The effects of food availability on thermal stress in Daphnia magna were investigated for 21 days, with a hypothesis that lower food condition would increase the adverse effect of elevated temperature on D. magna. Under higher food conditions (5 × 10⁵ cells mL⁻¹), elevated temperature (25 °C) did not induce higher oxidative stress (levels of antioxidant enzymes and lipid peroxidation) than reference temperature (20 °C). Thus, reproduction (number of offspring per female) was significantly (p < 0.05) higher at 25 °C compared with that at 20 °C. Under lower food condition (2 × 10⁵ cells mL⁻¹), however, elevated temperature significantly (p < 0.05) induced antioxidant enzyme activity (superoxide dismutase and catalase) and reduced adult somatic growth rate (5–21 days), whereas there was no significant change in reproduction between the two temperature groups. These findings suggest that food availability greatly influences the effect of elevated temperature on D. magna, possibly resulting in a trade-off among oxidative stress defense, somatic growth, and reproduction.

连续21天研究了食物供应量对水蚤（Daphnia magna）的热应激的影响，并提出了以下假设：较低的食物条件会增加高温对D. magna的不利影响。在较高的食物条件下（5×10 ⁵ 细胞mL ^-1），升高温度（25°C）不会引起高于参考温度（20°C）的氧化应激（抗氧化酶和脂质过氧化反应的水平）。因此， 与20°C相比，在25°C时繁殖（每个雌性的后代数量）显着更高（p <0.05）。在较低的食物条件下（2×10 ⁵ 细胞mL ^-1），温度显着升高（p <0.05）诱导抗氧化酶活性（超氧化物歧化酶和过氧化氢酶）并降低了成年体细胞生长速率（5-21天），而两个温度组之间的繁殖没有显着变化。这些发现表明，食物的可获得性极大地影响了高温对D. magna的影响，可能导致氧化应激防御，体细胞生长和繁殖之间的权衡。