Dispersion and Retention of Anadromous Rainbow Smelt (Osmerus mordax) Larvae in the Middle Estuary of the St. Lawrence River

1985 ◽  
Vol 42 (2) ◽  
pp. 332-341 ◽  
Author(s):  
Patrick Quellet ◽  
Julian J. Dodson
Keyword(s):  
Water Mass ◽  
High Tide ◽  
Horizontal Distribution ◽  
Circulation System ◽  
Larval Abundance ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Lawrence Estuary ◽  
Middle Estuary ◽  
St Lawrence River

The vertical and horizontal distribution of anadromous rainbow smelt (Osmerus mordax) larvae from hatching in their natal river to their occupation of nursery areas in the middle estuary of the St. Lawrence River was documented to describe the mechanism responsible for the retention of smelt larvae in this area. Peaks of larval abundance observed downstream of the spawning grounds indicate a 24-h periodicity in hatching and the introduction of larvae into the riverine circulation. No retention of larvae was observed between the spawning ground and the downstream portion of the natal river. Our evidence indicates daytime accumulation of larvae at the mouth of the natal river, possibly resulting from the negative phototaxis exhibited by small smelt larvae. Patches of smelt larvae were incorporated into the St. Lawrence estuarine water mass once every 24 h at night following high tide. The subsequent downstream transport of larvae in the St. Lawrence estuary appears slower than the advection of the water mass due to the tendency of larvae to remain deeper in the water column during ebb tides and to concentrate near the surface during flood tides. Smelt larvae are transported from the south shore to the partially mixed northern portion of the middle estuary which represents the principal zone of larval smelt accumulation. We propose that the vertical displacements exhibited by smelt larvae in combination with the two-layer circulation system of the northern middle estuary results in the retention of smelt larvae in this region.

A mtDNA analysis of spatiotemporal distribution of two sympatric larval populations of rainbow smelt (Osmerus mordax) in the St. Lawrence River estuary, Quebec, Canada

1998 ◽  
Vol 55 (7) ◽  
pp. 1739-1747 ◽  
Author(s):  
Dany Pigeon ◽  
Julian J Dodson ◽  
Louis Bernatchez
Keyword(s):  
Resource Partitioning ◽  
River Estuary ◽  
Osmerus Mordax ◽  
Relative Distribution ◽  
Sympatric Populations ◽  
Rainbow Smelt ◽  
Genetic Population ◽  
Spatial Homogeneity ◽  
Middle Estuary ◽  
St Lawrence River

Ecological isolation through resource partitioning is invoked as a major factor for explaining the persistence of genetically distinct yet closely related sympatric populations. Two genetically distinct sympatric populations of anadromous rainbow smelt (Osmerus mordax) exist in the middle estuary of the St. Lawrence River. The persistence of these coexisting populations in sympatry is in conflict with current theoretical concepts predicting population richness. In the present study, we performed mtDNA PCR-RFLP analysis of 922 larvae from 33 sampling stations to test the hypothesis that the larvae belonging to the two sympatric smelt populations of the St. Lawrence middle estuary are spatially segregated and that such segregation may promote the persistence of the populations. Results clearly revealed spatial homogeneity in the relative distribution of larvae from the two populations. Consequently, they did not support our working hypothesis that larvae belonging to the two sympatric smelt populations are spatially segregated. Two alternative explanations may account for the lack of spatial partitioning observed here. Competition may not be important enough to promote resource partitioning at the larval stage. Alternatively, resource partitioning occurs, but not spatially. This study also demonstrated that the effect of historical events may have been as important as contemporary ecological settings in determining genetic population structure in smelt.

Le Panache du Saguenay

1983 ◽  
Vol 40 (1) ◽  
pp. 52-60 ◽  
Author(s):  
J. Lebel ◽  
E. Pelletier ◽  
M. Bergeron ◽  
N. Belzile ◽  
G. Marquis
Keyword(s):  
Surface Layer ◽  
Deep Water ◽  
High Tide ◽  
Lawrence Estuary ◽  
Fresh Waters ◽  
Saguenay Fjord ◽  
Region Data ◽  
Saguenay River ◽  
St Lawrence Estuary ◽  
St Lawrence River

The large difference between the alkalinity of the fresh waters of the St. Lawrence River (1.475 mmol∙kg−1) and the Saguenay River (0.134 mmol∙kg−1) was used to locate the region on the St. Lawrence estuary which is under the influence of the Saguenay River. This method has the advantage over classical measurements such as salinity and temperature that it is independent of the upwelling of deep water in this region. Data was obtained in the St. Lawrence estuary near the mouth of the Saguenay fjord using a network of 33 stations at slack low tide and 23 stations at slack high tide. The results show that, at low tide, Saguenay water forms a plume which extends more than 10 km from the mouth of the fjord into the estuary. At high tide the plume is restricted to the surface layer as the Saguenay waters are pushed back into the fjord.

Climate change and abundance cycles of two sympatric populations of smelt (Osmerus mordax) in the middle estuary of the St. Lawrence River, Canada

2001 ◽  
Vol 58 (10) ◽  
pp. 2048-2058 ◽  
Author(s):  
M Mingelbier ◽  
F Lecomte ◽  
J J Dodson
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Climatic Factors ◽  
Future Climate Change ◽  
Osmerus Mordax ◽  
Sympatric Populations ◽  
North Shore ◽  
South Shore ◽  
Middle Estuary ◽  
St Lawrence River

Commercial catches of two ecologically distinct sympatric smelt (Osmerus mordax) populations segregated along the two shores of the St. Lawrence middle estuary exhibited inverse patterns with periodicities on the order of 30 years. The influence of water level in the St. Lawrence River and air temperature, chosen to reflect variations in hydrology and climate, differed markedly between the two populations. Analyses revealed that both water level and temperature were generally positively related with north-shore smelt landings and negatively related with south-shore smelt landings. For both populations, a number of significant climatic factors contributing to variance in smelt landings were lagged by one to three years relative to the year of landings, indicating that climatic variables influenced smelt recruitment. The contrasting role of hydroclimatic variables in driving these abundance cycles is likely related to differential exploitation of estuarine habitats; the south-shore population is associated with shallow shoal habitat, whereas the north-shore population is associated with deep channel habitat. The responses of the two smelt populations also reflect the fundamental ecological differences existing between shoal and channel habitats, indicating that future climate change may differentially affect other populations or species that are segregated between these two habitats.

Nutrient Distribution in the St. Lawrence Estuary

1977 ◽  
Vol 34 (11) ◽  
pp. 2104-2116 ◽  
Author(s):  
Paul Greisman ◽  
Grant Ingram
Keyword(s):  
Intermediate Layer ◽  
Internal Tide ◽  
Horizontal Distribution ◽  
Estuarine System ◽  
Nutrient Distribution ◽  
Surface Distribution ◽  
Lawrence Estuary ◽  
Freshwater Source ◽  
St Lawrence Estuary ◽  
St Lawrence River

The horizontal distribution of nutrients in the St. Lawrence estuary during early July of 1975 is presented. The major sources of nutrients to the estuarine system appeared to be from the St. Lawrence River and the intermediate layer of the Laurentian Channel. By the assumption of simple mixing and conservation, the surface distribution of nutrients has been calculated. Differences between the calculated and observed values may be attributable to consumption, variability of the freshwater source and of the internal tide amplitude. Key words: nutrient distribution, estuarine circulation, mixing

Tidal Exchange of Anadromous Rainbow Smelt (Osmerus mordax) Larvae Between a Shallow Spawning Tributary and the St, Lawrence Estuary

1985 ◽  
Vol 42 (8) ◽  
pp. 1352-1358 ◽  
Author(s):  
Patrick Ouellet ◽  
Julian J. Dodson
Keyword(s):  
Vertical Distribution ◽  
Yolk Sac ◽  
Osmerus Mordax ◽  
Estuarine Water ◽  
Tidal Exchange ◽  
Rainbow Smelt ◽  
Lawrence Estuary ◽  
Sampling Series ◽  
St Lawrence Estuary ◽  
Riverine Transport

The factors involved in the riverine transport and tidal exchange of yolk-sac rainbow smelt (Osmerus mordax) larvae between Ouelle River and the St. Lawrence estuary were documented. A 72-h sampling series provided evidence of synchronous nighttime hatching of larvae independent of water temperature and river hydrodynamics. Although light conditions influence the vertical distribution of yolk-sac larvae at the river's mouth, the influence of current speed on larval vertical distribution appears to be a more important element in the dynamics of riverine drift and tidal exchange. Yolk-sac larvae sink to the bottom as water currents decrease prior to low slack water. With the intrusion of estuarine water along the bottom during the flood, yolk-sac larvae drifting from the river appear to be mixed with larger post yolk-sac larvae of estuarine origin resulting in temporary retention at the mouth of Ouelle River. However, longer ebb phases in the river result in a net transport of smelt larvae towards the St. Lawrence estuary. We conclude that the riverine transport and mixing of yolk-sac larvae with the estuarine water mass is controlled principally by the hydrodynamics of the system and the nighttime hatching and specific gravity of yolk-sac larvae.

Gammarus lawrencianus (Amphipoda) as Intermediate Host of Echinorhynchus salmonis (Acanthocephala) in an Estuarine Environment

1993 ◽  
Vol 50 (10) ◽  
pp. 2182-2184 ◽  
Author(s):  
Lena N. Measures ◽  
Luci Bossé
Keyword(s):  
North America ◽  
Intermediate Host ◽  
Estuarine Environment ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
First Report ◽  
St Lawrence River

Echinorhynchus salmonis (Acanthocephala) were found in the stomach of a rainbow smelt, Osmerus mordax (Salmoniformes), collected at the confluence of the Aux-Outardes River and St. Lawrence River in Quebec. One acanthocephalan occupied the haemocoel of a recently ingested amphipod (Gammarus lawrencianus), while two other specimens were free in the stomach. This is the first report of G. lawrencianus, an estuarine amphipod, as intermediate host of E. salmonis. This is also the first report of transmission of E. salmonis in an estuarine environment in North America.

Use of Variation in Biological Characters for the Classification of Anadromous Rainbow Smelt (Osmerus mordax) Groups

1983 ◽  
Vol 40 (6) ◽  
pp. 718-727 ◽  
Author(s):  
A. Fréchet ◽  
J. J. Dodson ◽  
H. Powles
Keyword(s):  
Open Water ◽  
Growth Patterns ◽  
Osmerus Mordax ◽  
Rainbow Smelt ◽  
Lawrence Estuary ◽  
Saguenay Fjord ◽  
South Shore ◽  
Lower North Shore ◽  
St Lawrence Estuary

Analysis of meristics, growth patterns, and fecundity to somatic weight relationships of spawning anadromous rainbow smelt (Osmerus mordax) in Quebec waters demonstrated the existence of three geographical groups (Chaleur Bay, south shore of the St. Lawrence Estuary, and Saguenay Fjord). Although homing to spawning rivers does not appear to occur, the degree of heterogeneity of spawning smelt of different geographical areas is less at the extremes of their Quebec distribution. Classification of smelt from the commercial fishery catch indicates limited mixing of these groups during open-water migration. The existence of a fourth group is suggested by classification analysis of smelt caught along the lower north shore of the St. Lawrence Estuary.

A biophysical model of the interaction between vertical migration of crustacean zooplankton and circulation in the Lower St. Lawrence Estuary

1999 ◽  
Vol 56 (12) ◽  
pp. 2420-2432 ◽  
Author(s):  
Bruno A Zakardjian ◽  
Jeffrey A Runge ◽  
Stephane Plourde ◽  
Yves Gratton
Keyword(s):  
Population Dynamics ◽  
Vertical Migration ◽  
Horizontal Distribution ◽  
Calanus Finmarchicus ◽  
Biophysical Model ◽  
Crustacean Zooplankton ◽  
Simple Formulation ◽  
Lawrence Estuary ◽  
Circulation Patterns ◽  
St Lawrence Estuary

As an essential step in modeling the influence of circulation on the population dynamics of marine planktonic copepods, we define a simple formulation of swimming behavior that can be used in both Eulerian and Lagrangian models. This formulation forces aggregation of the population toward a preferential depth and can be stage specific and time varying, thus allowing description of either diurnal or seasonal vertical migration. We use the formulation to examine the interaction between the circulation and vertical distribution in controlling horizontal distribution of the common planktonic copepod Calanus finmarchicus in the Lower St. Lawrence Estuary, Canada. We first introduce diel migration into a simple one-dimensional model and then into a model of residual two-dimensional circulation patterns representative of conditions encountered in the Lower St. Lawrence Estuary. Results from the latter indicate that interactions between circulation and stage-specific swimming behaviors are the main mechanisms for aggregation of planktonic crustaceans at the head of the Laurentian Channel and highlight the implications of flushing of the surface-dwelling young stages for the population dynamics of C. finmarchicus in the Lower St. Lawrence Estuary.

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