Phytoplankton are primarily confined to the sunlit epipelagic zone, yet intact algal cells persist in the ocean’s mesopelagic twilight zone where light is minimal. However, their survival strategies in the deeper ocean remain unknown. Here, we isolate Chaetoceros sp. DS1 from 1000 m depth and reveal its survival mechanisms under prolonged darkness and high pressure, including membrane lipid remodeling and enhanced antioxidant defenses. Importantly, DS1 maintains a latent photosynthetic reserve that activates upon exposure to dim blue light and higher pressure typical of the twilight zone, enabling photosynthesis and nutrient uptake. It exhibits metabolic flexibility by utilizing stored carbon in darkness and assimilating organic carbon under dim light. Global meta-omics data show widespread, transcriptionally active Chaetoceros-like diatoms in the twilight zone, expressing blue-light sensors and protein synthesis genes. These findings identify the ocean twilight zone as a previously overlooked niche for metabolically active phytoplankton, expanding understanding of deep-ocean microbial ecology and carbon cycling.
Benzophenone-type UV filters (BPs) are widely used in personal care products and various industrial applications, resulting in their continuous release into aquatic environments. BPs have attracted significant attention as emerging contaminants because of their widespread use, structural diversity, environmental persistence, various exposure pathways, and adverse toxicological effects in aquatic organisms. Previous studies have largely focused on environmental occurrence and individual toxicological effects of BPs, whereas evidence regarding their interactions with multiple environmental stressors remains fragmented. Available evidence indicates that environmental factors and co-occurring contaminants can modify the environmental fate, bioavailability, bioaccumulation, and toxicity of BPs, resulting in antagonistic, additive, or synergistic effects depending on the stressor, organism, and exposure conditions. Therefore, this review describes the widespread distribution and toxicological effects of BPs in aquatic ecosystems, examining how environmental factors and co-occurring contaminants modify the environmental fate and toxicological effects of BPs under multi-stressor conditions. This review suggests that the ecological significance of BPs lies not only in their intrinsic toxicity but also in the way multi-stressor interactions modify their biological impacts, thereby defining directions for future ecological risk assessment.
Yuri Jin, Mi-Song Hong, Jin-Sol Lee et al.· Comparative biochemistry and...· 0 citations
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