Seasonality of phytoplankton cell size and the relation between photosynthesis and respiration in the Ría de Vigo (NW Spain)

Lozano, José Joaquín Martínez; Aranguren-Gassis, María; García-Martín, EE; Gonzalez, Joseph M.; Herrera, JL; Hidalgo-Robatto, Bettiana Marcela; Mártinez-Castrillón, D.; Pérez‐Lorenzo, María; Varela, RA; Serret, Pablo

doi:10.3354/meps13669

Cited by 2 publications

(8 citation statements)

References 40 publications

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“…This all indicates that the phytoplankton size structure is a poor predictor of regional differences in the functioning of food webs and in the trophic state of the pelagic ecosystem. This spatial analysis of variation concurs with the temporal observations of Lozano et al (2021) over a twice-monthly seasonal study in the temperate coastal upwelling system of the Rıá de Vigo. Results there only conformed to predictions of models when highly contrasting situations were compared (the highly autotrophic microphytoplankton-dominated upwelling vs. the almost in balance pico-and nanophytoplanktondominated winter mixing period), similar to the comparison of AMT22 data from the contrasting 26-23°N patch vs. the rest of the N gyre.…”

Section: Revisiting Meta-analysis Of Amt Datasupporting

confidence: 85%

“…reflect on differences in phytoplankton composition and community structure (see above). This strong relationship allows the estimation of a general daily assimilation number (ratio of photosynthetically O 2 produced per mg Chla per day) of 4.35 mmolO 2 mgChla -1 d -1 , which is near but below the maximum 5 mmolO 2 mgChla -1 d -1 characteristic of oligotrophic systems (Karl et al, 2002;Marra et al, 2007; assuming 10 h of light and PQ=1.1) and agrees well with values measured during stratification periods in coastal temperate ecosystems (4.15 ± 1.23 mmolO 2 mgChla -1 d -1 in the Rıá de Vigo during the summer; Lozano et al, 2021).…”

Section: Integrated Ratessupporting

confidence: 85%

“…The depth and latitudinal covariation observed between volumetric and integrated CR and GPP rates during the AMT22 (Figures 5, 6) is reflected in significant GPP : CR relationships (Figure 8). Volumetric rates depict a single GPP : CR relationship, with no differences between mesotrophic and oligotrophic provinces, contrasting with different system-dependent relationships previously observed (Serret et al, 2009;Serret et al, 2015;Lozano et al, 2021). The generalised GPP : CR relationship has a slope <1 and a threshold GPP for net heterotrophy (GPP<CR) of 0.63 mmolO 2 m -3 d -1 .…”

Section: Gpp: Cr Relationshipsmentioning

confidence: 61%

“…However, there is very little empirical confirmation of a relationship between direct measurements of the energy transfer efficiency or the degree of heterotrophy (e.g. GPP : CR ratio) and the phytoplankton size-structure, and only in coastal embayments and strong transition zones, and with unclear results (Serret et al, 2001;Smith and Kemp, 2001;Arbones et al, 2008;Soria-Pıŕiz et al, 2017;Wang et al, 2018;Juranek et al, 2020;Lozano et al, 2021). Such a relationship is an important validation for these models because it does not entail the improbable assumption that population and energy dynamics are tightly connected over nested spatial and temporal scales in the nonsteady state pelagic ecosystem.…”

Section: Revisiting Meta-analysis Of Amt Datamentioning

confidence: 99%

“…Conceptual and mechanistic models have often predicted that phytoplankton size determines the organisation and functioning of food webs, which should reflect on GPP : CR ratios and NCP (see Smith and Kemp, 2001 and references therein). However, the relationship between CR or NCP and the phytoplankton size-structure remains unresolved (Serret et al, 2001;Smith and Kemp, 2001;Arbones et al, 2008;Soria-Pıŕiz et al, 2017;Wang et al, 2018;Juranek et al, 2020;Lozano et al, 2021). One specific objective of this paper is to overcome the limitations of meta-analysis, studying the relationship of CR and NCP with the abundance and structure of the phytoplankton communities along a single latitudinal transect of the open Atlantic Ocean, with a focus on improved prediction.…”

Section: Introductionmentioning

confidence: 99%

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Respiration, phytoplankton size and the metabolic balance in the Atlantic gyres

Serret,

Lozano,

Harris

et al. 2023

Front. Mar. Sci.

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The balance between plankton photosynthesis (GPP) and community respiration (CR) in the euphotic zone (net community production, NCP) is an essential driver of the biological carbon pump. Deficient datasets and a lack of knowledge of the mechanisms regulating CR cause poor empirical models and oversimplified parameterisations that maintain NCP as one of the most important unknowns for projections of the carbon pump. One important unresolved issue is the unexpected lack of empirical relationships between CR and the biomass or size-structure of the phytoplankton, which undermines the use of remotely sensed observations to predict net community metabolism. Here we analyse the spatial variation of plankton metabolism, chlorophyll a concentration (Chla), pico- and nanophytoplankton abundance and size-fractionated primary production (14CPP) along a latitudinal (49°N–46°S) transect of 73 stations across the Atlantic Ocean (AMT-22 cruise). The use of depth-weighted rates (rates integrated to the depth of 0.1% PAR, divided by the regionally varying depth of integration) markedly improved the depiction of latitudinal patterns and the significance of relationships, over volumetric or integrated rates. Depth-weighted CR showed clear and consistent latitudinal patterns with relevance for the distribution of NCP. Depth-weighted Chla and CR exhibited a significant relationship (CRZ=1.42ChlaZ-0.21, r2 = 0.69, N=37, p<0.001) with potential for the difficult prediction of CR. A general ratio of 1.42 mmolO2 mgChla-1 d-1 and a threshold Chla for net heterotrophy of ca. 0.25 mgChla m-3 can be tentatively proposed for the Atlantic, although further analyses of spatial and seasonal variation are necessary. We observed unusually positive NCP rates in the central part of the N gyre, due to a marked decrease of CR in a patch of high Synechococcus spp. abundance and high 14CPP by large phytoplankton. However, no relationship was observed between size-fractionated 14CPP and CR or the GPP : CR ratio during the cruise, contradicting the hypothesis that food web functioning is determined by the phytoplankton size structure. Such independence, together with the persistence of distinct GPP : CR and 14CPP : NCP relationships in distinct biogeographic provinces suggest a resilience of trophic dynamics and the existence of alternative ecosystem states, whose implications for projections of the metabolic state of the ocean are discussed.

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Section: Revisiting Meta-analysis Of Amt Datasupporting

confidence: 85%

Section: Integrated Ratessupporting

confidence: 85%

Section: Gpp: Cr Relationshipsmentioning

confidence: 61%

Section: Revisiting Meta-analysis Of Amt Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Respiration, phytoplankton size and the metabolic balance in the Atlantic gyres

Serret,

Lozano,

Harris

et al. 2023

Front. Mar. Sci.

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Algal Biological Features Viewed in Satellite Observations: A Case Study of the Bohai Sea

Quan,

Chen

2023

Remote Sensing

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Algal cell abundance weakly depends on inherent optical properties and chlorophyll-a concentration in the Bohai Sea, so it is very hard to derive algal cell abundance (ACA) from ocean color data using a simple bio-optical model. To obtain ACA for biological communication at large scale, a neural network model has been developed and then applied for investigating the changing monthly trend of ACA, intracellular chlorophyll-a concentration, and cell size in the Bohai Sea using MODIS data from 2002 to 2015. The results showed that the neural network model could provide an accurate log-transformed value of algal cell abundance (LACA) from ocean color images whose retrieval uncertainty did not exceed 9%. Furthermore, when the model was applied to map the monthly mean LACA and then further convert it to cell size in the Bohai Sea, the results showed that the satellite-derived monthly mean cell size varied from 4.81 to 15.29 μm. The decreasing monthly mean algal cell abundance and increasing monthly mean chlorophyll-a concentration imply that the monthly mean intracellular chlorophyll-a concentration from 2002 to 2015 increased, which indicates that the waters in the Bohai Sea became more eutrophic over those 14 years. Moreover, due to seasonal variations in vertical mixing or other physical forcing factors, the ACA and cell size exhibited significant seasonal variations. Although further tests are required to validate the model’s robustness, these preliminary results indicate that the neural network model is an encouraging approach to exploiting more novel biological parameters such as the LACA from ocean color satellites for oceanic communication.

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Seasonality of phytoplankton cell size and the relation between photosynthesis and respiration in the Ría de Vigo (NW Spain)

Cited by 2 publications

References 40 publications

Respiration, phytoplankton size and the metabolic balance in the Atlantic gyres

Respiration, phytoplankton size and the metabolic balance in the Atlantic gyres

Algal Biological Features Viewed in Satellite Observations: A Case Study of the Bohai Sea

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