Biogeochemistry, macronutrient and carbon cycling in the benthic layer

我们周围的海岸和大陆架海在整个历史上一直是人类繁荣和福祉的焦点，因此对我们的文化产生了不成比例的影响。陆架海的社会重要性不仅限于粮食生产，还包括生物多样性、碳循环和储存、废物处理、营养循环、娱乐和可再生能源。然而，随着越来越多的全球人口向海岸靠近，我们的海洋正逐渐受到人类活动的侵蚀，包括过度捕捞、污染、栖息地干扰和气候变化。这是令人担忧的，因为海底状况、生物多样性和人类社会是密不可分的。因此，迫切需要了解一系列大陆架栖息地的相对敏感性，以便能够更有效地管理人类的压力，以确保我们的海洋的长期可持续性并提供社会效益。实现这些目标并非易事，因为海床提供我们所依赖的商品和服务的能力取决于基材的类型（岩石、砾石、沙子、泥浆）和当地条件；有些生境是自然动态的，对干扰相对不敏感，而另一些生境则相对稳定，易受变化的影响。这使得我们很难评估栖息地的敏感性，也很难对我们未来能从海洋中得到什么好处做出一般性的陈述。最近，NERC和DEFRA启动了一项关于陆架海洋生物地球化学的重大新研究计划，该计划将提高对这些问题的认识。为了响应这一呼吁，我们召集了一个由顶尖科学家组成的联盟，其中包括微生物学家、生态学家、物理海洋学家、生物地球化学家、数学建模师和政策顾问。在CEFAS、苏格兰海洋和AFBI等组织的帮助下，他们将在英国进行一系列的研究巡航，根据海底栖息地的物理状况、栖息在海底的微生物和动物群落、以及海底发现的氮和碳库的大小和动态，绘制海底栖息地的敏感性和状态图。最新的海洋技术将测量海底上方的混合量和流速，以及详细的海底地形。这些测量将使我们更好地了解沉积物、营养物质和碳的运动和混合的物理过程。同时，将检索包含微生物和动物群落的岩心，并将其活动和行为与特定的生物地球化学反应联系起来。高度专业化的自动驾驶车辆，称为着陆器，也将测量海底的营养物质浓度和通量。然后，可以通过实验操纵系统的组成部分来模拟变化的情景，例如变化的流体动力学、干扰或气候变化的组成部分。这将在现场通过使用水下水槽产生不同的流动状态来实现，或者在实验室中使用暴露于不同水平的二氧化碳、温度和氧气的完整沉积物群落来实现。通过测量微生物和动物群落对这些变化的生物地球化学反应和行为，我们将了解如果这些变化确实发生在我们的大陆架海域上可能会发生什么。我们将利用所有这些信息，通过将观测和实验结果叠加在各种人类压力的地图上，来评估英国海底地区的相对脆弱性，这将对规划者和决策者有价值。数学模型将测试未来的变化情景，例如开放或关闭易受伤害的捕鱼区域，或预测控制养分和碳储量的因素的变化。这将有助于探索对外部压力的不同反应，并有助于决定应该采取哪些管理措施为子孙后代保护我们的大陆架海。

The coasts and shelf seas that surround us have been the focal point of human prosperity and well-being throughout our history and, consequently, have had a disproportionate effect on our culture. The societal importance of the shelf seas extends beyond food production to include biodiversity, carbon cycling and storage, waste disposal, nutrient cycling, recreation and renewable energy. Yet, as increasing proportions of the global population move closer to the coast, our seas have become progressively eroded by human activities, including overfishing, pollution, habitat disturbance and climate change. This is worrying because the condition of the seabed, biodiversity and human society are inextricably linked. Hence, there is an urgent need to understand the relative sensitivities of a range of shelf habitats so that human pressures can be managed more effectively to ensure the long-term sustainability of our seas and provision of societal benefits. Achieving these aims is not straightforward, as the capacity of the seabed to provide the goods and services we rely upon depends on the type of substrate (rock, gravel, sand, mud) and local conditions; some habitats are naturally dynamic and relatively insensitive to disturbance, while others are comparatively stable and vulnerable to change. This makes it very difficult to assess habitat sensitivities or make general statements about what benefits we can expect from our seas in the future.Recently, NERC and DEFRA have initiated a major new research programme on Shelf Sea Biogeochemistry that will improve knowledge about these issues. In response to this call, we have assembled a consortium of leading scientists that includes microbiologists, ecologists, physical oceanographers, biogeochemists, mathematical modellers and policy advisors. With assistance from organisations like CEFAS, Marine Scotland and AFBI, they will carry out a series of research cruises around the UK that will map the sensitivity and status of seabed habitats based on their physical condition, the microbial and faunal communities that inhabit them, and the size and dynamics of the nitrogen and carbon pools found there. The latest marine technologies will measure the amount of mixing and flow rates just above the seabed, as well as detailed seabed topography. These measurements will allow better understanding of the physical processes responsible for movement and mixing of sediment, nutrient, and carbon. At the same time, cores will be retrieved containing the microbial and faunal communities and their activity and behaviour will be linked to specific biogeochemical responses. Highly specialised autonomous vehicles, called landers, will also measure nutrient concentrations and fluxes at the seabed. Components of the system can then be experimentally manipulated to mimic scenarios of change, such as changing hydrodynamics, disturbance or components of climate change. This will be achieved in the field by generating different flow regimes using a submerged flume or, in the laboratory, using intact sediment communities exposed to different levels of CO2, temperature and oxygen. By measuring the biogeochemical response and behaviour of the microbial and faunal communities to these changes, we will generate an understanding of what may happen if such changes did occur across our shelf seas.We will use all of this information to assess the relative vulnerability of areas of the UK seabed by overlaying the observation and experimental results over maps of various human pressures, which will be of value to planners and policymakers. Mathematical models will test future scenarios of change, such as opening or closing vulnerable areas to fishing or anticipated changes in the factors that control nutrient and carbon stocks. This will be valuable in exploring different responses to external pressures and for deciding which management measures should be put in place to preserve our shelf seas for future generations.