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.

scholarly journals Phytoplankton biomass, composition, and productivity along a temperature and stratification gradient in the Northeast Atlantic Ocean

2013 ◽  
Vol 10 (1) ◽  
pp. 1793-1829 ◽  
Author(s):  
W. H. van de Poll ◽  
G. Kulk ◽  
K. R. Timmermans ◽  
C. P. D. Brussaard ◽  
H. J. van der Woerd ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Phytoplankton Biomass ◽  
Nutrient Concentration ◽  
North Atlantic Ocean ◽  
Standing Stock ◽  
Biomass Composition ◽  
Nutrient Concentrations ◽  
Exponential Relationship ◽  
Near Surface ◽  
Chl A

Abstract. The North Atlantic Ocean experiences considerable variability in sea surface temperature (SST, >10 m) on seasonal and inter-annual time-scales. Relationships between SST and vertical density stratification, nutrient concentrations, and phytoplankton biomass, composition, and absorption were assessed in spring and summer from latitudes 30–62° N. Furthermore, a bio-optical model was used to estimate productivity for five phytoplankton groups. Nutrient concentration (integrated from 0–125 m) was inversely correlated with SST in spring and summer. SST was also inversely correlated with near surface (0–50 m) Chl a and productivity for stratified stations. However, near surface Chl a showed an exponential relationship with SST, whereas a linear relationship was found for productivity and SST. The response of phytoplankton to changes in SST is therefore most likely to be observed by changes in Chl a rather than productivity. The discrepancy between relationships of Chl a and productivity were probably related to changes in phytoplankton cell size. The contribution of cyanobacteria to water column productivity correlated positively with SST and inversely with nutrient concentration. This suggests that a rise in SST (over a 13–23 °C range) stimulates productivity by cyanobacteria at the expense of haptophytes, which showed an inverse relationship to SST. At higher latitudes, where rising SST may prolong the stratified season, haptophyte productivity may expand at the expense of diatom productivity. Depth integrated Chl a (0–410 m) was greatest in the spring at higher latitudes, where stratification in the upper 200 m was weakest. This suggests that stronger stratification does not necessarily result in higher phytoplankton biomass standing stock in this region.

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.

scholarly journals Coastal upwelling and seasonal variation in phytoplankton biomass in the Pemba Channel

2021 ◽  
pp. 19-32
Author(s):  
Margareth S. Kyewalyanga ◽  
Nyamisi Peter ◽  
Masumbuko Semba ◽  
Shigalla B. Mahongo
Keyword(s):  
Phytoplankton Biomass ◽  
Coastal Upwelling ◽  
Monsoon Season ◽  
Northeast Monsoon ◽  
Chl A ◽  
Physico Chemical ◽  
Northern Tanzania ◽  
High Nutrient ◽  
Chemical Factors ◽  
Physical And Chemical

This study was conducted in the Pemba Channel off Tanga Region in northern Tanzania to investigate physical and chemical factors that drive changes in phytoplankton biomass. Three transects off Mwaboza, Vyeru and Sahare were selected. For each transect, ten stations were sampled. Phytoplankton biomass was determined as chlorophyll-a (Chl-a) concentration. Similarly, physico-chemical variables (temperature, salinity, dissolved oxygen, pH and nutrients) were determined. It was observed that the Chl-a concentration was significantly higher during the northeast monsoon (median 1.44 mg m-3) as compared to the southeast monsoon (median 1.19 mg m-3; W = 2216, p = 0.029). The higher productivity during the northeast monsoon is attributed to the presence of high-nutrient water caused by coastal upwelling. It is concluded that indication of upwelling, observed through relatively low temperatures during the northeast monsoon season, could be responsible for bringing nutrient-rich waters to the surface, which in turn stimulated the increase in Chl-a concentration.

scholarly journals Phytoplankton chlorophyll <i>a</i> biomass, composition, and productivity along a temperature and stratification gradient in the northeast Atlantic Ocean

2013 ◽  
Vol 10 (6) ◽  
pp. 4227-4240 ◽  
Author(s):  
W. H. van de Poll ◽  
G. Kulk ◽  
K. R. Timmermans ◽  
C. P. D. Brussaard ◽  
H. J. van der Woerd ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Phytoplankton Biomass ◽  
Nutrient Concentration ◽  
Biomass Composition ◽  
Nutrient Concentrations ◽  
Near Surface ◽  
Specific Absorption ◽  
Northeast Atlantic ◽  
Chl A ◽  
Northeast Atlantic Ocean

Abstract. Relationships between sea surface temperature (SST, > 10 m) and vertical density stratification, nutrient concentrations, and phytoplankton biomass, composition, and chlorophyll a (Chl a) specific absorption were assessed in spring and summer from latitudes 29 to 63° N in the northeast Atlantic Ocean. The goal of this study was to identify relationships between phytoplankton and abiotic factors in an existing SST and stratification gradient. Furthermore, a bio-optical model was used to estimate productivity for five phytoplankton groups. Nutrient concentration (integrated from 0 to 125 m) was inversely correlated with SST in spring and summer. SST was also inversely correlated with near-surface (0–50 m) Chl a and productivity for stratified stations. Near-surface Chl a and productivity showed exponential relationships with SST. Chl a specific absorption and excess light experiments indicated photoacclimation to lower irradiance in spring as compared to summer. In addition, Chl a specific absorption suggested that phytoplankton size decreased in summer. The contribution of cyanobacteria to water column productivity of stratified stations correlated positively with SST and inversely with nutrient concentration. This suggests that a rise in SST (over a 13–23 °C range) stimulates productivity by cyanobacteria at the expense of haptophytes, which showed an inverse relationship to SST. At higher latitudes, where rising SST may prolong the stratified season, haptophyte productivity may expand at the expense of diatom productivity. Depth-integrated Chl a (0–410 m) was greatest in the spring at higher latitudes, where stratification in the upper 200 m was weakest. This suggests that stronger stratification does not necessarily result in higher phytoplankton biomass standing stock in this region.

scholarly journals Nutrient Loading, Temperature and Heat Wave Effects on Nutrients, Oxygen and Metabolism in Shallow Lake Mesocosms Pre-Adapted for 11 Years

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 127
Author(s):  
Erik Jeppesen ◽  
Joachim Audet ◽  
Thomas A. Davidson ◽  
Érika M. Neif ◽  
Yu Cao ◽  
...  
Keyword(s):  
Heat Wave ◽  
Shallow Lake ◽  
Nutrient Loading ◽  
Global Changes ◽  
Significant Positive Effect ◽  
Mixed Effect ◽  
Chl A ◽  
Nutrient Loadings ◽  
Positive Effect ◽  
Oxygen Concentrations

Global changes (e.g., warming and population growth) affect nutrient loadings and temperatures, but global warming also results in more frequent extreme events, such as heat waves. Using data from the world’s longest-running shallow lake experimental mesocosm facility, we studied the effects of different levels of nutrient loadings combined with varying temperatures, which also included a simulated 1-month summer heat wave (HW), on nutrient and oxygen concentrations, gross ecosystem primary production (GPP), ecosystem respiration (ER), net ecosystem production (NEP) and bacterioplankton production (BACPR). The mesocosms had two nutrient levels (high (HN) and low (LN)) combined with three different temperatures according to the IPCC 2007 warming scenarios (unheated, A2 and A2 + 50%) that were applied for 11 years prior to the present experiment. The simulated HW consisted of 5 °C extra temperature increases only in the A2 and A2 + 50% treatments applied from 1 July to 1 August 2014. Linear mixed effect modeling revealed a strong effect of nutrient treatment on the concentration of chlorophyll a (Chl-a), on various forms of phosphorus and nitrogen as well as on oxygen concentration and oxygen percentage (24 h means). Applying the full dataset, we also found a significant positive effect of nutrient loading on GPP, ER, NEP and BACPR, and of temperature on ER and BACPR. The HW had a significant positive effect on GPP and ER. When dividing the data into LN and HN, temperature also had a significant positive effect on Chl-a in LN and on orthophosphate in HN. Linear mixed models revealed differential effects of nutrients, Chl-a and macrophyte abundance (PVI) on the metabolism variables, with PVI being particularly important in the LN mesocosms. All metabolism variables also responded strongly to a cooling-low irradiance event in the middle of the HW, resulting in a severe drop in oxygen concentrations, not least in the HN heated mesocosms. Our results demonstrate strong effects of nutrients as well as an overall rapid response in oxygen metabolism and BACPR to changes in temperature, including HWs, making them sensitive ecosystem indicators of climate warming.

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 Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

2009 ◽  
Vol 6 (1) ◽  
pp. 85-102 ◽  
Author(s):  
G. Fischer ◽  
G. Karakaş
Keyword(s):  
Organic Carbon ◽  
Atlantic Ocean ◽  
Sediment Trap ◽  
Carbon Flux ◽  
Coastal Upwelling ◽  
Production Systems ◽  
Deep Ocean ◽  
Biogeochemical Model ◽  
Carbonate Content ◽  
Organic Carbon Flux

Abstract. The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opal-rich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of 0.29 Tg per year down to 3000 m off the NW African upwelling region between 5 and 35° N. Simple parameterisations of remineralisation and sinking rates in such models, however, limit their capability in reproducing the flux variation in the water column.

scholarly journals Selenium supply affects chlorophyll concentration and biomass production of maize (Zea mays L.)

2018 ◽  
Vol 69 (4) ◽  
pp. 249-255
Author(s):  
Aliu Sali ◽  
Dukagjin Zeka ◽  
Shukri Fetahu ◽  
Imer Rusinovci ◽  
Hans-Peter Kaul
Keyword(s):  
Biomass Production ◽  
Root Biomass ◽  
Zea Mays L ◽  
Chlorophyll Concentration ◽  
Total Chlorophyll ◽  
Chl A ◽  
Maize Population ◽  
Maize Genotypes ◽  
Positive Effect ◽  
Shoot And Root Biomass

Summary The objective of this work was to investigate the effect of selenium (Se) on the biomass production and the contents of photosynthetically active pigments. The pot experiment included two maize genotypes: hybrid 408BC originating from Croatia and a local maize population from Kosovo. The doses of Se applied were 0, 1.30, 6.57, 13, and 26 mg kg−1. The lowest Se dose (1.30 mg Se kg−1) had a positive effect on shoot and root biomass production as well as on the contents of chlorophyll b (Chl-b), total chlorophyll, and carotenoids (just for the hybrid). Chlorophyll a (Chl-a) was reduced with increasing Se doses, whereas chlorophyll b (Chl-b) and total chlorophyll further increased with medium Se doses. The highest Se dose strongly reduced biomass and the contents of photosynthetically active pigments. Chl-a and carotenoids positively correlated with shoot (for both genotypes) and root (for the hybrid) biomass, whereas no correlation was observed between Chl-b and biomass. Low amounts of Se application are favorable for biomass production and chlorophyll and carotenoids contents, whereas high amounts of Se application negatively affect both.

scholarly journals Investigation of the abundance, distribution and composition of microplastics at coastal upwelling sites in the Atlantic Ocean

2016 ◽  
Author(s):  
La Daana K Kanhai ◽  
Rick Officer ◽  
Ian O'Connor ◽  
Richard C Thompson
Keyword(s):  
Atlantic Ocean ◽  
Surface Waters ◽  
Primary Productivity ◽  
Null Hypothesis ◽  
Latitudinal Gradient ◽  
Coastal Upwelling ◽  
Abundance Distribution ◽  
Significant Difference ◽  
Benguela Upwelling ◽  
Canary Upwelling

Microplastics are an issue of international concern due to the fact that these substances may potentially threaten biota by (i) causing physical harm, (ii) transporting persistent, bioaccumulating and toxic (PBT) substances and, (iii) leaching plastic additives. Within the world’s oceans, areas which experience coastal upwelling are biota rich due to their high levels of primary productivity. The assessment of microplastic presence in areas which experience coastal upwelling is vital as it will indicate whether microplastics are an issue of concern in areas which support key biological resources. The null hypothesis of the present study is that microplastic abundance will be lower in areas where there is upwelling. As such, the present study aims to investigate whether microplastic abundance in upwelled areas in the Atlantic Ocean is significantly different from non-upwelled areas. Based on an opportunistic voyage aboard the RV Polarstern, microplastics will be sampled in sub-surface waters along a diverse latitudinal gradient in the Atlantic Ocean i.e. from Bremerhaven (Germany) to Cape Town (South Africa). Based on the proposed route, it will be possible to determine microplastic levels at two areas of coastal upwelling in the Atlantic Ocean (i) Canary Upwelling Ecosystem (CUE) and (ii) Benguela Upwelling Ecosystem (BUE). The results will then be analysed to determine whether there was a statistically significant difference between ‘upwelled areas’ and ‘non-upwelled areas’.

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