浮游植物
光呼吸
原绿藻
生物地球化学
海洋学
透光带
生物
海洋生态系统
生态学
生态系统
氧气最小区
光养
环境科学
光合作用
蓝藻
上升流
植物
营养物
联合球菌
地质学
细菌
遗传学
作者
Jane C. Y. Wong,John A. Raven,Montserrat Aldunate,Sebastián Silva,Juan Diego Gaitán-Espitia,Cristian A. Vargas,Osvaldo Ulloa,Peter von Dassow
摘要
It is commonly known that phytoplankton have a pivotal role in marine biogeochemistry and ecosystems as carbon fixers and oxygen producers, but their response to deoxygenation has scarcely been studied. Nonetheless, in the major oceanic oxygen minimum zones (OMZs), all surface phytoplankton groups, regardless of size, disappear and are replaced by unique cyanobacteria lineages below the oxycline. To develop reasonable hypotheses to explain this pattern, we conduct a review of available information on OMZ phytoplankton, and we re-analyze previously published data (flow cytometric and hydrographic) on vertical structure of phytoplankton communities in relation to light and O2 levels. We also review the physical constraints on O2 acquisition as well as O2-dependent metabolisms in phototrophs. These considerations, along with estimates of the photosynthetic capacity of phytoplankton along OMZ depth profiles using published data, suggest that top-down grazing, respiratory demand, and irradiance are insufficient to fully explain the vertical structure observed in the upper, more sunlit portions of OMZs. Photorespiration and water–water cycles are O2-dependent pathways with low O2 affinities. Although their metabolic roles are still poorly understood, a hypothetical dependence on such pathways by the phytoplankton adapted to the oxic ocean might explain vertical patterns in OMZs and results of laboratory experiments. This can be represented in a simple model in which the requirement for photorespiration in surface phytoplankton and O2-inhibition of OMZ lineages reproduces the observed vertical fluorescence profiles and the replacement of phytoplankton adapted to O2 by lineages restricted to the most O2-deficient waters. A high O2 requirement by modern phytoplankton would suggest a positive feedback that intensifies trends in OMZ extent and ocean oxygenation or deoxygenation, both in Earth's past and in response to current climate change.
科研通智能强力驱动
Strongly Powered by AbleSci AI