南非科技與工業(yè)研究會(huì)（CSIR）的湖泊學(xué)家保羅·奧博郝斯特博士研究出一種可以預(yù)測(cè)有毒的藍(lán)綠藻在淡水環(huán)境（如江河湖泊）中暴發(fā)的方法，這種早期預(yù)警方法對(duì)于監(jiān)測(cè)淡水環(huán)境，幫助水源管理部門采取恰當(dāng)?shù)乃欧挪呗詠頊p少下游污染和健康風(fēng)險(xiǎn)具有重要應(yīng)用意義,。
藍(lán)綠藻又稱藍(lán)藻或藍(lán)菌,，是一種生長(zhǎng)于水中的浮游生物,，當(dāng)水中的營養(yǎng)物質(zhì)過剩時(shí)，原本稀少的藍(lán)綠藻會(huì)在短時(shí)間內(nèi)迅速繁殖，在河流、湖泊或水庫的水面上形成龐大而濃密的藻墊,，這就是藍(lán)藻暴發(fā)。藍(lán)藻暴發(fā)打亂了湖泊水庫正常的生態(tài)系統(tǒng)和功能,，造成水中嚴(yán)重缺氧,，致使大量魚類和其他水生物死亡；同時(shí)會(huì)產(chǎn)生有腥臭味的“水華”現(xiàn)象,，令飲用水源受到威脅,，而藍(lán)藻中含有的毒素更是嚴(yán)重影響人類健康。
奧博郝斯特的研究小組考察了位于南非自由州的克魯格斯德瑞福特湖,，對(duì)其近岸水域的物理和化學(xué)特性以及生物相互作用進(jìn)行了研究,，特別是對(duì)在靠近該湖水壩區(qū)域暴發(fā)的有毒藍(lán)藻進(jìn)行了重點(diǎn)研究。通過比較參考點(diǎn)和有毒藍(lán)藻污染區(qū)域物種構(gòu)成的變化,，他們成功地利用大型無脊椎動(dòng)物的多樣性指數(shù)對(duì)有毒藍(lán)藻暴發(fā)的可能性進(jìn)行了評(píng)估,。他們采用水蛭作為生物指示物，因?yàn)榕c某些大型無脊椎動(dòng)物相反,，水蛭可以在被藍(lán)藻釋放的有毒物質(zhì)污染的水中生存，它們的存在往往是水質(zhì)差的證明,。如果水蛭出現(xiàn)在比較稠密的藍(lán)藻周圍,，說明這種藍(lán)藻極有可能是有毒的。
但水蛭不能說明水體中的毒性水平到底有多高,。為此,，他們同時(shí)采用基因技術(shù)來檢測(cè)可以合成藍(lán)綠細(xì)菌毒素的藍(lán)綠細(xì)菌基因的存在。這種靈敏的酶聯(lián)免疫吸收分析方法利用一種抗體可以識(shí)別出能產(chǎn)生毒性的基因片段,，并測(cè)出其含量,，由此可以確定毒性高低。
奧博郝斯特表示,，這是首次將這兩種方法結(jié)合起來對(duì)湖泊水庫的有毒藍(lán)藻暴發(fā)進(jìn)行早期預(yù)警評(píng)估,。有關(guān)結(jié)果發(fā)表在近期出版的《生態(tài)毒理學(xué)》雜志上(生物谷Bioon.com),。
生物谷推薦原始出處：
Ecotoxicology 2009年1月 :DOI:10.1007/s10646-008-0254-5
The influence of a toxic cyanobacterial bloom and water hydrology on algal populations and macroinvertebrate abundance in the upper littoral zone of Lake Krugersdrift, South Africa
Paul J. Oberholster1 , Anna-Maria Botha2 and Peter J. Ashton1
The biological interactions and the physical and chemical properties of the littoral zone of Lake Krugersdrift were studied for a 4-month period when a dense, toxic cyanobacterial bloom dominated by Microcystis aeruginosa was present in the main lake basin. The presence of a toxic strain of M. aeruginosa was confirmed through the use of ELISA and molecular markers that detect the presence of the mcyB and mcyD genes of the mcy gene cluster that synthesizes microcystin. An increase in Microcystis toxicity at sites dominated by the cyanobacterial scum was accompanied by an increase in total abundance of the macroinvertebrate families Hirudinae, Chironomidae, and Tubificidae. Sites located away from the cyanobacterial scum had a lower abundance but a higher diversity of macroinvertebrates. The water quality under the Microcystis scum was characterized by low pH values, low concentrations of dissolved oxygen, and lower total alkalinity values. The periphytic alga Ulothrix zonata was absent in areas dominated by the cyanobacterial scum, possibly as a result of overshadowing by the scum or direct toxic allelopathic effects on growth and photosynthesis. The diatom Diatoma vulgare dominated the benthic algal flora beneath the cyanobacterial scum.
(1) CSIR Natural Resources and the Environment, PO Box 395, Pretoria, ZA0001, South Africa
(2) Department of Genetics, University of Pretoria, Hillcrest, Pretoria, ZA002, South Africa
