Biogeochemical thallium cycling during a mesocosm phytoplankton spring bloom: Biotic versus abiotic drivers

Mori, Corinna; Beck, Mélanie; Hintz, Nils Hendrik; Merder, Julian; Bunse, Carina; Dittmar, Thorsten; Dlugosch, Leon; Böttcher, Lea; Pahnke, Katharina; Striebel, Maren; Schnetger, Bernhard; Simon, Meinhard; Brumsack, Hans‐Jürgen

doi:10.1016/j.gca.2021.08.002

Cited by 9 publications

(20 citation statements)

References 76 publications

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“…The planktotrons were mixed once an hour using rotating paddles spread over the whole depth of the tanks. Details of the experimental setup, as well as the sampling procedures can be found in Mori et al (2021). In the following, most essential information is briefly summarized.…”

Section: The Mesocosm Experiments and Observationsmentioning

confidence: 99%

“…3 ), nitrite (NO − 2 ), ammonium (NH + 4 ), dissolved inorganic phosphorus and silicate (DIP and DISi) are described by Mori et al (2021).…”

Section: Abiotic and Biotic Variables Assessedmentioning

confidence: 99%

“…TDN, DOC, DOC S and DOC L we considered DOC and total dissolved nitrogen (TDN) measurements that were available at 18:00 each day (see Mori et al (2021) for details). For DOC, measurements on the 23rd and 31st March at 18:00 were missing in planktotrons 2 and 4, respectively, which were filled by linear interpolation, prior to averaging the data across the planktotrons.…”

Section: Abiotic and Biotic Variables Assessedmentioning

confidence: 99%

“…In this study, we focused on a spring bloom observed in a mesocosm experiment. Starting from initial nutrient concentrations and phytoplankton assemblages in the coastal North Sea, and forcing the mesocosms with temperature and diurnally varying irradiance set up to reflect the natural field conditions, and given the absence of vertical heterogeneity within the tanks, a rapidly developing spring bloom was obtained within the first few days of the experiment, as reflected by the particulate organic matter (POM) and Chlorophyll-a (hereafter Chl-a) concentrations (see also Mori et al, 2021). This was followed by a sudden collapse of the phytoplankton biomass within a few days, again, as evidenced by 2/21 POM and Chl-a concentrations.…”

Section: Introductionmentioning

confidence: 99%

“…A rich observation set was acquired throughout the experiment, both in terms of the variety and temporal resolution of measurements (Mori et al, 2021). However, based on this data set, it is still not possible to disentangle the exact mechanisms causing the collapse of the bloom.…”

Section: Introductionmentioning

confidence: 99%

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Growth, organic matter release, aggregation and recycling during a diatom bloom: A model-based analysis of a mesocosm experiment

Kerimoglu

Hintz

Lücken

et al. 2022

Preprint

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Mechanisms terminating phytoplankton blooms are often not well understood. Potentially involved processes such as consumption by grazers, flocculation, and viral lysis each have different post-bloom consequences on the processing of the organic material, therefore it is important to develop a better understanding of the relevance of these processes, and potential interactions between them. In this study, we present a model-based analysis of a spring bloom observed in a mesocosm experiment. The intermediate-complexity (27-state variable) numerical model we extended from an earlier version to this end can resolve C, N, P and Si cycles, and relevant processes like formation of various organic material size classes (low and high molecular weight (hereafter small and large) dissolved organic carbon (DOC), transparent exopolymer particles (TEP), and small/large detritus) and their degradation by two bacterial sub-communities (free-living and particle-attached) and planktonic protists (heterotrophic flagellates and ciliates). The model can explain > 90% of the variation of a rich set of observations consisting of 11 independent variables over the course of 13 days during which a bloom largely dominated by diatoms develops, and disappears almost entirely. Fluxes estimated by the model point to the importance of coagulation (TEP formation) as a sink term for DOC, and a source term for POC. Consequently, aggregation with TEPs constitute an important loss term for phytoplankton. The flocculated phytoplankton, and detrital material, in turn become rapidly degraded by the particle attached bacteria and other protist heterotrophs. Through a scenario analysis, the relevance of nutrient-stress enhanced lysis rates; alterations between small and large DOC in phytoplankton exudates; and coagulation of smaller DOC molecules were investigated. Our results suggest that the former two processes have negligible effects in isolation, but when combined with the latter, they can synergistically cause substantial deviations in TEP formation, hence, in flocculation rates; and consequently in the peak magnitude of the diatom bloom, and in timing of its termination. Our results point to a need for better understanding of processes governing the termination of phytoplankton blooms, their inter-dependencies, and consequences on the global biogeochemical cycles.

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Section: The Mesocosm Experiments and Observationsmentioning

confidence: 99%

“…3 ), nitrite (NO − 2 ), ammonium (NH + 4 ), dissolved inorganic phosphorus and silicate (DIP and DISi) are described by Mori et al (2021).…”

Section: Abiotic and Biotic Variables Assessedmentioning

confidence: 99%

Section: Abiotic and Biotic Variables Assessedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Growth, organic matter release, aggregation and recycling during a diatom bloom: A model-based analysis of a mesocosm experiment

Kerimoglu

Hintz

Lücken

et al. 2022

Preprint

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Thallium isotope cycling between waters, particles, and sediments across a redox gradient

Ostrander

Nielsen

Gadol

et al. 2023

Geochimica et Cosmochimica Acta

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Naturally induced biphasic phytoplankton spring bloom reveals rapid and distinct substrate and bacterial community dynamics

Dlugosch,

Bunse,

Bunk

et al. 2023

FEMS Microbiology Ecology

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Phytoplankton spring blooms are typical features in coastal seas and provide heterotrophic bacteria with a rich blend of dissolved substrates. However, they are difficult to study in coastal seas in-situ. Here, we induced a phytoplankton spring bloom and followed its fate for 37 days in four 600 L-mesocosms. To specifically investigate the significance of phytoplankton-born dissolved organic carbon (DOC) we used artificial seawater with low DOC background and inoculated it with a 100 µm-prefiltered plankton community from the North Sea. A biphasic bloom developed, dominated by diatoms and Phaeocystis globosa respectively. In between, bacterial numbers peaked, followed by a peak in virus-like particles, implying that virus infection caused the collapse. Concentrations of dissolved free amino acids exhibited rapid changes, in particular during the diatom bloom and until the peak in bacterial abundance. Dissolved combined amino acids and neutral monosaccharides accumulated continuously, accounting for 22% of DOC as a mean and reaching levels as high as 44%. Bacterial communities were largely dominated by Bacteroidetes, especially the NS3a marine group (family Flavobacteriaceae), but Rhodobacteraceae and Gammaproteobacteria were also prominent members. Our study shows rapid organic matter and community composition dynamics that are hard to trace in natural coastal ecosystems.

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Biogeochemical thallium cycling during a mesocosm phytoplankton spring bloom: Biotic versus abiotic drivers

Cited by 9 publications

References 76 publications

Growth, organic matter release, aggregation and recycling during a diatom bloom: A model-based analysis of a mesocosm experiment

Growth, organic matter release, aggregation and recycling during a diatom bloom: A model-based analysis of a mesocosm experiment

Thallium isotope cycling between waters, particles, and sediments across a redox gradient

Naturally induced biphasic phytoplankton spring bloom reveals rapid and distinct substrate and bacterial community dynamics

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