Chalifour Annie, LeBlanc André, Sleno Lekha, Juneau Philippe
Department of Biological Sciences-GRIL-TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montréal, QC, H3C 3P8, Canada.
Department of Chemistry, Bioanalytical Mass Spectrometry Laboratory, Université du Québec à Montréal, C.P. 8888, Succursale Centre-Ville, Montréal, QC, H3C 3P8, Canada.
Ecotoxicology. 2016 Dec;25(10):1822-1831. doi: 10.1007/s10646-016-1728-5. Epub 2016 Sep 26.
Atrazine is an herbicide frequently detected in watercourses that can affect the phytoplankton community, thus impacting the whole food chain. This study aims, firstly, to measure the sensitivity of monocultures of the green alga Scenedemus obliquus and toxic and non-toxic strains of the cyanobacteria Microcystis aeruginosa before, during and after a 30-day acclimation period to 0.1 µM of atrazine. Secondly, the sensitivity of S. obliquus and M. aeruginosa to atrazine in mixed cultures was evaluated. Finally, the ability of these strains to remove atrazine from the media was measured. We demonstrated that both strains of M. aeruginosa had higher growth rate-based EC values than S. obliquus when exposed to atrazine, even though their photosynthesis-based EC values were lower. After being exposed to 0.1 µM of atrazine for 1 month, only the photosynthesis-based EC of S. obliquus increased significantly. In mixed cultures, the growth rate of the non-toxic strain of M. aeruginosa was higher than S. obliquus at high concentrations of atrazine, resulting in a ratio of M. aeruginosa to total cell count of 0.6. This lower sensitivity might be related to the higher growth rate of cyanobacteria at low light intensity. Finally, a negligible fraction of atrazine was removed from the culture media by S. obliquus or M. aeruginosa over 6 days. These results bring new insights on the acclimation of some phytoplankton species to atrazine and its effect on the competition between S. obliquus and M. aeruginosa in mixed cultures.
莠去津是一种在水道中经常检测到的除草剂，它会影响浮游植物群落，进而影响整个食物链。本研究旨在，首先，测量绿藻斜生栅藻的单培养物以及铜绿微囊藻的有毒和无毒菌株在30天适应期之前、期间和之后对0.1µM莠去津的敏感性。其次，评估斜生栅藻和铜绿微囊藻在混合培养物中对莠去津的敏感性。最后，测量这些菌株从培养基中去除莠去津的能力。我们证明，当暴露于莠去津时，两种铜绿微囊藻菌株基于生长速率的EC值均高于斜生栅藻，尽管它们基于光合作用的EC值较低。在暴露于0.1µM莠去津1个月后，只有斜生栅藻基于光合作用的EC显著增加。在混合培养物中，在高浓度莠去津下，铜绿微囊藻无毒菌株的生长速率高于斜生栅藻，导致铜绿微囊藻与总细胞数的比例为0.6。这种较低的敏感性可能与蓝藻在低光照强度下较高的生长速率有关。最后，在6天内，斜生栅藻或铜绿微囊藻从培养基中去除的莠去津比例可忽略不计。这些结果为一些浮游植物物种对莠去津的适应及其对混合培养物中斜生栅藻和铜绿微囊藻之间竞争的影响带来了新的见解。
