典型河口浮游动物种类数及生物量变化趋势的研究

依据国家海洋局2004-2006年每年5月和8月的黄河口、长江口和珠江口生态监控区浮游动物的监测结果，对上述河口浮游动物和桡足类种类数及浮游动物生物量分布进行了分析，并将结果与历史资料进行同测区、同季节的对比。结果表明，与全国海洋普查时期相比，2006年黄河口浮游动物种类数下降了50．6％，桡足类种类数下降了53.3％；桡足类在浮游动物中所占比重由1985年的42.4％下降到2006年的32．6％。长江口浮游动物种类数有所上升，但是桡足类种类数由1985年的62种降低到2006年的37种；桡足类在浮游动物中的比重从1958年的54．2％降低到2006年的42．5％。珠江口桡足类在浮游动物中所占的比例由1959年的59．3％下降到54．4％，未发生明显变化。黄河口春季、夏季浮游动物生物量上升趋势不明显，夏季增幅较小；长江口自2000年以后春季浮游动物平均生物量为528．36mg／m^3，是1958年的2．4倍，2005年与2006年夏季浮游动物生物量分别是1958年的2．2和2．7倍，增加趋势十分明显；珠江口春季浮游动物生物量上升趋势最为显著，2004-2006年3年春季浮游动物平均生物量是1959年同期的5．7—8．7倍，1981年、2006年夏季生物量分别比1959年增加了3．1倍和11倍。就这3个河口生物量变化趋势看，珠江口生物量的上升趋势最为明显，长江口次之，黄河口变化幅度较小。

VARIATION IN SPECIES NUMBER AND BIOMASS OF ZOOPLANKTON IN TYPICAL ESTUARIES OF CHINA

Zooplankton is sensitive to environmental changes caused naturally or anthropically. The zooplankton distribution and changes in number of species and biomass major estuaries of China were studied for estuaries of Changjiang (Yangtze) River, Pearl River, and Huanghe (Yellow) River. Data used in this paper were collected in May and August from 2004 to 2006 by the State Oceanic Administration of China. The data were analyzed against available previous data of the same area and season. The results show that, since 1958-1960, the number of zooplankton species decreased by 50.6% and copepoda by 53.3% in the Huanghe River Estuary, the proportion of copepoda in zooplankton decreased from 42.4% in 1985 to 32.6% in 2006. In the Changjiang River Estuary, the number of zooplankton species slightly changed, but that of copepoda decreased from 62 in 1985 to 37 in 2006; the proportion of copepoda in zooplankton decreased from 54.2% in 1958 to 42.5% in 2006. In the Pearl River Estuary, the proportion of copepoda in zooplankton decreased from 59.3% in 1959 to 54.4% in 2006, and no clear change was found as limited by available data. Compared with the results of 1958-1960 marine survey, the zooplankton biomass in spring and summer in the Huanghe River Estuary changed slightly, mostly in summer. The average biomass of zooplankton in springs of 2000 to 2006 was 528.36 mg/m³ in the Changjiang River Estuary, being 2.4 times over that of 1958, similarly for the summer biomass for 2.2-2.7 times higher. In the Pearl River Estuary, the spring biomass has significantly increased from 1959 to 2004-2006 by 5.7-8.7 times, while that of summer biomass in 1981 and 2006 increased by 3.1 and 11 times over that of 1959, respectively. Therefore, biomasses in all the three estuary areas show a tendency of increase, the largest in the Pearl River Estuary, and followed by the Changjiang River Estuary and the Huanghe River Estuary in turn.