The Arabian Sea is important in global biogeochemistry because of its high rates of primary production, its extensive zone of oxygen depletion and denitrification, and its expected strong response to global warming via ocean-atmosphere feedbacks to monsoon winds and upwelling intensity. Monsoon-driven upwelling leads to higher rates of primary production during the summer. However, the Arabian Sea paradoxically produces a weak and delayed phytoplankton response compared to other physically dynamic upwelling systems, and indeed has many of the characteristics of a high nutrient low chlorophyll (HNLC) regime. Thick blooms of large diatoms are uniquely not evident in the Arabian Sea despite apparently abundant nutrients (nitrogen, phosphorus and silicate), seed stocks and hydrographic conditions that appear conducive. The subdued bloom response shifts carbon export offshore of the coastal upwelling area and delays major flux events until the latter stages of the SW Monsoon.

While the US Joint Global Ocean Flux Study in the Arabian Sea concluded that these observations can be explained by top-down control of primary production by grazers, recent data suggest that primary production may be limited by iron, consistent with other upwelling regimes. In this review, we examine the evidence for each hypothesis and offer some explanations that are consistent with both control mechanisms. We also assess how each hypothesis might explain how shifts in monsoon intensity and duration associated with climate change will affect Arabian Sea biogeochemistry. A strengthening monsoon will exacerbate iron limitation. This will lead to an eastward shift in the utilization of upwelled nutrients and intensify the oxygen minimum zone. A weakening monsoon will probably make iron limitation less important in the system.

阿拉伯海在全球生物地球化学中具有重要地位，因为其初级生产的高速率，广泛的氧气消耗和反硝化作用区域以及通过海洋-大气对季风和上升强度的反馈对全球变暖的强烈期望。季风驱动的上升流导致夏季初生率提高。但是，与其他物理动态上升流系统相比，阿拉伯海自相矛盾地产生了微弱且延迟的浮游植物响应，并且确实具有高营养低叶绿素（HNLC）方案的许多特征。尽管看起来营养丰富（氮，磷和硅酸盐），种子种群和水文条件似乎有利，但阿拉伯海中并没有明显出现大型硅藻的浓密绽放。

尽管美国在阿拉伯海进行的全球海洋通量联合研究得出的结论是，可以通过放牧者自上而下地控制初级生产来解释这些观察结果，但是最近的数据表明，与其他上升趋势一致，初级生产可能受到铁的限制。在这篇综述中，我们检查了每种假设的证据，并提供了与两种控制机制都一致的解释。我们还评估了每种假设如何解释与气候变化有关的季风强度和持续时间的变化将如何影响阿拉伯海的生物地球化学。季风加强将加剧铁的限制。这将导致向上营养物质的利用向东转移，并增强了最低氧气含量。季风减弱可能会使铁限制在系统中的重要性降低。