Interannual variability of the initiation of the phytoplankton growing period in two French coastal ecosystems

Poppeschi, Coline; Charria, Guillaume; Daniel, Anne; Verney, Romaric; Rimmelin-Maury, Peggy; Rétho, Michaël; Goberville, Éric; Grossteffan, Emilie; Plus, Martin

doi:10.5194/bg-19-5667-2022

Cited by 7 publications

(4 citation statements)

References 80 publications

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“…CC BY 4.0 License. temperature and light (Poppeschi et al, 2022). Due to the modulation mechanism of the eddies on the MLD (AEs deepen the MLD and CEs make it shallower), AEs can contact deeper nutrient lines, the mixing of turbulent flow enables AEs to have higher nutrient concentrations and promotes phytoplankton growth(Figure 4c).…”

Section: Discussionmentioning

confidence: 99%

Eddy-induced chlorophyll profile characteristics and underlying dynamic mechanisms in the South Pacific Ocean

Hou,

Yang,

Chen

et al. 2023

Preprint

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Abstract. Many studies have consistently demonstrated that the near-surface phytoplankton chlorophyll (Chl) levels in anticyclonic eddies (AEs) are higher than in cyclonic eddies (CEs) in the South Pacific Ocean (SPO) using remote sensing data, which is attributed to higher phytoplankton biomass or physiological adjustments in AEs. However, the characteristics of the Chl profile induced by mesoscale eddies and their underlying dynamic mechanism have not been comprehensively studied by means of field measurement. In this study, we mainly utilized BGC-Argo data to investigate the relationships between Chl levels and environmental factors (CPhyto, Nitrate, Temperature and Light) and the underlying dynamic mechanisms of mesoscale eddies in SPO. Our findings showed that, the elevated Chl levels in AEs primarily result from increased phytoplankton biomass within the Mixed Layer Depth (MLD), which is induced by enhanced nutrient availability due to the deepening MLD in AEs. At depths ranging from 50 m to 110 m (the depth between the bottom of the mixed layer and pycnocline), the dominant factor affecting higher Chl levels in CEs is the physiological adaptation of phytoplankton, driven by reduced temperature and light availability. Between 110 m and 150 m (near the depth of pycnocline or bottom of the euphotic zone), both phytoplankton biomass induced by eddy pumping and physiological adjustments for lower light and temperature contributed to higher Chl levels in CEs. At depths exceeding 150 m (beyond the euphotic zone), higher Chl in AEs is primarily influenced by phytoplankton biomass as a result of the downwelling by eddy pumping. To a certain extent, this work would advance our comprehensive understanding of the physical-biological interactions of mesoscale eddies and their impacts on primary productivity throughout the water column, which has important implications for accurately assessing the biogeochemical processes and ocean carbon cycle.

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Section: Discussionmentioning

confidence: 99%

Eddy-induced chlorophyll profile characteristics and underlying dynamic mechanisms in the South Pacific Ocean

Hou,

Yang,

Chen

et al. 2023

Preprint

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“…The bay is a typical shallow (8–15 m depth) and semi‐enclosed coastal ecosystem in northwestern France that has been extensively researched in ecological and phytoplankton‐related studies over the past years. This constitutes the Bay of Brest as an ideal location to study potential geochemical responses in scallop shells to environmental signals such as large phytoplankton blooms whose initiation is largely controlled by sea surface temperature, nutrient inputs, light conditions, and ocean currents (e.g., Poppeschi et al 2022). Six specimens were collected from their natural habitat, specifically, scallops that lived and grew on the sediment surface (at approximately 8 m below sea surface; hereafter, these shells are referred to as “sediment shells”), and six specimens were retrieved from cages (hereafter referred to as “cage shells”) positioned about 1 m above the sediment–water interface (i.e., thin layer at the boundary between sediment surface and water column; SWI) ( see Supporting Information Table S1).…”

Section: Methodsmentioning

confidence: 99%

Uptake of barium, molybdenum, and lithium and incorporation into scallop shells: Refining proxies for primary production dynamics

Fröhlich,

Siebert,

Huang

et al. 2023

Limnology & Oceanography

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Ba/Cashell, Mo/Cashell, and Li/Cashell chronologies of Pecten maximus can provide information on past phytoplankton dynamics. Distinct Ba, Mo, and Li peaks in the shells are associated with algal blooms. This study evaluated the underlying hypothesis that respective element profiles reliably record variations in phytoplankton dynamics occurring within the water column. Therefore, the chemical content of scallops from the Bay of Brest, France, that lived on the sediment surface was compared to conspecific specimens living in a cage above the seafloor and compared with the phytoplankton abundance and the physicochemical properties of the water column. As demonstrated, Ba/Cashell and Mo/Cashell peaks occurred contemporaneously in specimens within the cage and on the sediment, but were higher in the latter. Furthermore, element/Ca peaks agreed with the timing of particulate Ba and Mo enrichments in the seawater. These data support the assumption of a dietary uptake of both elements. Differences in peak heights between shells living in a cage and on the seafloor were controlled by rates of filtration and biomineralization. While the timing and magnitude of Ba/Cashell peaks were linked to Ba‐containing diatoms, Mo/Cashell peaks were related to blooms of Mo‐enriched dinoflagellate and diatom aggregation events. Two episodes of slight Li enrichment occurred synchronously in cage and sediment shells. Although the exact mechanism causing such Li increases remains unresolved, the findings suggest a link to large diatom blooms or the presence of a specific diatom taxon. This study refines previously hypothesized relationships between trace element enrichments in scallop shells and phytoplankton dynamics.

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“…In the English Channel, Gómez and Souissi (2008) made the link between the MCS of 2005 and the absence of the spring bloom of Phaeocystis. A delay in the initiation of the phytoplankton bloom caused by the presence of MCSs at the end of winter in the Bay of Brest and in the Bay of Vilaine (in the northern part of the Bay of Biscay) is observed by Poppeschi et al (2022). The impact of MHWs on biology is even more studied than the cold counterpart.…”

Section: Introductionmentioning

confidence: 99%

Coastal and regional marine heatwaves and cold spells in the northeastern Atlantic

Simon,

Poppeschi,

Plecha

et al. 2023

Ocean Sci.

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Abstract. The latest Intergovernmental Panel on Climate Change (IPCC) report describes an increase in the number and intensity of marine heatwaves (MHWs) and a decrease in marine cold spells (MCSs) in the global ocean. However, these reported changes are not uniform on a regional to local basis, and it remains unknown if coastal areas follow the open-ocean trends. Surface ocean temperature measurements collected by satellites (from 1982–2022) and 13 coastal buoys (from 1990–2022) are analyzed in the northeastern Atlantic and three subregions: the English Channel, Bay of Brest and Bay of Biscay. The activity metric, combining the number of events, intensity, duration and spatial extent, is used to evaluate the magnitude of these extreme events. The results from in situ and satellite datasets for each of the studied regions are quite in agreement, although the satellite dataset underestimates the amplitude of activity for both MHWs and MCSs. This supports the applicability of the method to both in situ and satellite data, albeit with caution on the amplitude of these events. Also, this localized study in European coastal northeastern Atlantic water highlights that similar changes are being seen in coastal and open oceans regarding extreme events of temperature, with MHWs being more frequent and longer and extending over larger areas, while the opposite is seen for MCSs. These trends can be explained by changes in both the mean of and variance in sea-surface temperature. In addition, the pace of evolution and dynamics of marine extreme events differ among the subregions. Among the three studied subregions, the English Channel is the region experiencing the strongest increase in summer MHW activity over the last 4 decades. Summer MHWs were very active in the English Channel in 2022 due to long events, in the Bay of Biscay in 2018 due to intense events and in the Bay of Brest in 2017 due to a high occurrence of events. Winter MCSs were the largest in 1987 and 1986 due to long and intense events in the English Channel. Finally, our findings suggest that at an interannual timescale, the positive North Atlantic Oscillation favors the generation of strong summer MHWs in the northeastern Atlantic, while low-pressure conditions over northern Europe and a high off the Iberian Peninsula in winter dominate for MCSs. A preliminary analysis of air–sea heat fluxes suggests that, in this region, reduced cloud coverage is a key parameter for the generation of summer MHWs, while strong winds and increased cloud coverage are important for the generation of winter MCSs.

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Interannual variability of the initiation of the phytoplankton growing period in two French coastal ecosystems

Cited by 7 publications

References 80 publications

Eddy-induced chlorophyll profile characteristics and underlying dynamic mechanisms in the South Pacific Ocean

Eddy-induced chlorophyll profile characteristics and underlying dynamic mechanisms in the South Pacific Ocean

Uptake of barium, molybdenum, and lithium and incorporation into scallop shells: Refining proxies for primary production dynamics

Coastal and regional marine heatwaves and cold spells in the northeastern Atlantic

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