浒苔过量繁殖后海区环境因子与浮游植物群落演替规律研究

Relationship between phytoplankton community succession and environmental factors after Enteromorpha prolifra bloom

为了解浒苔绿潮对周边海域环境影响,在海阳和日照海域进行了8个航次的水质和浮游植物监测。结果表明,海区共采集到浮游植物62种,隶属于4门31属。其中硅藻门20属45种,占总种数的72.58%;甲藻门8属14种,占总种数的22.58%;黄藻门2属2种,占总种数的3.23%;金藻1属1种,占总种数的1.61%。浮游植物平均数量为352.3×10~4ind·m^3,其中硅藻平均324.2×10~4 ind·m^3,约占总数的92.02%;甲藻平均为23.6×10~4 ind·m^(-3),约占总数的6.70%;其他种类平均为4.5×10~4ind·m^(-3),约占总数的1.28%。海区物种丰度平均为1.266,变化范围为0.96～1.89,多样性指数平均为3.012,变化范围为2.06～4.17,均匀度平均为0.638,变化范围为0.43～0.79。浮游植物细胞数量平面分布总体呈现出由近岸向远海递减趋势。两海区浮游植物群落演替具有相似性,第一优势种经历了旋链角毛藻一三角角藻一窄隙角毛藻一中肋骨条藻一菱形海线藻的演替过程。海阳和日照近海平均富营养化指数分别为0.115和0.189,整个监测期间海区水质均成贫营养化状态。浒苔过量生长主要影响浮游植物数量和种群构成,特别是营养盐大幅消耗后,硅藻数量大幅减少,群落结构由三角角藻和叉状角藻等甲藻取代硅藻成为主要种群。浒苔死亡、腐烂分解后,海区底层活性磷酸盐较表层偏高,浒苔绿潮暴发严重的海阳近海尤为明显。

The paper is to present the results from eight surveys about the phytoplankton and water quality conducted near the Haiyang and Rizhao after the bloom of Enteromorpha prolifra from July to September 2008. The results include the identification of 62 phytoplankton species, belonging to 4 phyla, 31 genera. 72.58% of the identified phytoplankton species belong to Bacillariophyceae （20 genera, 45 species）, whereas 22.58% to Dinophyta （8 genera, 14 species）, with 3.23% being Xanthophyta （2 genera, 2 species）, and 1.61% Chrysophyta （1 genera, 1 species）. The average density of phytoplankton was 3.52×10^6 ind·m^-3, and the greatest percentage, that is, 92.02% is diatom （3.24×10^6 ind·m^-3）, with dinoflagellate and other species of phytoplankton accounting for 6.70% （2.36×10^5 ind·m^-3） and 1.28% （4.5×10^4 ind·m^-3）, respectively. In addition, the average community abundance, diversity index and homogeneity were 1.266 （0.96-1.89）, 3.012 （2.06-4.17） and 0.638 （0.43-0.79）, respectively. It was also found that the density of phytoplankton gradually decreased from the inshore area to the offshore area. The phytoplankton community successions of Haiyang and Rizhao were similar. The first dominant species were succeeded from Chaetoceros curvisetus, Ceratium tripos, Chaetoceros affinis, Skeletonema costatum to Thalassionema nitzschioides. The average eutrophication index were 0.115 （0.022-0.203） and 0.150 （0.059-0.349） of Haiyang and Rizhao, respectively, and the seawater were poorly eutrophicated. The green tide of Enteromorpha prolifra had an impact on seawater quantity and phytoplankton community. When the nutrient was decreased, the dominant species changed from the diatom to the dinoflagellate. After Enteromorpha prolifra was dead and decomposed, the activated phosphate in the bottom seawater was higher than that in the surface seawater in Haiyang.