湖北长湖夏、秋季浮游生物功能群特征及主要影响因子

为了解长湖浮游生物功能群特征及其主要影响因子, 于2017年7月(夏)及10月(秋)对长湖进行2次采样调查, 并结合冗余分析法(Redundancy analysis, RDA)和Pearson相关性分析法分析了浮游生物功能群的主要影响因子。结果显示, 鉴定出浮游植物7门49属, 共95种, 划分为25个浮游植物功能群, 平均密度为5.12×106 ind./L, 平均生物量为1.663 mg/L; 鉴定出浮游动物3门41属, 共59种, 划分为8个浮游动物功能群, 平均密度为3.76×103 ind./L, 平均生物量为2.803 mg/L。从功能群的平均密度和生物量来看, 夏季显著高于秋季(P＜0.01), 其中夏季H1站位浮游动物功能群的密度最高, 秋季Y4站位的浮游生物密度和生物量均较高, 且存在功能群A、LCF向E和K的演替趋势。从优势功能群种类来看, B、D、J、L₀、MP、P、T_C、PF、RF及SCF是夏、秋两季的共有优势功能群, 其中L₀、T_C、RF及PF是绝对优势功能群。综合各功能群的主要代表种构成及其适应的生境特征表明, 长湖鱼类对浮游生物的摄食压力较大且水质仍处于富营养化状态。冗余分析结果显示, TN、TP及DO为影响长湖浮游生物功能群的主要环境因子, 水温及pH也与多数功能群呈明显正相关性。Pearson相关性分析结果显示, 浮游植物功能群B、D、J、L₀、Y及浮游动物PF、RF、SCF等彼此间多数具有极显著的相关性(P＜0.01), 竞争及捕食等生物活动对功能群特征影响较明显。

CHARACTERISTICS AND MAIN INFLUENCING FACTORS OF PLANKTON FUNCTIONAL GROUPS IN SUMMER AND AUTUMN OF CHANGHU LAKE

Changhu Lake, is a typical eutrophication shallow lake in Jianghan Plain, Hubei Province, with comprehensive functions such as flood storage, irrigation, aquaculture and navigation, higher productivity, rich fishing. Plankton can reflect the water quality, the primary productivity of ecosystem, the fishing productivity, feeding pressure, and so on. By plenty of rainfall, the conditions of water temperature and light are suitable, the biomass and population density of plankton are the highest in the whole year in summer and autumn. The division of plankton into functional groups is one of the hot topics at present. To explore the characteristics of plankton functional groups and their main influencing factors, two sample surveys were conducted in Changhu Lake, in July (summer) and October (autumn) 2017. The main influencing factors were analyzed by RDA analysis and Pearson correlation analysis. The results showed that 95 species, 49 genera and 7 phyla of phytoplankton were identified, which were divided into 25 functional groups with an average density of 5.12×106 ind./L and an average biomass of 1.663 mg/L. There were 59 species in 41 genera, 3 phyla, which were divided into 8 zooplankton functional groups with an average density of 3.76×103 ind./L and an average biomass of 2.803 mg/L. The average density and biomass of plankton functional groups were significantly higher in summer than those in autumn (P＜0.01), and the highest density was at H1station in summer, the highest density and biomass were at Y4 station in autumn; and from summer to fall the function groups A and LCF are inherited by E and K. From the perspective of dominant functional groups, the dominant functional groups were B, D, J, L₀, MP, P, T_C, PF, RF and SCF in two seasons, among which functional groups L₀, T_C, RF and PF were the absolute dominant groups. Redundancy analysis showed that TN, TP and DO were the main environmental factors affecting plankton functional groups, and water temperature and pH were positively correlated with most of the functional groups. Pearson correlation analysis showed the phytoplankton functional groups B, D, J, L₀, Y and zooplankton PF, RF, SCF were significantly correlated with each other (P<0.01), and competition and predation and other biological activities had significant effects on the functional group characteristics. It is concluded that the feeding pressure of fishes to plankton is high and the water quality is still in the state of eutrophication in Changhu Lake. This study provides theoretical basis and reference for the subsequent assessment of the ecological restoration effect, artificial regulation, natural proliferation and sustainable development of large-surface fishery resources.