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Variation in particulate C and N isotope composition following iron fertilization in two successive phytoplankton communities in the Southern Ocean
Author(s) -
Berg Gry Mine,
Mills Matthew M.,
Long Matt C.,
Bellerby Richard,
Strass Volker,
Savoye Nicolas,
Röttgers Rudiger,
Croot Peter L.,
Webb Adrian,
Arrigo Kevin R.
Publication year - 2011
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2010gb003824
Subject(s) - polar front , phytoplankton , particulates , oceanography , iron fertilization , environmental chemistry , environmental science , nitrogen , chemistry , zoology , ecology , geology , biology , nutrient , organic chemistry
Surface δ 15 N PON increased 3.92 ± 0.48‰ over the course of 20 days following additions of iron (Fe) to an eddy in close proximity to the Antarctic Polar Front in the Atlantic sector of the Southern Ocean. The change in δ 15 N PON was associated with an increase in the >20 μ m size fraction, leading to a maximal difference of 6.23‰ between the >20 μ m and <20 μ m size fractions. Surface δ 13 C POC increased 1.18 ± 0.31‰ over the same period. After a decrease in particulate organic matter in the surface layer, a second phytoplankton community developed that accumulated less biomass, had a slower growth rate and was characterized by an offset of 1.56‰ in δ 13 C POC relative to the first community. During growth of the second community, surface δ 13 C POC further increased 0.83 ± 0.13‰. Here we speculate on ways that carboxylation, nitrogen assimilation, substrate pool enrichment and community composition may have contributed to the gradual increase in δ 13 C POC associated with phytoplankton biomass accumulation, as well as the systematic offset in δ 13 C POC between the two phytoplankton communities.