Biogeochemical cycling of silicon (Si), largely affected by biological drivers, is pivotal to the ecological functioning of the ocean. Most knowledge regarding biological utilization of Si derives from research on phototrophic organisms circumscribed to the photic ocean (i.e., diatoms). Utilization of Si in the aphotic ocean, where heterotrophic silicifiers become relevant Si users, remains poorly investigated. Here we quantify the flux rates and stocks characterizing Si cycling across dense aggregations of the hexactinellid sponge Vazella pourtalesii established in the aphotic zone of the central Scotian Shelf, Nova Scotia, Canada. Although individual rates of silicic acid consumption were low compared to other sponge species and diatoms, the large abundance of individuals (6.5 million) over the extension of these sponge grounds (2105 km²) leads to massive annual silicic acid consumption, invested in producing their siliceous skeletons of biogenic silica. This sponge activity accumulates large biogenic silica stocks both in the living population and in the sediments. Skeletal pieces in sediment revealed that a good portion of biogenic silica deposited to the bottom after sponge death recycles as silicic acid before being permanently buried. This biogenic silica–silicic acid turnover, facilitated by an unconventional silicification pattern that favors delamination and dissolution of V. pourtalesii spicules, causes silicic acid enrichment at oceanographic dimensions in the bottom water of the central Scotian Shelf. Silicic acid efflux from the bottom sustains a feedback mechanism that fulfills sponge needs for silicic acid and facilitates the persistence of sponge aggregations in the long term.

中文翻译：

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底栖-上层耦合反馈促进了大量硅的利用，维持了深海海绵的聚集

硅（Si）的生物地球化学循环在很大程度上受到生物驱动因素的影响，对海洋的生态功能至关重要。关于硅的生物利用的大多数知识来自对限制在光海中的光养生物（即硅藻）的研究。在异养硅化剂成为重要的硅使用者的无光海洋中，硅的利用仍未得到充分研究。在这里，我们量化通量率和储量，表征硅在十六进制海绵海绵Vazella pourtalesii的密集聚集中的循环成立于加拿大新斯科舍省中部斯科蒂货架无水区。尽管与其他海绵物种和硅藻相比，个人硅酸的消耗量较低，但在这些海绵地面（2105 km ²）的扩展范围内，个人的大量生活（650万））导致每年大量的硅酸消耗，用于生产其生物硅的硅质骨架。这种海绵活动在生物种群和沉积物中都积聚了大量的生物二氧化硅。沉积物中的骨骼碎片显示，海绵死亡后沉积在底部的大部分生物硅以硅酸的形式回收，然后被永久掩埋。这种生物成因的硅酸-硅酸转化，是由非常规的硅化模式促进的，该模式有利于青霉菌的分层和溶解。针刺会导致海洋学上的有机酸富集在中央斯科舍省大陆架底部水域。从底部流出的硅酸维持了一种反馈机制，该机制可以满足海绵对硅酸的需求，并在长期内促进海绵聚集的持久性。