Understanding how altered temperature regimes affect harmful cyanobacterial bloom formation is essential for managing aquatic ecosystems amidst ongoing climate warming. This is difficult because algal performance can depend on both current and past environments, as plastic physiological changes (acclimation) may lag behind environmental change. Here, we investigate how temperature variation on sub-weekly timescales affects population growth and toxin production given acclimation. We studied four ecologically important freshwater cyanobacterial strains under low- and high-nutrient conditions, measuring population growth rate after acclimation and new exposure to a range of temperatures. Cold-acclimated populations (15.7°C) outperformed fully acclimated populations (held in constant conditions) across 65% of thermal environments, while hot-acclimated populations (35.7–42.6°C) underperformed across 75% of thermal environments. Over a 5-day period, cold-acclimated Microcystis aeruginosa produced ~2.5-fold more microcystin than hot-acclimated populations experiencing the same temperature perturbation. Our results suggest that thermal variation and physiology interact in underappreciated ways to influence cyanobacterial growth, toxin production, and likely bloom formation.

中文翻译：

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热适应影响淡水蓝藻的生长和毒素产生

了解温度变化如何影响有害蓝藻水华的形成对于在持续的气候变暖中管理水生生态系统至关重要。这很困难，因为藻类的表现可能取决于当前和过去的环境，因为塑料生理变化（适应）可能落后于环境变化。在这里，我们研究了在适应环境的情况下，亚周时间尺度上的温度变化如何影响种群增长和毒素产生。我们在低营养和高营养条件下研究了四种具有重要生态学意义的淡水蓝藻菌株，测量了适应环境和新暴露于一系列温度后的种群增长率。在 65% 的热环境中，寒冷适应的种群 (15.7°C) 的表现优于完全适应的种群（保持在恒定条件下），而热适应人群（35.7–42.6°C）在 75% 的热环境中表现不佳。经过 5 天的冷适应与经历相同温度扰动的热驯化种群相比，铜绿微囊藻产生的微囊藻毒素多 2.5 倍。我们的研究结果表明，热变化和生理以未被充分认识的方式相互作用，影响蓝藻生长、毒素产生和可能的水华形成。