A Horizontally Resolving Physical–Biological Model of Nitrate Concentration and Primary Productivity in the Strait of Georgia

1993 ◽  
Vol 50 (7) ◽  
pp. 1456-1466 ◽  
Author(s):  
M. A. St. John ◽  
S. G. Marinone ◽  
J. Stronach ◽  
P. J. Harrison ◽  
J. Fyfe ◽  
...  
Keyword(s):  
Surface Layer ◽  
Water Column ◽  
Primary Productivity ◽  
River Runoff ◽  
Nitrate Concentration ◽  
Energy Requirement ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Wind Events ◽  
Wind Mixing

Model simulations revealed that wind mixing was the dominant physical mechanism that added nitrate to the surface layer and subsequently enhanced primary productivity in the Strait of Georgia. Simulations of high Fraser River runoff showed that the enhanced stability of the water column in the vicinity of the riverine plume made wind mixing of nutrients into the surface layer more difficult. We propose that this increase in stability results in an earlier onset of the spring bloom in regions influenced by Fraser River runoff. During the summer, an increase in the buoyancy of surface water due to the freshwater plume reduces nitrate concentration in the surface layer and thereby limits primary production in the plume area. The reduced impact of wind events on nitrate fluxes is the result of a greater energy requirement to break down the more buoyant surface layer. Results indicate that during the fall, when light is again limiting and surface nitrate concentrations increase due to wind mixing by fall storms, the freshwater runoff from the Fraser River results in a more stable water column (similar to the spring situation) in the southern Strait, resulting in the potential for a fall bloom.

Factors controlling the timing of the spring bloom in the Strait of Georgia estuary, British Columbia, Canada

1997 ◽  
Vol 54 (9) ◽  
pp. 1985-1995 ◽  
Author(s):  
K Yin ◽  
P J Harrison ◽  
R H Goldblatt ◽  
M A St.John ◽  
R J Beamish
Keyword(s):  
Spring Bloom ◽  
Juvenile Fish ◽  
Zooplankton Grazing ◽  
Interannual Variations ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Large Numbers ◽  
Wind Event ◽  
Neocalanus Plumchrus ◽  
Wind Events

We present a conceptual model to illustrate how wind events and the annual migration and grazing of the dominant copepod Neocalanus plumchrus interact and affect the development of the spring bloom. The model was supported by observations made during 1988, 1992, and 1993. For example, in 1992, an El Niño year, the annual freshet of the Fraser River and probably the spring bloom started 1 month earlier. The bloom was interrupted by a wind event in late March. A few days later, its full recovery was interrupted by the peak in zooplankton grazing, and ambient ammonium concentrations increased. In contrast, in 1988, the annual freshet started later (mid-April), and winds remained strong throughout the same period, hindering the development of the spring bloom. The spring bloom was further suppressed by large numbers of zooplankton during April, resulting in a prolonged spring bloom. These observations indicate that interannual variations in winds and the timing of the annual freshet determine the timing and duration of the spring bloom, which in turn, determine the matching of phytoplankton to zooplankton in the Strait of Georgia. The matching or mismatching bears significant implications for food availability for juvenile fish.

Review of the Biological Oceanography of the Strait of Georgia: Pelagic Environment

1983 ◽  
Vol 40 (7) ◽  
pp. 1064-1094 ◽  
Author(s):  
P. J. Harrison ◽  
J. D. Fulton ◽  
F. J. R. Taylor ◽  
T. R. Parsons
Keyword(s):  
Food Web ◽  
Primary Productivity ◽  
Larval Fish ◽  
Standing Stock ◽  
River Plume ◽  
Limiting Factors ◽  
Fraser River ◽  
Strait Of Georgia ◽  
The North ◽  
Rate Processes

Different components of the food web in the Strait of Georgia are reviewed. The phytoplankton are dominated by diatoms; however, flagellates may dominate in the winter. Chlorophyll a concentrations may range from < 1 mg∙m−3 in the winter to > 15 mg∙m−3 during blooms. The average annual primary productivity is about 280 g C∙m−2 for the strait, but it is higher in frontal areas at the north and south ends of the strait and near the Fraser River plume. Light limits primary productivity during the winter months, while nutrients (nitrogen) and grazing are the limiting factors during the late spring and summer. Turbidity and salinity effects occur near the Fraser River plume. The surface macrozooplankton community is composed chiefly of copepods. Mid- and deep-water communities consist of euphausiids, chaetognaths, and some deep-living copepods, which overwinter at depth. The standing stock of macrozooplankton (> 350 μm) to 400 m, ranges from 0.1 to 2.0 g wet wt∙m−3. Few estimates of secondary production and standing stock estimates of microzooplankton have been made. Horizontal patches of zooplankton have been encountered and may be important feeding sites for some fish. Standing stock associations of the dominant species in the food web of the strait are reasonably well known, but assessment of food web dynamics from these limited standing stock measurements is often inaccurate. There is a noticeable absence of data on how rate processes affect standing stocks, and it is particularly an understanding of these interrelationships that is needed for fisheries management. There is an urgent need for more interaction between biological oceanographers and fisheries scientists, particularly in the area of zooplankton grazing by larval fish.

Subglacial brine flow and wind-induced internal waves in Lake Bonney, Antarctica

2020 ◽  
Vol 32 (3) ◽  
pp. 223-237
Author(s):  
Jade P. Lawrence ◽  
Peter T. Doran ◽  
Luke A. Winslow ◽  
John C. Priscu
Keyword(s):  
Water Column ◽  
Internal Waves ◽  
Open Water ◽  
Surface Discharge ◽  
Katabatic Wind ◽  
Neutral Buoyancy ◽  
Cold Temperatures ◽  
Glacier Terminus ◽  
Wind Events ◽  
Taylor Glacier

AbstractBrine beneath Taylor Glacier has been proposed to enter the proglacial west lobe of Lake Bonney (WLB) as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the geochemistry of the water column of WLB. Year-round measurements from this study are the first to definitively identify brine intrusions from a subglacial entry point into WLB. Furthermore, we excluded input from Blood Falls by focusing on winter dynamics when the absence of an open water moat prevents surface brine entry. Due to the extremely high salinities below the chemocline in WLB, density stratification is dominated by salinity, and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude into the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. High-resolution measurements also reveal under-ice internal waves associated with katabatic wind events, a novel finding that challenges long-held assumptions about the stability of the WLB water column.

The Qualitative and Quantitative Distribution of Plankton in the Strait of Georgia in Relation to Certain Oceanographic Factors

1957 ◽  
Vol 14 (4) ◽  
pp. 521-552 ◽  
Author(s):  
Joseph Eugène Henri Légaré
Keyword(s):  
Salinity Gradient ◽  
General Distribution ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Quantitative Distribution ◽  
Qualitative And Quantitative ◽  
Chemical Factors ◽  
Physical And Chemical ◽  
Plankton Communities ◽  
Made In

In order to gain some picture of the seasonal variations in the plankton communities two cruises were made in the Strait of Georgia, one in June 1955, and the other in November 1955; 165 plankton collections were taken, also surface temperatures.The correlation of these data have resulted in a number of conclusions concerning the distribution of plankton in the Strait of Georgia. The chief factor affecting the general distribution of plankton is the salinity gradient. The inflow of fresh water from the Fraser River forms zones of varying properties, and leads to the development of different plankton communities. The extent to which physical and chemical factors may determine the presence or absence of certain organisms from the zones described is discussed.

scholarly journals A model for the evolution of the thermal bar system

2012 ◽  
Vol 24 (2) ◽  
pp. 161-177 ◽  
Author(s):  
DUNCAN E. FARROW
Keyword(s):  
Surface Layer ◽  
Water Column ◽  
Thermal Balance ◽  
Spring Warming ◽  
Entire Water Column ◽  
Horizontal Extent ◽  
Thermal Bar ◽  
Stable Surface Layer ◽  
Near Shore ◽  
New Framework

A new framework for modelling the evolution of the thermal bar system in a lake is presented. The model assumes that the thermal bar is located between two regions: the deeper region, where spring warming leads to overturning of the entire water column, and the near shore shallower region, where a stable surface layer is established. In this model the thermal bar moves out slightly more quickly than predicted by a simple thermal balance. Also, the horizontal extent of the thermal bar region increases as it moves out from the shore.

scholarly journals ESTIMACIÓN DE LA PRODUCTIVIDAD PRIMARIA EN DOS BAJOS DE LA PARTE SUR DEL GOLFO DE CALIFORNIA, MÉXICO

2008 ◽  
Vol 23 (1-2) ◽  
pp. 39
Author(s):  
G. Verdugo-Díaz ◽  
R. Cervantes Duarte ◽  
M. O. Albáñez-Lucero
Keyword(s):  
Surface Temperature ◽  
Water Column ◽  
Primary Productivity ◽  
Gulf Of California ◽  
Inorganic Nutrients ◽  
Water Transparency ◽  
Vertical Profiles ◽  
Subsurface Maximum ◽  
Natural Fluorescence ◽  
Productivity Estimation

Primary productivity estimation in two seamounts in the southern Gulf of California, México Vertical profiles of temperature and natural fluorescence from 100 m deep were made during February 2005. Water transparency was measured using Secchi’s disc, as well samples of superficial water and at maximum of fluorescence deep were collected to analyze inorganic nutrients. In “El Bajo Espiritu Santo” temperature (20 °C at surface) diminished gradually with depth, without significant stratification.Primary productivity shows superficial values close to 6 mg C m-3 h-1, recahing undetectable values at 20 m of depth. In “El Bajo Gorda” surface temperature reached 22 °C and the water column shows a thermocline between 35 m and 45 m of depth. The profiles of primary productivity presented a subsurface maximum (approximately 2 mg C m-3 h-1) associated with the thermocline.

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