction on environmental factors and phytoplankton in the coastal area of Lianyungang

Comprehensive investigations were conducted on the spatial distribution characteristics of chlorophyll a (Chl a), phytoplankton community structure and the environmental factors in the coastal area of Lianyungang in May 2009 (before marine engineering construction) and 2016 (after marine engineering construction), with the purpose of understanding the effects of marine engineering construction on environmental factors and phytoplankton community in this area. The results show that the environmental factors of the studying area changed significantly after engineering construction. An obvious high temperature zone was formed near the inshore area after engineering construction, with 3℃ higher than the offshore area. The nutrient concentrations were significantly decreased, and especially the dissolved silicon (DSi) which reduced by 70%. The concentration of Chl a and the biomass of phytoplankton increased obviously, with the dominant community shifting from diatoms alone to the co-dominant of diatoms and dinoflagellates. The main dominant species before engineering construction (e.g., Coscinodiscus asteromphalus and Noctiluca scientillans) were significantly decreased in 2016, while dominance of Skeletonema costatum was significantly increased. Redundancy analysis (RDA) showed that chemical oxygen demand (COD), dissolved inorganic nitrogen (DIN) and salinity (negative correlation) were the main factors affecting phytoplankton community before marine engineering construction, while the influence of temperature (T) was significantly increased after marine engineering construction. The increase of T, BOD₅ and DO may be the main factors that promoted the increase of phytoplankton in spring.