Cycling of Silicon and the Significance of Silicon Limitation to Cell Flocculation in Coastal Diatom Blooms

布热津斯基博士建议研究硅和硅酸在南加州硅藻华的发展和消亡过程中作为限制性营养物质的循环。这些和其他硅藻花经常絮状和下沉集体没有食草动物的干预，未知。絮凝往往发生在硅酸从透光区耗尽的同时，这表明硅的限制可以触发这些事件。他们将结合潜水员使用水肺的精细采样能力和复杂的示踪剂方法来测试硅限制是硅藻华大规模絮凝的先决条件的假设。最近来自墨西哥湾流暖核环的证据表明，来自泛光带的硅酸的消耗也伴随着支持二氧化硅生产的硅酸来源的转变。在枯竭之前，二氧化硅生产主要由从较深水域夹带的“新”硅酸支持。当营养物耗尽时，就转向严重依赖从硅质颗粒的局部溶解中提取的“再生”硅酸。他们建议研究这种转变是否发生在更富生产力的水域，并建立其与硅和碳的垂直通量的关系。

Dr. Brzezinski proposes to study the cycling of silicon and silicic acid as a limiting nutrient during the development and demise of diatom blooms of Southern California. These and other diatom blooms frequently flocculate and sink en masse without the intervention of grazers, unknown. Flocculation often occurs coincident with the depletion of silicic acid from the euphotic zone suggesting that silicon limitation can trigger these events. They will combine the fine scale sampling capabilities of divers using SCUBA with sophisticated tracer methods to test the hypothesis that silicon limitation is a prerequisite for the mass flocculation of diatom blooms. Recent evidence from a Gulf Stream warm-core ring suggests that the depletion of silicic acid from the euphotic zone is also accompanied by a shift in the source of silicic acid supporting silica production. Before depletion, silica production is supported mainly by "new" silicic acid entrained from deeper waters. Upon nutrient depletion, there is a shift to a heavy reliance on "regenerated" silicic acid derived from the local dissolution of siliceous particles. They propose to examine whether this transition occurs in more productive waters and to establish its relationship to the vertical flux of silicon and carbon.