Effect of elevated CO2 on organic matter pools and fluxes in a summer Baltic Sea plankton community.

Paul, Allanah J., Bach, Lennart T. , Schulz, Kai G., Boxhammer, Tim , Czerny, Jan, Achterberg, Eric P. , Hellemann, Dana, Trense, Yves, Nausch, M., Sswat, Michael and Riebesell, Ulf (2015) Effect of elevated CO2 on organic matter pools and fluxes in a summer Baltic Sea plankton community. Open Access Biogeosciences (BG), 12 (20). pp. 6181-6203. DOI 10.5194/bg-12-6181-2015.

[thumbnail of bg-12-6181-2015.pdf]
Preview
Text
bg-12-6181-2015.pdf - Published Version
Available under License Creative Commons: Attribution 3.0.

Download (4MB) | Preview

Supplementary data:

Abstract

Ocean acidification is expected to influence plankton community structure and biogeochemical element cycles. To date, the response of plankton communities to elevated CO2 has been studied primarily during nutrient-stimulated blooms. In this CO2 manipulation study, we used large-volume (~ 55 m3) pelagic in situ mesocosms to enclose a natural summer, post-spring-bloom plankton assemblage in the Baltic Sea to investigate the response of organic matter pools to ocean acidification. The carbonate system in the six mesocosms was manipulated to yield average fCO2 ranging between 365 and ~ 1230 μatm with no adjustment of naturally available nutrient concentrations. Plankton community development and key biogeochemical element pools were subsequently followed in this nitrogen-limited ecosystem over a period of 7 weeks. We observed higher sustained chlorophyll a and particulate matter concentrations (~ 25 % higher) and lower inorganic phosphate concentrations in the water column in the highest fCO2 treatment (1231 μatm) during the final 2 weeks of the study period (Phase III), when there was low net change in particulate and dissolved matter pools. Size-fractionated phytoplankton pigment analyses indicated that these differences were driven by picophytoplankton (< 2 μm) and were already established early in the experiment during an initial warm and more productive period with overall elevated chlorophyll a and particulate matter concentrations. However, the influence of picophytoplankton on bulk organic matter pools was masked by high biomass of larger plankton until Phase III, when the contribution of the small size fraction (< 2 μm) increased to up to 90 % of chlorophyll a. In this phase, a CO2-driven increase in water column particulate carbon did not lead to enhanced sinking material flux but was instead reflected in increased dissolved organic carbon concentrations. Hence ocean acidification may induce changes in organic matter partitioning in the upper water column during the low-nitrogen summer period in the Baltic Sea.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/228224
Additional Information: WOS:000364323500007
Keywords: R.V. Alkor; AL394; AL397; Baltic Sea; Plankton; OCEAN ACIDIFICATION; INORGANIC CARBON; NANOMOLAR CONCENTRATIONS; COASTAL PHYTOPLANKTON; MICROCOSM EXPERIMENTS; NATURAL-WATERS; TECHNICAL NOTE; SEAWATER; BLOOM; NITROGEN
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography > Water column biogeochemistry
Refereed: Yes
Open Access Journal?: Yes
Publisher: Copernicus Publications (EGU)
Projects: KOSMOS, Future Ocean, BIOACID, SOPRAN, MESOAQUA
Expeditions/Models/Experiments:
Date Deposited: 08 May 2015 11:11
Last Modified: 23 Apr 2021 08:53
URI: https://oceanrep.geomar.de/id/eprint/28763

Actions (login required)

View Item View Item