Nutrient availability as major driver of phytoplankton-derived dissolved organic matter transformation in coastal environment

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http://hdl.handle.net/10138/307042

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Asmala , E , Haraguchi , L , Jakobsen , H H , Massicotte , P & Carstensen , J 2018 , ' Nutrient availability as major driver of phytoplankton-derived dissolved organic matter transformation in coastal environment ' , Biogeochemistry , vol. 137 , no. 1-2 , pp. 93-104 . https://doi.org/10.1007/s10533-017-0403-0

Title: Nutrient availability as major driver of phytoplankton-derived dissolved organic matter transformation in coastal environment
Author: Asmala, Eero; Haraguchi, Lumi; Jakobsen, Hans H.; Massicotte, Philippe; Carstensen, Jacob
Contributor: University of Helsinki, Tvärminne Zoological Station
Date: 2018-01
Language: eng
Number of pages: 12
Belongs to series: Biogeochemistry
ISSN: 0168-2563
URI: http://hdl.handle.net/10138/307042
Abstract: Incubation experiments were performed to examine the processing of fresh autochthonous dissolved organic matter (DOM) produced by coastal plankton communities in spring and autumn. The major driver of observed DOM dynamics was the seasonally variable inorganic nutrient status and characteristics of the initial bulk DOM, whereas the characteristics of the phytoplankton community seemed to have a minor role. Net accumulation of dissolved organic carbon (DOC) during the 18-days experiments was 3.4 and 9.2 A mu mol l(-1) d(-1) in P-limited spring and N-limited autumn, respectively. Bacterial bioassays revealed that the phytoplankton-derived DOC had surprisingly low proportions of biologically labile DOC, 12.6% (spring) and 17.5% (autumn). The optical characteristics of the DOM changed throughout the experiments, demonstrating continuous heterotrophic processing of the DOM pool. However, these temporal changes in optical characteristics of the DOM pool were not the same between seasons, indicating seasonally variable environmental drivers. Nitrogen and phosphorus availability is likely the main driver of these seasonal differences, affecting both phytoplankton extracellular release of DOM and its heterotrophic degradation by bacteria. These findings underline the complexity of the DOM production and consumption by the natural planktonic community, and show the importance of the prevailing environmental conditions regulating the DOM pathways.
Subject: Extracellular release
Autochthonous organic matter
Carbon cycling
Colored dissolved organic matter
FRESH-WATER
FLUORESCENCE SPECTROSCOPY
BACTERIAL-DEGRADATION
MARINE ENVIRONMENTS
OPTICAL-PROPERTIES
TEMPERATE ESTUARY
LAND-USE
CARBON
NITROGEN
CDOM
1172 Environmental sciences
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