Combined effects of temperature and resource availability on organic matter degradation by Antarctic bacterioplankton

温度和资源可用性对南极浮游细菌降解有机物的综合影响

• 批准号: 366047019
• 负责人: Dr. Judith Piontek
• 金额: --
• 依托单位: Leibniz-Institut für Ostseeforschung Warnemünde (IOW)
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/366047019?language=en
• 关键词: Combined; effects; temperature; resource; availability

Global warming poses new threats to marine ecosystems since rising seawater temperature potentially induces cascading effects in biogeochemical cycles and food webs. The Scientific Committee on Antarctic Research (SCAR) identified a better understanding of potential effects of climate change on the physical and biological uptake of CO2 by the Southern Ocean as one of the most pressing tasks in Antarctic research. Heterotrophic bacteria are the main producers of CO2 in the ocean, thereby counteracting the biological drawdown of CO2 by primary production. In Antarctic marine systems, low seawater temperature, and the low availability of labile organic matter are major environmental constraints on bacterial growth and degradation activity. However, temperature and the availability of resources for heterotrophic bacteria undergo considerable change induced by climate warming combined with subsequent ice melt and changes in primary productivity. Previous laboratory experiments conducted with batch cultures revealed a high potential of temperature effects on bacterial growth near the lower temperature limit to interact with the concentration of organic substrates. Due to this interaction temperature effects on bacterial growth were disproportionately strong when substrates became available. However, the relevance of this synergistic effect for bacterial productivity and subsequent CO2 release by natural communities of the polar oceans is still unclear. This project aims to test single and combined effects of temperature and organic matter availability on Antarctic marine bacterioplankton. For this purpose, activation energies of extracellular enzymatic reactions, substrate uptake rates and biomass production will be examined in bacterial communities of the Weddell Sea. Rate measurements in the Weddell Sea will be combined with the analysis of organic matter to estimate temperature effects on fluxes of labile and semi-labile organic carbon. Results will be used to explore the natural range of temperature sensitivity and its modulation by abiotic and biotic factors. On-board experiments will investigate combined effects of warming and substrate addition on bacterial community composition, patterns in gene expression and organic matter turnover to link changes in community structure to changes in community functioning. Furthermore, chemostat experiments with bacterial isolates from the Southern Ocean will be conducted to quantify temperature effects on growth efficiencies and the chemical composition of bacterial biomass at substrate-limited growth on carbohydrates of different molecular complexity. A better determination of bacterial remineralization and its dependence on temperature and substrate concentration will help to improve the parameterization of biogeochemical models that aim to project the marine carbon cycle and the ocean-atmosphere CO2 exchange in a changing climate.

全球变暖对海洋生态系统构成了新的威胁，因为海水温度上升有可能导致生物地球化学循环和食物网的级联效应。南极研究科学委员会（南极研委会）确定，更好地了解气候变化对南大洋二氧化碳物理和生物吸收的潜在影响是南极研究中最紧迫的任务之一。异养细菌是海洋中CO2的主要生产者，从而通过初级生产抵消CO2的生物减少。在南极海洋系统中，低海水温度和不稳定有机物的低可用性是细菌生长和降解活性的主要环境限制。然而，温度和异养细菌资源的可用性经历了相当大的变化，气候变暖与随后的冰融化和初级生产力的变化相结合。以前的实验室实验进行了分批培养揭示了一个高的潜在的温度对细菌生长的影响，在较低的温度限制与有机底物的浓度相互作用。由于这种相互作用，当底物可用时，温度对细菌生长的影响不成比例地强烈。然而，这种协同效应对细菌生产力和随后极地海洋自然群落释放的二氧化碳的相关性仍然不清楚。该项目旨在测试温度和有机物质供应对南极海洋浮游细菌的单一和综合影响。为此目的，细胞外酶促反应，底物吸收率和生物量生产的活化能将在威德尔海的细菌群落进行检查。威德尔海的速率测量将与有机物分析相结合，以估计温度对不稳定和半不稳定有机碳通量的影响。研究结果将用于探索温度敏感性的自然范围及其受非生物和生物因素的调节。船上实验将调查升温和基质添加对细菌群落组成、基因表达模式和有机物周转的综合影响，以将群落结构变化与群落功能变化联系起来。此外，恒化器实验从南大洋的细菌分离株将进行量化的生长效率和细菌生物量的化学组成的温度影响，在底物限制生长的不同分子复杂性的碳水化合物。更好地确定细菌矿化及其对温度和底物浓度的依赖性，将有助于改善生物地球化学模型的参数化，这些模型旨在预测气候变化中的海洋碳循环和海洋-大气CO2交换。