Open AccessDust‐induced changes in phytoplankton composition in the Tasman Sea during the last four glacial cycles
Author(s) -
Calvo Eva,
Pelejero Carles,
Logan Graham A.,
De Deckker Patrick
Publication year - 2004
Publication title -
paleoceanography
Language(s) - English
Resource type - Journals
eISSN - 1944-9186
pISSN - 0883-8305
DOI - 10.1029/2003pa000992
Subject(s) - iron fertilization , phytoplankton , glacial period , oceanography , southern hemisphere , productivity , biogenic silica , aeolian processes , middle latitudes , environmental science , northern hemisphere , paleoceanography , last glacial maximum , geology , atmospheric sciences , diatom , ecology , climatology , holocene , nutrient , biology , paleontology , macroeconomics , economics
An increase in iron supply associated with enhanced dust inputs could be responsible for higher marine phytoplankton production leading to the typically lower glacial atmospheric CO 2 concentrations, as suggested by the “iron hypothesis.” The enhanced dust supply may also have provided the oceans with significant amounts of silica, which would have favored the growth of diatoms over coccolithophores, as suggested by the “silica hypothesis.” Here we present new data on molecular biomarkers in a sediment core from the midlatitudes of the Southern Hemisphere, which reveal dust‐induced changes in the relative contribution of the phytoplankton to total productivity. Our results illustrate a shift in the relative abundance of siliceous over calcareous organisms during glacial times, when terrestrial aeolian input was enhanced. Although we did not detect a significant glacial decrease in coccolithophorid productivity, the decrease in the CaCO 3 /Corg rain ratio could have still contributed to some extent in lowering atmospheric CO 2 levels.