Controls on tropical Pacific Ocean productivity revealed through nutrient stress diagnostics
Controls on tropical Pacific Ocean productivity revealed through nutrient stress diagnostics
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DOI：
10.1038/nature05083
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发表时间：
2006-08-31
期刊：
影响因子：
64.8
通讯作者：
Shea, Donald M.
中科院分区：
文献类型：
--
作者：
Behrenfeld, Michael J.;Worthington, Kirby;Shea, Donald M.
原位富集实验表明，世界海洋主要高硝酸盐低叶绿素 (HNLC) 区域中形成水华的硅藻的生长受到铁的可用性的限制(1-3)。然而，即使是这些操纵实验中规模最大的，也只代表了海洋盆地的一小部分，而且观察到的反应很大程度上受到稀有物种增殖的影响，而不是自然优势种群增长的影响(4,5)。在这里，我们将浮游植物独特的荧光属性与对营养胁迫的特定生理反应联系起来，并利用这些关系来评估在前所未有的空间尺度上限制热带太平洋浮游植物生长的因素。根据 12 年来进行的荧光测量，我们描绘了该地区的三个主要生态生理状况。我们发现，铁在调节赤道附近和更南部的 HNLC 和贫营养水域中的浮游植物生长方面具有关键作用，而氮和浮游动物放牧是调节北方生物量生产的主要因素。将我们的研究结果应用于卫星叶绿素场的解释表明，热带太平洋盆地的生产力可能比之前的估计低1.2 - 2.5 Pg C yr(-1)，这一差异与有记录以来最大的厄尔尼诺到拉尼娜转变所伴随的全球海洋生产变化相当(6)。
In situ enrichment experiments have shown that the growth of bloom-forming diatoms in the major high-nitrate low-chlorophyll (HNLC) regions of the world's oceans is limited by the availability of iron(1-3). Yet even the largest of these manipulative experiments represents only a small fraction of an ocean basin, and the responses observed are strongly influenced by the proliferation of rare species rather than the growth of naturally dominant populations(4,5). Here we link unique fluorescence attributes of phytoplankton to specific physiological responses to nutrient stress, and use these relationships to evaluate the factors that constrain phytoplankton growth in the tropical Pacific Ocean on an unprecedented spatial scale. On the basis of fluorescence measurements taken over 12 years, we delineate three major ecophysiological regimes in this region. We find that iron has a key function in regulating phytoplankton growth in both HNLC and oligotrophic waters near the Equator and further south, whereas nitrogen and zooplankton grazing are the primary factors that regulate biomass production in the north. Application of our findings to the interpretation of satellite chlorophyll fields shows that productivity in the tropical Pacific basin may be 1.2 - 2.5 Pg C yr(-1) lower than previous estimates have suggested, a difference that is comparable to the global change in ocean production that accompanied the largest El Nino to La Nina transition on record(6).