Riera Steven F, Cohen Risa A
Department of Biology, Georgia Southern University, PO Box 8042-1, Statesboro, GA, 30460, USA.
Ecotoxicology. 2016 Oct;25(8):1458-1467. doi: 10.1007/s10646-016-1697-8. Epub 2016 Jul 21.
Synthetic surfactants in cleaners and detergents commonly contaminate freshwater systems, therefore use of low-toxicity alternatives is becoming increasingly important. Alkyl polyglucosides (APGs) derived from natural products are less toxic than synthetic surfactants, and degrade rapidly reducing chemical exposure time. However, single species toxicity tests showed APGs have toxic effects on aquatic primary producers and zooplankton, and that species demonstrate different sensitivities to APGs. Furthermore, species unaffected by APGs directly may be indirectly affected by removal of a food source or changes in predator densities, thereby changing plankton community structure. To determine the effects of APGs on plankton communities under environmental conditions, floating mesocosms were deployed in a shallow pond in southeast Georgia, USA and dosed with 0, 0.01, 2.5, 5, or 10 mg L APG. Zooplankton community composition and abundance, phytoplankton abundance (as chlorophyll a), and water column dissolved oxygen concentration were determined weekly for 1 month. Zooplankton abundance decreased primarily due to loss of copepods, and community composition shifted toward small-bodied cladocerans (Bosmina sp.), and chlorophyll a concentrations declined by up to 81 % following exposure to APG concentrations of 2.5 mg L or greater. Concentrations of dissolved oxygen never dropped below 5.70 mg L, but the observed declines of ~2 mg L could become stressful during periods of high water temperatures. Nevertheless, the APG-induced shift from copepod to cladoceran dominated communities and decrease in autochthonous carbon availability has important implications for food availability and quality to higher trophic levels such as planktivorous fishes.
清洁剂和洗涤剂中的合成表面活性剂常常污染淡水系统，因此使用低毒性替代品变得越来越重要。源自天然产物的烷基多苷（APG）毒性低于合成表面活性剂，且降解迅速，可减少化学物质暴露时间。然而，单一物种毒性测试表明，APG对水生初级生产者和浮游动物具有毒性作用，而且不同物种对APG的敏感性不同。此外，未直接受到APG影响的物种可能会因食物来源的去除或捕食者密度的变化而受到间接影响，从而改变浮游生物群落结构。为了确定在环境条件下APG对浮游生物群落的影响，在美国佐治亚州东南部的一个浅池塘中设置了漂浮式中型生态系统，并分别加入0、0.01、2.5、5或10 mg/L的APG。连续1个月每周测定浮游动物群落组成和丰度、浮游植物丰度（以叶绿素a表示）以及水柱溶解氧浓度。浮游动物丰度下降主要是由于桡足类动物数量减少，群落组成向小型枝角类动物（Bosmina sp.）转变，并且在暴露于2.5 mg/L或更高浓度的APG后，叶绿素a浓度下降高达81%。溶解氧浓度从未降至5.70 mg/L以下，但在水温较高时，观察到的约2 mg/L的下降可能会造成压力。尽管如此，APG诱导的从以桡足类动物为主导的群落向以枝角类动物为主导的群落的转变以及自源碳可用性的降低，对于诸如食浮游生物鱼类等高营养级的食物可用性和质量具有重要影响。
