title: Effects of multigenerational exposure to elevated temperature on reproduction, oxidative stress, and Cu toxicity in Daphnia magna.
abstract: This study evaluated the effect of temperature (20 and 25°C) on reproduction, oxidative stress, and copper (Cu) toxicity in Daphnia magna across three generations (F0, F1, and F2). Exposing D. magna to elevated temperature significantly decreased the number of offspring per female per day, the time to first brood, and body length compared to exposure to the optimal temperature (p<0.05). In addition, elevated temperature induced a significantly higher production of reactive oxygen species and lipid peroxidation (p<0.05). These findings suggest that D. magna likely responded to thermal stress by investing more energy into defense mechanisms, rather than growth and reproduction. In addition, oxidative stress at the elevated temperature gradually increased with each generation, possibly owing to the reduced fitness of the offspring. Exposing D. magna to 25°C (EC50=34±3µgL(-1)) substantially increased the median effective concentration of Cu in all generations compared to exposure to 20°C (EC50=25±3µgL(-1)), indicating a decrease in acute toxicity at elevated temperature. However, elevated temperature significantly increased the oxidative stress induced by a sublethal concentration of Cu (10µgL(-1)). The interaction between elevated temperature and Cu exposure appears to be synergistic; however, this needs to be confirmed using multiple generations in a long-term experiment.
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
authors.forename: Eunhye
authors.initials: E
authors.lastname: Bae
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
authors.forename: Palas
authors.initials: P
authors.lastname: Samanta
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
authors.forename: Jisu
authors.initials: J
authors.lastname: Yoo
authors.affiliation: Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea. Electronic address: jjung@korea.ac.kr.
authors.forename: Jinho
authors.initials: J
authors.lastname: Jung
mesh_terms: D000818:Animals; D003300:Copper / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects*; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D018384:Oxidative Stress / Q000187:drug effects; D012098:Reproduction / Q000187:drug effects; D013696:Temperature
chemical_list: D003300:Copper
keywords: Daphnia; Heavy metal; Oxidative stress; Reproduction; Thermal stress