Importance of wind and river discharge in influencing nutrient dynamics and phytoplankton production in summer in the central Strait of Georgia

High-resolution vertical profiles of salinity, temperature, fluorescence, and nutrients (NO3 and SiO4) were taken along a transect in the central Strait of Georgia, British Columbia. The Fraser River discharge increased rapidly over 4 days and then decreased over the following 3 days (June 16-19, 1991). The thickness and extent of the estuarine plume increased as a response to the increased river discharge. As the estuarine plume flowed seaward, the nutricline (NO3) became shallower and broader, resulting in an increase in NO3 in the euphotic zone. Entrainment of NO3 may explain the increase in NO3 in the surface layer, and the amount of NO3 entrained was estimated to be 5-10 times higher than river-borne NO3. The utilization of entrained nutrients increased Chl a concentrations and primary production to levels comparable with spring bloom values. Our results clearly demonstrated for the first time that entrainment of nutrients and phytoplankton production in the central Strait of Georgia are closely coupled to fluctuations in the Fraser River discharge as the estuarine plume moves seaward. The timing and magnitude of the May-June freshet could control the entrainment of nutrients and thus maintain high primary productivity in late spring - early summer.

Download Full-text

Implications of Nutrient Enrichment and Related Environmental Impacts in the Pearl River Estuary, China: Characterizing the Seasonal Influence of Riverine Input

Water ◽

10.3390/w12113245 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3245

Author(s):

Lixia Niu ◽

Pieter van Gelder ◽

Xiangxin Luo ◽

Huayang Cai ◽

Tao Zhang ◽

...

Keyword(s):

Nutrient Enrichment ◽

River Discharge ◽

Nutrient Dynamics ◽

Southern China ◽

Salinity Gradient ◽

River Estuary ◽

Pearl River Estuary ◽

Pearl River ◽

The Pearl River Estuary ◽

The Pearl River

The Pearl River estuary is an ecologically dynamic region located in southern China that experiences strong gradients in its biogeochemical properties. This study examined the seasonality of nutrient dynamics, identified related environmental responses, and evaluated how river discharge regulated nutrient sink and source. The field investigation showed significant differences of dissolved nutrients with seasons and three zones of the estuary regarding the estuarine characteristics. Spatially, nutrients exhibited a clear decreasing trend along the salinity gradient; temporally, their levels were obviously higher in summer than other seasons. The aquatic environment was overall eutrophic, as a result of increased fluxes of nitrogen and silicate. This estuary was thus highly sensitive to nutrient enrichment and related pollution of eutrophication. River discharge, oceanic current, and atmospheric deposition distinctly influenced the nutrient status. These factors accordingly may influence phytoplankton that are of importance in coastal ecosystems. Phytoplankton (in terms of chlorophyll) was potentially phosphate limited, which then more frequently resulted in nutrient pollution and blooms. Additionally, the nutrient sources were implied according to the cause–effect chains between nutrients, hydrology, and chlorophyll, identified by the PCA-generated quantification. Nitrogen was constrained by marine-riverine waters and their mutual increase-decline trend, and a new source was supplemented along the transport from river to sea, while a different source of terrestrial emission from coastal cities contributed to phosphate greatly.

Download Full-text

Environmental Variation and Recruitment of Pacific Herring (Clupea harengus pallasi) in the Strait of Georgia

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f85-272 ◽

1985 ◽

Vol 42 (S1) ◽

pp. s174-s180 ◽

Cited By ~ 32

Author(s):

Max Stocker ◽

Vivian Haist ◽

David Fournier

Keyword(s):

Environmental Variables ◽

River Discharge ◽

Clupea Harengus ◽

Pacific Herring ◽

Strait Of Georgia ◽

Clupea Harengus Pallasi ◽

Age Structured ◽

Age Structured Model ◽

The Relationship ◽

Spawning Success

We used an age-structured model to estimate recruitment for the Strait of Georgia Pacific herring (Clupea harengus pallasi) population. The model used for herring is a version of the model described in Fournier and Archibald (1982. Can. J. Fish. Aquat. Sci. 39: 1195–1207), modified to include spawn survey information. Three structural assumptions are made to include the spawn data: (1) the form of the relationship between the actual spawn and the observed spawn, (2) the form of the relationship between escapement and actual spawn, and (3) the existence of a Ricker spawn–recruitment relationship, with a multiplicative environmental component. In order to determine which environmental factors had a significant effect on recruitment, we attempted to explain the residual variation from the Ricker curve with the environmental variables using exploratory correlations. Temperature, river discharge, sea level, and sunlight were examined. A multiplicative, environmental-dependent Ricker spawn–recruitment model was used to identify significant environmental variables. The model suggests a significant dome-shaped relationship between temperature and spawning success with an optimal temperature during larval stages resulting in maximum production of recruits. Also, increased spawning success is associated with increased summer river discharge. The significant environmental variables were included in the age-structured model in a stock–environment–recruitment relationship, and all model parameters were reestimated. The overall model fit improved only marginally with the inclusion of environmental variables, as indicated by the objective function value. However, the S–R component of the objective function dropped by 23% when environmental variables were included.

Download Full-text

Salt and Freshwater Exchange on Roberts Bank, British Columbia

Water Quality Research Journal ◽

10.2166/wqrj.1988.012 ◽

1988 ◽

Vol 23 (1) ◽

pp. 160-178 ◽

Cited By ~ 2

Author(s):

P.B. Crean ◽

T.S. Murty ◽

J.A. Stronach

Keyword(s):

Fresh Water ◽

Seasonal Changes ◽

River Discharge ◽

Retaining Wall ◽

Surface Currents ◽

Fraser River ◽

Strait Of Georgia ◽

Shallow Layer ◽

Layer Flow ◽

Incoming Tide

Abstract One of the aspects of the seaward movement of fresh water from the Fraser River is its passage tangential to Roberts Bank and subsequent recirculation onto the bank. A synoptic study of the oceanography of the bank is described, part, of a larger study of surface currents in the Strait of Georgia. Seasonal changes in salinity and temperature over Roberts Bank are presented. The freshwater flows and motions of the salt wedges in the river and on the bank are described. Under the restraints of a retaining wall immediately north of the river, and on the incoming tide, a shallow layer of fresh water briefly forms an eddy, varying in size with river discharge and extending over the bank to the south. The influence of the two-layer flow on sedimentation is also discussed.

Download Full-text

Phytoplankton Ecology of the Strait of Georgia, British Columbia

Journal of the Fisheries Research Board of Canada ◽

10.1139/f79-095 ◽

1979 ◽

Vol 36 (6) ◽

pp. 657-666 ◽

Cited By ~ 55

Author(s):

J. G. Stockner ◽

D. D. Cliff ◽

K. R. S. Shortreed

Keyword(s):

Surface Waters ◽

Light Attenuation ◽

Marine Phytoplankton ◽

Phytoplankton Production ◽

Fraser River ◽

Heterogeneous Distribution ◽

Phytoplankton Primary Production ◽

Strait Of Georgia ◽

Phytoplankton Ecology ◽

Phytoplankton Distribution

Observations of phytoplankton production, abundance, and distribution were made at 16 stations in the Strait of Georgia from 1975 to 1977. The discharge of turbid Fraser River water exerts a strong influence on phytoplankton production and distribution in surface waters by rapid light attenuation and horizontal advection. At plume boundaries and back eddies where light conditions improve, very high production occurs (> 4–5 g C∙m−2∙d−1), because of rapidly replenished nutrients supplied by the Fraser River. Advection, turbulence, zooplankton grazing, and summer nitrate depletion collectively impart a heterogeneous distribution pattern to phytoplankton in the surface waters of the Strait of Georgia. Mean annual production varies from lows of 150 g C∙m−2 in Fraser River plume to highs of over 500 g C∙m−2 in sheltered boundary waters of inlets. Recent increases in ammonia and nitrate from land drainage and domestic sewage, mainly through the Fraser River, are related to increases in phytoplankton standing stocks in the Strait. Key words: phytoplankton, primary production, eutrophication, coastal marine, phytoplankton distribution and succession, chlorophyll a, pelagic

Download Full-text

Factors favouring phytoplankton blooms in the northern Adriatic: towards the northern Adriatic empirical ecological model

Ocean Science ◽

10.5194/os-12-19-2016 ◽

2016 ◽

Vol 12 (1) ◽

pp. 19-37 ◽

Cited By ~ 12

Author(s):

R. Kraus ◽

N. Supić ◽

R. Precali

Keyword(s):

River Discharge ◽

Ecological Model ◽

Circulation Pattern ◽

Surface Fluxes ◽

Phytoplankton Production ◽

Phytoplankton Blooms ◽

Po River ◽

Northern Adriatic ◽

Discharge Rates

Abstract. Influenced by one of the largest Mediterranean rivers, Po, the northern Adriatic (NA) production is highly variable seasonally and interannually. The changes are especially pronounced between winters and seemingly reflect on total Adriatic bioproduction of certain species (anchovy). We analysed the long-term changes in the phytoplankton production in the region, as derived from monthly oceanographic cruises, in relation to concomitant geostrophic currents distribution in the area and to Po River discharge rates in days preceding the cruises. In winter and early spring the phytoplankton abundances depended on existing circulation fields, in summer and autumn they were related to Po River discharge rates 1–15 days earlier and on concomitant circulation fields, while in late spring phytoplankton abundances increased 1–3 days after high Po River discharge rates regardless of the circulation fields. During the entire year the phytoplankton abundances were dependent on forcing of the previous 1–12 months of surface fluxes and/or Po River rates. The role of wind was uncertain but that was partly due to unmatched sampling time frames between meteorological and sea data. Low evaporation rates in November reflected significantly on the next February circulation pattern and, although with somewhat lower significance, on large phytoplankton blooms in the same month. We showed that the role of wind in evaporative flux enhancements is not straightforward as evaporative fluxes are highly dependent on other factors, e.g. air–sea temperature difference. Wind-induced vertical mixing was only sporadically related to phytoplankton abundances. From 1990 to 2004 a shift towards large winter bioproduction induced by circulation changes appeared. The investigations performed represent the preliminary actions in the construction of an empirical ecological model of the NA which can be used in the sustainable economy of the region, as well as for validation of the numerical ecological model of the region, which is currently being developed.

Download Full-text

A review: iron and nutrient supply in the subarctic Pacific and its impact on phytoplankton production

Journal of Oceanography ◽

10.1007/s10872-021-00606-5 ◽

2021 ◽

Author(s):

Jun Nishioka ◽

Hajime Obata ◽

Toru Hirawake ◽

Yoshiko Kondo ◽

Youhei Yamashita ◽

...

Keyword(s):

Nutrient Dynamics ◽

Biological Response ◽

Nutrient Supply ◽

Phytoplankton Production ◽

Atmospheric Dust ◽

Biological Production ◽

Future Directions ◽

Subarctic Pacific ◽

Oceanographic Research ◽

High Nutrient

AbstractOne of the most important breakthroughs in oceanography in the last 30 years was the discovery that iron (Fe) controls biological production as a micronutrient, and our understanding of Fe and nutrient biogeochemical dynamics in the ocean has significantly advanced. In this review, we looked back both previous and updated knowledge of the natural Fe supply processes and nutrient dynamics in the subarctic Pacific and its impact on biological production. Although atmospheric dust has been considered to be the most important source of Fe affecting biological production in the subarctic Pacific, other oceanic sources of Fe have been discovered. We propose a coherent explanation for the biological response in subarctic Pacific high nutrient low chlorophyll (HNLC) waters that incorporates knowledge of both the atmospheric Fe supplies and the oceanic Fe supplies. Finally, we extract future directions for Fe oceanographic research in the subarctic Pacific and summarize the uncertain issues identified thus far.

Download Full-text

Observations Inform Improvements in Model Silicon Cycling in a Semi-enclosed Coastal Sea

10.5194/egusphere-egu21-10502 ◽

2021 ◽

Author(s):

Elise Olson ◽

Nina Nemcek ◽

Susan Allen

Keyword(s):

Functional Groups ◽

Nutrient Dynamics ◽

Biological Model ◽

Model Parameters ◽

Dissolved Silica ◽

Strait Of Georgia ◽

Silicon Cycle ◽

Phytoplankton Functional Groups ◽

Coastal Sea ◽

The Impact

<p>We have developed a coupled physical-biological model representing plankton and nutrient dynamics of the Strait of Georgia, a fjord-like semi-enclosed coastal sea on the west coast of Canada. The nutrient-phytoplankton-zooplankton-detritus (NPZD)-type biological model is based on nitrogen uptake and remineralization with a coupled silicon cycle and includes both diatom and non-siliceous phytoplankton functional groups. The Strait of Georgia exhibits an estuarine circulation driven by input from the Fraser River as well as many smaller rivers and streams. It has high levels of dissolved silica (can be >50 &#956;M even at the surface). Silicon-replete conditions shape key characteristics of the local ecosystem, which include heavily silicified glass sponge reefs as well as frequent diatom and occasional silicoflagellate blooms. We therefore consider the ability of the model to match observed silicon levels an indicator of the fidelity of its representation of local biogeochemistry. Silicon in the model may be in the form of dissolved silica, living diatoms, or particulate biogenic silica, and model diatom growth may be limited by nitrogen, light, or dissolved silica availability. We will discuss the challenges involved in accurately representing important drivers of the regional silicon cycle. These include accurately capturing the division of primary productivity between diatoms and non-siliceous phytoplankton functional groups, as well as uncertainties in the magnitude of terrestrial inputs and sediment fluxes. We will show how evaluating the model functional groups by comparison with phytoplankton community composition determined by high performance liquid chromatography (HPLC) has informed our interpretation of model results and provided direction for efforts at improving model performance. We will discuss the impact of targeted adjustments to model parameters on the model silicon cycle in light of comparisons to observations.</p>

Download Full-text

Factors favouring large organic production in the northern Adriatic: towards the northern Adriatic empirical ecological model

Ocean Science Discussions ◽

10.5194/osd-12-1219-2015 ◽

2015 ◽

Vol 12 (3) ◽

pp. 1219-1262 ◽

Cited By ~ 1

Author(s):

R. Kraus ◽

N. Supić ◽

R. Precali

Keyword(s):

River Discharge ◽

Ecological Model ◽

Early Spring ◽

Organic Production ◽

Surface Fluxes ◽

Phytoplankton Production ◽

Po River ◽

Northern Adriatic ◽

Discharge Rates ◽

Circulation Patterns

Abstract. Influenced by one of the largest Mediterranean rivers, Po, the northern Adriatic production is highly variable seasonally and interannually. The changes are especially pronounced between winters and seemingly reflect on total Adriatic bioproduction of certain species (anchovy). We analysed the long-term changes in the phytoplankton production at the transect in the region, as derived from monthly oceanographic cruises, in relation to concomitant geostrophic currents distribution in the area and in the Po River discharge rates in days preceding the cruises. In winter and early spring the phyto-abundances depended on existing circulation fields, in summer and autumn they were related to 1–15 days earlier Po River discharge rates and on concomitant circulation fields, while in late spring phyto-abundances increased 1–3 days after high Po River discharge rates regardless of circulation fields. During the entire year the phyto-abundances were dependant on forcing of the previous 1–12 months of surface fluxes and/or Po River rates. Large February blooms are, as well as February circulation patterns, precondited by low evaporation rates in previous November. From 1990 to 2004 a shift towards large winter bioproduction induced by circulation changes appeared. Performed investigations represent the preliminary actions in building of an empirical ecological model of the northern Adriatic which can be used in the sustainable economy of the region, however also in validation of the numerical ecological model of the region, which is currently being developed.

Download Full-text

Phytoplankton Production and Distribution in Howe Sound, British Columbia: A Coastal Marine Embayment–Fjord Under Stress

Journal of the Fisheries Research Board of Canada ◽

10.1139/f77-142 ◽

1977 ◽

Vol 34 (7) ◽

pp. 907-917 ◽

Cited By ~ 22

Author(s):

John G. Stockner ◽

David D. Cliff ◽

Douglas B. Buchanan

Keyword(s):

British Columbia ◽

Surface Layer ◽

Light Attenuation ◽

Marine Phytoplankton ◽

Annual Production ◽

Phytoplankton Production ◽

Strong Light ◽

Strait Of Georgia ◽

Coastal Marine ◽

Production And Distribution

Phytoplankton production and distribution were examined over a 2-yr period in relation to man-induced and natural factors that stress the system by mainly affecting the light regime in surface layer(s) of Howe Sound, British Columbia. Production rate and biomass values were greatest at the seaward boundary of the Sound where surface waters mix with the Strait of Georgia. Production decreases linearly in an up-inlet direction, reaching minimum values at the head of the Sound where the influence of the turbid Squamish River discharge is greatest. Annual production in the boundary waters of the Sound for 1973 and 1974 was 300 and 516 g C∙m−2, compared to an average of 118 and 163 for remaining stations. Strong light attenuation by the turbid Squamish River and flushing by the seaward moving surface layer were considered the most important factors controlling phytoplankton production and distribution in Howe Sound. Colored effluent from two pulp mills and turbid mine tailings and gravel washing water were minor perturbants to the system as a whole, but in affected bays and subregions of the Sound their effects on phytoplankton production were considerable. Annual production in Howe Sound was slightly higher than values for the Strait of Georgia and considerably greater than estimates from the North Pacific. Key words: phytoplankton, production, fjord–embayment, coastal marine, phytoplankton distribution, succession

Download Full-text