scholarly journals Photosynthetic parameters in the Beaufort Sea in relation to the phytoplankton community structure

2013 ◽  
Vol 10 (1) ◽  
pp. 1551-1576
Author(s):  
Y. Huot ◽  
M. Babin ◽  
F. Bruyant
Keyword(s):  
Community Structure ◽  
Primary Production ◽  
Environmental Variables ◽  
The Arctic ◽  
Initial Slope ◽  
Photosynthetic Parameters ◽  
Remotely Sensed Data ◽  
Phytoplankton Primary Production ◽  
Functional Relationships ◽  
Rate Of Photosynthesis

Abstract. To model phytoplankton primary production from remotely sensed data a method to estimate photosynthetic parameters describing the photosynthetic rates per unit biomass is required. Variability in these parameters must be related to environmental variables that are measurable remotely. In the Arctic, a limited number of measurements of photosynthetic parameter have been carried out with the concurrent environmental variables needed. Therefore, to improve the accuracy of remote estimates of phytoplankton primary production as well as our ability to predict changes in the future such measurements and relationship to environmental variables are required. During the MALINA cruise, a large dataset of these parameters were obtained. Together with previously published datasets, we use environmental and trophic variables to provide functional relationships for these parameters. In particular, we describe several specific aspects: the maximum rate of photosynthesis (Pmaxchl) normalized to chlorophyll decreases with depth and is higher for communities composed of large cells; the saturation parameter (Ek) decreases with depth but is independent of the community structure; and the initial slope of the photosynthesis versus irradiance curve (αchl) normalized to chlorophyll is independent of depth but is higher for communities composed of larger cells. The photosynthetic parameters were not influenced by temperature over the range encountered during the cruise (−2 to 8 °C).

scholarly journals Photosynthetic parameters in the Beaufort Sea in relation to the phytoplankton community structure

2013 ◽  
Vol 10 (5) ◽  
pp. 3445-3454 ◽  
Author(s):  
Y. Huot ◽  
M. Babin ◽  
F. Bruyant
Keyword(s):  
Community Structure ◽  
Primary Production ◽  
Environmental Variables ◽  
Remotely Sensed ◽  
The Arctic ◽  
Initial Slope ◽  
Photosynthetic Parameters ◽  
Remotely Sensed Data ◽  
Phytoplankton Primary Production ◽  
Functional Relationships

Abstract. To model phytoplankton primary production from remotely sensed data, a method to estimate photosynthetic parameters describing the photosynthetic rates per unit biomass is required. Variability in these parameters must be related to environmental variables that are measurable remotely. In the Arctic, a limited number of measurements of photosynthetic parameters have been carried out with the concurrent environmental variables needed. Such measurements and their relationship to environmental variables will be required to improve the accuracy of remotely sensed estimates of phytoplankton primary production and our ability to predict future changes. During the MALINA cruise, a large dataset of these parameters was obtained. Together with previously published datasets, we use environmental and trophic variables to provide functional relationships for these parameters. In particular, we describe several specific aspects: the maximum rate of photosynthesis (Pmaxchl) normalized to chlorophyll decreases with depth and is higher for communities composed of large cells; the saturation parameter (Ek) decreases with depth but is independent of the community structure; and the initial slope of the photosynthesis versus irradiance curve (αchl) normalized to chlorophyll is independent of depth but is higher for communities composed of larger cells. The photosynthetic parameters were not influenced by temperature over the range encountered during the cruise (−2 to 8 °C).

scholarly journals Primary Production, an Index of Climate Change in the Ocean: Satellite-Based Estimates over Two Decades

2020 ◽  
Vol 12 (5) ◽  
pp. 826 ◽  
Author(s):  
Gemma Kulk ◽  
Trevor Platt ◽  
James Dingle ◽  
Thomas Jackson ◽  
Bror F. Jönsson ◽  
...  
Keyword(s):  
Primary Production ◽  
Environmental Variables ◽  
Linear Trend ◽  
In Situ Measurements ◽  
Marine Phytoplankton ◽  
Initial Slope ◽  
Model Parameters ◽  
Photosynthetic Parameters ◽  
Photosynthetic Response

Primary production by marine phytoplankton is one of the largest fluxes of carbon on our planet. In the past few decades, considerable progress has been made in estimating global primary production at high spatial and temporal scales by combining in situ measurements of primary production with remote-sensing observations of phytoplankton biomass. One of the major challenges in this approach lies in the assignment of the appropriate model parameters that define the photosynthetic response of phytoplankton to the light field. In the present study, a global database of in situ measurements of photosynthesis versus irradiance (P-I) parameters and a 20-year record of climate quality satellite observations were used to assess global primary production and its variability with seasons and locations as well as between years. In addition, the sensitivity of the computed primary production to potential changes in the photosynthetic response of phytoplankton cells under changing environmental conditions was investigated. Global annual primary production varied from 38.8 to 42.1 Gt C yr − 1 over the period of 1998–2018. Inter-annual changes in global primary production did not follow a linear trend, and regional differences in the magnitude and direction of change in primary production were observed. Trends in primary production followed directly from changes in chlorophyll-a and were related to changes in the physico-chemical conditions of the water column due to inter-annual and multidecadal climate oscillations. Moreover, the sensitivity analysis in which P-I parameters were adjusted by ±1 standard deviation showed the importance of accurately assigning photosynthetic parameters in global and regional calculations of primary production. The assimilation number of the P-I curve showed strong relationships with environmental variables such as temperature and had a practically one-to-one relationship with the magnitude of change in primary production. In the future, such empirical relationships could potentially be used for a more dynamic assignment of photosynthetic rates in the estimation of global primary production. Relationships between the initial slope of the P-I curve and environmental variables were more elusive.

scholarly journals Planktonic primary production in the western Dutch Wadden Sea

2020 ◽  
Vol 639 ◽  
pp. 53-71
Author(s):  
P Jacobs ◽  
JC Kromkamp ◽  
SM van Leeuwen ◽  
CJM Philippart
Keyword(s):  
Primary Production ◽  
Environmental Variables ◽  
Carbon Fixation ◽  
Wadden Sea ◽  
Marine Ecosystem ◽  
Light Attenuation ◽  
Initial Slope ◽  
Photosynthetic Parameters ◽  
Observation Data ◽  
Curve Fit

Pelagic primary production measurements provide fundamental information about the trophic status of a marine ecosystem. Measured carbon fixation rates generally have a limited temporal and spatial resolution, but can be combined with Earth Observation data to extrapolate the measurements. Here, P-E curves were fitted for 3 yr of 14C incubation data from the western Wadden Sea, using 4 different models; 2 with and 2 without photo-inhibition. The curve-fit model by Jassby & Platt (1976) best fit the data. Applying this model showed that the photosynthetic parameters, normalised for chlorophyll a concentration, of maximum production (PBmax) and initial slope of the P-E curve (αB) were correlated. Seasonality in photosynthetic parameters of this model and the relationship with environmental variables were explored, with a focus on variables that can be inferred from satellite algorithms. There were no significant correlations between αB and any of the environmental variables measured. While PBmax correlated with sea surface temperature (SST), the vertical light attenuation coefficient, silicate and nitrate + nitrite concentration, the multivariate model that best explained the variation in estimates of PBmax was a model that included SST and year. In the period from 2012-2014, daily and annual production ranged between 3.4 and 3800 mg C d-1 and between 131 and 239 g C m-2 yr-1, respectively. Comparison of these results with historical data (1990-2003) indicates that the decline in planktonic primary production that has been happening since the 1990s has halted. Although not tested, we believe that our approach is generally applicable to coastal waters.

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.

scholarly journals Increasing cloudiness in Arctic damps the increase in phytoplankton primary production due to sea ice receding

2012 ◽  
Vol 9 (10) ◽  
pp. 13987-14012 ◽  
Author(s):  
S. Bélanger ◽  
M. Babin ◽  
J.-E. Tremblay
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Sea Surface ◽  
The Arctic ◽  
Diagnostic Model ◽  
Arctic Seas ◽  
Sea Ice Concentration ◽  
Phytoplankton Primary Production ◽  
Ice Concentration

Abstract. The Arctic Ocean and its marginal seas are among the marine regions most affected by climate change. Here we present the results of a diagnostic model used to elucidate the main drivers of primary production (PP) trends over the 1998–2010 period at pan-Arctic and local (i.e. 9.28 km resolution) scales. Photosynthetically active radiation (PAR) above and below the sea surface was estimated using precomputed look-up tables of spectral irradiance and satellite-derived cloud optical thickness and cloud fraction parameters from the International Satellite Cloud Climatology Project (ISCCP) and sea ice concentration from passive microwaves data. A spectrally resolved PP model, designed for optically complex waters, was then used to produce maps of PP trends. Results show that incident PAR above the sea surface (PAR(0+)) has significantly decreased over the whole Arctic and sub-Arctic Seas, except over the perrennially sea ice covered waters of the Central Arctic Ocean. This fading of PAR(0+) (+8% decade–1) was caused by increasing cloudiness May and June. Meanwhile PAR penetrating the ocean (PAR(0–)) increased only along the sea ice margin over the large Arctic continental shelf where sea ice concentration declined sharply since 1998. Overall, PAR(0–) slightly increased in the Circum Arctic (+3.4% decade–1), while it decreased when considering both Arctic and sub-Arctic Seas (–3% decade–1). We showed that rising phytoplankton biomass (i.e. chlorophyll a) normalized by the diffuse attenuation of photosynthetically usable radiation (PUR) by phytoplankton accounted for a larger proportion of the rise in PP than did the increase in light availability due to sea-ice loss in several sectors and particularly in perrennially and seasonally open waters. Against a general backdrop of rising productivity over Arctic shelves, significant negative trends were observed in regions known for their great biological importance such as the coastal polynyas of Northern Greenland.

scholarly journals Increasing cloudiness in Arctic damps the increase in phytoplankton primary production due to sea ice receding

2013 ◽  
Vol 10 (6) ◽  
pp. 4087-4101 ◽  
Author(s):  
S. Bélanger ◽  
M. Babin ◽  
J.-É. Tremblay
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Sea Surface ◽  
The Arctic ◽  
Diagnostic Model ◽  
Arctic Seas ◽  
Sea Ice Concentration ◽  
Phytoplankton Primary Production ◽  
Ice Concentration

Abstract. The Arctic Ocean and its marginal seas are among the marine regions most affected by climate change. Here we present the results of a diagnostic model used to assess the primary production (PP) trends over the 1998–2010 period at pan-Arctic, regional and local (i.e. 9.28 km resolution) scales. Photosynthetically active radiation (PAR) above and below the sea surface was estimated using precomputed look-up tables of spectral irradiance, taking as input satellite-derived cloud optical thickness and cloud fraction parameters from the International Satellite Cloud Climatology Project (ISCCP) and sea ice concentration from passive microwaves data. A spectrally resolved PP model, designed for optically complex waters, was then used to assess the PP trends at high spatial resolution. Results show that PP is rising at a rate of +2.8 TgC yr−1 (or +14% decade−1) in the circum-Arctic and +5.1 TgC yr−1 when sub-Arctic seas are considered. In contrast, incident PAR above the sea surface (PAR(0+)) has significantly decreased over the whole Arctic and sub-Arctic Seas, except over the perennially sea-ice covered waters of the Central Arctic Ocean. This fading of PAR(0+) (−8% decade−1) was caused by increasing cloudiness during summer. Meanwhile, PAR penetrating the ocean (PAR(0−)) increased only along the sea ice margin over the large Arctic continental shelf where sea ice concentration declined sharply since 1998. Overall, PAR(0−) slightly increased in the circum-Arctic (+3.4% decade−1), while it decreased when considering both Arctic and sub-Arctic Seas (−3% decade−1). We showed that rising phytoplankton biomass (i.e. chlorophyll a) normalized by the diffuse attenuation of photosynthetically usable radiation (PUR), accounted for a larger proportion of the rise in PP than did the increase in light availability due to sea-ice loss in several sectors, and particularly in perennially and seasonally open waters. Against a general backdrop of rising productivity over Arctic shelves, significant negative PP trends and the timing of phytoplankton spring-summer bloom were observed in regions known for their great biological importance such as the coastal polynyas of northern Greenland.

Sign in / Sign up

Export Citation Format

Share Document