| 摘要: |
| 依据1998年11月、1999年5月、2000年11月和2001年5月4个航次在长江口及其邻近海区调查所获得的大型浮游生物网垂直拖样品，对测区的浮游动物总生物量的总体水平，分布和种类组成进行了分析，并将研究结果与1958—1959年全国海洋普查的资料和1985—1986年“三峡工程对长江口及邻近海区生态与环境的影响”调查资料进行了同测区、同月份的对比。结果显示，测区1999年和2001年5月份浮游动物总生物量近几年比50年代末和80年代中期有明显增加，分别增加了1.43—1.76和0.95—1.22倍；11月份总生物量的分布格局和种类组成没有大的变化。这可能反映长江口及其邻近海区浮游动物的变动趋势，但仍需要更多的资料证实。 |
| 关键词: 长江口,浮游动物,生物量 |
| DOI： |
| 分类号: |
| 基金项目:国家重点基础研究发展项目(973)资助，G1999043707号 |
附件 |
|
| ANALYSIS OF ZOOPLANKTON BIOMASS IN CHANGJIANG RIVER ESTUARY AND ADJACENT WATERS |
|
WANG Ke, WANG Rong, ZUO Tao, GAO Shang-Wu
|
|
Key laboratory of Marine Ecology and Environmental Sciences，Institute of Oceanology，Chinese Academy of Sciences
|
| Abstract: |
| The Changjiang (Yangtze) River Estuary and its adjacent waters is a highly productive and economically valuable zone, providing spawning and breeding grounds for many important fishes. Zooplankton is very sensitive to in the hydrography changes resulted from human activities and climate change. In order to describe the patterns of zooplankton distribution and provide a basis for future research on long—term seawater changes near the Changjiang River Estuary, studies of seasonal changes in zooplankton species compositions, biomass spatial distributions in this area have been carried out and reported in this paper with the comparism to the previous data.
Zooplankton samples were collected in four cruises in November 1998, May 1999, November 2000 and May 2001 in 29 stations located in the Changjiang River estuary and adjacent waters, west of 123°30′E. between 30°45′—32°00′N. All the samples were towed from the sea-bottom to the surface with a large plankton net (80cm in diameter, mesh size 500μm), fixed and stored in 5% formalin sea water solution, and then classified and counted under the microscope and weighed in the lab. About 73 species and 2 taxa were identified. According to the biogeographic pattern, these species can be divided into three ecotypes: i) neritic species, such as Labidocera euchaeta and Pseudeuphausia sinica; ii) low-temperature and high-salinity temperate species, e.g. Calanus sinicus and Euphausia pacifica; iii) warm species e.g. Euchaeta concinna and Sagitta enflata. Based on species abundance and frequency at stations, the dominant species of the study area were identified. Dominant species compositions showed 2 seasonal variations: in November, the dominant species were Paracalanus parvus, Euphausia pacifica and P.sinica, S.crassa, Euchaeta concinna, L.euchaeta, while in May, it included P.parvus, Euphausia pacifica and P.sinica, S.nagae and Brachyura larvae. In addition, zooplankton biomass was relatively hygh in May. Regarding geographical distribution, high values were mainly found in the south of the studied area and low values were found near the estuary in both seasons. Comparing these results with same season/area data in historical reports (Comprehensive Oceanology, Expedition in 1958—1959, Eco-environmental Changes Investigations in Changjiang River Estuary and its adjacent area part of the the Three-Georges Dam Project 1985—1986), it was found that zooplankton changed a little in species compositions but increased greatly in total biomass. Significant changes to biomass occurred especially in May in the range 1.43—1.76 and 0.95—1.22 times. Due to the limitations in study area, time of sampling, and current data availability, final conclusions could not be drawn to forecast long-term changes in zooplankton based on currently available data. Some helpful information, however, may be inferred for future study on ecosystem productivity and trophic structure in the Changjiang River estuary. Temperature and salinity of the seawater were discussed and considered to be important environmental factors responsible for the variations of zooplankton biomass in this area. |
| Key words: Changjiang River Estuary, Zooplankton, Biomass |
