日照紫菜养殖海域营养盐的时空分布特征及其与浮游植物群落结构的相关性分析

The Temporal and Spatial Distribution Characteristics of the Nutrients and Community Structures of Phytoplankton and Their Relationships in the Pyropia culture Areas of Rizhao, China

中文关键词: 紫菜养殖  浮游植物  营养盐  分布

英文关键词: Pyropia cultivation  Phytoplankton  Nutrients  Distribution

中文摘要:

      2016年11月~2017年3月对山东日照阜鑫渔港紫菜(Pyropia sp.)养殖海域开展调查，分析该海域浮游植物群落结构和营养盐的时空分布特征及其相关性。结果显示，调查海区中无机氮(DIN)、磷酸盐(PO43–-P)及硅酸盐(SiO32–-Si)浓度均表现为自近岸海区到外海区逐渐降低的趋势；硝酸盐、SiO32–-Si、PO43–-P、DIN和溶解有机氮(DON)等营养盐的浓度均因月份的不同具有显著差异；调查海区营养水平总体为中营养型，浮游植物丰度为(0.049~3.031)×104 cells/L，浮游植物的生长受控于SiO32–-Si和PO43–-P的几率较大；该海区共检出硅藻门27属37种，甲藻门7属8种，金藻门1属1种，主要优势种为骨条藻(Skeletonema sp.)、角毛藻(Chaetoceros sp.)、圆筛藻(Coscinodiscus sp.)等；盐度的大幅降低和丰富的营养盐、氨氮(NH4+-N)和PO43–-P浓度的显著变化可能分别是导致1、3月浮游植物多样性指数显著降低的主要原因；调查海区NH4+-N浓度和DIN/P值与浮游植物多样性指数均呈负相关关系，其中，非紫菜养殖区的负相关程度达到显著水平，而养殖区的负相关程度不显著，表明条斑紫菜(Pyropia yezoensis)养殖可能有利于降低该海域的NH4+-N水平和DIN/P值、提高浮游植物群落结构稳定性及物种多样性，从而有利于防止赤潮的发生。研究结果可为该海域环境保护、赤潮防治以及水产养殖活动的开展等提供基础数据。

英文摘要:

      The culture area of Pyropia sp. at Fuxin fishing port, in Rizhao City, China, were investigated from November 2016 to March 2017. The temporal and spatial distribution characteristics of the nutrient and community structures of phytoplankton and their relationships were analyzed. The main conclusions were as follows: Generally, the spatial horizontal distribution of inorganic nitrogen, phosphate and silicate concentrations showed a decreasing trend between the nearshore area and offshore sea areas. Nitrate, silicate, phosphate, dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen concentrations were significantly different in the different months. Over, all the surveyed sea area was at a mesotrophic level. The range of phytoplankton density was (0.049~3.031) × 104 cells/L and the phytoplankton growth was likely to be controlled by the silicate and phosphate. 37 species of diatom belonging to 27 genera, followed by dinoflagellates represented by 8 taxa (7 genera) and chrysophyceae by 1 taxa (1 genera) were recorded. The most common and dominant species were Skeletonema sp., Chaetoceros sp., and Coscinodiscus sp. The diversity index of phytoplankton decreased significantly in January and March, which may be caused by the sharp decrease in salinity and richness of nutrients in January, significant rises in ammonia nitrogen concentrations, and significant decrease in phosphate concentration in March. The ammonia nitrogen concentration and DIN/P ratio were both negatively correlated with the diversity index of phytoplankton. The negative relationship was significant for the non-cultured area, while it was not significant for the cultured area. It can be inferred from the above correlation analysis results that Pyropia sp. cultivation is beneficial for reducing the ammonia nitrogen levels and DIN/P ratio in the sea area, thus increasing the stability of phytoplankton community structures and the species diversity of phytoplankton, which will help to prevent the occurrence of red tides. These results provide information valuable for marine environment protection, red tide prevention and future developments of aquaculture systems.