Control of phytoplankton production by physical forcing in a strongly tidal, well-mixed estuary

Desmit, Xavier; Vanderborght, Jean-Pierre; Regnier, Pierre; Wollast, Roland

doi:10.5194/bg-2-205-2005

Cited by 50 publications

(47 citation statements)

References 64 publications

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“…Therefore, turbidity is typically high and consequently light, rather than nutrients, usually controls phytoplankton growth in these regions (SIN et al, 1999). In fact, it has been shown for phytoplankton primary production models that the most significant errors occur when the temporal pattern of light penetration, linked to the tidal cycle of solids settling and resuspension, is neglected (DESMIT et al, 2005). Microcosm experiments recently carried out in the Guadiana upper estuary confirmed that phytoplankton is co-limited by nutrients (mainly nitrogen) during the productive period and by light throughout the year (DOMINGUES, unpublished data).…”

Section: Tidal Variability Of Environmental Drivers Of Phytoplanktonmentioning

confidence: 99%

Tidal Variability of Phytoplankton and Environmental Drivers in the Freshwater Reaches of the Guadiana Estuary (SW Iberia)

Domingues

Anselmo

Barbosa

et al. 2010

International Review of Hydrobiology

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The effects of different phases of semidiurnal and spring-neap tidal cycles on phytoplankton and environmental drivers were evaluated in a tidal, freshwater location of a mesotidal estuary (Guadiana estuary, SW Iberia). An Eulerian approach was used and sampling covered different seasons during 2008. Samples were collected during spring and neap tides, at high tide, mid-ebb, low tide and mid-flood. Several physical-chemical variables were measured, as well as phytoplankton abundance and biomass.Salinity was higher at high-tide and suspended particulate matter was higher during spring tides and flood, due to higher vertical mixing and resuspension of bottom sediments. Chlorophyll a concentration during winter and summer neap tides was higher than during spring tides, whilst the abundance of pennate diatoms was higher during winter and Spring spring tides than during neap tides, probably reflecting differences in river discharge. Overall, tidally-induced differences detected in the freshwater tidal reaches of the Guadiana estuary were not as considerable as those observed in the lower estuary. However, the occurrence of tidally-induced variability in some seasons reflects that thorough sampling programs to study estuarine tidal dynamics should be conducted throughout the year. Occasional sampling will not reflect the typical variability of these highly dynamic systems.

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Section: Tidal Variability Of Environmental Drivers Of Phytoplanktonmentioning

confidence: 99%

Tidal Variability of Phytoplankton and Environmental Drivers in the Freshwater Reaches of the Guadiana Estuary (SW Iberia)

Domingues

Anselmo

Barbosa

et al. 2010

International Review of Hydrobiology

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“…(1) Net Primary Production (NPP) by diatoms (dia) is the fraction of the vertically averaged gross primary production (GPP) which is not used for respiration associated with growth and maintenance, or for cellular excretion (Desmit et al, 2005):…”

Section: Appendix Amentioning

confidence: 99%

Reactive-transport modelling of C, N, and O2 in a river–estuarine–coastal zone system: Application to the Scheldt estuary

et al. 2007

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A fully coupled, two-dimensional hydrodynamic and reactive-transport model of C, N, O 2 and Si along a river-estuarinecoastal zone system is presented. It is applied to the Scheldt continuum, a macrotidal environment strongly affected by anthropogenic perturbations. The model extends from the upper tidal river and its tributaries to the southern Bight of the North Sea. Five dynamically linked nested grids are used, with a spatial resolution progressively increasing from 33 m to 2.7 km. The biogeochemical reaction network consists of aerobic degradation, nitrification, denitrification, phytoplankton growth and mortality, as well as reaeration. Diagnostic simulations of a typical summer situation in the early 1990s are compared to field data taken from the OMES database (>300 samples per variable). Results demonstrate that the process rates in the tidal river are very high and far larger than in the saline estuary, with maximum nitrification rates in the water column up to 70 mM N day − 1 , and maximum aerobic respiration and denitrification up to 70 and 40 mM C day − 1 , respectively. Phytoplankton production is about one order of magnitude lower, a result which confirms the dominance of heterotrophic processes in this system. The influence of secondary and tertiary wastewater treatment in the catchment is then assessed. Results show a significant decrease of organic matter and ammonium concentrations above Antwerp, which in turn leads to a partial restoration of oxygen levels. The model also predicts a reduction of denitrification rates, which locally results in a 4-fold increase of the nitrate concentration. Mass budgets for carbon, nitrogen and oxygen are established for the saline estuary (km 0 to 100) and for the tidal river network (km 100 to 160). Three scenarios, corresponding to the situation in the early 1990s, the years 2000 and the situation expected in 2010 are considered. They show that the tidal river and the estuary contribute almost equally to the overall biogeochemical cycling of these elements, despite the very different water volumes involved. For the simulated periods, the large decrease in nitrogen input (> 55%) expected between 1990 and 2010 will not lead to a significant decrease of N export to the coastal zone during the summer period.

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“…A consequence of this high turbidity is that photosynthesis is usually severely light limited. Net primary production is possible only when the euphotic-mixing depth ratio remains sufficiently high (Cole et al, 1992;Soetaert et al, 1994;Kromkamp & Peene, 1995;Desmit et al, 2005). In addition, bacterial production and bacterial respiration are often high due to elevated organic carbon loading (Goosen et al, 1999;Gazeau et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Photosynthetic characteristics of the phytoplankton in the Scheldt estuary: community and single-cell fluorescence measurements

Dijkman

Kromkamp

2006

European Journal of Phycology

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Estuaries present a very dynamic environment for phytoplankton with large changes in salinity occurring over relatively short distances, usually with high turbidity. We investigated the photosynthetic characteristics of phytoplankton in the Scheldt estuary (Belgium and the Netherlands) along a salinity gradient using community and single-cell fluorescence measurements. Single-cell fluorescence measurements offer the opportunity to study differences between species that were formerly possible only using uni-algal cultures. The objective was to study differences in the photochemical efficiency of photosystem II (F v /F m ) between different species or different genera (when identification to the species level was not possible) and to investigate the effect of salinity on individual species. The difference in F v /F m between species was small, but often significant (ANOVA, p < 0.05), and was found to be a true characteristic of species, as opposed to being caused by stochastic processes affecting cells of all species more or less equally. High algal mortality is implied by a large decline of biomass from freshwater towards higher salinity, as well as a complete change in the phytoplankton composition. Nevertheless, cells with low F v /F m , which would indicate decreased health, were rare. F v /F m of 93% of the measured cells was between 0.5 and 0.8. There was no obvious relation between F v /F m and species abundance. In laboratory studies, green algae are often reported to have a higher F v /F m than diatoms, but we found no indication of this in the Scheldt estuary.

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Control of phytoplankton production by physical forcing in a strongly tidal, well-mixed estuary

Cited by 50 publications

References 64 publications

Tidal Variability of Phytoplankton and Environmental Drivers in the Freshwater Reaches of the Guadiana Estuary (SW Iberia)

Tidal Variability of Phytoplankton and Environmental Drivers in the Freshwater Reaches of the Guadiana Estuary (SW Iberia)

Reactive-transport modelling of C, N, and O2 in a river–estuarine–coastal zone system: Application to the Scheldt estuary

Photosynthetic characteristics of the phytoplankton in the Scheldt estuary: community and single-cell fluorescence measurements

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