Yangtze River Estuary plays a key role in linking the river and ocean ecosystems. Our understanding on its biodiversity and associated ecological processes remains poor, which is especially true for the invertebrate assemblage. Here, we investigated invertebrate assemblage pattern and associated environmental drivers based on four different seasonal comprehensive investigations across this region in 2014. A total of 35 species, belonging to 20 families, 10 orders and three phylums were identified. Crustaceans (19 species) and mollusks (13 species) were the taxa with higher richness. Dominant invertebrate included Palaemon gravieri, Crangon affinis, Ovalipes punctatus, Acetes chinensis, Portunus trituberculatus and Charybdis bimaculata. Total density and biomass was 4518.96 kN·km-2 and 173.09 kg·km-2 respectively, with the highest value in spring and the lowest in autumn. Biodiversity indices peaked in winter and spring and reached the lowest in summer. Invertebrate assemblage structure showed significant seasonal variation, appearing in a significant difference between the near-shore and the off-shore in spring, and between the northern-waters and southern-waters in other seasons. Results from ordination analysis showed that the spatial variation of invertebrate was mainly regulated by temperature and dissolved oxygen, whereas Chla and nutrient factors played key roles in driving the temporal community assemblage in this region.
长江口及其邻近海域是连接河流和海洋的重要枢纽,但对该海域生物多样性和相关生态过程,尤其是无脊椎动物群落的了解仍然较少.本研究根据2014年2月、5月、8月和11月4个航次长江口及其邻近海域渔业资源综合调查数据,探讨该海域无脊椎动物群落时空分布特征及其群聚结构变化与环境因子的关系.结果表明: 2014年长江口及其邻近海域4个航次渔业资源调查共采集无脊椎动物35种,隶属于3门10目20科,以甲壳动物(19种)和软体动物(13种)的物种数最为丰富,资源优势种包括葛氏长臂虾、脊腹褐虾、细点圆趾蟹、中国毛虾、三疣梭子蟹和双斑蟳.2014年长江口无脊椎动物丰度和生物量分别为4518.96 kN·km-2和173.09 kg·km-2,春季最高,秋季最低.春季和冬季无脊椎动物多样性最高,夏季最低.长江口无脊椎动物各季节群聚结构存在显著差异,冬季、夏季和秋季以南部和北部的差异为主,春季则以近岸和远岸的差异为主.温度和溶解氧驱动无脊椎动物群落季节的时间变异,初级生产水平和营养要素驱动群落季节内的空间变异.
Keywords: Yangtze River Estuary; assemblage structure; environmental factor; invertebrate; seasonal variation.