Croissance de la plie rouge (Pseudopleuronectes americanus) de l'estuaire maritime du Saint-Laurent

1985 ◽  
Vol 63 (7) ◽  
pp. 1610-1616 ◽  
Author(s):  
Robert Vaillancourt ◽  
Jean-Claude F. Brêthes ◽  
Gaston Desrosiers
Keyword(s):  
Linear Growth ◽  
Sampling Period ◽  
The Other ◽  
Pseudopleuronectes Americanus ◽  
Spawning Period ◽  
Lawrence Estuary ◽  
Growth Equations ◽  
South Shore ◽  
Males And Females ◽  
St Lawrence Estuary

A study on the growth in size and weight of the Winter Flounder, Pseudopleuronectes americanus (Walbaum), was conducted from samples collected during the summers of 1979 and 1980, in the bay of Saint-Fabien-sur-Mer (Québec) on the south shore of the Lower St. Lawrence Estuary. Age was determined by otolith readings and length–weight relationships were calculated. Linear growth equations were not statistically different for males and females. On the other hand, weight was found to be higher for females than for males of equal sizes. This relationship also varies with the sampling period, and a substantial weight increase follows the spawning period. The growth of P. americanus is slower in the estuary than in more southern areas, while the weights at equal sizes are higher. These results reflect the severe environmental conditions, which necessitate a large accumulation of food energy by the fish as reserves, to the detriment of growth.

Ichthyoplankton of the St. Lawrence Estuary: Composition, Distribution, and Abundance

1978 ◽  
Vol 35 (12) ◽  
pp. 1518-1531 ◽  
Author(s):  
Kenneth W. Able
Keyword(s):  
Key Words ◽  
Sampling Period ◽  
Nursery Area ◽  
Composition Distribution ◽  
Lawrence Estuary ◽  
Demersal Eggs ◽  
June July ◽  
Saguenay River ◽  
St Lawrence Estuary ◽  
Eggs And Larvae

The composition, distribution, and abundance of ichthyoplankton in the St. Lawrence estuary, including adjacent portions of the Saguenay River and the northwestern Gulf of St. Lawrence, were investigated during June–July 1973, June–October 1974, and May–September 1975. The eggs and larvae of 25 species from 14 families (principally osmerids, gadids, cottids, cyclopterids, and pleuronectids) were represented. The larvae, in every year, were almost exclusively forms with demersal eggs. Larvae were consistently more abundant in the upper estuary during every sampling period due to its use as a major spawning and nursery area for several species. Both eggs and larvae were most abundant in June and July. Probable spawning times, areas, and growth of larvae are discussed for selected species. Key words: ichthyoplankton, St. Lawrence estuary, distribution, larvae, osmerids, gadids, cottids, cyclopterids, pleuronectids

Le contrôle de la variabilité à court terme du phytoplancton estuarien: stabilité verticale et profondeur critique

1979 ◽  
Vol 36 (11) ◽  
pp. 1325-1335 ◽  
Author(s):  
L. Fortier ◽  
L. Legendre
Keyword(s):  
Water Column ◽  
Tidal Cycle ◽  
Richardson Number ◽  
Low Frequency ◽  
The Other ◽  
Critical Depth ◽  
Lawrence Estuary ◽  
Vertical Stability ◽  
St Lawrence Estuary ◽  
C Assimilation

Hourly series of summer phytoplankton biomass (ATP and chlorophyll a) and photosynthetic capacity (14C assimilation and ATP increase in saturating light) were sampled in the lower St. Lawrence Estuary during the summer of 1977. Vertical stability of the water column was estimated by the Richardson number. From the results it is concluded that the mean level of biomass is an inverse function of critical depth, likely linked to the neap-spring tidal cycle (Mf). On the other hand, the fine fluctuations of biomass and photosynthetic activity were related to vertical stability, which varies according to the semi-diurnal tidal cycle (M2). A simple model was developed on the basis of Sverdrup's critical depth, combining the M2 fluctuations in stability (degree of vertical mixing) to Mf variations in critical depth. Net biomass increases, observed in a nonturbid stabilized water column, cannot be explained by the growth rates computed from 14C assimilation, but they are consistent with the measured rates of ATP production. Spectral analyses of time series of temperature and Richardson number suggest that low frequency water column stability variations amplify the spatial heterogeneity of a reacting parameter such as phytoplankton. On the other hand, a passive scalar such as temperature does not respond to these low frequency variations of stability. It follows that the study of stability spectra may give some insight into the low frequency control of phytoplankton dynamics. Key words: phytoplankton, St. Lawrence Estuary, variability, vertical stability, critical depth, Richardson number, Kendall's cross correlation, spectral analysis

scholarly journals La mer de Goldthwait au Québec

2010 ◽  
Vol 31 (1-2) ◽  
pp. 61-80 ◽  
Author(s):  
Jean-Claude Dionne
Keyword(s):  
Quebec City ◽  
The South ◽  
Lawrence Estuary ◽  
Marine Invasion ◽  
North Shore ◽  
The North ◽  
Upper Limit ◽  
South Shore ◽  
Anticosti Island ◽  
St Lawrence Estuary

The Goldthwait Sea is defined as the late- and post-Glacial marine invasion in the St. Lawrence Estuary and Gulf east of Québec City. In Québec, this sea has submerged an area of about 25 000 km2. The largest areas submerged are the north shore of the St. Lawrence between Les Escoumins and Blanc-Sablon, the south shore between Levis and Tourelles, and the Anticosti Island. The upper limit of the Goldthwait Sea varies from place to place. The Goldthwait Sea began 14 000 years ago and land emergence is still in progress, since the pre-Wisconsin marine level has not been recovered yet. For a better chronology, this long interval needs to be subdivided. Three main periods have been recognized: Goldthwaitian I, II and III. However, a geographical subdivision is also needed. Numerous shorelines were observed at various elevations throughout the area formely submerged by the Goldthwait Sea. However, only a few shorelines are well developed and extensive, and correlations between former shorelines are difficult to establish. Only three levels are widespead and common to the Estuary and parts of the Gulf. The isostatic recovery has been rapid during the first three thousand years after déglaciation of the area: about 75%.

Habitat segregation among the age groups of Gasterosteus aculeatus (Pisces: Gasterosteidae) in the middle St. Lawrence estuary, Canada

1990 ◽  
Vol 68 (6) ◽  
pp. 1202-1208 ◽  
Author(s):  
Paul Picard Jr. ◽  
Julian J. Dodson ◽  
Gérard J. FitzGerald
Keyword(s):  
Breeding Season ◽  
Gasterosteus Aculeatus ◽  
Age Groups ◽  
Minimum Size ◽  
Spawning Period ◽  
Lawrence Estuary ◽  
Age Related ◽  
Tidal Rivers ◽  
Marsh Pools ◽  
St Lawrence Estuary

Previous studies of migratory populations of sticklebacks (Pisces: Gasterosteidae) have been exclusively limited to their biology on the spawning grounds during the spring breeding season. In 1985 and 1986, we studied the ecology of the threespine stickleback (Gasterosteus aculeatus) in three subhabitats of the middle St. Lawrence estuary before, during, and after the breeding season: (i) the open waters of the estuary, (ii) a series of intertidal salt marsh pools, and (iii) two tidal rivers (Rivière des Vases and Rivière Trois-Pistoles). In spring, our catch data in the various subhabitats showed that adults moved from the open waters of the estuary towards the tidal rivers and tide pools. Catches of adults in all subhabitats subsequently declined, whereas the young of the year (age 0+) became increasingly abundant. In this area, G. aculeatus live for 2 years and are physiologically capable of breeding during their first summer as adults. However, we found age-related differences in habitat use between the two adult year classes. Age 1+ fish were never more abundant than age 2+ fish in Rivière des Vases, in the tide pools, and in the open waters of the estuary, whereas age 1+ fish were more abundant than age 2+ fish in Rivière Trois-Pistoles. Throughout the breeding season, gonadosomatic indices of female G. aculeatus were the same for the two age groups. Total lengths of age 0+ fish captured in the various subhabitats suggest that the major spawning period is limited to May and June. Age 0+ fish do not leave the tide pools for the open waters of the estuary before having attained a certain minimum size.

The food and feeding of common eiders in the St. Lawrence estuary in summer

1974 ◽  
Vol 52 (3) ◽  
pp. 319-334 ◽  
Author(s):  
M. Cantin ◽  
J. Bédard ◽  
H. Milne
Keyword(s):  
Intertidal Zone ◽  
Maximum Growth ◽  
Somateria Mollissima ◽  
Lawrence Estuary ◽  
Common Eiders ◽  
Feeding Activities ◽  
Food And Feeding ◽  
South Shore ◽  
Natural Foods ◽  
St Lawrence Estuary

The study was conducted in the St. Lawrence estuary during 1969 and 1970. The food abundance in the intertidal zone was measured in four Sampling stations located on the south shore of the river; the measurements revealed that over 95% of the available food of the common eider (Somateria mollissima) consisted of Littorina spp., Mytilus edulis, and Gammarus oceanicus. Both adult and young birds showed a distinct rhythm of feeding activities associated with tidal level. During the prenesting period, herring eggs and Nereis virens made up most of the food of adult common eiders. When accompanying ducklings, females ate mostly Littorina spp. and amphipods. Littorina spp. made up between 30 and 97% of the diet of the ducklings, the importance of this gastropod growing with age of the bird. Energy requirements during maximum growth were evaluated at about 460 kcal/bird per day on ducklings (age 54 days) fed natural foods, while between week 3 and week 8 it stood at about 520 kcal/bird per day in ducklings fed "turkey starter." These figures were used to assess the importance of the food removed by the eiders from the intertidal zone during the summer. We conclude that between 10 and 30% (according to the area) of the standing-crop biomass of Littorina alone (in July) is removed by the ducklings and the females accompanying them. At various moments through the season, these birds remove between 40 and 100 metric tons of mollusks per day from the intertidal zone.

scholarly journals TIDAL SEDIMENTATION IN GROS-CACOUNA HARBOR

1978 ◽  
Vol 1 (16) ◽  
pp. 120 ◽  
Author(s):  
Georges Drapeau ◽  
Guy Fortin
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediments ◽  
Suspended Sediment Transport ◽  
Lawrence Estuary ◽  
Seismic Profiling ◽  
Reflection Seismic ◽  
High Turbidity ◽  
South Shore ◽  
Bottom Sampling ◽  
St Lawrence Estuary

The harbor of Gros-Cacouna on the South shore of the St. Lawrence Estuary has been silting at the rate of 31 cm/yr. since it was dredged at the depth of 14 meters in 1968. Measurements of temperature, salinity, turbidity, current speed and direction were carried out as well as bottom sampling and reflection seismic profiling. A model of suspended sediment transport combines the tidal volumes and the current profiles at the harbor entrance. During a period of high turbidity (Spring) in the St.Lawrence Estuary, 54.2 tons of suspended sediments entered the harbor during the flood phase, while 41.1 tons were carried out during the ebb phase of a semi-diurnal tide, leaving 13.1 tons of sediments in the harbor. The transfer coefficient is 0.24 indicating that one quarter of the suspended sediment load settles in the harbor during one tidal cycle. In September, the turbidity is low in the Estuary and the suspended sediment budget in the harbor is 4 times smaller but the ratio of deposited sediments versus the total quantity of sediments transported in suspension is the same.

Nearshore Ichthyoplankton of a North Temperate Estuary

1984 ◽  
Vol 41 (11) ◽  
pp. 1653-1663 ◽  
Author(s):  
H. Powles ◽  
F. Auger ◽  
G. J. FitzGerald
Keyword(s):  
Early Life ◽  
Early Life History ◽  
Clupea Harengus ◽  
Winter Flounder ◽  
Nearshore Zone ◽  
Pseudopleuronectes Americanus ◽  
Lawrence Estuary ◽  
Clupea Harengus Harengus ◽  
St Lawrence Estuary ◽  
Spawning Biomass

Composition of ichthyoplankton in the nearshore zone (0–6 km from shore) of the St. Lawrence estuary showed important differences from that farther offshore. In particular, larvae of herring (Clupea harengus harengus), winter flounder (Pseudopleuronectes americanus), and smooth flounder (Liopsetta putnami) made up a greater proportion of the ichthyoplankton than in published surveys farther offshore. Peak catches of larval herring were 1–2 orders of magnitude higher than in offshore waters. Winter flounder and smooth flounder larvae were significantly more abundant [Formula: see text] from shore than 1–6 km offshore; significant abundance gradients were not found for other species. Nearshore areas have received considerably less effort than offshore areas in earlier studies, and we suggest that more intensive studies in the nearshore zone, at least for those species mentioned, would be of importance for elucidating early life history processes and for estimating spawning biomass based on ichthyoplankton surveys.

scholarly journals Densité agricole et charge humaine des terroirs : Essai méthodologique avec application à quatre comtés au sud de l’estuaire du Saint-Laurent

2005 ◽  
Vol 9 (17) ◽  
pp. 11-23
Author(s):  
Jean Raveneau
Keyword(s):  
Physical Environment ◽  
Population Based ◽  
Population Pressure ◽  
Direct Proportion ◽  
Lawrence Estuary ◽  
Real Population ◽  
Two Factors ◽  
Part Time ◽  
South Shore ◽  
St Lawrence Estuary

The density of agricultural population based on cleared land does not necessarily express the real population pressure in a given agricultural region. Two factors can upset the significance of this measure of density : (1) differences in the intensity of exploitation within a single territory ; and (2), variations in the proportion of part-time farmers. The author bas developed an index of the pressure of population on the land by making various calculations for jour counties in Québec, on the south shore of the St. Lawrence estuary. He bas found that the population pressure on the land varies in nearly direct proportion to the agricultural density based on cleared land, in spite of the lack of uniformity of the physical environment in question. The author concludes that the agricultural density retains its validity for expressing the population pressure on the land.

Changes in activity patterns, agonistic behavior, and territoriality of black ducks (Anas rubripes) during the breeding season in a Nova Scotia tidal marsh

1978 ◽  
Vol 56 (8) ◽  
pp. 1773-1785 ◽  
Author(s):  
Norman R. Seymour ◽  
Rodger D. Titman
Keyword(s):  
Nova Scotia ◽  
Breeding Season ◽  
Activity Patterns ◽  
Quantitative Description ◽  
Egg Laying ◽  
Spatial Displacement ◽  
Lawrence Estuary ◽  
Qualitative And Quantitative ◽  
Males And Females ◽  
St Lawrence Estuary

Observations of marked wild black ducks provided a qualitative and quantitative description of hostile interactions between pairs throughout the breeding season. This study was carried out on a tidal estuary on the St. Lawrence estuary shore of Nova Scotia from 1972 to 1974. Interactions occurred first on the communal part of the marsh and later on territories.Territories corresponded to tidal ponds (0.16–3.8 ha) at the marsh periphery and were established only after pairs were on the marsh 30–40 days. Territories were established approximately 5 days before egg laying began and females were responsible for their location. Females spent approximately 45 days on the territory and males stayed 27–32 days. Males remained almost continuously on territories during the prelaying and laying periods but left both females and territories during midincubation.The activity of males and females of pairs was analysed and compared according to three activities: foraging, loafing, and hostility. Females foraged at a faster rate and for longer durations than their mates in both the preterritorial and territorial periods. Hostility by territorial males toward intruding pairs provided seclusion for resident pairs. Changes in the form and intensity of hostility led to the spatial displacement of pairs. The pursuit flight by males was the main mechanism in the establishment and maintenance of territories.

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