Drivers of Biogeochemical Variability in a Central California Kelp Forest: Implications for Local Amelioration of Ocean Acidification
Drivers of Biogeochemical Variability in a Central California Kelp Forest: Implications for Local Amelioration of Ocean Acidification
复制标题
DOI：
10.1029/2020jc016320
复制
发表时间：
2020-11-01
影响因子：
3.6
通讯作者：
Dunbar, Robert B.
中科院分区：
文献类型：
--
作者：
Hirsh, Heidi K.;Nickols, Kerry J.;Dunbar, Robert B.
海带森林是世界上最具生产力的海洋生态系统之一，它们有可能在当地改善海洋酸化。为了了解海带代谢对当地生态地球化学的贡献，我们必须首先量化自然变异以及物理和生物驱动因素对空间和时间生态地球化学变化的相对贡献。我们部署了一个广泛的仪器阵列在蒙特雷湾，加利福尼亚州，内部和外部的海带森林，以评估在何种程度上巨型海带（Macrocystis pyrifera）局部改善目前的酸性条件，我们预计将加剧OA。温度，pH值和O-2的变化发生在半日，昼夜（潮汐和昼夜），和较长的上升流事件期间。平均条件是由海上风力和通过近岸内孔输送涌上水驱动的。虽然海带森林内外的近地表pH值和O-2相似，但与外部相比，海带内部的表面pH值升高，这表明海带冠层局部增加了表面pH值。我们观察到最大的酸化应力发生在水柱深处，其中pCO（2）达到高达1，300 mu atm的水平，文石欠饱和（omega（Ar）< 1）发生了几次。在这个地点，海带冠层对海水性质的改变，以及因此对酸化的任何改善作用，在狭窄的地表水中是最大的。在深度的压力暴露和减少酸化压力在表面之间的空间脱节，需要进一步评估利用海带森林作为当地OA缓解的供应商。
Kelp forests are among the world's most productive marine ecosystems, and they have the potential to locally ameliorate ocean acidification (OA). In order to understand the contribution of kelp metabolism to local biogeochemistry, we must first quantify the natural variability and the relative contributions of physical and biological drivers to biogeochemical changes in space and time. We deployed an extensive instrument array in Monterey Bay, CA, inside and outside of a kelp forest to assess the degree to which giant kelp (Macrocystis pyrifera) locally ameliorates present-day acidic conditions which we expect to be exacerbated by OA. Temperature, pH, and O-2 variability occurred at semidiurnal, diurnal (tidal and diel), and longer upwelling event periods. Mean conditions were driven by offshore wind forcing and the delivery of upwelled water via nearshore internal bores. While near-surface pH and O-2 were similar inside and outside the kelp forest, surface pH was elevated inside the kelp compared to outside, suggesting that the kelp canopy locally increased surface pH. We observed the greatest acidification stress deeper in the water column where pCO(2) reached levels as high as 1,300 mu atm and aragonite undersaturation (omega(Ar) < 1) occurred on several occasions. At this site, kelp canopy modification of seawater properties, and thus any ameliorating effect against acidification, is greatest in a narrow band of surface water. The spatial disconnect between stress exposure at depth and reduction of acidification stress at the surface warrants further assessment of utilizing kelp forests as provisioners of local OA mitigation.