Microzooplankton diversity and potential role in carbon cycling of contrasting Southern Ocean productivity regimes

Christaki, Urania; Skouroliakou, Dimitra-Ioli; Delegrange, Alice; Irion, Solène; Courcot, Lucie; Jardillier, Ludwig; Sassenhagen, Ingrid

doi:10.1016/j.jmarsys.2021.103531

Cited by 11 publications

(6 citation statements)

References 105 publications

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“…Despite small phytoplankton dominance, the contribution of larger forms (e.g., diatoms) typically increase in bottle (Sedwick et al 1999;Boyd et al 2001) and mesoscale iron addition experiments (Coale et al 2004), as well as in naturally fertilized sub-Antarctic island systems and plateaux (Korb et al 2008;Queguiner 2013;Irion et al 2020). These observations support the combined role of iron and grazing in regulating phytoplankton dynamics in sub-Antarctic HNLC waters (Banse 2013;Christaki et al 2021). However, phytoplankton taxon-specific growth and grazing rate measurements that contributed critically to evolve the "Ecumenical hypothesis" into the current paradigm (Strom and Welschmeyer 1991;Latasa et al 1997;Landry et al 2011) are lacking for the sub-Antarctic zone.…”

mentioning

confidence: 52%

Decoupled growth and grazing rates of diatoms and green algae drive increased phytoplankton productivity on HNLC sub‐Antarctic plateaux

Gutiérrez‐Rodríguez,

Latasa,

Safi

et al. 2023

Limnol Oceanogr Letters

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The combination of iron limitation and microzooplankton grazing controls phytoplankton productivity and taxonomic composition in high‐nutrient low‐chlorophyll (HNLC) regions. While increased productivity and diatom contribution triggered by iron enrichment support this view, direct measurements of underpinning group‐specific growth and grazing rates are scarce for the Southern Ocean. To assess these rates, we conducted dilution experiments coupled to high‐performance liquid chromatography and flow‐cytometry in sub‐Antarctic waters on and off Campbell Plateau, southeast of Aotearoa‐New Zealand. Off the plateau, growth and grazing were closely balanced for all groups despite a two‐fold difference between slow‐ and fast‐growing groups. On Campbell Plateau, where HNLC conditions were alleviated, the balance was disrupted, mainly by the preferential growth of diatoms and green algae, which was stimulated beyond grazing. Our results expand the recognized ability of diatoms to escape grazing control to picoplanktonic green algae that also avoid grazing and contribute significantly to phytoplankton productivity and biomass accumulation.

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confidence: 52%

Decoupled growth and grazing rates of diatoms and green algae drive increased phytoplankton productivity on HNLC sub‐Antarctic plateaux

Gutiérrez‐Rodríguez,

Latasa,

Safi

et al. 2023

Limnol Oceanogr Letters

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“…Dinoflagellates are known to be overrepresented in sequencing data, and their use in numerical analysis can lead to important biases (e.g., references ( 41 , 42 )). In this study, two small mixotrophic dinoflagellates ( Gymnodinium and Prorocentrum ) were included in the analysis because they were the only dinoflagellates to exhibit relatively high abundances in microscopy data, while they did not represent an exaggerated number of reads in metabarcoding data ( Fig.…”

Section: Discussionmentioning

confidence: 99%

Stochastic and Deterministic Processes Regulate Phytoplankton Assemblages in a Temperate Coastal Ecosystem

et al. 2022

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“…Here, higher k values could characterise prey switching events or increased handling time. Christaki et al (2021) found mesozooplankton in the Southern Ocean preferentially graze on microzooplankton over phytoplankton, due to slow growth rates of the latter.…”

Section: High Variability Of Inferred Grazing Dynamicsmentioning

confidence: 99%

Impact of spatial variability in zooplankton grazing rates on carbon export flux

Meyjes,

Petrik,

Rohr

et al. 2024

Preprint

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The biological carbon pump is a key controller of how much carbon is stored within the global ocean. This pathway is influenced by food web interactions between zooplankton and their prey. In global biogeochemical models, Holling Type functional responses are frequently used to represent grazing interactions. How these responses are parameterised greatly influences biomass and subsequent carbon export estimates. The half-saturation constant, or k value, is central to the Holling functional response. Empirical studies show k can vary over three orders of magnitude, however, this variation is poorly represented in global models. This study derives zooplankton grazing dynamics from remote sensing products of phytoplankton biomass, resulting in global distribution maps of the grazing parameter k. The impact of these spatially varying k values on model skill and carbon export flux estimates is then considered. This study finds large spatial variation in k values across the global ocean, with distinct distributions for micro- and mesozooplankton. High half-saturation constants, which drive slower grazing, are generally associated with areas of high productivity. Grazing rate parameterisation is found to be critical in reproducing satellite-derived distributions of nanophytoplankton biomass, highlighting the importance of top-down drivers for this size class. Spatially varying grazing dynamics decrease mean total carbon export by >17% compared to globally homogeneous dynamics, with increases in faecal pellet export and decreases in export from algal aggregates. This study highlights the importance of grazing dynamics to both community structure and carbon export, with implications for modelling marine carbon sequestration under future climate scenarios.

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Microzooplankton diversity and potential role in carbon cycling of contrasting Southern Ocean productivity regimes

Cited by 11 publications

References 105 publications

Decoupled growth and grazing rates of diatoms and green algae drive increased phytoplankton productivity on HNLC sub‐Antarctic plateaux

Decoupled growth and grazing rates of diatoms and green algae drive increased phytoplankton productivity on HNLC sub‐Antarctic plateaux

Stochastic and Deterministic Processes Regulate Phytoplankton Assemblages in a Temperate Coastal Ecosystem

Impact of spatial variability in zooplankton grazing rates on carbon export flux

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