Khandeparker Lidita, Kale Dipesh, Hede Niyati, Anil Arga Chandrashekar
CSIR-National Institute of Oceanography, Dona Paula, Goa, 403 004, India.
CSIR-National Institute of Oceanography, Dona Paula, Goa, 403 004, India.
J Environ Manage. 2025 Jan;373:123449. doi: 10.1016/j.jenvman.2024.123449. Epub 2024 Nov 30.
Ocean microbial communities form the base of marine food webs, facilitating energy transfer and nutrient cycling, thereby supporting higher trophic levels. We investigated their composition and functional profiles across depths (surface waters 0, 29, and 63 m and bottom waters 100, 150, and 200 m) in the central-eastern Arabian Sea (CEAS) using next-generation sequencing. It was hypothesized that the composition and functional diversity of these communities would be influenced by depth and environmental parameters. Our research showed that microbial communities vary with depth and are shaped by environmental factors like irradiance, temperature, dissolved oxygen, suspended particulate matter, chlorophyll a, and ammonia concentrations. Cyanobacteria (Prochlorococcus sp) and Mamiellaceae, belonging to picoeukaryotes, exhibited distinct depth-specific distributions up to subsurface chlorophyll maxima (SCM) at 63 m. On the other hand, a community shift in the microbial communities comprising Firmicutes, Bacteroidetes, and Actinobacteria phyla was observed at the deeper water depths. The profiling of functional genes pointed out the expression of carbon fixation by photosynthetic organisms at the surface (0, 29, and 63 m), which shifted to prokaryotic carbon fixation in deeper waters (0, 150, and 200 m). Microcosm experiments (mixing of surface water with water from the SCM) carried out simulating disturbances such as climate change forced mixing (cyclones), revealed shifts in microbial structure and function. It was observed that within 48 h, the carbon fixation activity changed from photosynthetic organisms to prokaryotes and indicated an increase in stress-related biosynthetic pathways such as expression of quorum sensing, biosynthesis of antibiotics, lipopolysaccharides, and secondary metabolites. These findings have implications for predictive modelling of food web dynamics and fisheries management in the context of climate change.
海洋微生物群落构成了海洋食物网的基础，促进了能量转移和营养物质循环，从而支持了更高的营养级。我们利用下一代测序技术，对阿拉伯海中东区域（CEAS）不同深度（表层水0米、29米和63米以及底层水100米、150米和200米）的微生物群落组成和功能特征进行了调查。据推测，这些群落的组成和功能多样性会受到深度和环境参数的影响。我们的研究表明，微生物群落随深度而变化，并受到光照、温度、溶解氧、悬浮颗粒物、叶绿素a和氨浓度等环境因素的影响。蓝细菌（原绿球藻属）和属于微微型真核生物的玛氏藻科，在63米的次表层叶绿素最大值（SCM）之前呈现出明显的深度特异性分布。另一方面，在更深的水深处，观察到由厚壁菌门、拟杆菌门和放线菌门组成的微生物群落发生了群落转变。功能基因分析指出，光合生物在表层（0米、29米和63米）进行碳固定表达，而在更深的水域（100米、150米和200米）则转变为原核生物的碳固定。模拟气候变化强迫混合（气旋）等干扰进行的微观实验（表层水与SCM水混合）揭示了微生物结构和功能的变化。观察到在48小时内，碳固定活动从光合生物转变为原核生物，并表明与压力相关的生物合成途径增加，如群体感应表达、抗生素生物合成、脂多糖和次生代谢产物的生物合成。这些发现对气候变化背景下食物网动态的预测建模和渔业管理具有重要意义。
