| 摘要: |
| 湖泊的浮游动物在种群演替和数量变化方面都有极明显的周期性(Chen et al., 1987)。浮游动物的周期性变化，除受湖泊环境温度、光照的周期性变化等因素外，同时还受到水体的水动力作用影响(陈伟民等，1998)。
王家楫等(1965)对东湖的轮虫数量进行了研究，陈受忠(1965)阐述了东湖近邻剑水蚤(Cyclops vicinus)、广布中剑水蚤(Mesocyclops leuckarti)、汤匙华指水蚤(Sinoialanub dorrii)、特异荡镖水蚤(Neutrodiaptomus incongreus)等都有显著昼夜垂直移动。Evans(1988)等在有关浮游动物的数量变动与水环境关系方面做了研究。但就水动力作用对浮游动物群落演替的实验研究较少见报道。
为研究水动力作用对浮游动物群落的种类数量变化，利用大型生态模拟槽，探讨不同水动力过程对浮游动物种类组成、数量变化过程和作用途径等，本文作者用模拟水动力的方法对湖泊浮游动物群落演替进行了实验研究，为今后的湖泊生态修复提供了科学依据。 |
| 关键词: 水动力 浮游动物群落 模拟 |
| DOI： |
| 分类号: |
| 基金项目:中国科学院资助项目KZCX2-311、KZ-T-0404号。 |
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| SIMULATED EXPERIMENT STUDY ON SUCCESSION OF ZOOPLANKTON CAUSED BY WATER FLOW |
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Chen Weimin, Qin Boqiang, Xu Qiujin
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Nanjing Institute of Geography and lominologu,CAS
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| Abstract: |
| Simulation experiments showed that the change of zooplanktonic species composition and abundance were larger than those of phytoplankton. In the stationary state, cladoceran and copepod comprised 23.1% of zooplankton abundance. The water was transparent to the bottom, and mean suspended solids was 2.85 mg/L. These conditions were favorable for cladoceran and copepod because they could freely filter food. The low abundance of protozoa and rotifera was probably caused by feeding pressure from cladoceran.
From stationary state to low-flow state, the abundance of protozoa and rotifera reached 1250 and 250 ind./L, respectively. Cladoceran and copepod abundance decreased to 6 and 4.8 ind./L, respectively. AT the low-flow state, zooplankton abundance reached the maximum value in the experiment. Water column transparency was 65 cm, and mean concentration of suspended solids was 12.04 mg/L. This provided sufficient food items for protozoa and rotifera and allowed their populations to increase dramatically. However, the suspended particles caused clogging of the mouth of the cladocera, and they died within 3 days.
Zooplankton abundance decreased during the period from low-flow to high-flow. Water column transparency decreased to 25 cm. When the suspended solids increased to 42.65 mg/L. The dominant species of protozoa were Difflugia acuminata and D. Pyriformis. Their shells were composed of chitin adhered to by inorganic particles. The high-flow conditions forced the benthic cladoceran Macrothrix rosea and harpacticoid copepods into the water column. These were the dominant cladocerans and copepods, respectively.
This experiment showed that wind-driven physical forces play an important role in plankton community structure. Wave action has direct effect on community structure by forcing benthic cladocerans and copepods into the water column. Indirect effects included clogging of the mouths of cladocerans leading to their death. Wind-driven wave action increases suspended solids in large, shallow lakes with soft sediments and decreases water column transparency. At the same time, wave action causes nutrients to be released from the sediments into the water column. This allows an increase in algae abundance. Under certain conditions like the low-flow state, an increase in suspended solids can stimulate population growth of protozoa and rotifera, but decrease the fiaction of cladoceran and copepods which are important in controlling algal abundance via grazing. This could contribute to eutrophication in the lake. When wind-driven wave action is too high, photosynthesis inhibited by increased turbidity and algal abundance decrease.
This simulation experiment showed that wind-driven wave action affected transparency, nutrient concentration and population structure of lake plankton communities. These factors could have an important role in lake eutrophication. |
| Key words: zooplankton community structure simulation |
