Collaborative Research: Silica Cycling in the Central North Pacific Gyre: Role of Rhizosolenia Mats and Suspended Diatoms

全球物质平衡、垂直营养物剖面和季节性营养物循环数据都表明，大型亚热带海洋中环流可能占全球海洋生物成因二氧化硅生产的大部分。尽管在这些地区，硅藻在春季繁殖时可能会变得丰富，但现有证据表明，每年二氧化硅的大部分产量在夏季和秋季。这一点在少营养的中北太平洋可能尤其正确，由于持续分层，那里没有浮游植物生产的强烈季节性循环。北太平洋中部的地表水是所有少营养环流中硅酸浓度最高的。目前尚不清楚硅酸的增加是否导致该地区的二氧化硅产量高于其他海洋中系统。据报道，该地区的硅质生物量绝大多数（90%）由厘米大小的垫状物占主导地位，传统的水瓶采样器无法有效取样，通常由潜水员采集。这就产生了一种独特的情况，即该地区的二氧化硅循环，在全球范围内可能很重要，可能由大型稀有销售主导，而采用传统采样方法的调查基本上是看不见的。这个项目将是第一个研究少营养的中北太平洋生物成因二氧化硅的生产和溶解。我们的研究将结合使用水瓶采样器的传统水柱采样和潜水员收集的垫子，比较这些大垫子和悬浮硅藻在该地区地表水生物源二氧化硅循环中的相对作用。本研究将有两个主要目标：(1)评估北太平洋中部环流二氧化硅产量的大小；(2)评估根梭菌在夏威夷外两次巡航中的相对贡献垫。

9414372 Villareal Global mass-balance consideration, vertical nutrient profiles, and seasonal nutrient cycle data all indicate that the large subtropical mid-ocean gyres may account for the majority of the global oceanic production of biogenic silica. Although diatoms can become abundant during spring blooms in these regions, the available evidence suggests that most of the annual silica production in summer and autumn. This may be especially true in the oligotrophic North Central Pacific which does not have a strong seasonal cycle of phytoplankton production due to Persistent stratification. The surface waters of the Central North Pacific contain the highest concentrations of silicic acid of any oligotrophic gyre. It is unknown whether this greater availability of silicic acid results in higher rates of silica production in this region compared to other mid ocean systems. Siliceous biomass in this region has been reported to be overwhelmingly dominated (90%) by centimeter- sized mats are not effectively sampled by traditional water bottle samplers and are typically collected by divers. This give rise to a unique situation where silica cycling in this region, which is likely to be significant in global terms, may be dominated by large rare sells that would be essentially invisible to investigations which employ traditional sampling methods. This project will be the first study of the production and dissolution of biogenic silica in the oligotrophic Central North Pacific Ocean. Our study will combine traditional water column sampling using water-bottle samplers with collections of mats made by divers to compare the relative roles of these large mats and suspended diatioms in the cycling of biogenic silica in the surface waters of this region. This study will have two major objectives: (1) to evaluate of the magnitude of silica production in the North Central Pacific Gyre, and (2) to assess the relative contribution mats of Rhizosolen ia two cruises out of Hawaii.