作者：Cao, R., Wu, X., Zhang, N., Wan, Q., Huang, T. & Wen, G.

Algal blooms (including cyanobacteria, green algae, and diatoms) suspended in the metalimnion can lead to the formation of metalimnetic oxygen minimum (MOM). Understanding the fate of the three algal bloom species under MOM conditions helps assess water quality risks. In this study, the apoptosis process of Microcystis aeruginosa (M. aeruginosa), Chlorella vulgaris (C. vulgaris), and Cyclotella meneghiniana (C. meneghiniana), as well as the subsequent algal organic matter (AOM) release, was investigated and compared. MOM stress induced a sequential physiological failure across all species. The decline in viability occurred in the following sequence: first in photosynthetic activity, followed by membrane integrity, and finally in algal density. Notably, C. meneghiniana exhibited the highest membrane damage rate (2.47 min-1), significantly surpassing that of M. aeruginosa (0.66 min-1) and C. vulgaris (0.44 min-1), indicating its superior susceptibility. It can be attributed to a critical energy imbalance: the larger size and higher single-cell photosynthetic activity (1.92/106 cells) resulted in excessive metabolic energy demands under MOM conditions (darkness), accelerating algal apoptosis. Consistent with its rapid membrane damage, C. meneghiniana triggered a swift AOM release within just 4 days, whereas M. aeruginosa and C. vulgaris showed a delayed response after 20 days. Crucially, the AOM released from C. meneghiniana was not only more abundant (0.8-1.75 mg/L vs. 0.08-0.16 mg/L) but also of greater concern, featuring higher aromaticity, fluorescence intensity, and disinfection byproduct formation potential at the same algae density. It revealed that species-specific apoptosis pathways under MOM conditions are a key determinant of AOM quantity and quality. Therefore, understanding the persistence of algae and AOM release under MOM conditions facilitates the monitoring and management strategies of water quality in a stratified reservoir.

悬浮于湖中层（金属下层，metalimnion）的藻华（包括蓝藻、绿藻与硅藻）可导致湖中层氧最小值（metalimnetic oxygen minimum, MOM）的形成。理解三种藻华物种在MOM条件下的归宿，有助于评估水质风险。比较研究了铜绿微囊藻（Microcystis aeruginosa）、普通小球藻（Chlorella vulgaris）与小环藻（Cyclotella meneghiniana）在MOM胁迫下的细胞凋亡过程及其后续的藻源有机物（AOM）释放。结果表明，MOM胁迫在所有物种中均诱导了序次性的生理功能衰竭：细胞活性按“光合活性 → 膜完整性 → 藻密度”的先后次序下降。值得注意的是，小环藻的膜损伤速率最高（2.47 min⁻¹），显著超过铜绿微囊藻（0.66 min⁻¹）与普通小球藻（0.44 min⁻¹），表明其敏感性最强。这可归因于关键的能量失衡：小环藻体型更大、单细胞光合活性更高（1.92/10⁶ cells），在MOM条件（黑暗）下代谢能量需求过高，从而加速了其凋亡。与膜快速损伤相一致，小环藻在短短4天内即触发了AOM的快速释放，而铜绿微囊藻与普通小球藻则在20天后才表现出迟滞响应。至关重要的是，小环藻释放的AOM不仅数量更多（0.8-1.75 mg/L vs. 0.08-0.16 mg/L），且水质风险更高——在相同藻密度下，其芳香性、荧光强度及消毒副产物生成潜势均更高。研究揭示了MOM条件下物种特异性的凋亡路径是决定AOM数量与质量的关键因素。因此，厘清藻类在MOM条件下的存续与AOM释放规律，可为分层水库的水质监测与管理策略提供支撑。

（来源：Water Research 2026  DOI: 10.1016/j.watres.2026.125691）