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Journal article
Factors controlling plankton productivity, particulate matter stoichiometry, and export fluxin the coastal upwelling system off Peru
Biogeosciences, Vol.17(19), pp.4831-4852
12/10/2020
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Abstract
Eastern boundary upwelling systems (EBUS) are among the most productive marine ecosystems on Earth. The high productivity in surface waters is facilitated by upwelling of nutrient-rich deep waters, with high light availability enabling fast phytoplankton growth and nutrient utilization. However, there are numerous biotic and abiotic factors modifying productivity and biogeochemical processes. Determining these factors is important because EBUS are considered hotspots of climate change, and reliable predictions on their future functioning requires understanding of the mechanisms driving biogeochemical cycles therein. In this study, we used in situ mesocosms to obtain mechanistic understanding of processes controlling productivity, organic matter export, and particulate matter stoichiometry in the coastal Peruvian upwelling system. Therefore, eight mesocosm units with a volume of ~50 m3 were deployed for 50 days ~6 km off Callao during austral summer 2017, coinciding with a coastal El Niño event. To compare how upwelling of different water bodies influences plankton succession patterns, we collected two subsurface waters at different locations in the regional oxygen minimum zone (OMZ) and injected these into four replicate mesocosms, respectively (mixing ratio ≈ 1.5:1 mesocosm: OMZ water). The differences in nutrient concentrations between the collected water bodies were relatively small, and therefore we do not consider treatment differences in the present paper. The phytoplankton communities were initially dominated by diatoms but shifted towards a pronounced dominance of the mixotrophic harmful dinoflagellate (Akashiwo sanguinea) when inorganic nitrogen was exhausted in surface layers. The community shift resulted in a major short-term increase in productivity during A. sanguinea growth which left a pronounced imprint on organic matter C:N:P stoichiometry. However, C, N, and P export fluxes were not affected by this ecological regime shift because A. sanguinea persisted in the water column and did not sink out during the experiment. Accordingly, ongoing export fluxes during the study were maintained mainly by a remaining “background” plankton community. Overall, biogeochemical pools and fluxes were surprisingly constant in between the ecological regime shifts. We explain this constancy by light limitation through self-shading by phytoplankton and inorganic nitrogen limitation which constrained phytoplankton growth. Thus, gain and loss processes seemed to be relatively well balanced and there was little opportunity for blooms, which represents an event where the system becomes unbalanced. The mesocosm study revealed key links between ecological and biogeochemical processes for one of the economically most important regions in the oceans.
Details
- Title
- Factors controlling plankton productivity, particulate matter stoichiometry, and export fluxin the coastal upwelling system off Peru
- Creators
- Lennart T Bach - GEOMAR Helmholtz Centre for Ocean Research KielAllanah Joy Paul - GEOMAR Helmholtz Centre for Ocean Research KielTim Boxhammer - GEOMAR Helmholtz Centre for Ocean Research KielElisabeth von der Esch - Technical University of MunichMichelle Graco - Instituto del Mar del PeruKai Georg Schulz - Southern Cross UniversityEric Achterberg - GEOMAR Helmholtz Centre for Ocean Research KielPaulina Aguayo - University of ConcepciónJavier Arístegui - Universidad de Las Palmas de Gran CanariaPatrizia Ayon - Instituto del Mar del PeruIsabel Banos - Universidad de Las Palmas de Gran CanariaAvy Bernales - Instituto del Mar del PeruAnne Sophie Boegeholz - Kiel UniversityFrancisco Chavez - Monterey Bay Aquarium Research InstituteShao-Min Chen - GEOMAR Helmholtz Centre for Ocean Research KielKristin Doering - GEOMAR Helmholtz Centre for Ocean Research KielAlba Filella - GEOMAR Helmholtz Centre for Ocean Research KielJan Hennke - GEOMAR Helmholtz Centre for Ocean Research KielNauzet Hernandez-Hernandez - Universidad de Las Palmas de Gran CanariaMark Hopwood - GEOMAR Helmholtz Centre for Ocean Research KielPatricia Grasse - GEOMAR Helmholtz Centre for Ocean Research KielMartin Fischer - Kiel UniversityMathias Haunost - GEOMAR Helmholtz Centre for Ocean Research KielMaricarmen Igarza - Universidad Peruana Cayetano HerediaVerena Kalter - GEOMAR Helmholtz Centre for Ocean Research KielLeila Kittu - GEOMAR Helmholtz Centre for Ocean Research KielPeter Kohnert - GEOMAR Helmholtz Centre for Ocean Research KielJesus Ledesma - Instituto del Mar del PeruChristian Lieberum - GEOMAR Helmholtz Centre for Ocean Research KielSilke Lischka - GEOMAR Helmholtz Centre for Ocean Research KielCarolin Löscher - University of Southern DenmarkAndrea Ludwig - GEOMAR Helmholtz Centre for Ocean Research KielUrsula Mendoza - Instituto del Mar del PeruJana Meyer - GEOMAR Helmholtz Centre for Ocean Research KielJudith Meyer - GEOMAR Helmholtz Centre for Ocean ResearchFabrizio Minutolo - University of Southern DenmarkJoaquin Ortiz Cortes - GEOMAR Helmholtz Centre for Ocean Research KielSonia Sanchez - Instituto del Mar del PeruClaudia Sforna - GEOMAR Helmholtz Centre for Ocean Research KielJonna Piiparinen - Finnish Environment InstituteCarsten Spisla - GEOMAR Helmholtz Centre for Ocean Research KielMichael Sswat - GEOMAR Helmholtz Centre for Ocean Research KielKristian Spilling - University of AgderMabel Zavala Moreira - Escuela Superior Politecnica del LitoralUlf Riebesell - GEOMAR Helmholtz Centre for Ocean Research Kiel
- Publication Details
- Biogeosciences, Vol.17(19), pp.4831-4852
- Publisher
- Copernicus GmbH
- Grant note
- This research has been supported by the Collaborative Research Center SFB 754 Climate-Biogeochemistry Interactions in the Tropical Ocean financed by the German Research Foundation (DFG), the EU project AQUACOSM, and the Leibniz Award 2012 (granted to Ulf Riebesell).
- Identifiers
- 991012926975402368
- Copyright
- © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.
- Academic Unit
- School of Environment, Science and Engineering; Centre for Coastal Biogeochemistry; Science; Faculty of Science and Engineering
- Language
- English
- Resource Type
- Journal article