TY  - JOUR
A1  - Engel, Anja
A1  - Piontek, Judith
A1  - Grossart, Hans-Peter
A1  - Riebesell, Ulf
A1  - Schulz, Kai Georg
A1  - Sperling, Martin
T1  - Impact of CO2 enrichment on organic matter dynamics during nutrient induced coastal phytoplankton blooms
JF  - Journal of plankton research
N2  - A mesocosm experiment was conducted to investigate the impact of rising fCO(2) on the build-up and decline of organic matter during coastal phytoplankton blooms. Five mesocosms (similar to 38 mA(3) each) were deployed in the Baltic Sea during spring (2009) and enriched with CO2 to yield a gradient of 355-862 A mu atm. Mesocosms were nutrient fertilized initially to induce phytoplankton bloom development. Changes in particulate and dissolved organic matter concentrations, including dissolved high-molecular weight (> 1 kDa) combined carbohydrates, dissolved free and combined amino acids as well as transparent exopolymer particles (TEP), were monitored over 21 days together with bacterial abundance, and hydrolytic extracellular enzyme activities. Overall, organic matter followed well-known bloom dynamics in all CO2 treatments alike. At high fCO(2,) higher Delta POC:Delta PON during bloom rise, and higher TEP concentrations during bloom peak, suggested preferential accumulation of carbon-rich components. TEP concentration at bloom peak was significantly related to subsequent sedimentation of particulate organic matter. Bacterial abundance increased during the bloom and was highest at high fCO(2). We conclude that increasing fCO(2) supports production and exudation of carbon-rich components, enhancing particle aggregation and settling, but also providing substrate and attachment sites for bacteria. More labile organic carbon and higher bacterial abundance can increase rates of oxygen consumption and may intensify the already high risk of oxygen depletion in coastal seas in the future.
KW  - mesocosm
KW  - ocean acidification
KW  - phytoplankton
KW  - organic matter
KW  - TEP
Y1  - 2014
U6  - https://doi.org/10.1093/plankt/fbt125
SN  - 0142-7873
SN  - 1464-3774
VL  - 36
IS  - 3
SP  - 641
EP  - 657
PB  - Oxford Univ. Press
CY  - Oxford
ER  -