烟台四十里湾浮游动物群落特征及与环境因子的关系

2009年3月—2010年12月在烟台四十里湾海域对浮游动物群落结构及其环境因子进行了连续20个航次的综合调查,记录到浮游动物8大类共计64种(类)。浮游动物主要类群为桡足类和浮游幼虫,分别发现22种、18类,占总种(类)数34%、28%;其次为水螅水母类,发现13种,占20%;毛颚动物和栉水母类各发现1种。浮游动物的优势种为中华哲水蚤(Y=0.183)、腹针胸刺水蚤(Y=0.078)、强壮箭虫(Y=0.078)和洪氏纺锤水蚤(Y=0.026)。浮游动物的生态类型主要为温带近岸种和广布性种。四十里湾海域浮游动物群落结构的季节变化较为明显,春、夏、秋、冬四季之间群落结构有显著性差异(P0.05),同一季节内群落结构相似度较高,达55%以上。浮游动物丰度中位值在5月份达到最高(546.3个/m~3);种类数、多样性指数中位值均在8月达到最高,分别为18种、3.20;浮游动物生物量呈现出双峰变化模型,5月份达到第1峰值(中位值870.4 mg/m~3),10月份为第2峰值(中位值362.0 mg/m~3)。浮游动物种类数高值区主要分布在养马岛北部海域,而丰度高值区主要分布在近岸尤其是辛安河口海域。浮游动物种类数及多样性指数与水温、化学需氧量、硅酸盐显著正相关(P0.01),与盐度、溶解氧、无机氮显著负相关(P0.01);水温和盐度是影响浮游动物分布的主要环境因子,其次是硅酸盐、叶绿素a和化学需氧量,活性磷酸盐、溶解氧、透明度以及无机氮对浮游动物分布的影响较小。

Zooplankton community structure in Sishili Bay and its relationship with environmental factors

Coastal waters are ecosystems of great human and ecological interest, where complex processes occur. The interaction of physical (e.g., coastal currents, upwelling, tides, and advection), chemical (variable chemical properties including nutrient inputs), and ecological (e.g., biological production and its dynamics, and prey/predator interactions) processes induce high spatial and temporal variability in the water. This variability determines the abundance and structure of different biological communities present in coastal waters, in particular zooplankton, which are at the lower levels of the oceanic food chain. To understand coastal zooplankton community structure and explore its relationship with various environmental factors, a zooplankton survey was conducted in Sishili Bay. Fifteen sampling stations were chosen to study water temperature, salinity, transparency, DO, COD, inorganic nitrogen, phosphorus, silicate, and Chl a from March 2009 to December 2010. Sampling and testing methods followed those of the Specifications for Oceanographic Surveys and Specifications for Marine Monitoring. The relationships between zooplankton communities and various environmental factors were conducted by Pearson correlation analysis and canonical correspondence analysis (CCA). A total of 64 zooplankton species, belonging to 8 taxonomic groups, were recorded in Sishili Bay over the study period. Copepods and zooplankton larvae were the main taxonomic groups, accounting for 34% and 28% of total species, respectively, followed by Hydromedusa, accounting for 20%. Only one species each of Ctenophora and Chaetognatha were identified. The dominant species, which exhibited significant seasonal variability (P < 0.05), were Calanus sinicus (Y=0.183), Centropages abdominalis (Y=0.078), Sagitta crassa (Y=0.078), and Acartia hongi (Y=0.026). The ecological type of zooplankton in Sishili Bay was primarily temperate coastal and wide spread species. Four zooplankton community structure types were observed from the cluster dendrogram. Similar seasonal variations in the zooplankton community were observed in 2009 and 2010. The zooplankton community had high stability and reproducibility and similarity in different months of the same season reached more than 55%. The median total zooplankton abundance in Sishili Bay from 2009 to 2010 ranged from 40.5 individuals/m³ to 546.3 individuals/m³, with highest median abundances observed in May. The highest median values of zooplankton species and for the diversity index were recorded in August. The zooplankton biomass exhibited a significant seasonal difference (P < 0.05). The zooplankton biomass revealed an obvious bimodal annual variation trend and reached a maxima peak in May and a minor peak in October, with median biomass of 870.4 mg/m³ and 362.0 mg/m³, respectively. The stations with high zooplankton species were mainly distributed in the northern area of Yangma Island, whereas the inshore area, especially the Xinan River mouth, exhibited the highest zooplankton biomass. In present study, water temperature, COD, and silicates revealed a significant positive relationship with zooplankton species and the diversity index, whereas salinity, DO, and inorganic nitrogen exhibited a significant negative relationship with them. Canonical correspondence analysis (CCA) indicated that water temperature and salinity accounted for most of the zooplankton species variation, followed by silicates, Chl a, and COD, whereas phosphorus, DO, transparency, and inorganic nitrogen exhibited a weak influence on zooplankton community distribution.