Sulfadiazine (SD), sulfamerazine (SM1), and sulfamethazine (SM2) are widely used and disorderly discharged into surface water, causing contamination of lakes and rivers. However, microalgae are regard as a potential resource to alleviate and degrade antibiotic pollution. The physiological changes of Chlorella vulgaris in the presence of three sulfonamides (SAs) with varying numbers of –CH₃ groups and its SA-removal efficiency were investigated following a 7-day exposure experiment. Our results showed that the growth inhibitory effect of SD (7.9–22.6%), SM1 (7.2–45.9%), and SM2 (10.3–44%) resulted in increased proteins and decreased soluble sugars. Oxidative stress caused an increase in superoxide dismutase and glutathione reductase levels but decreased catalase level. The antioxidant responses were insufficient to cope-up with reactive oxygen species (hydrogen peroxide and superoxide anion) levels and prevent oxidative damage (malondialdehyde level). The ultrastructure and DNA of SA-treated algal cells were affected, as evident from the considerable changes in the cell wall, chloroplast, and mitochondrion, and DNA migration. C. vulgaris-mediated was able to remove up to 29% of SD, 16% of SM1, and 15% of SM2. Our results suggest that certain concentrations of specific antibiotics may induce algal growth, and algal-mediated biodegradation process can accelerate the removal of antibiotic contamination.

Winter warming plays a vital role in spring phytoplankton community succession in temperate lakes due to variation of ice cover duration in winter. How winter conditions affect spring phytoplankton in subtropical lakes without winter ice cover is, however, largely unknown. In this study, covering 26 years, we elucidated the effects of both climate conditions and nutrient levels in winter on the phytoplankton community (expressed as Morpho‐Functional Groups) in spring in Lake Taihu, a large shallow subtropical lake in China. During this period, wind speed declined significantly in both winter and spring from 1992 to 2017 and the sunshine hours increased slightly from 2000 to 2017. The biomass of eight dominant phytoplankton groups showed increasing trends from 1992 to 2017, while it declined for one group, which mainly included filamentous green algae such as Ulothrix sp. Nonmetric multidimensional scaling (NMDS) results indicated that wind speed and sunshine duration in winter and spring were the most important factors affecting the spring phytoplankton community in Lake Taihu. Also, partial least squares path modeling (PLS‐PM) suggested that the spring phytoplankton community was strongly affected by winter conditions. Our study indicated that the “climate memory” effects on phytoplankton, resulting from winter and acting on the following spring, not only occur in north temperate winter ice‐covered shallow lakes but also in subtropical lakes without ice‐covered in winter.