Influence of the Shelf-Break Front Off Nova Scotia on Phytoplankton Standing Stock in Winter

1979 ◽  
Vol 36 (10) ◽  
pp. 1228-1237 ◽  
Author(s):  
R. O. Fournier ◽  
M. Van Det ◽  
J. S. Wilson ◽  
N. B. Hargreaves
Keyword(s):  
Nova Scotia ◽  
Key Words ◽  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Standing Stock ◽  
Euphotic Zone ◽  
Shelf Break ◽  
Growth Enhancement ◽  
Average Amount ◽  
Growth Increase

Observations made on the shelf-break front off Nova Scotia during winter on 2 successive yr show the concentration of chlorophyll a in the euphotic zone to be correlated to the inclination of the subsurface front. The steepness of the front influences the depth to which phytoplankton are mixed which in turn controls the average amount of illumination received by a given cell. The two winter observations showed the subsurface front at each of two extremes: vertical with little phytoplankton biomass and almost horizontal with significant quantities of chlorophyll. Calculations were made as to the amount of production enchancement that could result from shallowing of the mixed layer by decreased frontal inclination. They show that during the winter under ideal conditions as few as 35 d of intermittent growth increase annual production in the frontal region by 25%. Key words: front, winter production, phytoplankton, shelf-break, chlorophyll a, frontal oscillations, growth enhancement, stability, stratification

Vertical and Horizontal Distribution Patterns of Copepods Near the Shelf Break South of Nova Scotia

1981 ◽  
Vol 38 (9) ◽  
pp. 1065-1076 ◽  
Author(s):  
Alex W. Herman ◽  
Douglas D. Sameoto ◽  
Alan R. Longhurst
Keyword(s):  
Nova Scotia ◽  
Chlorophyll A ◽  
Depth Resolution ◽  
Food Concentration ◽  
Horizontal Distribution ◽  
Shelf Break ◽  
Plant Production ◽  
Depth Range ◽  
Shelf Water ◽  
Shelf Slope

The shelf water over the outer edge of the Scotian Shelf and the shelf/slope water front at the shelf break south of Nova Scotia have been sampled with a Batfish cycling over a 3- to 110-m-depth range while measuring salinity, temperature, depth, chlorophyll a, and copepods. Plant production and copepod abundance were much higher at the front than in surrounding shelf and slope waters. Convergence at the front is invoked as a possible transport mechanism which results in the accumulation of copepods in a region of high food concentration. Copepods exhibit diel vertical migration in shelf water but not in the front itself, and possible mechanisms are examined. Most Batfish profiles (with ≈1-m-depth resolution) indicated that the copepod maximum was situated ≈10 m above the chlorophyll maximum. A series of vertical profiles consisting of chlorophyll a, estimated production, and copepod abundances indicate a high correlation between the copepod and production profiles and low correlation between either of these and chlorophyll. Possible relationships between copepod layer depths and the depths of high plant production are considered.Key words: copepods, batfish, chlorophyll, production, front, migration

Lack of Effect of Arsenic on Phytoplankton Communities in Different Nutrient Conditions

1983 ◽  
Vol 40 (2) ◽  
pp. 156-161 ◽  
Author(s):  
Dolores Planas ◽  
Alain Lamarche
Keyword(s):  
Organic Matter ◽  
Key Words ◽  
Chlorophyll A ◽  
Bottom Sediments ◽  
Phytoplankton Biomass ◽  
Canadian Shield ◽  
Inorganic Nutrients ◽  
Phytoplankton Communities ◽  
Nutrient Conditions

One-metre diameter plastic cylinders open to bottom sediments were used to investigate the effect of 30–40 μmol∙L−1 concentrations of arsenic on phytoplankton communities of the Canadian Shield. Dissolved nutrient-rich organic matter (trypticase soy broth) and inorganic nutrients [Formula: see text] were also added in the presence or absence of arsenic. Arsenic caused little change in phytoplankton biomass, measured as chlorophyll a or as biovolumes, in any of the cylinders during the 1st week of the experiment. Thereafter the biomass increased in cylinders enriched with organic matter and nutrients (with and without arsenic).Key words: arsenic, chlorophyll a, biomass, nutrients

ATP as a Measure of Living Phytoplankton Carbon in Estuaries

1979 ◽  
Vol 36 (2) ◽  
pp. 180-186 ◽  
Author(s):  
Michael Sinclair ◽  
Edric Keighan ◽  
Jerry Jones
Keyword(s):  
Cell Count ◽  
Key Words ◽  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Constant Ratio ◽  
High Biomass ◽  
Bacterial Populations ◽  
Cell Counts ◽  
Count Method ◽  
Key Words Atp

An attempt has been made to evaluate the accuracy of ATP as a measure of living phytoplankton carbon in estuaries. Phytoplankton carbon estimated from ATP was compared to estimates from cell counts. In high biomass samples the agreement between the two estimates was quite good. In the low biomass samples the cell count method underestimated phytoplankton carbon relative to the ATP estimate. This was interpreted to be due in part to low cell counts in these samples. Contamination by microzooplankton (essentially only tintinnids) was, in 14 out of the 18 samples, < 3% of the ATP estimated carbon. However, it was as high as 19% in one case. In the lowest biomass samples (< 0.5 μg chlorophyll a/L) bacterial populations may contribute as much as 50% of the total living carbon. It is concluded that, with caution, ATP is a useful measure of living phytoplankton carbon in estuaries during periods of moderate to high biomass (> 1 μg chlorophyll a/L for the St. Lawrence). Since carbon to chlorophyll ratios in the high biomass samples varied considerably, a constant ratio appears inapplicable for transforming chlorophyll to carbon. Key words: ATP, phytoplankton biomass, estuaries, carbon to chlorophyll ratio

Preliminary Studies on the Export of Organic Matter During Phytoplankton Blooms off La Coruña (Northwestern Spain)

1998 ◽  
Vol 78 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Antonio Bode ◽  
Manuel Varela ◽  
Susana Barquero ◽  
Ma Teresa Ossorio-Alvarez ◽  
Nicolás Gonzalez
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Euphotic Zone ◽  
Phytoplankton Blooms ◽  
Coastal Site ◽  
Northwestern Spain ◽  
Western Spain ◽  
North Western

Sinking of particles was measured at a coastal site near La Coruña (north-western Spain) using sedimentation traps placed at the base of the euphotic zone during four short periods between March and June 1995. In addition, measurements of water column properties and particles were made at five stations. The cases studied were representative of the main oceanographic situations that occur in this area and were related to the wind-induced upwelling. Phytoplankton blooms (> 100 mg chlorophyll−a m−2) were observed on two occasions in April and June, both during favourable upwelling conditions. The two other cases were studied during low phytoplankton biomass concentrations in the water column.

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.

Differences between Nearshore and Offshore Phytoplankton Communities in Lake Ontario

1987 ◽  
Vol 44 (12) ◽  
pp. 2155-2163 ◽  
Author(s):  
I. M. Gray
Keyword(s):  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Algal Biomass ◽  
Phytoplankton Community ◽  
Seasonal Pattern ◽  
Principal Component ◽  
Lake Ontario ◽  
Dominant Group ◽  
Phytoplankton Communities ◽  
Eutrophic Species

Differences between nearshore and offshore phytoplankton biomass and composition were evident in Lake Ontario in 1982. Phytoplankton biomass was characterized by multiple peaks which ranged over three orders of magnitude. Perhaps as a consequence of the three times higher current velocities at the northshore station, phytoplankton biomass ranged from 0.09 to 9.00 g∙m−3 compared with 0.10 to 2.40 g∙m−3 for the midlake station. Bacillariophyceae was the dominant group at the northshore station until September when Cyanophyta contributed most to the biomass (83%). Although Bacillariophyceae was the principal component of the spring phytoplankton community at the midlake station, phytoflagellates (49%) and Chlorophyceae (25%) were responsible for summer biomass, with the Chlorophyceae expanding to 80% in the fall. The seasonal pattern of epilimnetic chlorophyll a correlated with temperature. While chlorophyll a concentrations were similar to values from 1970 and 1972, algal biomass had declined and a number of eutrophic species (Melosira binderana, Stephanodiscus tenuis, S. hantzschii var. pusilla, and S. alpinus) previously found were absent in 1982.

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.

The Deep Chlorophyll Maximum: Comparing Vertical Profiles of Chlorophyll a

1982 ◽  
Vol 39 (5) ◽  
pp. 791-803 ◽  
Author(s):  
John J. Cullen
Keyword(s):  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Physiological Adaptation ◽  
Organic Carbon Content ◽  
Deep Chlorophyll Maximum ◽  
Vertical Profiles ◽  
In Vivo Fluorescence ◽  
Chlorophyll Maximum ◽  
Vertical Distributions

The relationship between chlorophyll a and phytoplankton biomass (organic carbon content) is highly variable as is the yield of in vivo fluorescence per unit chlorophyll. Thus, vertical profiles of chlorophyll or in vivo fluorescence must be interpreted with caution if their ecological significance is to be established. Although the variability of carbon-to-chlorophyll ratios and fluorescence yield is large, much of it can be anticipated, corrected for, and usefully interpreted. Vertical profiles from different regions of the sea are presented; each has a deep chlorophyll maximum, but the probable mechanisms of their formation and maintenance differ widely. Most vertical distributions of chlorophyll can be explained by the interaction between hydrography and growth, behavior, or physiological adaptation of phytoplankton with no special consideration of grazing by herbivores, even though vertical distributions of epizooplankton are not uniform. The interaction between vertical profiles of zooplankton and chlorophyll will be better understood when the relationships between chlorophyll and phytoplankton biomass in those profiles is determined.Key words: chlorophyll a, fluorescence, phytoplankton, vertical structure

Change in biomass of benthic and planktonic algae along a disturbance gradient for 24 Great Lakes coastal wetlands

2003 ◽  
Vol 60 (6) ◽  
pp. 676-689 ◽  
Author(s):  
Sheila A McNair ◽  
Patricia Chow-Fraser
Keyword(s):  
Water Quality ◽  
Great Lakes ◽  
Chlorophyll A ◽  
Total Variation ◽  
Coastal Wetlands ◽  
Phytoplankton Biomass ◽  
Wetland Management ◽  
Percent Cover ◽  
Planktonic Algae ◽  
Wide Range

We quantified the chlorophyll a content of planktonic algae and benthic algae in periphyton on acrylic rods and in epiphyton growing on macrophytes in 24 coastal wetlands in all five Laurentian Great Lakes. Sites were selected to represent a wide range of environmental conditions ranging from nutrient-poor, clear-water marshes with abundant macrophytes to nutrient-enriched, turbid systems devoid of aquatic vegetation. Water quality and species and percent cover of submergent macrophytes were measured in each wetland. Principal components analysis (PCA) showed that total phosphorus, turbidity, and suspended solids, variables associated with human-induced degradation, were most strongly correlated with PC axis 1 (PC1), accounting for 69% of the total variation. The PC1 site score was significantly related to both periphyton and phytoplankton biomass, respectively accounting for 54 and 70% of the total variation in periphyton and phytoplankton data, whereas PC1 only accounted for 18% of the variation in epiphyton biomass. Periphytic and epiphytic biomass were negatively correlated with percent cover and species richness of submergent macrophytes, but phytoplankton biomass was not. We conclude that periphytic and planktonic chlorophyll a biomass are good indicators of human-induced water-quality degradation and recommend that both benthic and planktonic algal biomass should be routinely monitored as part of an effective wetland management program.

Bruce birdsfoot trefoil

2008 ◽  
Vol 88 (6) ◽  
pp. 1093-1094
Author(s):  
Y. A. Papadopoulos ◽  
K. B. McRae ◽  
D. Gehl ◽  
S. A. E. Fillmore
Keyword(s):  
Nova Scotia ◽  
Root Growth ◽  
Key Words ◽  
Lotus Corniculatus ◽  
Birdsfoot Trefoil ◽  
Mass Selection ◽  
Plant Vigour ◽  
Growth Vigour ◽  
Cultivar Description ◽  
Selection For

Bruce birdsfoot trefoil (Lotus corniculatus L.) is a 71-clone synthetic variety developed at the Nappan Research Farm, Agriculture and Agri-Food Canada, Nappan, Nova Scotia. Bruce was developed through two cycles of mass selection for plant vigour (top and root growth) and winterhardiness, and one cycle of mass selection for re-growth vigour under grazing. In Atlantic Canada, Bruce produced more forage than the check cultivar Leo during 3 post-seeding years. It was also superior in spring growth with high first-cut herbage yields. Key words: Birdsfoot trefoil, Lotus corniculatus, cultivar description

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