scholarly journals Biological response to hydrodynamic factors in estuarine-coastal systems: a numerical analysis in a micro-tidal bay

2021 ◽  
Author(s):  
Marta F.-Pedrera Balsells ◽  
Manel Grifoll ◽  
Margarita Fernández-Tejedor ◽  
Manuel Espino ◽  
Marc Mestres ◽  
...  
Keyword(s):  
Water Column ◽  
Wind Direction ◽  
Phytoplankton Biomass ◽  
Light Availability ◽  
Ocean Model ◽  
Phytoplankton Primary Production ◽  
Chl A ◽  
Biological Variables ◽  
Prevailing Wind Direction ◽  
Wind Events

Abstract. Phytoplankton primary production in coastal bays and estuaries is influenced by multiple physical variables, such as wind, tides, freshwater inputs or light availability. In a short-term perspective these factors may influence the composition of biological variables such as phytoplankton biomass, as well as the amount of nutrients within the waterbody. Observations in Fangar Bay, a small, shallow, stratified and micro-tidal bay in the Ebro Delta (NW Mediterranean Sea), have shown that during wind episodes the biological variables undergo sudden variations in terms of concentration and distribution within the bay. The Regional Ocean Model System (ROMS) coupled with a nitrogen-based nutrient, phytoplankton, zooplankton, and detritus (NPZD) model has been applied to understand this spatio-temporal variability of phytoplankton biomass in Fangar Bay. Idealised simulations prove that during weak wind events (< 6 m·s−1), the stratification is maintained and therefore there is not dynamic connection between surface and bottom layers, penalizing phytoplankton growth in the whole water column. Conversely, during intense wind events (> 10 m·s−1) water column mixing occurs, homogenising the concentration of nutrients throughout the column, and increasing phytoplankton biomass in the bottom layers. In addition, shifts in the wind direction generate different phytoplankton biomass distributions within the bay, in accordance with the dispersion of freshwater plumes from existing irrigation canals. Thus, the numerical results prove the influence of the freshwater plume evolution on the phytoplankton biomass distribution, which is consistent with remote sensing observations. The complexity of the wind-driven circulation due to the bathymetric characteristics and the modulation of the stratification implies that the phytoplankton biomass differs depending on the prevailing wind direction, leading to sharp Chl a gradients and complex patterns.

Influence of the hydrodynamics in spatio-temporal variability of clorophyll a in a small-scale and microtidal bay: Fangar Bay case (Ebro Delta)

2021 ◽  
Author(s):  
Marta F-Pedrera Balsells ◽  
Manel Grifoll ◽  
Margarita Fernández-Tejedor ◽  
Manuel Espino ◽  
Agustín Sánchez-Arcilla
Keyword(s):  
Water Column ◽  
Temporal Variability ◽  
Light Availability ◽  
Ebro Delta ◽  
Small Scale ◽  
Strong Wind ◽  
Chl A ◽  
Coastal Bays ◽  
Biological Variables ◽  
Field Campaigns

&lt;p&gt;Estuaries and coastal bays are areas of large spatial-temporal variability in physical and biological variables due to environmental factors such as local wind, light availability, freshwater inputs or tides. The physical characteristics of an estuary affect its hydrodynamics. These in turn modify the behaviour of biological variables such as the concentration of chlorophyll a (Chl a). In a small-scale, micro tidal bay such as the Fangar Bay (Ebro Delta), hydrodynamics is influenced above all by local winds, as well as by fresh water contributions. The results of two field campaigns and Sentinel-2 images show how the concentration of Chl a is affected by strong wind episodes typical of this area (NW-E winds). With these episodes of strong wind (&gt; 10 m-s-1) mixing occurs in the water column causing an increase in the concentration of Chl a. On the other hand, with sea breezes (&lt; 6 m-s-1) the water column is stratified causing a decrease in the Chl a concentration. However, the spatial-temporal variability of Chl a in small-scale estuaries and coastal bays is quite complex due to the many factors involved and deserves more intensive field campaigns and additional numerical modelling efforts.&lt;/p&gt;

Circulation patterns and eutrophication phenomena in the Thermaikos Gulf

2020 ◽  
Author(s):  
Yannis N. Krestenitis ◽  
Vasilis Kolovoyiannis ◽  
Yannis Androulidakis ◽  
Christos Makris ◽  
Vasilis Baltikas
Keyword(s):  
Water Column ◽  
Marine Ecosystem ◽  
Simulated Data ◽  
Aegean Sea ◽  
Ocean Model ◽  
Biological Parameters ◽  
Chl A ◽  
Physical Chemical ◽  
Circulation Patterns

&lt;p&gt;Thermaikos Gulf, located in the Northwestern Aegean Sea (Greece), is a marine ecosystem of major importance, not only environmentally (as an area of the deep water formation with contribution to the renewal of the North Aegean deep waters), but also due to the various socioeconomic activities associated with the area. Observational and simulated data are used to investigate the evolution of eutrophication events during the last two years in order to evaluate the current (2017-2019) quality state of the seawater in the Gulf. The quality of the marine environment of Thermaikos Gulf was appraised by measuring physical, chemical and biological parameters. Specific physical-chemical characteristics (temperature, salinity, density along with pH and dissolved oxygen) and biological parameters (chl-a and phytoplankton biomass) throughout the water column were evaluated by conducting in situ measurements during the sampling campaigns. Current fields, derived from a high-resolution 3-D ocean model, together with ADCP measurements, are used to describe the major circulation patterns, the river plume dynamics and the renewal pathways of the Gulf. The obtained results are discussed with regards to seasonal and spatial variability, and the water column stratification. Satellite ocean color data were also used to discuss the in-situ findings and confirm &amp;#8220;Dirty&amp;#8221; Sea and Red Tide phenomena, that were detected and analyzed based on the physical dynamics and especially the renewal patterns of the Gulf. Moreover, we compare these recent findings to respective observations from a previous period (1997 to 2007) to evaluate potential changes in the quality state of the Gulf with respect to meteorological and river discharge conditions.&amp;#160;&amp;#160;&amp;#160; &amp;#160;&lt;/p&gt;

scholarly journals Fe availability drives phytoplankton photosynthesis rates during spring bloom in the Amundsen Sea Polynya, Antarctica

Elem Sci Anth ◽  
2015 ◽  
Vol 3 ◽  
Author(s):  
Anne-Carlijn Alderkamp ◽  
Gert L. van Dijken ◽  
Kate E. Lowry ◽  
Tara L. Connelly ◽  
Maria Lagerström ◽  
...  
Keyword(s):  
Water Column ◽  
Phytoplankton Biomass ◽  
Spring Bloom ◽  
Mixed Layer Depth ◽  
Light Availability ◽  
Phytoplankton Growth ◽  
Amundsen Sea ◽  
Ice Shelves ◽  
Phytoplankton Photosynthesis ◽  
Fe Addition

Abstract To evaluate what drives phytoplankton photosynthesis rates in the Amundsen Sea Polynya (ASP), Antarctica, during the spring bloom, we studied phytoplankton biomass, photosynthesis rates, and water column productivity during a bloom of Phaeocystis antarctica (Haptophyceae) and tested effects of iron (Fe) and light availability on these parameters in bioassay experiments in deck incubators. Phytoplankton biomass and productivity were highest (20 µg chlorophyll a L−1 and 6.5 g C m−2 d−1) in the central ASP where sea ice melt water and surface warming enhanced stratification, reducing mixed layer depth and increasing light availability. In contrast, maximum photosynthesis rate (P*max), initial light-limited slope of the photosynthesis–irradiance curve (α*), and maximum photochemical efficiency of photosystem II (Fv/Fm) were highest in the southern ASP near the potential Fe sources of the Dotson and Getz ice shelves. In the central ASP, P*max, α*, and Fv/Fm were all lower. Fe addition increased phytoplankton growth rates in three of twelve incubations, and at a significant level when all experiments were analyzed together, indicating Fe availability may be rate-limiting for phytoplankton growth in several regions of the ASP early in the season during build-up of the spring bloom. Moreover, Fe addition increased P*max, α*, and Fv/Fm in almost all experiments when compared to unamended controls. Incubation under high light also increased P*max, but decreased Fv/Fm and α* when compared to low light incubation. These results indicate that the lower values for P*max, α*, and Fv/Fm in the central ASP, compared to regions close to the ice shelves, are constrained by lower Fe availability rather than light availability. Our study suggests that higher Fe availability (e.g., from higher melt rates of ice shelves) would increase photosynthesis rates in the central ASP and potentially increase water column productivity 1.7-fold, making the ASP even more productive than it is today.

scholarly journals Main drivers of transparent exopolymer particle distribution across the surface Atlantic Ocean

2018 ◽  
Author(s):  
Marina Zamanillo ◽  
Eva Ortega-Retuerta ◽  
Sdena Nunes ◽  
Pablo Rodríguez-Ros ◽  
Marta Estrada ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Phytoplankton Biomass ◽  
Coastal Upwelling ◽  
Chl A ◽  
Biological Variables ◽  
Total Phytoplankton ◽  
Heterotrophic Prokaryotes ◽  
Ocean Carbon ◽  
Positive Effect ◽  
Phytoplankton Group

Abstract. Transparent exopolymer particles (TEP) are a class of gel particles produced mainly by microorganisms. TEP play an important role in the ocean carbon cycle, affect sea–air gas exchange and contribute to organic aerosols. The first step to evaluate the TEP influence in these processes is the prediction of TEP occurrence in the ocean. Yet, little is known about the physical and biological variables that control their abundance, particularly in the open ocean. Here we describe horizontal TEP distribution in the surface waters along a North–South transect in the Atlantic Ocean during October–November 2014. Physical and biological variables were run in parallel. Two main regions were separated due to remarkable differences; the open Atlantic Ocean (OAO, n = 30), and the Southwestern Atlantic Shelf (SWAS, n = 10). TEP concentration in the entire transect ranged from 18.3 to 446.8 µg XG eq L−1 and averaged 117.1 ± 119.8 µg XG eq L−1, with the maximum concentrations in the edge of the Canary Coastal Upwelling (CU, n = 1) and the SWAS, but with the highest TEP to chlorophyll a (TEP : Chl a) ratios at the OAO (CU excluded, average 183 ± 56) and CU (1760.4). TEP were significantly and positively related to Chl a and phytoplankton biomass, expressed in terms of C, along the entire transect. In the OAO, TEP were positively related to some phytoplankton groups, mainly to Synechococcus, and negatively related to the previous 24–hours averaged solar radiation, suggesting the predominance of TEP breaking above the induction of TEP production by UV radiation. Multiple regression analyses showed the combined positive effect of phytoplankton and heterotrophic prokaryotes (HP) on TEP distribution in this region. In the SWAS, TEP were positively related to high nucleic acid prokaryotic cells (HNA) and total phytoplankton biomass, but not with any particular phytoplankton group. TEP constituted an important portion of the particulate organic carbon (POC) pool in the entire transect (28.1–109.8 %), and was generally higher than the phytoplankton and HP fraction, highlighting the importance of TEP in the cycle of organic matter in the ocean.

scholarly journals Main drivers of transparent exopolymer particle distribution across the surface Atlantic Ocean

2019 ◽  
Vol 16 (3) ◽  
pp. 733-749 ◽  
Author(s):  
Marina Zamanillo ◽  
Eva Ortega-Retuerta ◽  
Sdena Nunes ◽  
Pablo Rodríguez-Ros ◽  
Manuel Dall'Osto ◽  
...  
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
Phytoplankton Biomass ◽  
Coastal Upwelling ◽  
Surface Microlayer ◽  
Chl A ◽  
Biological Variables ◽  
Carbon Pump ◽  
Global Influence ◽  
Positive Effect

Abstract. Transparent exopolymer particles (TEPs) are a class of gel particles, produced mainly by microorganisms, which play important roles in biogeochemical processes such as carbon cycling and export. TEPs (a) are colonized by carbon-consuming microbes; (b) mediate aggregation and sinking of organic matter and organisms, thereby contributing to the biological carbon pump; and (c) accumulate in the surface microlayer (SML) and affect air–sea gas exchange. The first step to evaluate the global influence of TEPs in these processes is the prediction of TEP occurrence in the ocean. Yet, little is known about the physical and biological variables that drive their abundance, particularly in the open ocean. Here we describe the horizontal TEP distribution, along with physical and biological variables, in surface waters along a north–south transect in the Atlantic Ocean during October–November 2014. Two main regions were separated due to remarkable differences: the open Atlantic Ocean (OAO, n=30), and the Southwestern Atlantic Shelf (SWAS, n=10). TEP concentration in the entire transect ranged 18.3–446.8 µg XG eq L−1 and averaged 117.1±119.8 µg XG eq L−1, with the maximum concentrations in the SWAS and in a station located at the edge of the Canary Coastal Upwelling (CU), and the highest TEP to chlorophyll a (TEP:Chl a) ratios in the OAO (183±56) and CU (1760). TEPs were significantly and positively related to Chl a and phytoplankton biomass, expressed in terms of C, along the entire transect. In the OAO, TEPs were positively related to some phytoplankton groups, mainly Synechococcus. They were negatively related to the previous 24 h averaged solar irradiance, suggesting that sunlight, particularly UV radiation, is more a sink than a source for TEP. Multiple regression analyses showed the combined positive effect of phytoplankton and heterotrophic prokaryotes (HPs) on TEP distribution in the OAO. In the SWAS, TEPs were positively related to high nucleic acid-containing prokaryotic cells and total phytoplankton biomass, but not to any particular phytoplankton group. Estimated TEP–carbon constituted an important portion of the particulate organic carbon pool in the entire transect (28 %–110 %), generally higher than the phytoplankton and HP carbon shares, which highlights the importance of TEPs in the cycling of organic matter in the ocean.

Dynamics of annual nutrinets and bloom-forming cyanobacteria, revealed by daily observation in a hyper-eutrophic lake

2020 ◽  
Author(s):  
Mengyuan Zhu ◽  
Guangwei Zhu ◽  
Hans Paerl ◽  
Wei Zhang ◽  
Hai Xu
Keyword(s):  
Water Column ◽  
Phytoplankton Biomass ◽  
Lake Taihu ◽  
Eutrophic Lake ◽  
Trophic Levels ◽  
Monitoring Data ◽  
Limiting Factors ◽  
Nutrient Concentrations ◽  
Nitrogen And Phosphorus ◽  
Chl A

&lt;p&gt;Daily monitoring over a period of one year in Lake Taihu, China, included chlorophyll a (Chl-a) and nutrient measurements, determining the taxonomic composition of the phytoplankton community and various water column physicochemical parameters. Chl-a and nutrient concentrations showed strong circadian variations &amp;#8210; Chl-a rised during daylight hours, while ammonium and phosphate rised at night. Chl-a concentrations also showed strong seasonal variations, with one annual peak in spring and another from summer to autumn, dominated by Dolichospermum spp. and Microcystis spp. respectively. Temperature appeared to exert the most important effect in this species succession. A nutrient&amp;#8210;Chl-a balance calculation indicated that both nitrogen and phosphorus in the water column could be limiting factors for phytoplankton growth during bloom periods. Over two thirds of particulate nutrients was attributed to phytoplankton biomass during blooms. Daily (or weekly) monitoring data provided more precise description of water quality, capturing short-term peaks in phytoplankton biomass, and reduced risks of under- or overestimating trophic levels in lakes, which always happened when using monthly monitoring data.&lt;/p&gt;

Evaluation of Factors Related to the Unusually Low Chlorophyll Levels in Prairie Saline Lakes

1986 ◽  
Vol 43 (4) ◽  
pp. 846-854 ◽  
Author(s):  
C. E. Campbell ◽  
E. E. Prepas
Keyword(s):  
Phytoplankton Biomass ◽  
Saline Lakes ◽  
Inorganic Nitrogen ◽  
Algal Growth ◽  
Dry Weight ◽  
Inorganic Phosphorus ◽  
Total Dissolved Solids ◽  
Empirical Models ◽  
Phytoplankton Primary Production ◽  
Chl A

Prairie saline lakes in Canada have remarkably low chlorophyll a (Chl a) levels relative to total phosphorus (TP) and total nitrogen (TN) levels. To evaluate factors related to low Chl a levels, three Alberta saline lakes (total dissolved solids > 5 g∙L−1) were studied in 1983 and 1984. Mean summer phytoplankton Chl a ranged from 3 to 10 μg∙L−1, mean summer periphyton Chl a was less than 70 mg∙m−2, while mean summer TP and TN ranged from 2 to 13 and from 4 to 11 mg∙L−1, respectively. Chl a and phytoplankton primary production were extremely low relative to predictions from measured TP and TN levels and empirical models for freshwaters. Bioassays indicated that inorganic phosphorus was not limiting, whereas inorganic nitrogen was limiting algal growth. Bacterial densities and zooplankton dry weight were high (> 107 cells∙mL−1 and > 1.0 mg∙L−1, respectively) relative to predictions from Chl a and empirical models for freshwaters. Phytoplankton biomass was insufficient to maintain the zooplankton populations; bacteria and detritus were likely a major food source for zooplankton. This study suggests that freshwater models are not applicable to prairie saline lakes.

Subglacial brine flow and wind-induced internal waves in Lake Bonney, Antarctica

2020 ◽  
Vol 32 (3) ◽  
pp. 223-237
Author(s):  
Jade P. Lawrence ◽  
Peter T. Doran ◽  
Luke A. Winslow ◽  
John C. Priscu
Keyword(s):  
Water Column ◽  
Internal Waves ◽  
Open Water ◽  
Surface Discharge ◽  
Katabatic Wind ◽  
Neutral Buoyancy ◽  
Cold Temperatures ◽  
Glacier Terminus ◽  
Wind Events ◽  
Taylor Glacier

AbstractBrine beneath Taylor Glacier has been proposed to enter the proglacial west lobe of Lake Bonney (WLB) as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the geochemistry of the water column of WLB. Year-round measurements from this study are the first to definitively identify brine intrusions from a subglacial entry point into WLB. Furthermore, we excluded input from Blood Falls by focusing on winter dynamics when the absence of an open water moat prevents surface brine entry. Due to the extremely high salinities below the chemocline in WLB, density stratification is dominated by salinity, and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude into the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. High-resolution measurements also reveal under-ice internal waves associated with katabatic wind events, a novel finding that challenges long-held assumptions about the stability of the WLB water column.

scholarly journals Spatiotemporal Variability of Surface Phytoplankton Carbon and Carbon-to-Chlorophyll a Ratio in the South China Sea Based on Satellite Data

2020 ◽  
Vol 13 (1) ◽  
pp. 30
Author(s):  
Wenlong Xu ◽  
Guifen Wang ◽  
Long Jiang ◽  
Xuhua Cheng ◽  
Wen Zhou ◽  
...  
Keyword(s):  
South China Sea ◽  
Chlorophyll A ◽  
South China ◽  
Satellite Data ◽  
Phytoplankton Biomass ◽  
The South China Sea ◽  
Spatiotemporal Variability ◽  
The South ◽  
Chl A ◽  
China Sea

The spatiotemporal variability of phytoplankton biomass has been widely studied because of its importance in biogeochemical cycles. Chlorophyll a (Chl-a)—an essential pigment present in photoautotrophic organisms—is widely used as an indicator for oceanic phytoplankton biomass because it could be easily measured with calibrated optical sensors. However, the intracellular Chl-a content varies with light, nutrient levels, and temperature and could misrepresent phytoplankton biomass. In this study, we estimated the concentration of phytoplankton carbon—a more suitable indicator for phytoplankton biomass—using a regionally adjusted bio-optical algorithm with satellite data in the South China Sea (SCS). Phytoplankton carbon and the carbon-to-Chl-a ratio (θ) exhibited considerable variability spatially and seasonally. Generally, phytoplankton carbon in the northern SCS was higher than that in the western and central parts. The regional monthly mean phytoplankton carbon in the northern SCS showed a prominent peak during December and January. A similar pattern was shown in the central part of SCS, but its peak was weaker. Besides the winter peak, the western part of SCS had a secondary maximum of phytoplankton carbon during summer. θ exhibited significant seasonal variability in the northern SCS, but a relatively weak seasonal change in the western and central parts. θ had a peak in September and a trough in January in the northern and central parts of SCS, whereas in the western SCS the minimum and maximum θ was found in August and during October–April of the following year, respectively. Overall, θ ranged from 26.06 to 123.99 in the SCS, which implies that the carbon content could vary up to four times given a specific Chl-a value. The variations in θ were found to be related to changing phytoplankton community composition, as well as dynamic phytoplankton physiological activities in response to environmental influences; which also exhibit much spatial differences in the SCS. Our results imply that the spatiotemporal variability of θ should be considered, rather than simply used a single value when converting Chl-a to phytoplankton carbon biomass in the SCS, especially, when verifying the simulation results of biogeochemical models.

scholarly journals Atmospheric bromoform at Mace Head, Ireland: seasonality and evidence for a peatland source

2005 ◽  
Vol 5 (11) ◽  
pp. 2927-2934 ◽  
Author(s):  
L. J. Carpenter ◽  
D. J. Wevill ◽  
S. O'Doherty ◽  
G. Spain ◽  
P. G. Simmonds
Keyword(s):  
Boundary Layer ◽  
Wind Direction ◽  
Marine Boundary Layer ◽  
Land Breeze ◽  
Peat Bogs ◽  
Mixing Ratios ◽  
The North ◽  
Prevailing Wind Direction ◽  
Atmospheric Observations ◽  
Summer Minimum

Abstract. In situ atmospheric observations of bromoform (CHBr3) made over a 2.5 year period at Mace Head, Ireland from May 2001- Dec 2003, including during the NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, show broad maxima from spring until autumn and winter minima, with mixing ratios of 5.3+1.0 pptv (mid March - mid October) and 1.8+0.8 pptv (December-February). This indicates that, unlike CHCl3, which has a summer minimum and winter maximum at Mace Head, local biological sources of CHBr3 have a greater influence on the atmospheric data than photochemical decay during long-range transport. The emission sources are predominantly macroalgal, but we find evidence for a small terrestrial flux from peatland ecosystems, which so far has not been accounted for in the CHBr3 budget. Sharp increases in CHCl3 and CHBr3 concentrations and decreases in O3 concentrations occurred at night when the wind direction switched from an ocean- to a land-based sector (land breeze) and the wind speed dropped to below 5 ms-1. These observations infer a shallow atmospheric boundary layer with increased O3 deposition and concentration of local emissions of both CHCl3 and CHBr3. The ratio of ΔCHCl3/ΔCHBr3 varied strongly according to the prevailing wind direction; from 0.60+0.15 in south-easterly (100-170° and northerly (340-20°) air to 2.5+0.4 in north-easterly (40-70°) air. Of these land-sectors, the south-easterly air masses are likely to be strongly influenced by macroalgal beds along the coast and the emission ratios probably reflect those from seaweeds in addition to land sources. The north-easterly airmasses however had an immediate fetch inland, which locally is comprised of coastal peatland ecosystems (peat bogs and coastal conifer plantations), previously identified as being strong sources of atmospheric CHCl3 under these conditions. Although we cannot entirely rule out other local land or coastal sources, our observations also suggest peatland ecosystem emissions of CHBr3. We use correlations between CHCl3 and CHBr3 during the north-easterly land breeze events in conjunction with previous estimates of local wetland CHCl3 release to tentatively deduce a global wetland CHBr3 source of 20.4(0.4-948) Gg yr-1, which is approximately 7% of the total global source.

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