Exploring functional interfaces: extreme biogenic fluctuations may amplify or buffer environmental stress on organisms associated with marine macrophytes

该项目的总体目标是通过评估在生物体相关尺度上环境的强烈生物波动对压力调节的能力，来完善我们对沿海生态系统对预测的全球变化情景的理解。由于季节性或日间事件（如水混合、潮汐、初级生产），沿海社区经常受到强烈的环境波动的影响。这种波动的强度往往会随着空间尺度的减小而增加，并且在覆盖大型植物表面的亚毫米扩散边界层（DBL）中非常高。这些波动，例如温度、pH值、CO2和O2，往往比全球变化过程中预测的变化幅度大得多。它们可以提供暂时的避难所，免受环境压力的影响，也可以使生物体对环境变化更加敏感。沿海底栖生物科普这种环境波动的机制几乎没有得到研究。栖息在DBL的附生生物，包括钙化苔藓虫，管蠕虫和珊瑚藻的经验强大，但暂时不稳定的梯度和极端的O2，CO2和H+（pH值）浓度取决于大型植物的代谢活动（光合作用和呼吸速率）和环境条件（试点研究）。这些生物波动有可能掩盖、放大或缓冲包括全球变化压力在内的环境压力。考虑到大型植物（如海草，海带，膀胱残骸）作为生物工程师的多样性和生产性的沿海生态系统和多样性和生态上重要的附着生物，它们支持的重要性，这是至关重要的全球变化下的相互作用进行调查。因此，本研究的主要目的是：（1）研究不同全球变化情景下水生植物DBL的动态特征（ii）研究其对钙化表生生物的影响及其适应或适应强烈波动制度的能力，（iii）确定表生生物对不同微生境的潜在预先适应（大型植物与惰性表面DBL）和（iv）评估大型植物提供海洋酸化和缺氧暂时避难所的潜力。预计结果将阐明生物体科普波动的机制及其对全球变化的耐受性，而后者可能与传统的稳态公海全球变化实验结果有很大不同。

The overarching aim of the project is to refine our understanding of coastal ecosystem responses to predicted Global Change scenarios by evaluating the capacity of stress-modulation by strong biogenic fluctuations of the environment at an organism-relevant scale. Coastal communities are often exposed to strong environmental fluctuations due to seasonal or diurnal events (e.g. water mixing, tides, primary production). The intensity of such fluctuations tends to increase with decreasing spatial scale and is extremely high in the sub-mm diffusive boundary layer (DBL) covering macrophyte surfaces. These fluctuations, in, for example, temperature, pH, CO2 and O2, are often of much greater magnitude than predicted changes in the course of Global Change. They may either offer temporal refuges from environmental stress or they may harden organisms to environmental changes. The mechanism of coastal benthic organisms to cope with such environmental fluctuations is virtually unstudied. Epibionts inhabiting the DBL including calcifying bryozoans, tube worms and coralline algae experience strong but temporally instable gradients in and extremes of O2, CO2 and H+ (pH) concentrations depending on the macrophytes metabolic activity (photosynthesis and respiration rates) and ambient conditions (pilot study). These biogenic fluctuations have the potential to mask, amplify or buffer environmental stress including Global Change pressures. Considering the importance of macrophytes (e.g. seagrass, kelp, bladder wreck) as bioengineers of diverse and productive coastal ecosystems and the diverse and ecologically important epibionts they support, it is of primordial importance to investigate their interaction under Global Change. Therefore, the specific aims of this project are (i) to characterize the dynamics of the DBL of macrophytes under different Global Change scenarios (warming, ocean acidification, hypoxia), (ii) to investigate its effect on calcifying epibionts and their ability to acclimatize or adapt to a strongly fluctuating regime, (iii) to identify potential pre-adaptation of epibionts to different micro-habitats (macrophyte vs. inert surface DBL) and (iv) to assess the potential of macrophytes to provide temporal refuge from ocean acidification and hypoxia. Results are expected to shed light on mechanisms of organisms to cope with fluctuations and their tolerance towards Global Change, while latter may differ significantly from results based on traditional steady-state open-ocean Global Change experiments.