Exploring the sources, sinks and uptake of carbon and nitrogen in the coastal ocean

海洋在加拿大的经济和文化中扮演着重要的角色。不断上升的大气温度、不断变化的天气模式以及人类活动的变化正在加剧陆地上的变化，这些变化直接影响到海洋生态系统的化学成分和生产力。被称为浮游植物的光合微生物构成了海洋食物网的基础，对从大气中吸收二氧化碳至关重要。碳和氮等元素是地球上所有生命的关键组成部分，其浓度和组成的变化可以促进或抑制浮游植物的生长，从而影响海洋的生产力。浮游植物种类、丰度和生长速度的变化也会对水生食物网、生物地球化学通量和气候反馈产生重大影响。因此，能够更深入地了解当前流程并增强对未来生产力的预测能力的研究是至关重要的。

The ocean plays an important role in the economy and culture of Canada. Rising atmospheric temperatures, changing weather patterns, and alterations in human activities are fueling changes on land that directly impact the chemistry and productivity of ocean ecosystems. Photosynthetic microorganisms called phytoplankton form the base of the ocean food web and are critical to the sequestration of carbon dioxide from the atmosphere. Shifts in the concentration and composition of elements like carbon and nitrogen, key components of all life on earth, can promote or inhibit phytoplankton growth and thus ocean productivity. Variations in the types of phytoplankton, their abundance and how fast they grow can also have substantial ramifications for aquatic food webs, biogeochemical fluxes, and climate feedbacks. Therefore, research that will lead to a deeper understanding of current processes and enhanced predictive capabilities of future productivity is paramount. By coupling in situ ecosystem observations with explicit experimentation the proposed research program will uncover linkages between key environmental change variables, elemental cycles and ocean productivity. This program will investigate the impacts of climate change, variations in microbial physiology and direct human influence (via changes in industry and land-use) on phytoplankton and bacterial growth by identifying the factors and thresholds that impact their ability to use different carbon and nitrogen sources. Specifically, it will assess the physiological capabilities of existent and emergent microorganisms, characterize the composition of land-based chemical inputs, identify regions most at risk to changes in water chemistry, and determine incremental improvements that will achieve the best long-term ecological and economic benefits. This will enable a fundamental understanding critical to predicting future changes in marine ecosystems and connect upstream changes to their down-stream consequences. The results will be of interest to climate and ecosystem modelers, industries, and management and governmental agencies. The contribution to the modeling community will be carbon and nitrogen utilization, fixation and regeneration rate measurements required for accurate ecosystem models capable of predicting environmental change effects on ocean productivity and global elemental cycles. This research will contribute economically through its connection to the expanding aquaculture industry. Knowing where not to establish an aquaculture facility will help growers be more productive over the long term. This work will also serve to inform management decisions by identifying and prioritizing critical natural and anthropogenic chemical inputs that need to be reduced or mediated in the future to maintain and improve ecosystem health and productivity.