scholarly journals Importance and nutritional value of large ciliates for the reproduction of Acartia clausi during the post spring-bloom period in the North Sea

2008 ◽  
Vol 50 ◽  
pp. 261-277 ◽  
Author(s):  
J Dutz ◽  
J Peters
Keyword(s):  
North Sea ◽  
Nutritional Value ◽  
Spring Bloom ◽  
Bloom Period ◽  
The North ◽  
Acartia Clausi ◽  
The North Sea

scholarly journals Tidal impacts on primary production in the North Sea

2018 ◽  
Author(s):  
Changjin Zhao ◽  
Ute Daewel ◽  
Corinna Schrum
Keyword(s):  
Primary Production ◽  
North Sea ◽  
Tidal Cycle ◽  
Spring Bloom ◽  
Tidal Mixing ◽  
Nutrient Depletion ◽  
Tidal Forcing ◽  
The North ◽  
Shelf Seas ◽  
The North Sea

Abstract. This study highlights the importance of tides in controlling the spatial and temporal distributions of phytoplankton and other factors related to growth, such as nutrients and light availability. To quantify the responses of net primary production (NPP) to tidal forcing, we conducted scenario model simulations considering M2 and S2 tidal constituents using the physical-biogeochemical coupled model ECOSMO. The results were analysed with respect to a reference simulation without tidal forcing, with particular focus on the spatial scale of the tidally induced changes. Tidal forcing regulates the mixing-stratification processes in shelf seas such as the North Sea and hence also influences ecosystem dynamics. In principle, the results suggest three different response types with respect to primary production: (i) in southern shallow areas with strong tidal energy dissipation, tidal mixing dilutes phytoplankton concentrations in the upper water layers and thereby decreases NPP. Additionally, tides increase turbidity in near-coastal shallow areas, which has the potential to further hamper NPP. (ii) In the frontal region of the southern North Sea, which is a transition zone between stratified and mixed areas, tidal mixing infuses nutrients into the surface mixed layer and resolves summer nutrient depletion, thus sustaining the NPP during the summer season after spring bloom nutrient depletion. (iii) In the northern North Sea, the NPP response to tidal forcing is limited. Additionally, our simulations indicate that spring bloom phenology is impacted by tidal forcing, leading to a later onset of the spring bloom in large parts of the North Sea and to generally higher spring bloom peak phytoplankton biomasses. By testing the related changes in stratification, light conditions and grazing pressure, we found that all three factors potentially contribute to the change in spring bloom phenology with clear local differences. Finally, we also analysed the impact of the spring-neap tidal cycle on NPP. The annual mean impact of spring-neap tidal forcing on NPP is limited. However, locally, we found substantial differences in NPP either in-phase or anti-phase with the spring-neap tidal cycle. These differences could be attributed to locally different dominant factors such as light or nutrient availability during spring tides. In general, we conclude that in shallow shelf seas such as the North Sea, intensified vertical mixing induced by tidal forcing could either promote NPP by counteracting nutrient depletion or hinder NPP by deteriorating the light environment because of the resuspension and mixing of suspended matter into the euphotic zone.

scholarly journals Tidal impacts on primary production in the North Sea

2019 ◽  
Vol 10 (2) ◽  
pp. 287-317 ◽  
Author(s):  
Changjin Zhao ◽  
Ute Daewel ◽  
Corinna Schrum
Keyword(s):  
Primary Production ◽  
North Sea ◽  
Tidal Cycle ◽  
Spring Bloom ◽  
Tidal Mixing ◽  
Nutrient Depletion ◽  
Tidal Forcing ◽  
The North ◽  
Shelf Seas ◽  
The North Sea

Abstract. This study highlights the importance of tides in controlling the spatial and temporal distributions of phytoplankton and other factors related to growth, such as nutrients and light availability. To quantify the responses of net primary production (NPP) to tidal forcing, we conducted scenario model simulations considering M2 and S2 tidal constituents using the physical–biogeochemical coupled model ECOSMO (ECOSystem MOdel). The results were analyzed with respect to a reference simulation without tidal forcing, with particular focus on the spatial scale of the tidally induced changes. Tidal forcing regulates the mixing–stratification processes in shelf seas such as the North Sea and hence also influences ecosystem dynamics. In principle, the results suggest three different response types with respect to primary production: (i) in southern shallow areas with strong tidal energy dissipation, tidal mixing dilutes phytoplankton concentrations in the upper water layers and thereby decreases NPP. Additionally, tides increase turbidity in near-coastal shallow areas, which has the potential to further hamper NPP. (ii) In the frontal region of the southern North Sea, which is a transition zone between stratified and mixed areas, tidal mixing infuses nutrients into the surface mixed layer and resolves summer nutrient depletion, thus sustaining the NPP during the summer season after spring bloom nutrient depletion. (iii) In the northern North Sea, the NPP response to tidal forcing is limited. Additionally, our simulations indicate that spring bloom phenology is impacted by tidal forcing, leading to a later onset of the spring bloom in large parts of the North Sea and to generally higher spring bloom peak phytoplankton biomasses. By testing the related changes in stratification, light conditions and grazing pressure, we found that all three factors potentially contribute to the change in spring bloom phenology with clear local differences. Finally, we also analyzed the impact of the spring–neap tidal cycle on NPP. The annual mean impact of spring–neap tidal forcing on NPP is limited. However, locally, we found substantial differences in NPP either in phase or anti-phase with the spring–neap tidal cycle. These differences could be attributed to locally different dominant factors such as light or nutrient availability during spring tides. In general, we conclude that in shallow shelf seas such as the North Sea, intensified vertical mixing induced by tidal forcing could either promote NPP by counteracting nutrient depletion or hinder NPP by deteriorating the light environment because of the resuspension and mixing of suspended matter into the euphotic zone.

Analysis of 20 years of daily cloud-free chlorophyll and suspended particulate matter in the North Sea

2021 ◽  
Author(s):  
Aida Alvera-Azcárate ◽  
Dimitry Van der Zande ◽  
Alexander Barth ◽  
Samuel Martin ◽  
Jean-Marie Beckers
Keyword(s):  
Missing Data ◽  
Interannual Variability ◽  
North Sea ◽  
Spring Bloom ◽  
Suspended Particle ◽  
Chlorophyll Concentration ◽  
Empirical Orthogonal Functions ◽  
Spatial And Temporal Variability ◽  
The North ◽  
The North Sea

<p>The evolution of chlorophyll concentration (CHL) and suspended particle matter (SPM) in the North Sea over the <span><span>period 1998-2017</span></span> is analysed. The domain covers 48 to 66 degrees North and -8 to 13 degrees East. Through the years between 76% and 87% of marine pixels are missing data due to cloud cover and satellite product quality control. A daily cloud-free dataset is produced with the help of DINEOF (Data Interpolating Empirical Orthogonal Functions). The gap-free dataset is used to <span><span>investigate</span></span> interannual variability and trends in the concentration of these variables in the North Sea, and their relation to long-term climatic signals such as the Atlantic Multidecadal Oscillation (AMO). The interannual variability of the initiation and length of the Spring bloom is studied, as well as its spatial <span><span>dispersion</span></span>. High latitudes (higher than 60<span>°N</span>) present large amounts of missing data due to the presence of clouds and low sun angles in winter, and therefore are more difficult to study using optical satellite data. The spatial and temporal variability of the CHL and SPM signals is assessed in these zones, like the occurrence and strength of the Spring bloom <span><span>around</span></span> the Faroe islands.</p>

scholarly journals ECOSMO II(CHL): a marine biogeochemical model for the North Atlantic and the Arctic

2021 ◽  
Author(s):  
Veli Çağlar Yumruktepe ◽  
Annette Samuelsen ◽  
Ute Daewel
Keyword(s):  
Primary Production ◽  
Baltic Sea ◽  
Chlorophyll A ◽  
North Sea ◽  
North Atlantic ◽  
Spring Bloom ◽  
The Arctic ◽  
The North ◽  
The North Sea ◽  
The North Atlantic

Abstract. ECOSMO II is a fully coupled bio-physical model of 3d-hydrodynamics with an intermediate complexity N(utrient) P(hytoplankton) Z(ooplankton) D(etritus) type biology including sediment-water column exchange processes originally formulated for the North Sea and Baltic Sea. Here we present an updated version of the model incorporating chlorophyll a as a prognostic state variable: ECOSMO II(CHL). The version presented here is online coupled to the HYCOM ocean model. The model is intended to be used for regional configurations for the North Atlantic and the Arctic incorporating coarse to high spatial resolutions for hind-casting and operational purposes. We provide the full descriptions of the changes in ECOSMO II(CHL) from ECOSMO II and provide the evaluation for the inorganic nutrients and chlorophyll variables, present the modeled biogeochemistry of the Nordic Seas and the Artic and experiments on various parameterization sets as use cases targeting chlorophyll a dynamics. The model evaluations demonstrated that the simulations are consistent with the large-scale climatological nutrient settings, and are capable of representing regional and seasonal changes. The Norwegian and Barents Seas primary production show distinct seasonal patterns with a pronounced spring bloom dominated by diatoms and low biomass during winter months. The Norwegian Sea annual primary production is around double that of the Barents Sea while also having an earlier spring bloom. The parameterization experiments showed that the representation of open ocean chlorophyll a benefits from using higher phytoplankton growth and zooplankton grazing rates with less photosynthesis efficiency compared to the original implementation of ECOSMO II, which was valid for the North Sea and the Baltic Sea representing coastal domains. Thus, for open ocean modeling studies, we suggest the use of the parameterization sets presented in this study.

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