生态学报Issue(23)：7615-7624,10.DOI:10.5846/stxb201405211049
产毒与不产毒铜绿微囊藻对模拟酸雨及紫外辐射的生理响应
Physiological responses of toxigenic and non-toxigenic strains of Microcystis aeruginosa to simulated acid rain and UV radiation
摘要
Abstract
Acid precipitation from natural and human activities can lead to different extents of acidification in different freshwater ecosystems, with noticeable changes in the carbonate system and aquatic chemistry. For example, acidification is known to decrease the ionic concentrations of magnesium and calcium, but enhance aluminum concentrations. The changes to chemicals associated with freshwater acidification could induce physiological disturbance to most aquatic organisms, which would then need to spend additional energy to cope with acidic stress. Phytoplankton species with different sensitivities to acid stress may have differential physiological responses; thus, acid stress may lead to altered community structure and species richness. Alternatively, UV-B ( 280—320 nm) irradiance has been increasing due to stratospheric ozone depletion, which would also impact freshwater phytoplankton. Meanwhile, significantly decreased dissolved organic matter as a result of acid rain may further enhance the penetration of solar UV radiation ( UVR, 280—400 nm) in the water column due to decreased light attenuation. Therefore, freshwater acidification and solar UVR may interact to influence phytoplankton physiology. This study examined the physiological responses of a freshwater bloom forming cyanobacterium, Microcystis aeruginosa, to acidification and UVR. Two strains were used for the experiments; a toxigenic strain ( FACHB-905) and a non-toxigenic strain ( FACHB-469) . Microcystis aeruginosa cells were grown under simulated acid rain ( with a mole ratio of H2 SO4∶HNO3= 8∶1 ) under a solar simulator with and without UVR, to observe whether photosynthetic performance and sensitivity to UV irradiance differed between the two strains. Three pH levels were used, pH 7.10 ( regular BG11+N medium), 5.65, and 4.50, with the latter two pH levels reflecting acidification conditions. Two solar radiation treatments were carried out, including:photosynthetically active radiation alone ( PAR, 400—700 nm) and PAR+UV-A+UV-B ( PAB, 295—700 nm) . Our results indicate that the mean cell size and cell volume of the 905 strain was significantly higher than those of the 469 strain in all pH treatments. Acidification treatment significantly lowered mean cell size and volume, but enhanced the chlorophyll a content in both strains. Under the lowest pH (4.50), higher mortality rates were observed for both strains, with decreased effective quantum yield. The inhibition of the growth rate was more pronounced in the non-toxigenic strain. The effective quantum yield declined with decreasing pH level when cells were exposed to high levels of PAR and PAR+UVR. UV-induced inhibition of effective quantum yield was much higher in the non-toxigenic strain compared to the toxigenic strain. This differential response may be attributed to different contents to UV absorbing compounds and carotenoids. Under the global climate change scenario, increasing aquatic acidification and UV irradiance might decrease the competence of the non-toxigenic strain over the toxigenic one.关键词
铜绿微囊藻/酸雨/紫外辐射/生长/光合特性Key words
Microcystis aeruginosa/acid rain/UV radiation/growth/photosynthesis引用本文复制引用
李伟,杨雨玲,黄松,董丽丽,潘健,李亚鹤,周月,高坤山..产毒与不产毒铜绿微囊藻对模拟酸雨及紫外辐射的生理响应[J].生态学报,2015,(23):7615-7624,10.基金项目
安徽省自然科学基金青年项目(1508085QC67) （1508085QC67）
黄山学院博士启动项目(2014xkjq002) （2014xkjq002）
安徽省大学生创新创业项目( AH2014103753126) （ AH2014103753126）
近海海洋环境科学国家重点实验室(厦门大学)访问学者基金( MEL Visiting Fellowship)( MELRS1314) （厦门大学）
