月湖底泥疏浚后底栖动物群落的恢复及其与环境的关系

研究对月湖底泥疏浚后底栖动物群落动态进行逐月的周年调查,并分析了底栖动物密度、生物多样性与环境因子的关系,结果表明：疏浚导致大型底栖动物基本消失,现存量从疏浚前的（4387±885）ind·m-2降低至（80±21）ind·m-2。疏浚后,寡毛类成为受干扰系统恢复过程中的先锋种类,在春季（4月）和秋冬之际（11月）出现2个密度高峰,分别为（1010±230）ind·m-2和（1538±408）ind·m-2,而摇蚊幼虫在疏浚一年后的秋冬季密度达到高峰（2021±612）ind·m-2,二者均基本恢复到疏浚前的密度水平。种类组成与疏浚前相似,优势种类数较疏浚前多,7月份以前,以霍甫水丝蚓占绝对优势,7月份以后以长足摇蚊占绝对优势。生物多样性在秋冬季恢复到疏浚前水平。寡毛类、摇蚊幼虫的密度、生物多样性与湖水溶氧、透明度呈显著正相关,与水体营养水平（TN、TP、有机碎屑）呈显著负相关（P〈0.05）。分析认为疏浚后底栖动物群落的季节变化与动物的生命周期（繁殖和生长）密切相关,而营养水平不是限制动物种群密度分布的主要因子。从底栖动物群落的恢复情况来看,疏浚后的底质环境更有利于底栖动物群落的生存和底栖生态系统的重建。

Zoobenthos recovering process and the relations with environment after sediment dredging in Lake Yuehu

This study has made monthly investigation on dynamic of zoobenthos community for one year after sediment dredging in Lake Yuehu,and also analyzed the relationship between zoobenthos community and environmental factors.The results indicated as follows： dredging led to nearly whole disappearing of zoobenthos,and the standing crop declined from（4 387±885） ind·m-2 before dredging to（80±21） ind·m-2.The oligochaetes became the pioneer species in the recovering process of disturbed ecologic system after dredging,and it showed two high densities in the turn of spring-summer（April） and autumn-winter（November）,i.e.（1 010±209） ind·m-2and（1 538±354） ind·m-2respectively,as for chironomids,the high density（2 021±612） ind·m-2appeared in the autumn-winter,which both nearly achieved the level before dredging.The species composition was similar to before dredging,there were more dominant species compared with before dredging.Before July,Limnodrilus hoffmeisteri was the most dominant species,but Tanypus sp after July.Seasonally dynamic of diversity was consistent with oligochates,and the diversity achieved the level of before dredging in autumn-winter.Densities of oligochaetes ＆ chironomids,diversity were significantly positively correlated with DO and ZSD/ZM,but negatively with trophic factors（TN,TP,OD）.It can be concluded that the seasonal dynamic of zoobenthos community was closely correlated with the life cycle（reproduce and growth） of zoobenthos after dredging.The trophic level was not the primary factor that controlled the zoobenthos density.The benthic environment after dredging was fit for zoobenthos to live in and for benthic ecologic system rebuilding.