Journal of Ecology and Rural Environment ›› 2015, Vol. 31 ›› Issue (5): 743-747.doi: 10.11934/j.issn.1673-4831.2015.05.020

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Effects of Stresses of Different Heavy Metals on Growth and ChlorophyⅡ Fluorescence of Scendesmus obliquus.

WANG Lin,LIU Ran,LI Wen-hui,CHEN Lei,ZHAO He-juan,ZHENG Qing-song   

  1. College of Natural Resources and Environmental Sciences, Key Laboratory of Marine Biology, Nanjing Agricultural University
  • Received:2014-12-08 Revised:2015-07-16 Online:2015-09-25 Published:2015-09-30

Abstract:

Scenedesmus obliquus, a typical representative of the Phytoplankton group in freshwater ecosystems, is often used in aquatic toxicology tests and evaluation. Changes in cell density (D650) and fluorescenceⅡparameters of Scendesmus obliquus under stresses of heavy metals ( Cu2+ , Zn2+ and Mn2+ ) different in concentration and different in duration ( 12 h, 24 h, 48 h, 72 h and 96 h )  were studied. The main parameters include maximal phototransformation efficiency of PSII (Fv / Fm), actual phototransformation efficiency of PSII in the light (Y), maximal relative electron transport rate (Re,t,max), half-saturation light intensity (Ik) and light use efficiency (α) were determined. Results show that the heavy metals did not have much effect on growth of Scendesmus obliquus within 12 h and 24 h of exposure; however, Cu2+ and Zn2+ did have some significant effect inhibiting the growth of S. obliquus after 48 h of exposure. However, after 96 h of exposure, all the heavy metal treatments, except for the treatment of 100 µmol•L-1 Mn2+, displayed significant effects inhibiting growth of the algae, and the treatments of Cu2+.did especially so. With the exposure going on, all fluorescence parameters (Fv / Fm,Y, Re,t,max, Ik, α) decreased in value, but increased steadily in magnitude of the fall. All in all, in terms of toxicity to S. obliquus, the heavy metals displayed an order of Cu2+ > Zn2+ > Mn2+.  The findings of the study indicate that Fv/Fm, Yield and Ik can be used as indicators to evaluate adaptability of S. obliquus to Mn2+ and Zn2+, and fluorescenceⅡ parameters can be used to evaluate adaptability of the algae to Cu2+.

Key words: Scendesmus obliquus, Cu2+, Mn2+, Zn2+, fluorescenceⅡ parameters, toxicity