Across the Southern Ocean, phytoplankton growth is governed by iron and light, while bacterial growth is regulated by iron and labile dissolved organic carbon (LDOC). We use a mechanistic model to examine how competition for iron between phytoplankton and bacteria responds to changes in iron, light, and LDOC. Consistent with experimental evidence, increasing iron and light encourages phytoplankton dominance, while increasing LDOC and decreasing light favors bacterial dominance. Under elevated LDOC, bacteria can outcompete phytoplankton for iron, most easily under lower iron. Simulations reveal that bacteria are major iron consumers and suggest that luxury storage plays a key role in competitive iron uptake. Under seasonal conditions typical of the Southern Ocean, sources of LDOC besides phytoplankton exudation modulate the strength of competitive interactions. Continued investigations on the competitive fitness of bacteria in driving changes in primary production in iron‐limited systems will be invaluable in refining these results.

中文翻译：

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资源共同限制导致南大洋浮游植物和细菌之间的竞争


在整个南大洋，浮游植物的生长受到铁和光的控制，而细菌的生长则受到铁和不稳定溶解有机碳（LDOC）的调节。我们使用机械模型来研究浮游植物和细菌之间对铁的竞争如何响应铁、光和 LDOC 的变化。与实验证据一致，增加铁和光照有利于浮游植物的优势，而增加 LDOC 和减少光照则有利于细菌的优势。在 LDOC 升高的情况下，细菌可以与浮游植物竞争铁，在铁含量较低的情况下最容易获胜。模拟显示细菌是主要的铁消耗者，并表明奢侈储存在竞争性铁吸收中发挥着关键作用。在南大洋典型的季节性条件下，除了浮游植物分泌物之外，LDOC 的来源也调节竞争相互作用的强度。继续研究细菌在推动铁限制系统初级生产变化方面的竞争适应性，对于完善这些结果将具有无价的价值。