Abstract
Modern biogeochemical conditions of the Eastern Equatorial Pacific (EEP) region are characterized by high macronutrient concentrations but low phytoplankton abundance due to both iron and silicic acid limitation. Since primary producers significantly impact the global carbon cycle, paleoproductivity in relation to climate change and nutrient availability in this region has been a topic of a number of studies. However, the complex dynamics of this region, especially east of the Galapagos Islands, has led to some discrepancies when linking reconstructed paleoproductivity with potential mechanisms for higher primary productivity. Here we focus on reconstructing primary productivity of haptophyte algae and diatoms, as well as continental material input, sea surface salinity, and sea surface temperature, and compare these reconstructions with existing records for the period comprised between 150 and 110 ka (the penultimate deglaciation period) with the aim to understand the mechanisms that most significantly influence phytoplankton growth over the EEP region east of the Galapagos Islands. Our results suggest enhanced upwelling in the EEP system during the penultimate deglaciation and increased phytoplankton abundance mainly as the result of both the increasing influence of nutrient-rich Southern Ocean sourced waters through the Equatorial Undercurrent and a higher input of iron through atmospheric deposition. The highest phytoplankton abundances recorded at the study site during the penultimate deglaciation also suggest that maximum input of nutrients might have occurred during the millennial-scale event Heinrich Event 11 in the North Atlantic as a result of global atmospheric and oceanic reorganizations.
| Original language | English |
|---|---|
| Article number | e2019PA003777 |
| Number of pages | 18 |
| Journal | Paleoceanography and Paleoclimatology |
| Volume | 35 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 1 Jul 2020 |
Funding
We acknowledge funding from the Spanish Ministry of Science, Innovation and Universities through Grants CTM2009-08849 (ACDC Project), CTM2012-32017 (MANIFEST Project), and CGL2015-68194-R (SCORE Project) and from Generalitat de Catalunya through Grant 2017SGR1011 (Marine Biogeochemistry and Global Change Research Group). This research was also funded by the European Research Council (ERC) under the European Union's Seventh Framework Program (FP7/2007-2013) ERC grant agreement [339206] to S.S. S.S. and M.v.d.M. received financial support from the Netherlands Earth System Science Centre (NESSC). L.P. acknowledges support from the Ram?n y Cajal program and CHIMERA project (Ref. CTM2016-75411-R, MINECO, Spain). This work used samples provided by the Ocean Drilling Program, which is sponsored by the U.S. National Science Foundation and participating countries under management of Joint Oceanographic Institutions, Inc. We are very grateful to the Editor, Stephen Barker, to Jennifer Hertzberg, and one anonymous reviewer for their helpful comments and suggestions.
