scholarly journals Fertilization of an oligotrophic lake with a deep chlorophyll maximum: predicting the effect on primary productivity

1997 ◽  
Vol 54 (5) ◽  
pp. 1177-1189 ◽  
Author(s):  
H P Gross ◽  
W A Wurtsbaugh ◽  
C Luecke ◽  
P Budy
Keyword(s):  
Primary Production ◽  
Chlorophyll A ◽  
Primary Productivity ◽  
Sockeye Salmon ◽  
Deep Chlorophyll Maximum ◽  
Light Penetration ◽  
Low Light ◽  
Nutrient Additions ◽  
Light Levels ◽  
The Mean

We investigated how epilimnetic fertilization would affect chlorophyll levels and light penetration of oligotrophic sockeye salmon (Oncorhynchus nerka) lakes and how the resulting self-shading would affect primary production of the prominent deep chlorophyll maxima (DCM) of the lakes. Epilimnetic nutrient additions to large mesocosms (330 m3) in Redfish Lake, Idaho, increased levels of primary productivity and chlorophyll a but decreased Secchi depths and light available in the metalimnion and hypolimnion. Redfish Lake and other Sawtooth Valley (Idaho) lakes had DCM in which the mean chlorophyll a peaks were 240-1000% of mean epilimnetic chlorophyll a concentrations. The DCM existed at low light levels and accounted for 36-72% of the lakes' primary production. Simulations using photosynthesis-irradiance (P-I) curves demonstrated that fertilization would increase predicted water column primary production by 75-101%. Most of this increase occurred in the epilimnion, with only a slight decrease occurring in the DCM as the result of increased shading.

Primary Productivity of Southern Indian Lake before, during, and after Impoundment and Churchill River Diversion

1984 ◽  
Vol 41 (4) ◽  
pp. 591-604 ◽  
Author(s):  
R. E. Hecky ◽  
S. J. Guildford
Keyword(s):  
Light Intensity ◽  
Primary Production ◽  
Water Column ◽  
Primary Productivity ◽  
Phosphorus Deficiency ◽  
Light Environment ◽  
Phytoplankton Production ◽  
Light Penetration ◽  
The Mean ◽  
Chlorophyll Concentrations

The primary productivity of seven regions of Southern Indian Lake and neighboring Wood Lake was measured during open-water seasons from 1974 to 1978. The lake had regional differences in chlorophyll concentrations and daily rates of integral primary production in 1974 and 1975 prior to impoundment of the lake. Regions receiving Churchill River flow tended to have higher chlorophyll concentrations and production rates than those regions marginal to the flow. Impoundment of the lake resulted in higher efficiencies of primary production in all regions, as indicated by higher light-saturated rates of carbon uptake per unit chlorophyll and by higher initial slopes of the hyperbolic light response relation of the phytoplankton. Many large basins of the lake had light penetration reduced by high concentrations of suspended sediment from eroding shorelines, while other areas had relatively unchanged light penetration. The increased efficiency of carbon fixation per unit chlorophyll resulted in higher rates of integral production in those regions where light penetration was not greatly affected. Daily rates of integral primary production in lake regions where light penetration had decreased markedly were not significantly different after impoundment because efficiencies of light utilization were higher. Comparison of the mean water column light intensities for those turbid regions with the values of Ik (light intensity at the onset of light saturation) for phytoplankton indicated that these turbid regions are now light deficient on average. Phosphorus deficiency, as indicated by alkaline phosphatase activity per unit ATP, which was present before impoundment, has been eliminated as the mean water column light intensity declined below 5 mEinsteins∙m−2∙min−1. The light environment of a new reservoir can be a significant determinant of integral production, and predicting the consequences of impoundment on phytoplankton production requires accurate prediction of the light environment.

Effect of Vineyard Row Orientation on Growth and Phenology of Glyphosate-Resistant and Glyphosate-Susceptible Horseweed (Conyza canadensis)

Weed Science ◽  
2011 ◽  
Vol 59 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Marisa Alcorta ◽  
Matthew W. Fidelibus ◽  
Kerri L. Steenwerth ◽  
Anil Shrestha
Keyword(s):  
Leaf Area ◽  
Growth And Development ◽  
Dry Weight ◽  
Conyza Canadensis ◽  
Light Penetration ◽  
Low Light ◽  
Weed Growth ◽  
Light Levels ◽  
East West ◽  
Number Of Seeds

Horseweed has become increasingly common and difficult to control in San Joaquin Valley vineyards, due in part, to the evolution of glyphosate resistance. The development of weed-suppressive vineyard designs in which the trellis design, spacing, and row orientation combine to cast dense shade on the weed canopy zone (WCZ) may reduce weed growth. The relevance of such a system to horseweed, which can grow to be as tall, or taller, than a typical grapevine trellis, is uncertain. Also unknown is whether a glyphosate-resistant (GR) biotype and glyphosate-susceptible (GS) biotype would perform similarly under such conditions. Therefore, we compared the growth and development of two potted horseweed biotypes (GR and GS) in vinerows oriented east–west (EW) and north–south (NS). Rows oriented EW allowed less light penetration to the WCZ than NS rows throughout the study, and horseweed biotypes responded to low light levels by producing leaves with larger specific leaf area and leaf area ratios than those in the NS rows. Also, the leaf, stem, and root dry weight of the horseweed plants in the EW rows was reduced by 30% compared to the horseweed plants in NS rows. Leaf number was also reduced in the horseweed plants in the EW rows, but only for the GS biotype. Row orientation did not affect phenological development or the number of seeds produced by the GR or GS biotypes, but the GR biotype budded, flowered, and set seed approximately 1 wk earlier than the GS biotype. Thus, shade associated with the EW vinerows reduced horseweed growth, but not fecundity, and the GR biotype reached reproductive maturity earlier than the GS biotype.

scholarly journals Seasonal and spatial patterns of primary production in a high-latitude fjord affected by Greenland Ice Sheet run-off

2019 ◽  
Vol 16 (19) ◽  
pp. 3777-3792 ◽  
Author(s):  
Johnna M. Holding ◽  
Stiig Markager ◽  
Thomas Juul-Pedersen ◽  
Maria L. Paulsen ◽  
Eva F. Møller ◽  
...  
Keyword(s):  
Primary Production ◽  
Primary Productivity ◽  
Phytoplankton Biomass ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Day Length ◽  
Light Limitation ◽  
Spatial Gradient ◽  
Low Light ◽  
Run Off

Abstract. Primary production on the coast and in Greenland fjords sustains important local and sustenance fisheries. However, unprecedented melting of the Greenland Ice Sheet (GrIS) is impacting the coastal ocean, and its effects on fjord ecology remain understudied. It has been suggested that as glaciers retreat, primary production regimes may be altered, rendering fjords less productive. Here we investigate patterns of primary productivity in a northeast Greenland fjord (Young Sound, 74∘ N), which receives run-off from the GrIS via land-terminating glaciers. We measured size fractioned primary production during the ice- free season along a spatial gradient of meltwater influence. We found that, apart from a brief under-ice bloom during summer, primary production remains low (between 50 and 200 mg C m−2 d−1) but steady throughout the ice-free season, even into the fall. Low productivity is due to freshwater run-off from land-terminating glaciers causing low light availability and strong vertical stratification limiting nutrient availability. The former is caused by turbid river inputs in the summer restricting phytoplankton biomass to the surface and away from the nitracline. In the outer fjord where turbidity plays less of a role in light limitation, phytoplankton biomass moves higher in the water column in the fall due to the short day length as the sun angle decreases. Despite this, plankton communities in this study were shown to be well adapted to low-light conditions, as evidenced by the low values of saturating irradiance for primary production (5.8–67 µmol photons m−2 s−1). With its low but consistent production across the growing season, Young Sound offers an alternative picture to other more productive fjords which have highly productive spring and late summer blooms and limited fall production. However, patterns of primary productivity observed in Young Sound are not only due to the influence from land-terminating glaciers but are also consequences of the nutrient-depleted coastal boundary currents and the shallow entrance sill, features which should also be considered when generalizing about how primary production will be affected by glacier retreat in the future.

Novel Technique for Rapid and Accurate Insertion of a Microguidewire Tail Into Low-Profile Devices During Endovascular Procedures: The Paper Rail Method

2018 ◽  
Vol 25 (5) ◽  
pp. 614-616 ◽  
Author(s):  
Tomotaka Ohshima ◽  
Shigeru Miyachi ◽  
Naoki Matsuo ◽  
Reo Kawaguchi ◽  
Aichi Niwa ◽  
...  
Keyword(s):  
Operating Room ◽  
Endovascular Procedures ◽  
Nonwoven Fabric ◽  
Low Light ◽  
Novel Technique ◽  
Light Levels ◽  
Low Profile ◽  
The Mean ◽  
The Times ◽  
Mean Time

Purpose: To report a novel technique (“paper rail”) to facilitate inserting the tail of a microguidewire into the tip of a low-profile device during endovascular procedures. Technique: A sterilized nonwoven fabric tape with a smooth glossy paper backing is used. The tape has several linear folds ideal for a paper rail. Holding each piece of equipment about 5 cm from its respective tip, both the tail of the guidewire and the tip of the catheter are navigated at a 30° angle toward each other in the crease until the guidewire enters the catheter. The paper rail technique was compared with the conventional freehand method under varying luminosities found in an operating room. The paper rail technique was most effective in suboptimal lighting, where the mean time was reduced from 83 seconds with the conventional method to 20 seconds with the paper rail maneuver. The times required to insert the wire with the paper rail method were comparable (~22 seconds) at all light levels. Conclusion: The paper rail method may help improve the speed and accurate insertion of the tail of a microguidewire into the tip of low-profile devices during endovascular procedures. It may be particularly useful for physicians in a low-light environment or trainees.

Importance of Latitude and Organic Color on Phytoplankton Primary Productivity in Florida Lakes

1991 ◽  
Vol 48 (7) ◽  
pp. 1145-1150 ◽  
Author(s):  
John R. Beaver ◽  
Thomas L. Crisman
Keyword(s):  
Primary Production ◽  
Chlorophyll A ◽  
Primary Productivity ◽  
Phytoplankton Biomass ◽  
Nutrient Concentrations ◽  
Empirical Equations ◽  
Strongly Correlated ◽  
Florida Lakes ◽  
Vegetative Season

A characterization of primary productivity patterns in subtropical Florida lakes along increasing gradients of both dissolved organic color and phytoplankton biomass is presented. Volumetric expression of gross primary productivity was more strongly correlated with chlorophyll a and nutrient concentrations than was areal expression. Primary production in clearwater (<75 Pt units) lakes was more predictable than colored (>75 Pt units) lakes. Areal production in Florida lakes was intermediate to the tropical and temperate regions, although volumetric productivity during the vegetative season (May–September) was not significantly different from temperate zone lakes for the same period. Predictive abilities of empirical equations describing primary productivity in Florida lakes are improved by distinguishing colored and clear lakes.

scholarly journals Seasonal and spatial patterns of primary production in a high-latitude fjord affected by Greenland Ice Sheet run-off

2019 ◽  
Author(s):  
Johnna M. Holding ◽  
Stiig Markager ◽  
Thomas Juul-Pedersen ◽  
Maria L. Paulsen ◽  
Eva F. Møller ◽  
...  
Keyword(s):  
Primary Production ◽  
Primary Productivity ◽  
Phytoplankton Biomass ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Day Length ◽  
Light Limitation ◽  
Spatial Gradient ◽  
Low Light ◽  
Run Off

Abstract. Primary production on the coast and in Greenland fjords sustains important local and sustenance fisheries. However, unprecedented melting of the Greenland Ice Sheet (GrIS) is impacting the coastal ocean, and its effects on fjord ecology remain understudied. It has been suggested that as glaciers retreat, primary production regimes may be altered rendering fjords less productive. Here we investigate patterns of primary productivity in a Northeast Greenland fjord (Young Sound, 74 N), which receives run-off from the GrIS via land-terminating glaciers. We measured size fractioned primary production during the ice- free season along a spatial gradient of meltwater influence. We found that, apart from a brief under-ice bloom during summer, primary production remains low (between 50–200 mg C m−2 day−1) however steady throughout the ice-free season, even into the fall. Low productivity is due to freshwater run-off from land-terminating glaciers causing low light availability and strong vertical stratification limiting nutrient availability. The former is caused by turbid river inputs in the summer restricting phytoplankton biomass to the surface and away from the nitracline. In the outer fjord where turbidity plays less of a role in light limitation, phytoplankton biomass moves higher in the water column in the fall due to the short day- length as the sun angle decreases. Despite this, plankton communities in this study were shown to be well adapted to low light conditions, as evidenced by the low values of saturating irradiance for primary production (5.8–67 µmol photons m−2 s−1). With its low but consistent production across the growing season, Young Sound offers an alternative picture to other more productive fjords which have highly productive spring and late summer blooms and limited fall production. However, patterns of primary productivity observed in Young Sound are not only due to the influence from land-terminating glaciers but are also consequences of the nutrient deplete coastal boundary currents and the shallow entrance sill, features which should also be considered when generalizing about how primary production will be affected by glacier retreat in the future.

In Vivo Fluorescence of Chlorophyll A: Estimation of Phytoplankton Biomass and Activity in Římov Reservoir (Czech Republic)

1993 ◽  
Vol 28 (6) ◽  
pp. 29-33 ◽  
Author(s):  
V. Vyhnálek ◽  
Z. Fišar ◽  
A. Fišarová ◽  
J. Komárková
Keyword(s):  
Czech Republic ◽  
Chlorophyll Fluorescence ◽  
Primary Production ◽  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
In Vivo Fluorescence ◽  
Fluorescence Of Chlorophyll A ◽  
Římov Reservoir ◽  
Natural Phytoplankton

The in vivo fluorescence of chlorophyll a was measured in samples of natural phytoplankton taken from the Římov Reservoir (Czech Republic) during the years 1987 and 1988. The fluorescence intensities of samples either with or without addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron, DCMU) were found reliable for calculating the concentration of chlorophyll a during periods when cyanobacteria were not abundant. The correction for background non-chlorophyll fluorescence appeared to be essential. No distinct correlation between a DCMU-induced increase of the fluorescence and primary production of phytoplankton was found.

scholarly journals Remote Sensing to Study Mangrove Fragmentation and Its Impacts on Leaf Area Index and Gross Primary Productivity in the South of Peninsular Malaysia

2021 ◽  
Vol 13 (8) ◽  
pp. 1427
Author(s):  
Kasturi Devi Kanniah ◽  
Chuen Siang Kang ◽  
Sahadev Sharma ◽  
A. Aldrie Amir
Keyword(s):  
Remote Sensing ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Primary Productivity ◽  
Peninsular Malaysia ◽  
Area Index ◽  
Mangrove Area ◽  
The Mean ◽  
Shape Complexity ◽  
The Impact

Mangrove is classified as an important ecosystem along the shorelines of tropical and subtropical landmasses, which are being degraded at an alarming rate despite numerous international treaties having been agreed. Iskandar Malaysia (IM) is a fast-growing economic region in southern Peninsular Malaysia, where three Ramsar Sites are located. Since the beginning of the 21st century (2000–2019), a total loss of 2907.29 ha of mangrove area has been estimated based on medium-high resolution remote sensing data. This corresponds to an annual loss rate of 1.12%, which is higher than the world mangrove depletion rate. The causes of mangrove loss were identified as land conversion to urban, plantations, and aquaculture activities, where large mangrove areas were shattered into many smaller patches. Fragmentation analysis over the mangrove area shows a reduction in the mean patch size (from 105 ha to 27 ha) and an increase in the number of mangrove patches (130 to 402), edge, and shape complexity, where smaller and isolated mangrove patches were found to be related to the rapid development of IM region. The Moderate Resolution Imaging Spectro-radiometer (MODIS) Leaf Area Index (LAI) and Gross Primary Productivity (GPP) products were used to inspect the impact of fragmentation on the mangrove ecosystem process. The mean LAI and GPP of mangrove areas that had not undergone any land cover changes over the years showed an increase from 3.03 to 3.55 (LAI) and 5.81 g C m−2 to 6.73 g C m−2 (GPP), highlighting the ability of the mangrove forest to assimilate CO2 when it is not disturbed. Similarly, GPP also increased over the gained areas (from 1.88 g C m−2 to 2.78 g C m−2). Meanwhile, areas that lost mangroves, but replaced them with oil palm, had decreased mean LAI from 2.99 to 2.62. In fragmented mangrove patches an increase in GPP was recorded, and this could be due to the smaller patches (<9 ha) and their edge effects where abundance of solar radiation along the edges of the patches may increase productivity. The impact on GPP due to fragmentation is found to rely on the type of land transformation and patch characteristics (size, edge, and shape complexity). The preservation of mangrove forests in a rapidly developing region such as IM is vital to ensure ecosystem, ecology, environment, and biodiversity conservation, in addition to providing economical revenue and supporting human activities.

scholarly journals Shading Effects on Leaf Gas Exchange, Leaf Pigments and Secondary Metabolites of Polygonum minus Huds., an Aromatic Medicinal Herb

Plants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 608
Author(s):  
Fairuz Fatini Mohd Yusof ◽  
Jamilah Syafawati Yaacob ◽  
Normaniza Osman ◽  
Mohd Hafiz Ibrahim ◽  
Wan Abd Al Qadr Imad Wan-Mohtar ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Secondary Metabolites ◽  
Chlorophyll A ◽  
Leaf Gas Exchange ◽  
Photosynthesis Rate ◽  
Total Phenolic ◽  
Chlorophyll B ◽  
Low Light ◽  
Total Anthocyanin ◽  
Polygonum Minus

The growing demand for high value aromatic herb Polygonum minus-based products have increased in recent years, for its antioxidant, anticancer, antimicrobial, and anti-inflammatory potentials. Although few reports have indicated the chemical profiles and antioxidative effects of Polygonum minus, no study has been conducted to assess the benefits of micro-environmental manipulation (different shading levels) on the growth, leaf gas exchange and secondary metabolites in Polygonum minus. Therefore, two shading levels (50%:T2 and 70%:T3) and one absolute control (0%:T1) were studied under eight weeks and 16 weeks of exposures on Polygonum minus after two weeks. It was found that P. minus under T2 obtained the highest photosynthesis rate (14.892 µmol CO2 m−2 s−1), followed by T3 = T1. The increase in photosynthesis rate was contributed by the enhancement of the leaf pigments content (chlorophyll a and chlorophyll b). This was shown by the positive significant correlations observed between photosynthesis rate with chlorophyll a (r2 = 0.536; p ≤ 0.05) and chlorophyll b (r2 = 0.540; p ≤ 0.05). As the shading levels and time interval increased, the production of total anthocyanin content (TAC) and antioxidant properties of Ferric Reducing Antioxidant Power (FRAP) and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) also increased. The total phenolic content (TPC) and total flavonoid content (TFC) were also significantly enhanced under T2 and T3. The current study suggested that P.minus induce the production of more leaf pigments and secondary metabolites as their special adaptation mechanism under low light condition. Although the biomass was affected under low light, the purpose of conducting the study to boost the bioactive properties in Polygonum minus has been fulfilled by 50% shading under 16 weeks’ exposure.

Sign in / Sign up

Export Citation Format

Share Document