Resource colimitation drives competition between phytoplankton and bacteria in the Southern Ocean
journal contributionposted on 2023-05-21, 11:20 authored by Ratnarajah, L, Blain, S, Philip BoydPhilip Boyd, Fourquez, M, Obernosterer, I, Tagliabue, A
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.
Publication titleGeophysical Research Letters
Department/SchoolInstitute for Marine and Antarctic Studies
PublisherAmer Geophysical Union
Place of publication2000 Florida Ave Nw, Washington, USA, Dc, 20009
Rights statementCopyright 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.