Brännäs Eva, Nilsson Marie-Charlotte, Nilsson Linda, Gallet Christiane, Brännäs Kurt, Berglind Rune, Eriksson Lars-Ove, Leffler Per-Erik, Zackrisson Olle
Department of Aquaculture, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
J Chem Ecol. 2004 Jan;30(1):215-27. doi: 10.1023/b:joec.0000013192.25938.c8.
The common evergreen dwarf shrub Empetrum hermaphroditum has influence on the functioning of boreal terrestrial ecosystems in northern Sweden. The negative effects of E. hermaphroditum are partly attributed to the production of the dihydrostilbene, batatasin-III, which is released from leaves and litter by rain and snowmelt. In this study, we investigated whether batatasin-III is carried by runoff into streams and lakes during the snowmelt period and whether it is also potentially hazardous to aquatic fauna. Sampling of water from streams and a lake for which the surrounding terrestrial vegetation is dominated by E. hermaphroditum was done during the snowmelt period in May 1993 and in 1998, and analyzed for batatasin-III. Using 24- and 48-hr standard toxicity tests, we analyzed toxicity to brown trout (Salmo trutta) alevins and juvenile water fleas (Daphnia magna). Toxicity (proportion of dead individuals) to trout was tested at pH 6.5 and compared with that of a phenol within a range of concentrations. In the toxicity (proportion of immobilized individuals) test on D. magna, the interactive effect of pH (pH 5.5-7.0) was included. Concentration of batatasin-III was generally higher in 1998 than in 1993 and showed peak levels during snowmelt. Concentration in ephemeral runnels > the lake > streams running through clear-cuts dominated by E. hermaphroditum > control streams lacking adjacent E. hermaphroditum vegetation. The maximum concentration of batatasin-III found was 1.06 mg l(-1). The proportion of dead yolk sac alevins increased significantly (P < 0.001) with increasing concentrations of batatasin-III and time of exposure. After 24 hr, EC50 was 10 mg l(-1). It was 2 mg l(-1) after 48 hr. The effect of phenol was negligible, indicating a specific phytotoxic effect of the bibenzyl structure of batatasin-III. The proportion of mobile D. magna became significantly smaller (P < 0.001) with increasing concentrations of batatasin-III, with decreasing pH, and with increasing exposure time. EC50 varied between 7 and 17 mg l(-1) at pH 5.5 and 7.0, respectively. After 24 hr EC50 decreased and was 2.5 at pH 5.5 and 12 mg l(-1) at pH 7.0. The levels of batatasin-III found in the field samples were below the lowest EC50 in acute toxicity tests. However, in view of the interactive effect of pH and exposure time, this study suggests that this stable plant metabolite may impose a lethal effect on the aquatic fauna in small streams.
常见的常绿矮灌木雌雄同株岩高兰对瑞典北部寒带陆地生态系统的功能有影响。雌雄同株岩高兰的负面影响部分归因于二氢茋类化合物甘薯素-III的产生，该物质通过雨雪融水从叶片和凋落物中释放出来。在本研究中，我们调查了甘薯素-III在融雪期是否会随径流进入溪流和湖泊，以及它对水生动物是否也有潜在危害。1993年5月和1998年融雪期，对周围陆地植被以雌雄同株岩高兰为主的溪流和一个湖泊的水样进行了采集，并分析其中的甘薯素-III。通过24小时和48小时的标准毒性试验，我们分析了其对褐鳟（Salmo trutta）仔鱼和幼年水蚤（大型溞，Daphnia magna）的毒性。在pH值为6.5的条件下测试了对鳟鱼的毒性（死亡个体比例），并在一系列浓度范围内与苯酚的毒性进行了比较。在对大型溞的毒性（固定个体比例）试验中，纳入了pH值（pH 5.5 - 7.0）的交互作用。1998年甘薯素-III的浓度总体上高于1993年，且在融雪期呈现峰值水平。临时径流中的浓度 > 湖泊 > 流经以雌雄同株岩高兰为主的皆伐地的溪流 > 缺乏相邻雌雄同株岩高兰植被的对照溪流。所发现的甘薯素-III的最高浓度为1.06毫克/升。随着甘薯素-III浓度的增加和暴露时间的延长，卵黄囊仔鱼的死亡比例显著增加（P < 0.001）。24小时后，半数致死浓度（EC50）为10毫克/升。48小时后为2毫克/升。苯酚的影响可忽略不计，表明甘薯素-III的联苄结构具有特定的植物毒性作用。随着甘薯素-III浓度的增加、pH值的降低以及暴露时间的延长，大型溞活动个体的比例显著减小（P < 0.001）。在pH 5.5和7.0时，EC50分别在7至17毫克/升之间变化。24小时后，EC50降低，在pH 5.5时为2.5，在pH 7.0时为12毫克/升。在野外样本中发现的甘薯素-III水平低于急性毒性试验中的最低EC50。然而，鉴于pH值和暴露时间的交互作用，本研究表明这种稳定的植物代谢产物可能会对小溪流中的水生动物产生致命影响。
