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.

Régime alimentaire et principaux facteurs influençant l'alimentation des larves de capelan (Mallotus villosus), d'éperlan (Osmerus mordax) et de hareng (Clupea harengus harengus) dans un estuaire partiellement mélangé

1986 ◽  
Vol 43 (5) ◽  
pp. 968-979 ◽  
Author(s):  
R. Courtois ◽  
J. J. Dodson
Keyword(s):  
Feeding Rate ◽  
Water Masses ◽  
Clupea Harengus ◽  
Gut Contents ◽  
Osmerus Mordax ◽  
Lawrence Estuary ◽  
Daily Cycles ◽  
Food And Feeding ◽  
Clupea Harengus Harengus ◽  
St Lawrence Estuary

The food and feeding rate periodicity of larvae of capelin (Mallotus villiosus), smelt (Osmerus mordax), and herring (Clupea harengus harengus) were studied to determine the existence of potential interactions between the larvae of these three species. Analyses of the gut contents showed that larvae of capelin started to feed before yolk sac absorption but that the feeding rate was low (<20%) in the lower St. Lawrence estuary; the small size of capelin larvae restricted their feeding to tintinnids. Larvae of the two other species feed at a greater rate than capelin larvae and their food is more diverse. The temporal sequence of feeding incidences showed daily cycles for the three species and semidiurnal cycles for larvae of capelin and herring. The importance of light for feeding of larvae was confirmed by the daily cycles and by the greater abundance of larvae with gut contents in surface waters (0–20 m). From the absence of a relation between biotic factors (density of larvae) and the temporal evolution of feeding incidences, we suggest that semidiurnal cycles are mainly related to temperature changes associated with advection of water masses at the sampling stations. Even though similar reactions to certain environmental variables were observed, we concluded that interspecific competition is minimal between larvae of the three species. Although present at the same stations, larvae of different species mainly occurred in distinct water masses; they are also mainly of different size. Those characteristics force them to exploit organisms of different size and mainly of different species.

ESTABLISHING A BREEDING EIDER DUCK POPULATION IN MASSACHUSETTS

1989 ◽  
Vol 1989 (1) ◽  
pp. 493-495 ◽  
Author(s):  
Philip B. Stanton
Keyword(s):  
Oil Spills ◽  
Reproductive Potential ◽  
Release Site ◽  
Breeding Population ◽  
Somateria Mollissima ◽  
Breeding Ground ◽  
Breeding Range ◽  
Common Eiders ◽  
Management Techniques ◽  
Natural Foods

ABSTRACT In an effort to make a waterfowl population with a limited breeding range—Maine to the Canadian Maritimes—less vulnerable to local catastrophe from petroleum activities, a population of common eiders (Somateria mollissima dressesi) was transplanted from Maine to Massachusetts. The objective of the relocation of the eiders was to see if a population of seabirds could successfully be moved from an area subject to petroleum activities to a new breeding ground. This move involved taking a group of birds from its existing breeding ground to a nonbreeding territory and establishing another breeding population. Such wildlife management techniques could contribute to increasing the reproductive potential of birds lost to oil spills, thus decreasing the need for high-cost oiled bird rehabilitation, which is often ecologically unsound. From 1973 to 1975, adult eiders and eggs were collected from Casco Bay, Maine. Eggs were hatched and hand-reared for several weeks both at the Wildlife Rehabilitation Center and on Penikese Island in Massachusetts. The birds were released on Penikese in Buzzard's Bay, about 240 kilometers (150 miles) south of their known breeding range, but in an area of habitat similar to that of the islands of Casco Bay. An acclimation program included rearing the birds at the release site for one to three weeks and introducing a saltwater environment and natural foods to the birds. The released eiders began breeding in 1976 on Penikese and have since colonized at least three nearby islands. By 1988 the population had increased to an estimated 200 breeding pairs.

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%.

Assessment of the Importance of Nutrient Recycling by Seabirds in the St. Lawrence Estuary

1980 ◽  
Vol 37 (4) ◽  
pp. 583-588 ◽  
Author(s):  
J. Bédard ◽  
J. C. Therriault ◽  
J. Bérubé
Keyword(s):  
Nutrient Recycling ◽  
Vertical Mixing ◽  
Nutrient Budget ◽  
Somateria Mollissima ◽  
Nutrient Regeneration ◽  
Lawrence Estuary ◽  
Nitrogenous Compounds ◽  
The One ◽  
Excretion Rates ◽  
St Lawrence Estuary

Feeding and excretion rates of the herring, great black-backed, and ring-billed gulls (Larus argentatus, L. marinus, and L. delawarensis), and of the common eider (Somateria mollissima) were measured in captive individuals and the concentration of soluble nutrients in their excreta was established.The bird population in a 30.6-km2 coastal study area varied between 2500 and 12 500 individuals between early May and mid-November. These birds excreted a seasonal total of 5.8, 4.2, and 48.1 kg-at. of soluble silicate, phosphate, and nitrogenous compounds, respectively. Such quantities, when introduced in the nutrient budget of the coastal area studied, are found to be negligible, considering the levels of nutrients generally recorded in these waters on the one hand, and the relative importance of alternate sources such as land drainage and vertical mixing on the other. Thus, the seabirds can hardly be viewed, except perhaps under the most special circumstances, as important agents in the dynamic nutrient regeneration processes of marine coastal waters of the St. Lawrence Estuary.Key words: nutrient recycling, seabirds, St. Lawrence Estuary

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.

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.

Mud Cracks and Polygons on Ice Push Ridges, in Tidal Flats of the St. Lawrence Estuary

1974 ◽  
Vol 11 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Jean-Claude Dionne
Keyword(s):  
Water Level ◽  
Tidal Flats ◽  
The South ◽  
Lawrence Estuary ◽  
Waves And Currents ◽  
South Shore ◽  
Break Up ◽  
St Lawrence Estuary

Mud cracks and polygons form during summer in tidal flats of the south shore of the St. Lawrence Estuary. They occur near mean low water level at the top surface of ice push mud ridges formed during winter and break-up. They are a source of mud clasts which settle in the surroundings when carried away by waves and currents.

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