Primary Production and Nutrient Assimilation by Natural Phytoplankton Populations of the Eastern Canadian Arctic

1982 ◽  
Vol 39 (2) ◽  
pp. 335-345 ◽  
Author(s):  
W. G. Harrison ◽  
Trevor Platt ◽  
Brian Irwin
Keyword(s):  
Solar Radiation ◽  
Primary Production ◽  
Mixed Layer ◽  
Growth Rates ◽  
Euphotic Zone ◽  
Open Water ◽  
Production Rates ◽  
Phytoplankton Primary Production ◽  
Baffin Bay ◽  
Ambient Temperatures

Phytoplankton biomass (chlorophyll a) and primary production rates in Baffin Bay during summer 1978 were comparable to levels reported for other open water arctic and subarctic regions. Values were moderately high ([Formula: see text] mg Chl∙m−2; 227 mg C-fixed∙m−2∙d−1) considering the low mixed-layer nutrient (nitrogen) concentrations, low ambient temperatures ([Formula: see text] euphotic zone = −0.2 °C), and variable and moderately low daily solar radiation ([Formula: see text] MW∙m−2). Biomass maxima were consistently found at or near the bottom of the euphotic zone, and were 6 times higher than surface values on the average. Nitrate and ammonium were assimilated in approximately equal proportions despite the relatively greater abundance of nitrate in the euphotic zone, particularly below the mixed layer. Average C:N assimilation ratios were slightly lower (5:1) than the chemical composition ratio of the particulate matter (7:1). High phosphate assimilation rates reflected the abundance of this nutrient in the euphotic zone and resulted in low C:P (22:1) and N:P (6:1) assimilation ratios. Growth rates computed from carbon and nitrogen (NO3− + NH4+) assimilation rates averaged 0.31 and 0.35 doublings∙d−1, respectively, for the euphotic zone, and were half the maximum expected growth rates for prevailing water temperatures and optimal conditions of light and nutrients. Baffin Bay phytoplankton populations exhibited no obvious signs of severe nitrogen limitation despite low euphotic zone concentrations of the nutrient. Furthermore, the strong correspondence between: (1) normalized primary production rates (photosynthetic index) and incident solar radiation and (2) growth rates and incubation temperatures suggests that nutrients may play a relatively less important role in controlling arctic primary production than previously considered.Key words: phytoplankton, primary production, nutrients, arctic, light, and temperature

Changes in phytoplankton concentration now drive increased Arctic Ocean primary production

Science ◽  
2020 ◽  
Vol 369 (6500) ◽  
pp. 198-202 ◽  
Author(s):  
K. M. Lewis ◽  
G. L. van Dijken ◽  
K. R. Arrigo
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Open Water ◽  
Water Area ◽  
The Arctic ◽  
Carbon Export ◽  
Phytoplankton Primary Production ◽  
Open Water Area ◽  
The Arctic Ocean

Historically, sea ice loss in the Arctic Ocean has promoted increased phytoplankton primary production because of the greater open water area and a longer growing season. However, debate remains about whether primary production will continue to rise should sea ice decline further. Using an ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018. Surprisingly, whereas increases were due to widespread sea ice loss during the first decade, the subsequent rise in primary production was driven primarily by increased phytoplankton biomass, which was likely sustained by an influx of new nutrients. This suggests a future Arctic Ocean that can support higher trophic-level production and additional carbon export.

Phytoplankton Productivity Changes in a Small, Double-Basin Lake in Response to Termination of Experimental Fertilization

1987 ◽  
Vol 44 (S1) ◽  
pp. s47-s54 ◽  
Author(s):  
J. A. Shearer ◽  
E. J. Fee ◽  
E. R. DeBruyn ◽  
D. R. DeClercq
Keyword(s):  
Numerical Model ◽  
Primary Production ◽  
The Other ◽  
Production Rates ◽  
Nitrogen And Phosphorus ◽  
Phytoplankton Productivity ◽  
Phytoplankton Primary Production ◽  
Carbon And Nitrogen ◽  
Model Technique ◽  
Reference Lakes

One basin of a small, double-basin lake was fertilized with carbon, nitrogen, and phosphorus for eight years, and then fertilization was stopped. The other basin was fertilized simultaneously with equivalent amounts of carbon and nitrogen only. Phytoplankton primary production was monitored using an incubator–numerical model technique. Production increased dramatically in the basin receiving artificial additions of C, N, and P. The increase was particularly large in the epilimnion where Cyanophyte blooms occurred during each year of fertilization and production rates averaged 2 to 10 times higher than in nearby, unfertilized reference lakes. Phosphorus, not nitrogen or carbon, was the critical nutrient. The productivity of the other basin also increased, but to a lesser degree and no Cyanophyte blooms were observed in this basin. When all fertilization was terminated, production in both basins immediately decreased. No more surface blooms were observed in either basin. Within 3 yr, the production had dropped to levels typical of reference lakes.

scholarly journals Production regime and associated N cycling in the vicinity of Kerguelen Island, Southern Ocean

2015 ◽  
Vol 12 (21) ◽  
pp. 6515-6528 ◽  
Author(s):  
A. J. Cavagna ◽  
F. Fripiat ◽  
M. Elskens ◽  
P. Mangion ◽  
L. Chirurgien ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Primary Production ◽  
Mixed Layer ◽  
Nitrate Uptake ◽  
Net Primary Production ◽  
N Uptake ◽  
Euphotic Zone ◽  
Global Ocean ◽  
Kerguelen Plateau ◽  
New Production

Abstract. Although the Southern Ocean is considered a high-nutrient, low-chlorophyll (HNLC) area, massive and recurrent blooms are observed over and downstream of the Kerguelen Plateau. This mosaic of blooms is triggered by a higher iron supply resulting from the interaction between the Antarctic Circumpolar Current and the local bathymetry. Net primary production, N uptake (NO3− and NH4+), and nitrification rates were measured at eight stations in austral spring 2011 (October–November) during the KEOPS 2 cruise in the Kerguelen Plateau area. Natural iron fertilization stimulated primary production, with mixed layer integrated net primary production and growth rates much higher in the fertilized areas (up to 315 mmol C m−2 d−1 and up to 0.31 d−1 respectively) compared to the HNLC reference site (12 mmol C m−2 d−1 and 0.06 d−1 respectively). Primary production was mainly sustained by nitrate uptake, with f ratios (corresponding to NO3−-uptake / (NO3−-uptake + NH4+-uptake)) lying at the upper end of the observations for the Southern Ocean (up to 0.9). We report high rates of nitrification (up to ~ 3 μmol N L−1 d−1, with ~ 90 % of them < 1 μmol N L−1 d−1) typically occurring below the euphotic zone, as classically observed in the global ocean. The specificity of the studied area is that at most of the stations, the euphotic layer was shallower than the mixed layer, implying that nitrifiers can efficiently compete with phytoplankton for the ammonium produced by remineralization at low-light intensities. Nitrate produced by nitrification in the mixed layer below the euphotic zone is easily supplied to the euphotic zone waters above, and nitrification sustained 70 ± 30 % of the nitrate uptake in the productive area above the Kerguelen Plateau. This complicates estimations of new production as potentially exportable production. We conclude that high productivity in deep mixing system stimulates the N cycle by increasing both assimilation and regeneration.

Nutrition Considerations for Open-Water Swimming

2014 ◽  
Vol 24 (4) ◽  
pp. 373-381 ◽  
Author(s):  
Gregory Shaw ◽  
Anu Koivisto ◽  
David Gerrard ◽  
Louise M. Burke
Keyword(s):  
Solar Radiation ◽  
Extreme Environments ◽  
Open Water ◽  
Hydration Status ◽  
Ambient Temperatures ◽  
Open Water Swimming ◽  
Glycogen Stores ◽  
Variable Water ◽  
International Circuit ◽  
Fluid Sources

Open-water swimming (OWS) is a rapidly developing discipline. Events of 5–25 km are featured at FINA World Championships, and the international circuit includes races of 5–88 km. The Olympic OWS event, introduced in 2008, is contested over 10 km. Differing venues present changing environmental conditions, including water and ambient temperatures, humidity, solar radiation, and unpredictable tides. Furthermore, the duration of most OWS events (1–6 hr) creates unique physiological challenges to thermoregulation, hydration status, and muscle fuel stores. Current nutrition recommendations for open-water training and competition are either an extension of recommendations from pool swimming or are extrapolated from other athletic populations with similar physiological requirements. Competition nutrition should focus on optimizing prerace hydration and glycogen stores. Although swimmers should rely on self-supplied fuel and fluid sources for shorter events, for races of 10 km or greater, fluid and fuel replacement can occur from feeding pontoons when tactically appropriate. Over the longer races, feeding pontoons should be used to achieve desirable targets of up to 90 g/hr of carbohydrates from multitransportable sources. Exposure to variable water and ambient temperatures will play a significant role in determining race nutrition strategies. For example, in extreme environments, thermoregulation may be assisted by manipulating the temperature of the ingested fluids. Swimmers are encouraged to work with nutrition experts to develop effective and efficient strategies that enhance performance through appropriate in-competition nutrition.

scholarly journals Primary production in the Chukchi Sea with potential effects of freshwater content

2016 ◽  
Vol 13 (3) ◽  
pp. 737-749 ◽  
Author(s):  
M. S. Yun ◽  
T. E. Whitledge ◽  
D. Stockwell ◽  
S. H. Son ◽  
J. H. Lee ◽  
...  
Keyword(s):  
Primary Production ◽  
Chukchi Sea ◽  
Euphotic Zone ◽  
Northern Region ◽  
Current Status ◽  
Production Rates ◽  
Significant Relationships ◽  
Using Data ◽  
Seasonal And Interannual Variations

Abstract. The in situ primary production rates and various environmental variables were investigated in the Chukchi Sea during the RUSALCA expedition, which was conducted in 2012, to identify the current status of primary production. A 13C–15N dual-tracer technique was used to measure the daily primary production rates, which ranged from 0.02 to 1.61 g C m−2 d−1 (mean ±SD  =  0.42 ± 0.52 g C m−2 d−1). The primary production rates showed large regional differences, with the southern region (0.66 ± 0.62 g C m−2 d−1) producing approximately 5 times as much as the northern region (0.14 ± 0.10 g C m−2 d−1), which was primarily due to the differences in phytoplankton biomasses induced by regional nutrient conditions. The primary production rates in the Chukchi Sea were averaged using data acquired during the three different RUSALCA expeditions (2004, 2009, and 2012) as 0.33 g C m−2 d−1 (SD  =  0.40 g C m−2 d−1), which was significantly lower than previously reported rates. In addition to strong seasonal and interannual variations in primary production, recent decreases in the concentrations of major inorganic nutrients and chlorophyll a could be among the reasons for the recent low primary production in the Chukchi Sea because the primary production is mainly affected by nutrient concentration and phytoplankton biomass. The nutrient inventory and primary production appear to be largely influenced by the freshwater content (FWC) variability in the region due to the significant relationships between FWC, nitrate inventory (r  =  0.54, p < 0.05), and primary production rates (r  =  0.56, p < 0.05). Moreover, we found highly significant relationships between the nutrient inventory and the primary production rates (r  =  0.75, p < 0.001). In conclusion, the primary production in the Chukchi Sea is primarily controlled by nutrient availability, which is strongly related to the FWC variability. Our results imply that the predicted increase in freshwater accumulation might cause a decrease in primary production by lowering the nutrient inventory in the euphotic zone of the Chukchi Sea.

scholarly journals The potential effects of fresh water content on the primary production in the Chukchi Sea

2015 ◽  
Vol 12 (16) ◽  
pp. 13511-13544
Author(s):  
M. S. Yun ◽  
T. E. Whitledge ◽  
D. Stockwell ◽  
J. H. Lee ◽  
J. W. Park ◽  
...  
Keyword(s):  
Primary Production ◽  
Chukchi Sea ◽  
Euphotic Zone ◽  
Northern Region ◽  
Current Status ◽  
Production Rates ◽  
Significant Relationships ◽  
Using Data ◽  
Seasonal And Interannual Variations

Abstract. The in situ primary production rates and various environmental variables were investigated in the Chukchi Sea during the 3rd RUSALCA expedition, which was conducted in 2012, to identify the current status of primary production. A 13C-15N dual tracer technique was used to measure the daily primary production rates, which ranged from 0.02 to 1.61 g C m−2 d−1 (mean ± SD = 0.42 ± 0.52 g C m−2 d−1). The primary production rates showed large regional differences, with the southern region (0.66 ± 0.62 g C m−2 d−1) producing approximately five times as much as the northern region (0.14 ± 0.10 g C m−2 d−1), which was primarily due to the differences in phytoplankton biomasses induced by regional nutrient conditions. The primary production rates in the Chukchi Sea were averaged using data acquired during the three different RUSALCA expeditions (2004, 2009, and 2012) as 0.33 g C m−2 d−1 (SD = 0.40 g C m−2 d−1), which was significantly lower than previously reported rates. In addition to strong seasonal and interannual variations in primary production, recent decreases in the concentrations of major inorganic nutrients and chlorophyll a could be among the reasons for the recent low primary production in the Chukchi Sea because the primary production is mainly affected by nutrient concentration and phytoplankton biomass. The nutrient inventory and primary production appear to be largely influenced by the freshwater content (FWC) variability in the region due to the significant relationships between FWC, nitrate concentrations (r = 0.54, p < 0.05) and primary production rates (r = 0.56, p < 0.05). Moreover, we found highly significant relationships between the nutrient levels and the primary production rates (r = 0.75, p < 0.001). In conclusion, the primary production in the Chukchi Sea is primarily controlled by nutrient availability which is strongly related to the FWC variability. Our results imply that the predicted increase in freshwater accumulation might cause a decrease in primary production by lowering the nutrient inventory in the euphotic zone of the Chukchi Sea.

ENERGY TRANSFER EFFICIENCIES ON LOWER TROPHIC LEVELS WITH INTENSIVE OYSTER FARMING IN HIROSHIMA BAY, JAPAN

2017 ◽  
Author(s):  
Akira Umehara ◽  
Akira Umehara ◽  
Satoshi Asaoka ◽  
Satoshi Asaoka ◽  
Naoki Fujii ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Primary Production ◽  
Skeletonema Costatum ◽  
Warm Season ◽  
Nutrient Supply ◽  
Trophic Levels ◽  
Phytoplankton Primary Production ◽  
Mean Values ◽  
Hiroshima Prefecture ◽  
Study Species

In enclosed water areas, organic matters are actively produced by phytoplankton due to abundant nutrient supply from the rivers. In our study area of the semi-enclosed Hiroshima Bay, oyster farming consuming high primary production has been developed since the 1950s, and the oyster production of Hiroshima prefecture have had the largest market share (ca. 60%) in Japan. In this study, species composition of phytoplankton, primary production, and secondary production of net zooplanktons and oysters were determined seasonally at seven stations in the bay between November 2014 and August 2015. In the bay, diatoms including Skeletonema costatum dominated during the period of the study. The primary productions markedly increased during summer (August), and its mean values in the northern part of the bay (NB) and the southern part (SB) were 530 and 313 mgC/m2/d, respectively. The productions of net zooplankton and oyster increased during the warm season, and its mean values in the NB were 14 and 1.2 mgC/m2/d, and in SB were 28 and 0.9 mgC/m2/d, respectively. The energy transfer efficiencies from the primary producers to the secondary producers in the NB and SB were 2.8% and 9.1%, respectively. However, the transfer efficiency to the oysters was approximately 0.3% in the bay. This study clearly showed the spatial difference of the productions and transfer efficiencies, and the low contribution of the production of oysters in secondary productions in Hiroshima Bay.

The Influence of Phytoplankton Primary Production on the Cycle of Biogenic Elements in the Coastal Waters off Sevastopol, Black Sea

2018 ◽  
Vol 44 (3) ◽  
pp. 240-247 ◽  
Author(s):  
V. N. Egorov ◽  
V. N. Popovichev ◽  
S. B. Gulin ◽  
N. I. Bobko ◽  
N. Yu. Rodionova ◽  
...  
Keyword(s):  
Primary Production ◽  
Black Sea ◽  
Coastal Waters ◽  
Biogenic Elements ◽  
Phytoplankton Primary Production

scholarly journals Niche partitioning by photosynthetic plankton as a driver of CO2-fixation across the oligotrophic South Pacific Subtropical Ocean

2021 ◽  
Author(s):  
Julia Duerschlag ◽  
Wiebke Mohr ◽  
Timothy G. Ferdelman ◽  
Julie LaRoche ◽  
Dhwani Desai ◽  
...  
Keyword(s):  
Mixed Layer ◽  
Niche Partitioning ◽  
Euphotic Zone ◽  
South Pacific ◽  
Niche Differentiation ◽  
Surface Mixed Layer ◽  
The South ◽  
The Core ◽  
Photosynthetic Eukaryotes ◽  
Phytoplankton Communities

AbstractOligotrophic ocean gyre ecosystems may be expanding due to rising global temperatures [1–5]. Models predicting carbon flow through these changing ecosystems require accurate descriptions of phytoplankton communities and their metabolic activities [6]. We therefore measured distributions and activities of cyanobacteria and small photosynthetic eukaryotes throughout the euphotic zone on a zonal transect through the South Pacific Ocean, focusing on the ultraoligotrophic waters of the South Pacific Gyre (SPG). Bulk rates of CO2 fixation were low (0.1 µmol C l−1 d−1) but pervasive throughout both the surface mixed-layer (upper 150 m), as well as the deep chlorophyll a maximum of the core SPG. Chloroplast 16S rRNA metabarcoding, and single-cell 13CO2 uptake experiments demonstrated niche differentiation among the small eukaryotes and picocyanobacteria. Prochlorococcus abundances, activity, and growth were more closely associated with the rims of the gyre. Small, fast-growing, photosynthetic eukaryotes, likely related to the Pelagophyceae, characterized the deep chlorophyll a maximum. In contrast, a slower growing population of photosynthetic eukaryotes, likely comprised of Dictyochophyceae and Chrysophyceae, dominated the mixed layer that contributed 65–88% of the areal CO2 fixation within the core SPG. Small photosynthetic eukaryotes may thus play an underappreciated role in CO2 fixation in the surface mixed-layer waters of ultraoligotrophic ecosystems.

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