Phytoplankton distribution and production in Port Hacking Estuary, and an empirical model for estimating daily primary production

1983 ◽  
pp. 77-89 ◽  
Author(s):  
Barry D. Scott
Keyword(s):  
Primary Production ◽  
Empirical Model ◽  
Phytoplankton Distribution

scholarly journals Parameterization of vertical chlorophyll <i>a</i> in the Arctic Ocean: impact of the subsurface chlorophyll maximum on regional, seasonal and annual primary production estimates

2013 ◽  
Vol 10 (1) ◽  
pp. 1345-1399 ◽  
Author(s):  
M. Ardyna ◽  
M. Babin ◽  
M. Gosselin ◽  
E. Devred ◽  
S. Bélanger ◽  
...  
Keyword(s):  
Primary Production ◽  
Arctic Ocean ◽  
Empirical Model ◽  
Ocean Color ◽  
The Arctic ◽  
Winter Period ◽  
Substantial Impact ◽  
Near Surface ◽  
Chl A ◽  
The Arctic Ocean

Abstract. Predicting water-column phytoplankton biomass from near-surface measurements is a common approach in biological oceanography, particularly since the advent of satellite remote sensing of ocean color (OC). In the Arctic Ocean, deep subsurface chlorophyll maxima (SCMs) that significantly contribute to primary production (PP) are often observed. These are neither detected by ocean color sensors nor accounted for the primary production models applied to the Arctic Ocean. Here, we assemble a large database of pan-Arctic observations (i.e. 5206 stations) and develop an empirical model to estimate vertical chlorophyll a (chl a) according to: (1) the shelf-offshore gradient delimited by the 50 m isobath, (2) seasonal variability along pre-bloom, post-bloom and winter periods, and (3) regional differences across ten sub-Arctic and Arctic seas. Our detailed analysis of the dataset shows that, for the pre-bloom and winter periods, as well as for high surface chl a concentration (chl asurf; 0.7–30 mg m−3) throughout the open water period, the chl a maximum is mainly located at or near the surface. Deep SCMs occur chiefly during the post-bloom period when chl asurf is low (0–0.5 mg m−3). By applying our empirical model to annual chl asurf time series, instead of the conventional method assuming vertically homogenous chl a, we produce novel pan-Arctic PP estimates and associated uncertainties. Our results show that vertical variations in chl a have a limited impact on annual depth-integrated PP. Small overestimates found when SCMs are shallow (i.e. pre-bloom, post-bloom > 0.05 mg m−3 and the winter period) somehow compensate for the underestimates found when SCMs are deep (i.e. post-bloom < 0.05 mg m−3). SCMs are, however, important seasonal features with a substantial impact on depth-integrated PP estimates, especially when surface nitrate is exhausted in the Arctic Ocean and where highly stratified and oligotrophic conditions prevail.

scholarly journals Phytoplankton distribution in the Western Arctic Ocean during a summer of exceptional ice retreat

2011 ◽  
Vol 8 (4) ◽  
pp. 6919-6970 ◽  
Author(s):  
P. Coupel ◽  
H. Y. Jin ◽  
D. Ruiz-Pino ◽  
J. F. Chen ◽  
S. H. Lee ◽  
...  
Keyword(s):  
Primary Production ◽  
Ice Melting ◽  
Phytoplankton Distribution ◽  
Pacific Waters ◽  
Phytoplankton Communities ◽  
Ice Retreat ◽  
Western Arctic ◽  
Canadian Basin ◽  
Chukchi Borderland ◽  
Chukchi Shelf

Abstract. A drastic ice decline in the Arctic Ocean, triggered by global warming, could generate rapid changes in the upper ocean layers. The ice retreat is particularly intense over the Canadian Basin where large ice free areas were observed since 2007. The CHINARE 2008 expedition was conducted in the Western Arctic (WA) ocean during a year of exceptional ice retreat (August–September 2008). This study investigates whether a significant reorganization of the primary producers in terms of species, biomass and productivity has to be observed in the WA as a result of the intense ice melting. Both pigments (HPLC) and taxonomy (microscopy) acquired in 2008 allowed to determine the phytoplanktonic distribution from Bering Strait (65° N) to extreme high latitudes over the Alpha Ridge (86° N) encompassing the Chukchi shelf, the Chukchi Borderland and the Canadian Basin. Two different types of phytoplankton communities were observed. Over the ice-free Chukchi shelf, relatively high chl-a concentrations (1–5 mg m−3) dominated by 80 % of diatoms. In the Canadian Basin, surface waters are oligotrophic (<0.1 mg m−3) and algal assemblages were dominated by haptophytes and diatoms while higher biomasses (~0.4 mg m−3) related to a deep Subsurface Chlorophyll Maximum (SCM) are associated to small-sized (nano and pico) phytoplankton. The ice melting onset allows to point out three different zones over the open basin: (i) the ice free condition characterized by deep and unproductive phytoplankton communities dominated by nanoplankton, (ii) an extended (78°–83° N) Active Melting Zone (AMZ) where light penetration associated to the stratification start off and enough nutrient availability drives to the highest biomass and primary production due to both diatoms and large flagellates, (iii) heavy ice conditions found north to 83° N allowing light limitation and consequently low biomass and primary production associated to pico and nanoplankton. To explain the poverty (Canadian Basin) and the richness (Chukchi shelf) of the WA, we explore the role of the nutrient-rich Pacific Waters, the bathymetry and two characteristics linked to the intense ice retreat: the stratification and the Surface Freshwater Layer (SFL). The freshwater accumulation induced a strong stratification limiting the nutrient input from the subsurface Pacific waters. This results in a biomass impoverishment of the well-lit layer and compels the phytoplankton to grow in subsurface. The phytoplankton distribution in the Chukchi Borderland and north Canadian Basin, during the summer of exceptional ice retreat (2008), suggested when compared to in-situ data from a more ice covered year (1994), recent changes with a decrease of the phytoplankton abundance while averaged biomass was similar. The 2008 obtained phytoplankton data in the WA provided a state of the ecosystem which will be useful to determine both past and future changes in relation with predicted sea ice decline.

Phytoplankton diversity and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)

2011 ◽  
Vol 8 (1) ◽  
pp. 487-525 ◽  
Author(s):  
E. J. Rochelle-Newall ◽  
V. T. Chu ◽  
O. Pringault ◽  
D. Amouroux ◽  
R. Arfi ◽  
...  
Keyword(s):  
Community Structure ◽  
Primary Production ◽  
Bacterial Production ◽  
Methyl Mercury ◽  
Phytoplankton Community ◽  
Inorganic Mercury ◽  
Phytoplankton Community Structure ◽  
Wet Season ◽  
Phytoplankton Diversity ◽  
Phytoplankton Distribution

Abstract. The factors controlling estuarine phytoplankton diversity and production are relatively well known in temperate systems. Less however is known about the factors affecting phytoplankton community distribution in tropical estuaries. This is surprising given the economic and ecological importance of these large, deltaic ecosystems, such as are found in South East Asia. Here we present the results from an investigation into the factors controlling phytoplankton distribution and phytoplankton-bacterial coupling in the Bach Dang Estuary, a sub-estuary of the Red River system, in Northern Vietnam. Phytoplankton diversity and primary and bacterial production, nutrients and metallic contaminants (mercury and organotin) were measured during two seasons: wet (July 2008) and dry (March 2009). Phytoplankton community composition differed between the two seasons with only a 2% similarity between July and March. The large spatial extent and complexity of defining the freshwater sources meant that simple mixing diagrams could not be used in this system. We therefore employed multivariate analyses to determine the factors influencing phytoplankton community structure. Salinity and suspended particulate matter were important factors in determining phytoplankton distribution, particularly during the wet season. We also show that phytoplankton community structure is probably influenced by the concentrations of mercury species (inorganic mercury and methyl mercury in both the particulate and dissolved phases) and of tri-, di, and mono-butyl tin species found in this system. Freshwater phytoplankton community composition was associated with dissolved methyl mercury and particulate inorganic mercury concentrations during the wet season, whereas, during the dry season, dissolved methyl mercury and particulate butyl tin species were important factors for the discrimination of the phytoplankton community structure. Phytoplankton-bacterioplankton coupling was also investigated during both seasons. In the inshore, riverine stations the ratio between bacterial production and dissolved primary production was high supporting the hypothesis that bacterial carbon demand is supported by allochthonous riverine carbon sources. The inverse was true in the offshore stations, where BP:DPP values were less than 1, potentially reflecting differences in primary production due to shifting phytoplankton community diversity.

scholarly journals Parameterization of vertical chlorophyll <i>a</i> in the Arctic Ocean: impact of the subsurface chlorophyll maximum on regional, seasonal, and annual primary production estimates

2013 ◽  
Vol 10 (6) ◽  
pp. 4383-4404 ◽  
Author(s):  
M. Ardyna ◽  
M. Babin ◽  
M. Gosselin ◽  
E. Devred ◽  
S. Bélanger ◽  
...  
Keyword(s):  
Primary Production ◽  
Arctic Ocean ◽  
Empirical Model ◽  
Ocean Color ◽  
The Arctic ◽  
Winter Period ◽  
Substantial Impact ◽  
Near Surface ◽  
Chl A ◽  
The Arctic Ocean

Abstract. Predicting water-column phytoplankton biomass from near-surface measurements is a common approach in biological oceanography, particularly since the advent of satellite remote sensing of ocean color (OC). In the Arctic Ocean, deep subsurface chlorophyll maxima (SCMs) that significantly contribute to primary production (PP) are often observed. These are neither detected by ocean color sensors nor accounted for in the primary production models applied to the Arctic Ocean. Here, we assemble a large database of pan-Arctic observations (i.e., 5206 stations) and develop an empirical model to estimate vertical chlorophyll a (Chl a) according to (1) the shelf–offshore gradient delimited by the 50 m isobath, (2) seasonal variability along pre-bloom, post-bloom, and winter periods, and (3) regional differences across ten sub-Arctic and Arctic seas. Our detailed analysis of the dataset shows that, for the pre-bloom and winter periods, as well as for high surface Chl a concentration (Chl asurf; 0.7–30 mg m−3) throughout the open water period, the Chl a maximum is mainly located at or near the surface. Deep SCMs occur chiefly during the post-bloom period when Chl asurf is low (0–0.5 mg m−3). By applying our empirical model to annual Chl asurf time series, instead of the conventional method assuming vertically homogenous Chl a, we produce novel pan-Arctic PP estimates and associated uncertainties. Our results show that vertical variations in Chl a have a limited impact on annual depth-integrated PP. Small overestimates found when SCMs are shallow (i.e., pre-bloom, post-bloom > 0.7 mg m−3, and the winter period) somehow compensate for the underestimates found when SCMs are deep (i.e., post-bloom < 0.5 mg m−3). SCMs are, however, important seasonal features with a substantial impact on depth-integrated PP estimates, especially when surface nitrate is exhausted in the Arctic Ocean and where highly stratified and oligotrophic conditions prevail.

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