Enhanced carbon overconsumption in response to increasing temperatures during a mesocosm experiment

Taucher, Jan, Schulz, Kai G., Dittmar, T., Sommer, Ulrich, Oschlies, Andreas and Riebesell, Ulf (2012) Enhanced carbon overconsumption in response to increasing temperatures during a mesocosm experiment Biogeosciences (BG), 9 . pp. 3531-3545. DOI 10.5194/bg-9-3531-2012.

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Abstract

Increasing concentrations of atmospheric carbon dioxide are projected to lead to an increase in sea surface temperatures, potentially impacting marine ecosystems and biogeochemical cycling. Here we conducted an indoor mesocosm experiment with a natural plankton community taken from the Baltic Sea in summer. We induced a plankton bloom via nutrient addition and followed the dynamics of the different carbon and nitrogen pools for a period of one month at temperatures ranging from 9.5 °C to 17.5 °C, representing a range of ± 4 °C relative to ambient temperature. The uptake of dissolved inorganic carbon (DIC) and the net build-up of both particulate (POC) and dissolved organic carbon (DOC) were all enhanced at higher temperatures and almost doubled over a temperature gradient of 8 °C. Furthermore, elemental ratios of carbon and nitrogen (C:N) in both particulate and dissolved organic matter increased in response to higher temperatures, both reaching very high C:N ratios of >30 at +4 °C. Altogether, these observations suggest a pronounced increase in excess carbon fixation in response to elevated temperatures. Most of these findings are contrary to results from similar experiments conducted with plankton populations sampled in spring, revealing large uncertainties in our knowledge of temperature sensitivities of key processes in marine carbon cycling. Since a major difference to previous mesocosm experiments was the dominant phytoplankton species, we hypothesize that species composition might play an important role in the response of biogeochemical cycling to increasing temperatures.

Document Type: Article
Additional Information: WOS:000310472600003
Keywords: Biological Oceanography; ocean acidification, plankton summer bloom, Diatom, phytoplankton, mesocosm, carbon overconsumption; DISSOLVED ORGANIC-MATTER; TRANSPARENT EXOPOLYMER PARTICLES; PHYTOPLANKTON BLOOMS; MARINE-PHYTOPLANKTON; INORGANIC CARBON; CLIMATE-CHANGE; DIATOM BLOOM; SPRING BLOOM; GROWTH-RATE; OCEAN
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-N Experimental Ecology - Food Webs
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
DOI etc.: 10.5194/bg-9-3531-2012
ISSN: 1726-4170
Projects: MESOAQUA, Future Ocean
Date Deposited: 19 Apr 2012 10:19
Last Modified: 29 Nov 2012 12:47
URI: http://eprints.uni-kiel.de/id/eprint/14236

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