白鹭作为无锡太湖地区环境污染指示生物的研究

2000年4—6月对分布在无锡太湖地区的4种要鸟中的白鹭(Egretta garzetta)行为生态学及其生境污染状况进行了调查研究．调查地白鹭主要栖息树种包括马尾松(Pnus masson±ana)、香樟树(C±nnamomum hupehanum)、麻砾树(Quercus acut±ssema)、榆树(Ulmus prm±la)和杨梅树（Myr±ca rubra)．栖息地总面积为7hm^2，白鹭总巢数为4200个，每棵树平均0．38个．白鹭的孵化期为19—21d，卵重23．9±4．0g(n=41)，平均卵大小(44．5±4．1)mm×(32．6±4．9)mm(n＝41)，平均窝卵数5．02(2—8)枚，平均窝雏数3．86(2—7)只，孵化成功率为84．25％．对白鹭雏鸟左右跗Zhe的测量分析表明不对称性不显著(P>0．05)．白鹭雏鸟食物较小，繁殖期间主要以小型鱼类和虾类为食．污染物分析结果表明，白鹭卵中除例外，六氯苯、六六六、环二烯类、DDTs、DDE、PCBs、Cr、Hg和Pb均检测到．食物链(底泥-食物-白鹭雏鸟)中，有机杀虫剂和重金属都逐级富集．通过与相对无污染的鄱阳湖地区比较，太湖地区和鄱阳湖地区卵样品中的DDs(包括DDT、DDE和DDD)浓度最高(超过2μg·g^1)，其它污染物浓度均较小．太湖地区白鹭卵中的DDTs、Cd和Cr浓度低于鄱阳湖地区，其它污染物浓度鄱阳湖地区均低于太湖地区．经比较分析，两地样品中有机氯杀虫剂、PCBs和各种重金属浓度都未达到影响白鹭繁殖成功率的阈值．

Egretta garzetta as a bioindicator of environmental pollution in Tai Lake region

There were four species of Ardeidae in Tai Lake. The dominant vegetations in the habitat were Pinus massoniana, Cinnamomum hupehanum, Quercus acutissema, Ulmus prmila and Myrica rubra, which were suitable for Egretta garzetta to make nests. The area of the habitat was about 7 hm2, where there were totally 4200 Egretta garzetta nests with the density of 0.38 nest per tree in average. Studies on Egretta garzetta breeding ecology showed that the incubating time was 19-21 days, the average egg weight was 23.9 +/- 4.0 g(n = 41), and the average egg size was 44.5 +/- 4.1 mm x 32.6 +/- 4.9 mm(n = 41). The mean clutch size and brood size were 5.02(2-8) and 3.86(2-7), respectively, and the hatching rate was 84.25%. The measurements of Egretta garzetta nestling tarsus did not show any asymmetry (P > 0.05). Egretta garzetta fed mainly on small fish and shrimps in Tai Lake. The analysis results of Tai Lake samples showed that the pollutants including HCH, HCB, cyclodience, DDTs (DDT, DDE and DDD), PCBs, Cr, Hg and Pb in Egretta garzetta eggs were detected except Cd, and these pollutants accumulated through prey chain from sediments and preys to nestlings. Comparing samples from Tai Lake and those from Poyang Lake as relatively unpolluted area, only the concentration of DDTs residues was higher than 2 micrograms.g-1 in both lakes, and the other residues from Tai Lake like organochlorine insecticides, PCBs and heavy metals were all lower than those from Poyang Lake, and did not affect the development and breeding success of Egretta garzetta at present.