One Dimensional Ecosystem Model Simulation of the Effects of Vertical Dilution by the Winter Mixing on the Spring Diatom Bloom
One Dimensional Ecosystem Model Simulation of the Effects of Vertical Dilution by the Winter Mixing on the Spring Diatom Bloom
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DOI：
10.1023/b:joce.0000009586.02554.d3
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发表时间：
2003-10
影响因子：
2.3
通讯作者：
N. Yoshie;Y. Yamanaka;M. Kishi;H. Saito
中科院分区：
文献类型：
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作者：
N. Yoshie;Y. Yamanaka;M. Kishi;H. Saito
利用一维生态系统模型研究了在亚北极太平洋西部生物地球化学循环中起重要作用的春季硅藻华的相关过程。该模型反映了春季硅藻华的浮游生物动态和养分循环；结果表明，冬季深度混合稀释的重要性。推测浮游植物垂直整合生物量在冬季减少是由于光合作用的减少，这是由于深层混合将浮游植物输送到光照较弱的层。随着混合层的加深，硅藻总生物量增加。这是因为由于混合稀释导致浓度降低，导致硅藻放牧压力不如硅藻光合作用显著。换句话说，稀释对放牧速率的影响比对光合速率的影响更显著，因为放牧速率取决于硅藻和食草动物的浓度，而光合速率仅取决于硅藻浓度。平均特定硅藻食草率（食草率除以硅藻生物量）随着深度的增加下降了35%，而硅藻的平均特定光合作用速率下降了11%。因此，深层混合期间的平均净比硅藻生长率约为春季硅藻华期间最大值的70%。深度混合不仅通过营养物的供给，而且通过稀释作用显著降低放牧压力，显著影响春季硅藻华的幅度。
A one-dimensional ecosystem model has been used to investigate the processes relevant to the spring diatom bloom which play important roles in the biogeochemical cycle in the western subarctic Pacific. The model represents the plankton dynamics and the nutrient cycles in the spring diatom bloom; its results show the importance of dilution by deep mixing in winter. It is supposed that the vertically integrated biomass of phytoplankton decreases in the winter due to the decrease of photosynthesis, because the deep mixing transports phytoplankton to a layer with a low light level. However, the observed integrated diatom biomass increases as the mixed layer deepens. This is because the decrease of concentration due to dilution by mixing causes the diatom grazed pressure to be less significant than diatom photosynthesis. In other words, the effect of dilution on the grazed rate is more significant than the effect on the photosynthesis rate because the grazed rate depends on the concentrations of both diatom and grazer, whereas the photosynthesis rate depends only diatom concentration. The average specific diatom grazed rate, defined as grazed rate divided by diatom biomass, decreases by 35% associated with the deepening, while the average specific photosynthesis rate of diatom decreases by 11%. As a result, the average specific net diatom growth rate during the deep mixing is about 70% of its maximum during the spring diatom bloom. The deep mixing significantly affects the amplitude of the spring diatom bloom not only by the supply of nutrients but also by the dilution which drastically decreases the grazed pressure.