长江下游南京段至河口近岸带底栖动物分布格局及影响因素

The littoral zone macroinvertebrate distribution in relation to environment variables in the lower Yangtze River Channel from Nanjing to the estuary

长江南京段至河口近岸带底栖动物组成特征是了解长江下游干流生物分布格局和影响机制的重要参考. 2017年4月对长江干流南京段至河口6个江段43个样点的水体理化因子、栖息地和底栖动物开展了调查,共采集和鉴定底栖动物3门7纲17目35科63种.优势类群是节肢动物和软体动物,优势物种是水丝蚓Limnodrilus sp.,发现原分布于河口区域的圆锯齿吻沙蚕Dentinephtys glabra已成为南京段至河口的最常见多毛纲物种.镇江段物种丰富度和香农多样性均为最高,分别为31和1.71,其次为江阴段,长江北支的物种丰富度和香农多样性最低,分别为12和0.90.典范对应分析(CCA)表明水污染、适宜生境的退化或消失以及航运是长江下游干流南京至河口段底栖动物群落组成变化的主要影响因子.因此,长江下游干流底栖动物分布格局明显受人类活动的影响,水污染控制和生境修复等措施有利于底栖动物多样性的保护恢复.

Macroinvertebrates are promising indictors for the elucidation of community distribution patterns in relation to environmental variables in the lower Yangtze River channel. We conducted a survey on the littoral zone macroinvertebrates,water physical-chemical variables, and habitat quality of 43 sites distributed in 6 sections from Nanjing down to the estuary in April 2017. Our goal was to examine the macroinvertebrate distribution pattern and explore the potential drivers in the lower Yangtze River channel. A total of 63 taxa belonging to 35 families, 17 orders, 3 classes, and 7 phyla, and were recorded and Arthropoda and Mollusca were dominant groups and Limnodrilus sp. was the dominant species. Interestingly, Dentinephtys glabra, previously recorded in the estuary only, was a common species of nereid from the estuary up to Nanjing. In terms of the species richness, the Shannon-Wiener index has conducted in 6 sections, Zhenjiang had the highest richness with 31 and a diversity index of 1.71, followed by Jiangyin, and the north branch of the estuary had the lowest richness of 12 and diversity index of 0.90. Results of canonical correspondence analysis showed that water pollution, habitat degradation or loss, and shipping were the major factors influencing the macroinvertebrate distribution. The distribution pattern of macroinvertebrates was highly influenced by human activities, and water pollution control and habitat restoration were equally important for the conservation of macroinvertebrate diversity in the lower Yangtze River channel.