Temporal and spatial variations in benthic nitrogen cycling in a temperate macro-tidal coastal ecosystem: Observation and modeling

Ratmaya, Widya; Laverman, Anniet M.; Akbarzadeh, Zahra; Andrieux-Loyer, Françoise; Barillé, Laurent; Barillé, Anne‐Laure; Merrer, Yoann Le; Souchu, Philippe

doi:10.1016/j.csr.2022.104649

Cited by 10 publications

(12 citation statements)

References 109 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This bay is well known as one of the European Atlantic coastal ecosystems most sensitive to eutrophication (Ménesguen et al, 2019). The Bay of Vilaine has undergone eutrophication over recent decades mainly due to high nutrient inputs from the Vilaine and Loire rivers (Rossignol-Strick, 1985;Ratmaya et al, 2019).…”

Section: Study Areasmentioning

confidence: 99%

“…advance or delay) the IPGP, we focus on the 15 d before the mean day of the IPGP (day 68) and of each annual IPGP. The considered 15 d length is related to the typical water residence time in both bays (Frère et al, 2017, andPoppeschi et al, 2021, for the Bay of Brest; Chapelle et al, 1994, andRatmaya et al, 2019, for the Bay of Vilaine).…”

Section: Impact Of Environmental Conditions On the Ipgpmentioning

confidence: 99%

“…Our study is based on two geographically close, but hydrodynamically different, nearshore ecosystems: (1) the Bay of Brest, a shallow semi-enclosed bay with well-mixed waters (Le Pape and Menesguen, 1997), and (2) the Bay of Vilaine, a shallow open bay with long water residence times (Chapelle et al, 1994). These two coastal ecosystems are strongly impacted by anthropogenic pressures, such as intensive agricul-ture (Ragueneau et al, 2018;Ratmaya et al, 2019), which induces highly rich nutrient waters.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

et al. 2022

View full text Add to dashboard Cite

Abstract. Decadal time series of chlorophyll a concentrations sampled at high and low frequencies are explored to study climate-induced impacts on the processes inducing interannual variations in the initiation of the phytoplankton growing period (IPGP) in early spring. We specifically detail the IPGP in two contrasting coastal temperate ecosystems under the influence of rivers highly rich in nutrients: the Bay of Brest and the Bay of Vilaine. In both coastal ecosystems, we observed a large interannual variation in the IPGP influenced by sea temperature, river inputs, light availability (modulated by solar radiation and water turbidity), and turbulent mixing generated by tidal currents, wind stress, and river runoff. We show that the IPGP is delayed by around 30 d in 2019 in comparison with 2010. In situ observations and a one-dimensional vertical model coupling hydrodynamics, biogeochemistry, and sediment dynamics show that the IPGP generally does not depend on one specific environmental factor but on the interaction between several environmental factors. In these two bays, we demonstrate that the IPGP is mainly caused by sea surface temperature and available light conditions, mostly controlled by the turbidity of the system before first blooms. While both bays are hydrodynamically contrasted, the processes that modulate the IPGP are similar. In both bays, the IPGP can be delayed by cold spells and flood events at the end of winter, provided that these extreme events last several days.

show abstract

Section: Study Areasmentioning

confidence: 99%

Section: Impact Of Environmental Conditions On the Ipgpmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

et al. 2022

View full text Add to dashboard Cite

show abstract

“…A recent study based on tritium signatures of the Loire and the Gironde rivers suggested a significant input of water from the Loire off the Gironde in summer and autumn (Oms, 2019). As recurrent summer hypoxia occur in the lower Loire estuary (Schmidt et al, 2019) and the Vilaine Bay (Retho et al, 2020;Ratmaya et al, 2022), the southward spreading of these oxygendepleted waters may reinforce the deoxygenation off the Gironde. In contrast, the Gironde does likely not exacerbate deoxygenations by supplying deoxygenated waters to the shelf as seasonal hypoxia is episodic and limited to the upper estuary (Lanoux et al, 2013;Schmidt et al, 2019).…”

Section: Probable Causes Of Deoxygenationsmentioning

confidence: 99%

“…In fact, the only reported anoxia episode along the French shelf of the Bay of Biscay has been registered in July 1982 in its northernmost sector, off the smaller and eutrophicated Vilaine river (Figure 1A, Rossignol-Strick, 1985). Following this event, a high frequency monitoring of the Vilaine Bay revealed recurrent deoxygenations and even hypoxia in bottom waters (Retho et al, 2020;Ratmaya et al, 2022). The lack of such in situ data in the southern sector of the Bay of Biscay precludes confirming the occurrence of deoxygenation suggested by the models.…”

Section: Introductionmentioning

confidence: 99%

First observations of seasonal bottom water deoxygenation off the Gironde estuary (Bay of Biscay, North East Atlantic)

Dubosq

Schmidt

Sudre³

et al. 2022

Front. Mar. Sci.

View full text Add to dashboard Cite

Although not systematically considered as oxygen minimum zones, River-dominated Ocean Margins are sensitive to oxygen depletions. For example, the continental shelf off the Gironde, which flows into the Bay of Biscay, had not yet been studied from this perspective although recent simulations suggested that this area should already have experienced deoxygenations in recent decades. To fill this gap, profiles of temperature, salinity and dissolved oxygen were performed in the water column of the continental shelf off the Gironde during seven cruises distributed over the different seasons between 2016 and 2021. Turbidity, chlorophyll-a and pH were also measured during some of these cruises. In winter, the water column was slightly stratified due to high river flows. Then, a seasonal thermal stratification was present from spring to autumn. Similarly, dissolved oxygen showed a seasonal dynamic with: a well-oxygenated water column in winter, an oxygen oversaturation in the first 20 meters during the spring bloom, and then a progressive oxygen depletion in bottom waters until reaching an oxygen saturation minimum down to 45% in autumn. These deoxygenations are explained by the seasonal stratification that isolates the bottom waters from spring to autumn, and are likely enhanced by the advection of deoxygenated waters from the north of the Bay of Biscay and the settling of the organic matter produced in surface waters. A better understanding of these processes in the context of global warming undoubtedly requires better documentation of dissolved oxygen variability through the implementation of a long-term and continuous in situ monitoring.

show abstract

Spatio-temporal dynamics of nutrients at the water-sediment interface: case of the Nokoue lagoon in Southern Benin

Socohou,

Djihouessi,

Tigo

et al. 2023

Environ Monit Assess

View full text Add to dashboard Cite

Temporal and spatial variations in benthic nitrogen cycling in a temperate macro-tidal coastal ecosystem: Observation and modeling

Cited by 10 publications

References 109 publications

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

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

First observations of seasonal bottom water deoxygenation off the Gironde estuary (Bay of Biscay, North East Atlantic)

Spatio-temporal dynamics of nutrients at the water-sediment interface: case of the Nokoue lagoon in Southern Benin

Contact Info

Product

Resources

About