Northern North Atlantic biogenic habitat calcium carbonate production: geographic variation and vulnerability to climate change

钙质藻类和冷水珊瑚是在北大西洋冷水环境中产生碳酸钙骨架的栖息地形成生物。它们构建骨架的能力，以及这些骨架在藻类或珊瑚死亡后能够持续存在的能力，对它们形成栖息地和产生碳酸钙沉积物的能力至关重要。海洋酸化威胁到骨骼的形成，尤其是在藻类或珊瑚死亡后，骨骼建立栖息地的能力。居住在加拿大东部寒冷水域的钙质藻类和钙质软珊瑚特别容易受到海洋酸化的影响，因为它们的骨骼由高镁方解石组成。本研究的目的是了解海洋酸化对石灰质藻类和冷水珊瑚形成的栖息地的当前和预测影响。该研究项目将比较西北大西洋（加拿大，特别是纽芬兰和拉布拉多，以及加拿大东部北极地区）和东北大西洋（欧洲北部，特别是法国西北部）之间自然海洋酸化梯度的骨骼形成、死后骨骼损失和碳酸盐产量。此外，这项研究将研究过去几百到几千年的钙质藻类和冷水珊瑚生态系统的历史。沉积物岩心将从软底的钙质藻类和冷水珊瑚栖息地收集和分析，以揭示这些栖息地如何随着海洋学或气候条件的变化或沿海土地利用的变化而演变。在硬底环境中，我们将利用钙质藻类或冷水珊瑚骨架的化学成分来揭示过去气候或海洋条件的记录。根据减排目标或一切照旧预测的高二氧化碳条件下，对钙质藻类或冷水珊瑚骨骼的溶解进行加压水族馆实验，将测量冷水珊瑚骨骼对酸化的深海的反应。钙质藻类，特别是被称为rhodoliths的独立藻类和冷水珊瑚已经受到人类活动的直接影响，例如海底捕捞。从长远来看，了解和预测它们与气候变化和海洋酸化有关的命运将有助于保护这些栖息地。rhodolith床和冷水珊瑚林承载其他生物多样性的能力部分取决于它们维持正净碳酸盐预算的能力，即产生比碳酸盐溶解、生物侵蚀和沉积物输出损失更多的碳酸钙骨架和沉积物。拥有生物多样性可以支持渔业。了解海洋酸化对碳酸盐生物栖息地的影响将有助于保护大西洋和加拿大北部的生物多样性和可持续渔业。

Calcareous algae and cold-water corals are habitat-forming organisms that produce calcium carbonate skeletons in the cold-water environments of the North Atlantic. Their ability to build skeletons, and for those skeletons to endure after the algae or corals have died, is crucial for their ability to form habitats and produce calcium carbonate sediments. Ocean acidification threatens skeleton formation, and especially the ability of skeletons to make a habitat that will remain after the algae or corals are dead.   Calcareous algae, and the calcareous soft corals that inhabit the cold waters of eastern Canada are particularly vulnerable to ocean acidification because their skeletons are composed of high-magnesium calcite. The goal of this research is to understand the current and predicted impacts of ocean acidification on the habitats formed by calcareous algae and cold-water corals. This research program will compare skeleton formation, post-mortem skeleton loss, and carbonate production across the natural ocean acidification gradient between the Northwest Atlantic (Canada, specifically Newfoundland and Labrador, and the Eastern Canadian Arctic) and the Northeast Atlantic (N Europe, specifically NW France). Furthermore, this research will examine the history of calcareous algae and cold-water coral-based ecosystems over the last several hundred to several thousand years. Sediment cores will be collected and analyzed from calcareous algae and cold-water coral habitats on soft bottoms to reveal how these habitats have evolved in relation to changing oceanographic or climatic conditions or changes in coastal land use.  In hard-bottom environments, we will use the chemistry of the calcareous algae or cold-water coral skeletons to reveal the records of past climatic or oceanographic conditions.  Pressurized aquarium experiments on dissolution of calcareous algae or cold-water coral skeletons under high CO2 conditions predicted under emissions reduction targets or business-as-usual will measure the response of cold-water coral skeletons to acidified deep oceans. Calcareous algae, especially unattached algae called rhodoliths, and cold-water corals are already threatened by direct impacts of human activities, such as bottom-contact fishing. Understanding and predicting their fate in relation to climate change and ocean acidification will help protect these habitats in the long term. The ability of rhodolith beds and cold-water coral forests to host other biodiversity depends partly on their ability to maintain a positive net carbonate budget, that is, to be producing more calcium carbonate skeletons and sediment than the carbonate lost to dissolution, biological erosion, and sediment export.    Hosting biodiversity supports fisheries.  Understanding the effects of ocean acidification on carbonate biogenic habitats will help protect biodiversity and sustainable fisheries in Atlantic and Northern Canada.