Ratnarajah Lavenia, Blain Stéphane, Boyd Philip W, Fourquez Marion, Obernosterer Ingrid, Tagliabue Alessandro
Department of Earth Ocean and Ecological Sciences School of Environmental Sciences University of Liverpool Liverpool UK.
Sorbonne Université CNRS Laboratoire d'Océanographie Microbienne (LOMIC) Observatoire Océanologique de Banyuls Banyuls sur mer France.
Geophys Res Lett. 2021 Jan 16;48(1):e2020GL088369. doi: 10.1029/2020GL088369. Epub 2021 Jan 12.
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.
在南大洋，浮游植物的生长受铁和光照控制，而细菌的生长则受铁和不稳定溶解有机碳（LDOC）调节。我们使用一个机理模型来研究浮游植物和细菌之间对铁的竞争如何响应铁、光照和LDOC的变化。与实验证据一致，增加铁和光照会促进浮游植物占主导地位，而增加LDOC和降低光照则有利于细菌占主导地位。在LDOC升高的情况下，细菌在争夺铁的过程中能够胜过浮游植物，在铁含量较低时最为容易。模拟结果表明，细菌是主要的铁消费者，并表明过量储存在竞争性铁吸收中起关键作用。在南大洋典型的季节性条件下，除浮游植物渗出物外，LDOC的来源会调节竞争相互作用的强度。继续研究细菌在驱动铁限制系统初级生产变化中的竞争适应性，对于完善这些结果将非常有价值。
