Contrasting patterns of carbon cycling and dissolved organic matter processing in two phytoplankton-bacteria communities

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http://hdl.handle.net/10138/338307

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Elovaara , S , Eronen-Rasimus , E , Asmala , E , Tamelander , T & Kaartokallio , H 2021 , ' Contrasting patterns of carbon cycling and dissolved organic matter processing in two phytoplankton-bacteria communities ' , Biogeosciences , vol. 18 , no. 24 , pp. 6589-6616 . https://doi.org/10.5194/bg-18-6589-2021

Title: Contrasting patterns of carbon cycling and dissolved organic matter processing in two phytoplankton-bacteria communities
Author: Elovaara, Samu; Eronen-Rasimus, Eeva; Asmala, Eero; Tamelander, Tobias; Kaartokallio, Hermanni
Contributor organization: Tvärminne Zoological Station
Marine Ecosystems Research Group
Date: 2021-12-23
Language: eng
Number of pages: 28
Belongs to series: Biogeosciences
ISSN: 1726-4170
DOI: https://doi.org/10.5194/bg-18-6589-2021
URI: http://hdl.handle.net/10138/338307
Abstract: Microbial consumption of phytoplankton-derived organic carbon in the pelagic food web is an important component of the global C cycle. We studied C cycling in two phytoplankton-bacteria systems (non-axenic cultures of a dinoflagellate Apocalathium malmogiense and a cryptophyte Rhodomonas marina) in two complementary experiments. In the first experiment we grew phytoplankton and bacteria in nutrient-replete conditions and followed C processing at early exponential growth phase and twice later when the community had grown denser. Cell-specific primary production and total community respiration were up to 4 and 7 times higher, respectively, in the A. malmogiense treatments. Based on the optical signals, accumulating dissolved organic C (DOC) was degraded more in the R. marina treatments, and the rate of bacterial production to primary production was higher. Thus, the flow of C from phytoplankton to bacteria was relatively higher in R. marina treatments than in A. malmogiense treatments, which was further supported by faster C-14 transfer from phytoplankton to bacterial biomass. In the second experiment we investigated consumption of the phytoplankton-derived DOC by bacteria. DOC consumption and transformation, bacterial production, and bacterial respiration were all higher in R. marina treatments. In both experiments A. malmogiense supported a bacterial community predominated by bacteria specialized in the utilization of less labile DOC (class Bacteroidia), whereas R. marina supported a community predominated by copiotrophic Alphaand Gammaproteobacteria. Our findings suggest that large dinoflagellates cycle relatively more C between phytoplankton biomass and the inorganic C pool, whereas small cryptophytes direct relatively more C to the microbial loop.
Subject: SCRIPPSIELLA-HANGOEI
NATURAL ASSEMBLAGES
MOLECULAR-WEIGHT
NITROGEN UPTAKE
BALTIC SEA
MARINE
RELEASE
ALGAE
FLUORESCENCE
CONSUMPTION
1172 Environmental sciences
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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