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Elevated iron to nitrogen recycling by mesozooplankton in the Northeast Atlantic Ocean
Author(s) -
Giering Sarah L. C.,
Steigenberger Sebastian,
Achterberg Eric P.,
Sanders Richard,
Mayor Daniel J.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl051776
Subject(s) - phytoplankton , zooplankton , oceanography , nutrient , iron fertilization , nitrogen , ammonium , environmental chemistry , new production , dry weight , environmental science , zoology , chemistry , ecology , biology , geology , botany , organic chemistry
Low dissolved iron (DFe) concentrations limit primary production in most high‐nutrient low‐chlorophyll (HNLC) regions. Increased recycling of iron (Fe) relative to nitrogen (N) by zooplankton may help to sustain phytoplankton production in these conditions. We concurrently determined rates of DFe and ammonium (NH 4 + ) recycling by natural mesozooplankton communities in HNLC conditions of the Northeast Atlantic. NH 4 + excretion remained constant and ranged between 14.2–54.1 nmol NH 4 + mg dry weight −1 h −1 . Fe recycling ranged between 6–138 pmol DFe mg dry weight −1 h −1 during the first hour and decreased thereafter, reflecting the transition from the loss of phytoplankton‐derived Fe to basal DFe excretion. Mesozooplankton‐driven nutrient recycling was estimated to support 6–59% and <1–13% of the respective phytoplankton requirements for DFe and N; DFe:N regeneration ratios were 5–26 times larger than those required by phytoplankton. Our data suggest that Fe recycling by grazing organisms has the potential to reduce the intensity of HNLC conditions.