摘要:对近15年（2004-2018年）长江口海域海洋生物变化趋势进行分析，评价海洋生物健康状况，并对陆源污染物排放与海洋生物变化进行相关性分析。结果表明，（1）长江口海域海洋生物群落结构组成发生了一定变化，与20世纪90年代末相比，浮游植物种类数有所减少，浮游动物、底栖生物种类数有所增加。浮游植物以硅藻为主，但甲藻占比有所增加，2010年以来硅藻、甲藻群落结构进入新的平衡状态；浮游动物以节肢动物为主，主要类群桡足类占比有所下降；底栖生物种类数明显升高。（2）生物多样性总体水平一般，浮游植物多样性指数总体较低，第一优势种的优势度较高；浮游动物多样性指数和丰富度指数多年呈现下降趋势；底栖生物多样性水平一般，优势种渐趋单一。（3）海洋生物总体处于"不健康"状态，主要影响指标为浮游植物密度偏高，浮游动物密度偏低、生物量偏高，底栖动物密度偏高、生物量偏低。生态系统变化与陆源主要污染物排放、营养结构变化及水体富营养化均具有一定的相关性，其中无机氮（DIN）、石油类入海通量与生物健康指数呈显著负相关关系（P < 0.05），无机磷（DIP）与底栖生物生物量呈显著负相关关系。N/P与浮游植物丰度呈显著负相关，但与浮游植物均匀度和多样性指数呈显著正相关；Si/N与浮游植物多样性指数呈显著负相关。海域严重富营养化面积比例与硅藻甲藻种类数比值呈显著正相关关系。



Abstract:Using marine organism monitoring data in Changjiang estuary in the past 15 a, biodiversity dynamics and ecosystem health were evaluated in this study. The results showed that (1) comparing with the late 1990s, the species number of phytoplankton decreased but zooplankton and benthos increased. Diatomophyceae was the largest proportion of the total phytoplankton species and its species ratio was also increased till 2010. Copepoda always plays an indispensable role in zooplankton community but its species ratio decreased alarmingly in this study. Number of Benthos increased during the past 15 a and exceeded 100 from 2015-2018. (2) In a long time, the biodiversity was at a low level. The Shannon-Weaver index of phytoplankton was not as high as expected. Compared with phytoplankton, the values of diversity and evenness of the zooplankton were higher than that of phytoplankton but it decreased during the research time. The diversity of benthos was at a relatively low level and the dominant species were lower than before. (3) The average health index was 21.9 and the estuarine ecosystem was determined as "sub healthy" according The Guidance for the Assessment of Coastal Marine Ecosystem Health (HY/T 087-2005). The factors that influence the biodiversity of the Changjiang estuary include density of phytoplankton, zooplankton and benthos, and biomass of zooplankton and benthos. Factors influenced ecosystem health included sewage discharge, ration of N/P and Si/N, eutrophication etc. The riverine inorganic nitrogen and oil loads to the sea were negatively correlated with health index (P < 0.05). The riverine inorganic phosphorus loads to the sea was negatively correlated with benthos biomass while ratio of N/P was correlated negatively with phytoplankton density but positively with phytoplankton diversity and evenness. Ratio of Si/N correlated negatively with phytoplankton diversity while the factor of eutrophication area was positively correlated with the Diatomophyceae and Dinophyceae species ratio.





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