title: Combined toxic effects and mechanisms of microsystin-LR and copper on Vallisneria Natans (Lour.) Hara seedlings.
abstract: Microcystin-LR (MCLR) and copper are commonly found in eutrophic water bodies because of eutrophic run-offs, cyanobacterial blooms, and copper algicide applications. However, the ecotoxicological risk of their combination remains unknown. This study investigated the effect of MCLR, Cu, and their mixture on the growth and physiological responses of Vallisneria natans. Results showed that the combined toxicity of them was concentration dependent. Synergistic effects were elicited at low concentrations of MCLR and Cu exposure (≤0.25+0.64mg/L). Additive or antagonistic effects were induced at higher concentrations. Single and combined exposures could induce oxidative stress, such as increased superoxide anion radical levels. To cope with oxidative stress, V. natans could activate their antioxidant defense systems, such as enhanced superoxide dismutase production and changes in peroxidase activities. Exposure to combined MCLR and Cu (even only with 0.005+0.041mg/L) adversely affected their antioxidant defense systems. As a consequence, malondialdehyde levels significantly increased. The interaction of MCLR and Cu could also significantly increase the bioaccumulations of MCLR and Cu. This increase could be accounted for their synergistic toxic effects on V. natans. Our results suggested that the exacerbated ecological hazard of MCLR and Cu with environmental concentrations may harm aquatic ecosystems.
authors.affiliation: Key Laboratory for Environment and Disaster Monitoring and Evaluation, Hubei, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China. Electronic address: zwang@whigg.ac.cn.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Junqian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Environment and Disaster Monitoring and Evaluation, Hubei, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China.
authors.forename: Enhua
authors.initials: E
authors.lastname: Li
authors.affiliation: Key Laboratory for Environment and Disaster Monitoring and Evaluation, Hubei, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Environment and Disaster Monitoring and Evaluation, Hubei, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China.
authors.forename: Xuelei
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China. Electronic address: lrsong@ihb.ac.cn.
authors.forename: Lirong
authors.initials: L
authors.lastname: Song
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D018533:Biomass; D003300:Copper / Q000633:toxicity*; D004357:Drug Synergism; D031321:Hydrocharitaceae / Q000187:drug effects / Q000254:growth & development; D008387:Marine Toxins; D052998:Microcystins / Q000633:toxicity*; D016877:Oxidants / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010544:Peroxidases / Q000378:metabolism; D012639:Seeds / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000032:analysis / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D008387:Marine Toxins; D052998:Microcystins; D016877:Oxidants; D014874:Water Pollutants, Chemical; D013481:Superoxides; D003300:Copper; D010544:Peroxidases; D013482:Superoxide Dismutase; C057862:cyanoginosin LR
keywords: Bioaccumulation; Joint toxicity; Metals; Microcystins; Superoxide anion radical