Department of Biological Oceanography, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
Sci Rep. 2020 Nov 26;10(1):20599. doi: 10.1038/s41598-020-77645-3.
The main source of marine organic carbon (OC) is autotrophic production, while heterotrophic degradation is its main sink. Increased anthropogenic CO release leads to ocean acidification and is expected to alter phytoplankton community composition, primary production rates and bacterial degradation processes in the coming decades with potential consequences for dissolved and particulate OC concentration and composition. Here we investigate effects of increased pCO on dissolved and particulate amino acids (AA) and carbohydrates (CHO), in arctic and sub-arctic planktonic communities in two large-scale mesocosm experiments. Dissolved AA concentrations responded to pCO/pH changes during early bloom phases but did not show many changes after nutrient addition. A clear positive correlation in particulate AA was detected in post-bloom phases. Direct responses in CHO concentrations to changing pCO/pH were lacking, suggesting that observed changes were rather indirect and dependent on the phytoplankton community composition. The relative composition of AA and CHO did not change as a direct consequence of pCO increase. Changes between bloom phases were associated with the prevailing nutrient status. Our results suggest that biomolecule composition will change under future ocean conditions but responses are highly complex, and seem to be dependent on many factors including bloom phase and sampling site.
海洋有机碳（OC）的主要来源是自养生产，而异养降解是其主要汇。人为 CO 释放的增加导致海洋酸化，并预计在未来几十年内改变浮游植物群落组成、初级生产力和细菌降解过程，从而对溶解和颗粒 OC 的浓度和组成产生潜在影响。在这里，我们在两项大型中观实验中研究了增加 pCO 对北极和亚北极浮游生物群落中溶解和颗粒氨基酸（AA）和碳水化合物（CHO）的影响。在早期繁殖阶段，溶解 AA 浓度对 pCO/pH 的变化有反应，但在添加营养物后没有显示出许多变化。在繁殖后期，检测到颗粒 AA 中存在明显的正相关。CHO 浓度对 pCO/pH 变化的直接反应缺乏，这表明观察到的变化是间接的，取决于浮游植物群落的组成。AA 和 CHO 的相对组成并没有因 pCO 增加而直接改变。繁殖阶段之间的变化与流行的营养状况有关。我们的研究结果表明，在未来的海洋条件下，生物分子组成将发生变化，但反应非常复杂，似乎取决于许多因素，包括繁殖阶段和采样地点。
