scholarly journals Independent iron and light limitation in a low-light-adapted Prochlorococcus from the deep chlorophyll maximum

2020 ◽  
Vol 15 (1) ◽  
pp. 359-362
Author(s):  
Nicholas J. Hawco ◽  
Feixue Fu ◽  
Nina Yang ◽  
David A. Hutchins ◽  
Seth G. John
Keyword(s):  
Light Intensity ◽  
High Efficiency ◽  
Iron Concentration ◽  
Euphotic Zone ◽  
Theoretical Models ◽  
Light Limitation ◽  
Deep Chlorophyll Maximum ◽  
North Pacific Subtropical Gyre ◽  
Low Light ◽  
Chlorophyll Maximum

AbstractThroughout the open ocean, a minimum in dissolved iron concentration (dFe) overlaps with the deep chlorophyll maximum (DCM), which marks the lower limit of the euphotic zone. Maximizing light capture in these dim waters is expected to require upregulation of Fe-bearing photosystems, further depleting dFe and possibly leading to co-limitation by both iron and light. However, this effect has not been quantified for important phytoplankton groups like Prochlorococcus, which contributes most of the productivity in the oligotrophic DCM. Here, we present culture experiments with Prochlorococcus strain MIT1214, a member of the Low Light 1 ecotype isolated from the DCM in the North Pacific subtropical gyre. Under a matrix of iron and irradiance matching those found at the DCM, the ratio of Fe to carbon in Prochlorococcus MIT1214 cells ranged from 10–40 × 10−6 mol Fe:mol C and increased with light intensity and growth rate. These results challenge theoretical models predicting highest Fe:C at lowest light intensity, and are best explained by a large photosynthetic Fe demand that is not downregulated at higher light. To sustain primary production in the DCM with the rigid Fe requirements of low-light-adapted Prochlorococcus, dFe must be recycled rapidly and at high efficiency.

High-efficiency Sb2S3-based hybrid solar cell at low light intensity: cell made of synthesized Cu and Se-doped Sb2S3

2015 ◽  
Vol 24 (5) ◽  
pp. 704-715 ◽  
Author(s):  
Valentina Janošević ◽  
Miodrag Mitrić ◽  
Nenad Bundaleski ◽  
Zlatko Rakočević ◽  
Ivana Lj Validžić
Keyword(s):  
Solar Cell ◽  
Light Intensity ◽  
High Efficiency ◽  
Hybrid Solar Cell ◽  
Low Light ◽  
Low Light Intensity

scholarly journals Analytical solution of nitracline with the evolution of subsurface chlorophyll maximum in stratified water columns

2016 ◽  
Author(s):  
Xiang Gong ◽  
Wensheng Jiang ◽  
Linhui Wang ◽  
Huiwang Gao ◽  
Emmanuel Boss ◽  
...  
Keyword(s):  
Light Intensity ◽  
Analytical Solution ◽  
Primary Production ◽  
Attenuation Coefficient ◽  
Light Attenuation ◽  
Euphotic Zone ◽  
Light Level ◽  
Chlorophyll Maximum ◽  
Subsurface Chlorophyll Maximum ◽  
Light Attenuation Coefficient

Abstract. In a stratified water column, the nitracline is a layer where the nitrate concentration increases below the nutrient-depleted upper layer, exhibiting a strong vertical gradient in the euphotic zone. The subsurface chlorophyll maximum layer (SCML) forms near the bottom of euphotic zone, acting as a trap to diminish the upward nutrient supply. Depth and steepness of the nitracline are important measurable parameters related to the vertical transport of nitrate into the euphotic zone. The correlation between the SCML and the nitracline has been widely reported in the literature, but the analytic solution for the relationship between them is not well established. By incorporating a piecewise function for the approximate Gaussian vertical profile of chlorophyll, we derive analytical solutions for the system of phytoplankton and nutrient. The analytical solution shows that the nitracline depth is deeper than the depth of SCML, shoaling with an increase in light attenuation coefficient and with a decrease in surface light intensity. The inverse proportional relationship between the light level at the nitracline depth and the maximum rate of new primary production is derived, suggesting that the light level at the nitracline can be used as an indicator for integrated new primary production. Analytic solutions also show that a thinner SCML corresponds to a steeper nitracline. The nitracline steepness is positively related to light attenuation coefficient, but independent of surface light intensity. The derived equations of the nitracline in relation to the SCML provide further insight into the important role of the nitracline in marine pelagic ecosystems.

Contribution of Rhizosolenia eriensis and Cyclotella spp. to the Deep Chlorophyll Maximum of Sproat Lake, British Columbia, Canada

1990 ◽  
Vol 47 (1) ◽  
pp. 128-135 ◽  
Author(s):  
Leland J. Jackson ◽  
John G. Stockner ◽  
Paul J. Harrison
Keyword(s):  
Spatial Separation ◽  
Deep Chlorophyll Maximum ◽  
Nitrogen And Phosphorus ◽  
Low Light ◽  
Temporal And Spatial Distribution ◽  
Neutral Buoyancy ◽  
Chlorophyll Maximum ◽  
Centric Diatoms ◽  
Temporal And Spatial ◽  
Lake Fertilization

Experimental fertilization of Sproat Lake with nitrogen and phosphorus greatly increased the abundance of two centric diatoms: Cyclotella spp. and Rhizosolenia eriensis. A decrease in sinking rates to neutral buoyancy at 17.5–22.5 m, an area of high nutrients and low light, coupled with sedimentation estimates of 106–107 celis∙m−2∙d−1, provide strong evidence that diatoms contribute to the formation of a seasonal deep chlorophyll maximum (DCM). The position of the Sproat Lake DCM, occurring at or just above the 1% light depth, appears to be largely determined by the light regime. R. eriensis bloomed and sank out of the mixed layer early in the spring before lake fertilization began. Immediately after fertilization, concentrations of nitrate and phosphate were elevated for 1 h only in the top 1 m of the water column. Most R. eriensis cells were well below 1 m and benefited little from the nutrient addition because of temporal and spatial separation. Cyclotella spp. occurred in the upper epilimnion and bloomed later in the year and consequently benefited (by large density increases) from fertilization. It is important to consider the temporal and spatial distribution of phytoplankton in determining which species will increase in abundance as a result of areal fertilization.

scholarly journals How Diffusivity, Thermocline and Incident Light Intensity Modulate the Dynamics of Deep Chlorophyll Maximum in Tyrrhenian Sea

PLoS ONE ◽  
2015 ◽  
Vol 10 (1) ◽  
pp. e0115468 ◽  
Author(s):  
Davide Valenti ◽  
Giovanni Denaro ◽  
Bernardo Spagnolo ◽  
Fabio Conversano ◽  
Christophe Brunet
Keyword(s):  
Light Intensity ◽  
Incident Light ◽  
Tyrrhenian Sea ◽  
Deep Chlorophyll Maximum ◽  
Incident Light Intensity ◽  
Chlorophyll Maximum

scholarly journals Steady-state solutions for subsurface chlorophyll maximum in stratified water columns with a bell-shaped vertical profile of chlorophyll

2015 ◽  
Vol 12 (4) ◽  
pp. 905-919 ◽  
Author(s):  
X. Gong ◽  
J. Shi ◽  
H. W. Gao ◽  
X. H. Yao
Keyword(s):  
Steady State ◽  
Light Intensity ◽  
Vertical Profile ◽  
Light Attenuation ◽  
Gaussian Function ◽  
Light Limitation ◽  
Chl A ◽  
Chlorophyll Maximum ◽  
Subsurface Chlorophyll Maximum ◽  
Steady State Solutions

Abstract. A bell-shaped vertical profile of chlorophyll a (Chl a) concentration, conventionally referred to as a subsurface chlorophyll maximum (SCM) phenomenon, has frequently been observed in stratified oceans and lakes. This profile is assumed to be a general Gaussian distribution in this study. By substituting the general Gaussian function into ecosystem dynamical equations, the steady-state solutions for SCM characteristics (i.e., SCM layer depth, thickness, and intensity) in various scenarios are derived. These solutions indicate that (1) the maximum concentration of Chl a occurs at or below the depth of maximum growth rates of phytoplankton located at the transition from nutrient limitation to light limitation, and the depth of SCM layer deepens logarithmically with an increase in surface light intensity; (2) thickness and intensity of the SCM layer are mainly affected by nutrient supply, but independent of surface light intensity; and (3) intensity of the SCM layer is proportional to the diffusive flux of nutrients from below, which becomes stronger as a result of this layer being shrunk by a higher light attenuation coefficient or a larger sinking velocity of phytoplankton. In addition, the limitation and potential application of the analytical solutions are also presented.

scholarly journals Analytical solution of the nitracline with the evolution of subsurface chlorophyll maximum in stratified water columns

2017 ◽  
Vol 14 (9) ◽  
pp. 2371-2386 ◽  
Author(s):  
Xiang Gong ◽  
Wensheng Jiang ◽  
Linhui Wang ◽  
Huiwang Gao ◽  
Emmanuel Boss ◽  
...  
Keyword(s):  
Light Intensity ◽  
Analytical Solution ◽  
Attenuation Coefficient ◽  
Light Attenuation ◽  
Euphotic Zone ◽  
Vertical Gradient ◽  
Light Level ◽  
Chlorophyll Maximum ◽  
Subsurface Chlorophyll Maximum ◽  
Light Attenuation Coefficient

Abstract. In a stratified water column, the nitracline is a layer where the nitrate concentration increases below the nutrient-depleted upper layer, exhibiting a strong vertical gradient in the euphotic zone. The subsurface chlorophyll maximum layer (SCML) forms near the bottom of the euphotic zone, acting as a trap to diminish the upward nutrient supply. Depth and steepness of the nitracline are important measurable parameters related to the vertical transport of nitrate into the euphotic zone. The correlation between the SCML and the nitracline has been widely reported in the literature, but the analytic solution for the relationship between them is not well established. By incorporating a piecewise function for the approximate Gaussian vertical profile of chlorophyll, we derive analytical solutions of a specified nutrient–phytoplankton model. The model is well suited to explain basic dependencies between a nitracline and an SCML. The analytical solution shows that the nitracline depth is deeper than the depth of the SCML, shoaling with an increase in the light attenuation coefficient and with a decrease in surface light intensity. The inverse proportional relationship between the light level at the nitracline depth and the maximum rate of new primary production is derived. Analytic solutions also show that a thinner SCML corresponds to a steeper nitracline. The nitracline steepness is positively related to the light attenuation coefficient but independent of surface light intensity. The derived equations of the nitracline in relation to the SCML provide further insight into the important role of the nitracline in marine pelagic ecosystems.

Effect of Nutrient Additions on Lower Trophic Levels of an Oligotrophic Lake with a Seasonal Deep Chlorophyll Maximum

1990 ◽  
Vol 47 (2) ◽  
pp. 262-273 ◽  
Author(s):  
Ken S. Shortreed ◽  
John G. Stockner
Keyword(s):  
Inorganic Nitrogen ◽  
Euphotic Zone ◽  
Fold Increase ◽  
Trophic Levels ◽  
Deep Chlorophyll Maximum ◽  
Nitrogen And Phosphorus ◽  
Chlorophyll Maximum ◽  
Nutrient Additions ◽  
Prominent Component ◽  
Dominant Member

Inorganic nitrogen and phosphorus were added to the surface of selected areas of Sproat Lake, Vancouver Island, British Columbia for varying periods in 1985 and 1986. The lake is monomictic, oligotrophic, and for much of each year has a deep chlorophyll maximum (DCM) located near the bottom of the euphotic zone (20–25 m). Epilimnetic chlorophyll concentrations are low (ca. 0.5 μg∙L−1) in summer, and DCM concentrations are from three to 10 times higher. The diatom Rhizosolenia eriensis was a dominant species in the epilimnion in spring and at the DCM for much of the year, but was rare in the epilimnion during summer, and consequently was not affected by the nutrient additions. Cyclotella spp. were also abundant in spring, were a prominent component of the DCM, and increased in abundance during nutrient additions. The cyanobacterium Synechococcus was the dominant member of the autotrophic picoplankton community and during the nutrient additions densities reached 300 000∙mL−1 (a 10-fold increase). Bacterioplankton numbers also increased during nutrient additions, at times exceeding 3.0 × 106∙mL−1. The DCM was formed and maintained by sinking cells, by occasional active photosynthesis at the DCM, and by an increase in chlorophyll/cell.

scholarly journals Steady-state solutions for subsurface chlorophyll maximum in stratified water columns with a bell-shape vertical profile of chlorophyll

2014 ◽  
Vol 11 (6) ◽  
pp. 9511-9538
Author(s):  
X. Gong ◽  
J. Shi ◽  
H. W. Gao ◽  
X. H. Yao
Keyword(s):  
Steady State ◽  
Light Intensity ◽  
Vertical Profile ◽  
Light Attenuation ◽  
Gaussian Function ◽  
Light Limitation ◽  
Chl A ◽  
Chlorophyll Maximum ◽  
Subsurface Chlorophyll Maximum ◽  
Steady State Solutions

Abstract. A bell-shape vertical profile of chlorophyll a (Chl a) concentration, conventionally referred as Subsurface Chlorophyll Maximum (SCM) phenomenon, has frequently been observed in stratified oceans and lakes. This profile is assumed to be a general Gaussian distribution in this study. By substituting the general Gaussian function into ecosystem dynamical equations, the steady-state solutions for SCM characteristics (i.e. SCM layer depth, thickness, and intensity) in various scenarios are derived. These solutions indicate that: (1) The maximum in Chl a concentrations occurs at or below the depth with the maximum in growth rates of phytoplankton locating at the transition from nutrient limitation to light limitation, and the depth of SCM layer deepens logarithmically with an increase in surface light intensity; (2) The shape of SCM layer (thickness and intensity) is mainly influenced by nutrient supply, but independence of surface light intensity; (3) The intensity of SCM layer is proportional to the diffusive flux of nutrient from below, getting stronger as a result of this layer being shrank by a higher light attenuation coefficient or a larger sinking velocity of phytoplankton. The analytical solutions can be useful to estimate environmental parameters difficultly obtained from on-site observations.

Seasonal Dynamics of the Deep-Chlorophyll Maximum in Castle Lake, California

1983 ◽  
Vol 40 (2) ◽  
pp. 208-214 ◽  
Author(s):  
John C. Priscu ◽  
Charles R. Goldman
Keyword(s):  
Primary Productivity ◽  
Chlorophyll Concentration ◽  
Euphotic Zone ◽  
Deep Chlorophyll Maximum ◽  
Deep Basin ◽  
Photoautotrophic Growth ◽  
Chlorophyll Maximum ◽  
Early Portion ◽  
Castle Lake ◽  
Do So

Vertical profiles of chlorophyll concentration measured during 1980 in Castle Lake showed that a deep maximum developed immediately after ice thaw and persisted in the deep basin of the lake until autumn overturn. In the early portion of the ice-free season, low epilimnetic turbidity allows enough light to reach this deep-chlorophyll layer to produce a deep-primary productivity maximum. Photoautotrophic growth appears to maintain the deep-chlorophyll maximum early in the season whereas the accumulation of sinking organisms appears to do so later in the season. Although the deep-water phytoplankton have reduced rates of photosynthesis late in the season, they maintain their ability to photosynthesize immediately upon exposure to light. Consequently, the redistribution of deepwater chlorophyll at fall overturn can increase the chlorophyll concentration of the euphotic zone (0–15 m) by 58% which can potentially increase primary productivity in this zone by 81%.Key words: deep-chlorophyll maximum, primary productivity, aphotic viability

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