Fountain M T, Hopkin S P
Division of Zoology, School of Animal and Microbial Sciences, The University of Reading, Reading, UK.
Ecotoxicology. 2004 Aug;13(6):573-87. doi: 10.1023/b:ectx.0000037194.66321.2c.
We examined the species diversity and abundance of Collembola at 32 sampling points along a gradient of metal contamination in a rough grassland site (Wolverhampton, England), formerly used for the disposal of metal-rich smelting waste. Differences in the concentrations of Cd, Cu, Pb and Zn between the least and most contaminated part of the 35 metre transect were more than one order of magnitude. A gradient of Zn concentrations from 597 to 9080 microg g(-1) dry soil was found. A comparison between field concentrations of the four metals and previous studies on their relative toxicities to Collembola, suggested that Zn is likely to be responsible for any ecotoxicological effects on springtails at this site. Euedaphic (soil dwelling) Collembola were extracted by placing soil cores into Tullgren funnels and epedaphic (surface dwelling) species were sampled using pitfall traps. There was no obvious relationship between the total abundance, or a range of commonly used diversity indices, and Zn levels in soils. However, individual species showed considerable differences in abundance. Metal "tolerant" (e.g., Ceratophysella denticulata) and metal "sensitive" (e.g., Cryptopygus thermophilus) species could be identified. Epedaphic species appeared to be influenced less by metal contamination than euedaphic species. This difference is probably due to the higher mobility and lower contact with the soil pore water of epedaphic springtails in comparison to euedaphic Collembola. In an experiment exposing the standard test springtail, Folsomia candida, to soils from all 32 sampling points, adult survival and reproduction showed small but significant negative relationships with total Zn concentrations. Nevertheless, juveniles were still produced from eggs laid by females in the most contaminated soils with 9080 microg g(-1) Zn. Folsomia candida is much more sensitive to equivalent concentrations of Zn in the standard OECD soil. Thus, care should be taken in extrapolating the results of laboratory toxicity tests on metals in OECD soil to field soils, in which, the biological availability of contaminants is likely to be lower. Our studies have shown the importance of ecotoxicological effects at the species level. Although there may be no differences in overall abundance, sensitive species that are numerous in contaminated sites, and which may play important roles in decomposition ("keystone species") can be greatly reduced in numbers by pollution.
我们在英国伍尔弗汉普顿一处曾经用于处置富含金属的冶炼废料的粗糙草原场地，沿着金属污染梯度在32个采样点对弹尾目昆虫的物种多样性和丰度进行了研究。在35米样带污染最轻和最重的部分之间，镉、铜、铅和锌的浓度差异超过一个数量级。发现土壤中锌的浓度梯度为597至9080微克/克干土。将这四种金属的现场浓度与先前关于它们对弹尾目昆虫相对毒性的研究进行比较后表明，锌可能是造成该场地对跳虫产生任何生态毒理学效应的原因。通过将土芯放入杜尔格伦漏斗中来提取土壤栖居的弹尾目昆虫，并用陷阱诱捕法对地表栖居的物种进行采样。土壤中锌含量与总丰度或一系列常用的多样性指数之间没有明显关系。然而，单个物种在丰度上表现出相当大的差异。可以识别出金属“耐受”物种（如齿状角跳虫）和金属“敏感”物种（如嗜热隐棘跳虫）。地表栖居物种似乎比土壤栖居物种受金属污染的影响更小。这种差异可能是由于与土壤栖居的弹尾目昆虫相比，地表栖居的跳虫具有更高的移动性且与土壤孔隙水的接触更少。在一项将标准测试跳虫——白色符氏跳虫暴露于所有32个采样点土壤的实验中，成虫的存活和繁殖与总锌浓度呈现出虽小但显著的负相关关系。然而，在锌含量为9080微克/克的污染最严重的土壤中，雌性产下的卵仍能孵化出幼虫。白色符氏跳虫对经合组织标准土壤中同等浓度的锌更为敏感。因此，在将经合组织土壤中金属的实验室毒性测试结果外推至现场土壤时应谨慎，因为在现场土壤中，污染物的生物有效性可能较低。我们的研究表明了物种水平上生态毒理学效应的重要性。尽管总体丰度可能没有差异，但在污染场地数量众多且可能在分解过程中发挥重要作用的敏感物种（“关键物种”）可能会因污染而数量大幅减少。
