The role of grazing in nutrient-rich areas of the open sea
The role of grazing in nutrient-rich areas of the open sea
复制标题
DOI：
10.4319/lo.1991.36.8.1616
复制
发表时间：
1991-12
影响因子：
4.5
通讯作者：
B. Frost
中科院分区：
文献类型：
--
作者：
B. Frost
没有任何单一因素能够完全解释公海营养丰富地区浮游植物储量持续偏低的原因。然而，放牧对于消耗因物理过程和下沉而产生的超出损失的浮游植物起着必要的作用。在没有放牧的情况下，即使浮游植物的特定生长速率对于当时的光照和温度条件来说不是最佳的，例如在铁等微量营养物质的限制下，浮游植物种群仍然会积累，并伴随着营养物质的消耗。在开放的亚北极太平洋春季和夏季的观察结果反对浮游植物生长的限制，即在没有放牧的情况下浮游植物种群无法增加。浮游植物-食草动物相互作用的生态系统过程模型表明，浮游植物种群的放牧控制和浮游植物对 NIH 的优先利用这两个过程足以解释浮游植物种群持续较低和常量营养素浓度较高的原因。然而，放牧控制可以施加在由铁限制构成的浮游植物群落上。特别是，在开放的亚北极太平洋地区，潜在快速生长的硅藻的内在增长率似乎受到抑制。这些条件可能适用于公海的另外两个营养丰富的区域，太平洋赤道上升流区域和亚南极环极地海洋，尽管在后一个区域，浮游植物生长的光限制可能更严重，并且硅限制可能影响浮游植物组合的具体组成。
No single factor accounts fully for the persistently low phytoplankton stocks in the nutrient-rich areas of the open sea. However, grazing plays the necessary role of consuming phytoplankton produced in excess of losses due to physical processes and sinking. Without grazing, even if specific growth rate of the phytoplankton is less than optimal for the prevailing light and temperature conditions, as might be so under limitation by a trace nutrient such as Fe, the phytoplankton stock would still accumulate with attendant depletion of nutrients. Observations during spring and summer in the open subarctic Pacific argue against limitation of phytoplankton growth to the point where phytoplankton stock could not increase in the absence of grazing. An ecosystem process model of the phytoplankton-grazer interaction suggests that two processes-grazing control of phytoplankton stock and preferential utilization of NIH, by the phytoplankton-are sufficient to explain the continuously low phytoplankton stock and high concentrations of macronutrients. However, the grazing control may be exerted on a p:hytoplankton assemblage structured by Fe limitation. In particular, the intrinsic growth rates of potentially fast-growing diatoms seem to be depressed in the open subarctic Pacific. These conditions probably apply to two other nutrientrich areas of the open sea, the Pacific equatorial upwelling region and the subantarctic circumpolar ocean, although in the latter region light limitation of phytoplankton growth may be more severe and silica limitation may influence the specific composition of the phytoplankton assemblage.