高滤食压力下贻贝筏式养殖场及周边海域浮游植物群落特征

本文基于2020年7月至2021年3月浙江省枸杞岛贻贝筏式养殖场及周边海域5个航次的调查数据，分析了养殖场内、外浮游植物群落特征及其优势种与环境因子变化的关系。调查海域共鉴定到浮游植物4门63属146种，优势种主要有中肋骨条藻（Skeletonema costatum）、夜光藻（Noctiluca scintillans）、具槽帕拉藻（Paralia sulcata）等，优势种组成、香农-威纳指数、物种均匀度和物种丰富度随季节的更替变化显著。浮游植物细胞丰度在时间上呈现7月>10月>9月>12月>3月的变化趋势。空间分布上，在浮游植物高生物量的季节，5 m以浅养殖贝类所处水层中养殖场内的浮游植物平均丰度较养殖场外表层显著偏低，也显著低于场内的全水层平均丰度，最大可低一个数量级以上。上述现象在浮游植物生物量较高的7月和10月尤为明显；低生物量的冬季，冷却对流导致水体垂向混合强烈，且贻贝因水温偏低和浊度升高而降低了滤食率，故场内外和表底层的浮游植物丰度差异均较小。养殖贻贝分别通过滤食和排泄改变浮游植物种群构成和水体营养盐循环速率，直接或间接影响了养殖场内浮游植物群落...

The characteristics of phytoplankton community of mussel raft farms and surrounding waters under high filtration pressure

Based on the five voyages observed data measured from July 2020 to March 2021 of the suspended aquaculture farm off Gouqi island in Zhejiang province, the characteristics of phytoplankton community inside and outside the farm and the relationship between the dominant species and variations of environmental factors were analyzed. Totally 146 species of phytoplankton belonging to 63 genera and 4 phyla were identified in the research sea area. The dominant species mainly include Skeletonema costatum, Noctiluca scintillans, Paralia sulcata etc. The dominant species composition, index of Shannon-Wiener, Pielou and Margalef changed significantly with seasonal variation. The cell abundance of phytoplankton cells showed a trend of July>October>September>December>March. In terms of spatial distribution, in the season of high phytoplankton biomass, the average cell abundance of phytoplankton in the water layer inside the farm where shellfish are cultured at a depth less than 5 m is significantly lower than that in the water layer outside the farm, and also significantly lower than that in the whole water layer inside the farm, which can be both more than one order of magnitude lower at most. The above phenomenon is particularly obvious in July and October when phytoplankton biomass is high. In winter with low biomass, cooling convection leads to strong vertical mixing of water column, and mussels reduce the filtration rate due to low water temperature and increased turbidity. Therefore, there is little difference in phytoplankton abundance between inside and outside the farm and between the surface and bottom. Cultured mussel change the composition of phytoplankton population and the circulation rate of water nutrient by filtration and excretion respectively, which directly or indirectly affects the spatiotemporal distribution of phytoplankton community in the farm and makes the phytoplankton community structure inside the farm more stable than that outside the farm due to top-down or bottom-up control.