Etude préliminaire du phytoplancton du lac Saint-Louis, élargissement du fleuve Saint-Laurent près de Montréal, Québec

1974 ◽  
Vol 52 (3) ◽  
pp. 489-501 ◽  
Author(s):  
Edith Alaerts-Smeesters ◽  
Etienne Magnin
Keyword(s):  
Seasonal Variation ◽  
Dominant Species ◽  
General View ◽  
Saint Louis ◽  
Ottawa River ◽  
Number Of Cells ◽  
St Lawrence River

Seventeen samples were collected at regular intervals from September 1970 to December 1971 from four sites on lake St. Louis; these stations received their water either from the St. Lawrence River, the Ottawa River, or both. For each species and sample of the 178 phytoplankton entities found, the number of cells per liter was estimated. A general view of the distribution of plankton organisms at each station is given as well as the seasonal variation of the major systematic groups and the dominant species.

Movements and biological statistics of lake sturgeon (Acipenser fulvescens) populations from the St. Lawrence and Ottawa River system, Quebec

1993 ◽  
Vol 71 (3) ◽  
pp. 638-650 ◽  
Author(s):  
Réjean Fortin ◽  
Jean-René Mongeau ◽  
Gilles Desjardins ◽  
Pierre Dumont
Keyword(s):  
Total Mortality ◽  
River System ◽  
Lake Sturgeon ◽  
Acipenser Fulvescens ◽  
Commercial Fishing ◽  
Commercial Catch ◽  
Saint Louis ◽  
Ottawa River ◽  
Biological Statistics ◽  
St Lawrence River

Our objective was to compare movements and biological statistics of lake sturgeon (Acipenser fulvescens) populations from two fluvial lakes on the St. Lawrence River, Lac Saint-Louis and Lac Saint-Pierre, which are main commercial fishing sectors, and from Lac des Deux Montagnes on the Ottawa River. Sturgeon can move freely among these three lakes. Lac des Deux Montagnes sturgeon differ from the other groups by their higher degree of sedentariness, slower growth, and lower condition factor. Lac Saint-Louis and Lac Saint-Pierre sturgeon are also sedentary, but some movement between the two lakes was observed. Sturgeon tagged on the Rivière des Prairies and Rivière L'Assomption spawning grounds, located in the central part of the study area, and also on pre- and post-spawning concentration sites, were recaptured throughout the St. Lawrence River, from Lac Saint-Louis to Lac Saint-Pierre. Length, weight, and age composition of the commercial catch, growth, and total mortality varied between Lac Saint-Louis and Lac Saint-Pierre. Higher commercial exploitation rates in the latter could be responsible for some differences. The management implications of these results are discussed.

Managing the Impacts of Human Activities on Fish Habitat: The Governance, Practices, and Science

2015 ◽  
Keyword(s):  
Mississippi River ◽  
Fish Habitat ◽  
Organizational Structures ◽  
Mature Female ◽  
Cumulative Effects ◽  
Past Century ◽  
Sargasso Sea ◽  
Ottawa River ◽  
Governance Practices ◽  
St Lawrence River

<em>Abstract.</em>—American Eel mortality has increased substantially over the past century due largely to significant cumulative effects of fishing and fish passage through hydro-electric turbines across their range. Nowhere has this been more pronounced than in waters of the St. Lawrence River, Lake Ontario, Ottawa River and associated watersheds. We illustrate this by examining the cumulative effects of hydro-electric facilities on eels migrating downstream through the Mississippi River and Ottawa River, and outline further impacts eels encounter en route to spawn in the Sargasso Sea. The probability of a mature female eel surviving its emigration through the Mississippi and Ottawa River to the upper St. Lawrence River is estimated to be as low as 2.8% due to turbine mortalities alone (2.8–40%). Mortality risk increases as the eel attempts to run the gauntlet of fisheries in the lower St. Lawrence River and the probability of out-migration survival is estimated to be as low as 1.4%. Some mortalities could be mitigated through improved application of existing laws, development of policy requiring consideration of cumulative effects and improved integration among program areas responsible for sustainable management of fisheries, biodiversity, dams and hydro-electric facilities. We recommend changes to policy, procedures and internal organizational structures provided with clear directions, and call for increased accommodation of Aboriginal perspectives.

Aging of Cryptosporidium parvum oocysts in river water and their susceptibility to disinfection by chlorine and monochloramine

1998 ◽  
Vol 44 (12) ◽  
pp. 1154-1160 ◽  
Author(s):  
Christian Chauret ◽  
Kerry Nolan ◽  
Ping Chen ◽  
Susan Springthorpe ◽  
Syed Sattar
Keyword(s):  
Cryptosporidium Parvum ◽  
Environmental Fate ◽  
Water Environment ◽  
Water Disinfection ◽  
Ottawa River ◽  
In Situ Conditions ◽  
Cryptosporidium Parvum Oocysts ◽  
St Lawrence River

Cryptosporidium parvum oocysts were aged in waters from both the St. Lawrence River and the Ottawa River. In situ survival experiments were carried out by incubating the oocysts in either dialysis cassettes or microtubes floated into an overflow tank. A significant portion of the oocysts survived in the test waters for several weeks. Oocyst survival in the St. Lawrence River was better in membrane-filtered (0.2-µm-pore diameter) water than in unfiltered water, suggesting that biological antagonism may play a role in the environmental fate of the parasite. Oocysts aged in river waters under in situ conditions and control oocysts kept refrigerated in synthetic water (100 ppm as CaCO3; pH 7.0) were subjected to the same disinfection protocol. Aged oocysts were at least as resistant as, if not more resistant than, the control oocysts to disinfection. This indicates that the oocysts surviving in the water environment may be just as difficult to inactivate by potable water disinfection as freshly shed oocysts. Therefore, water treatment should not be based on the assumption that environmental oocysts may be more easily inactivated than freshly shed oocysts. First-order kinetics die-off rates varied from one river to another (from 0.013 to 0.039 log10·day-1) and from one experiment to another with water from the same river collected at different times. Calculation of the die-off rates based on either in vitro excystation or in vitro excystation in combination with total counts (overall die-off rates) showed that the assessment of oocyst viability by microscopic methods must account for the total oocyst loss observed during long-term inactivation assays of river waters.Key words: Cryptosporidium, survival, disinfection, biological antagonism.

Les groupements benthiques du fleuve Saint-Laurent près des centrales nucléaires de Gentilly (Québec)

1978 ◽  
Vol 56 (7) ◽  
pp. 1585-1592 ◽  
Author(s):  
B. Vincent ◽  
G. Vaillancourt
Keyword(s):  
Present State ◽  
Littoral Zone ◽  
Dominant Species ◽  
Nuclear Reactors ◽  
Deep Waters ◽  
Limnodrilus Hoffmeisteri ◽  
Sublittoral Zone ◽  
Bithynia Tentaculata ◽  
Lotic Environment ◽  
St Lawrence River

The structure and distribution of the macrobenthos were determined to evaluate the present state of the section of the St. Lawrence River which might be affected by the cooling waters of the Gentilly nuclear reactors. Ten groups were recognized, characterized by the presence of one to three constant and dominant species. In lentic conditions characterized by the presence of the gastropod Bithynia tentaculata the zonation is depth dependent. Three groups inhabit the littoral zone characterized by the Glossoscolecidae Sparganophilus tamesis. There are two groups in the sublittoral zone characterized by the Tubificidae Limnodrilus hoffmeisteri and two groups in the deep waters characterized by the Sphaeriidae Sphaerium striatinum. Bithynia tentaculata, a hydrobiid, seldom inhibits the lotic environment where the Tubificidae Limnodrilus hoffmeisteri is the only typical species.

Seasonal variation in population and community structure of shrews in a tropical forest of Gabon

2005 ◽  
Vol 21 (2) ◽  
pp. 161-169 ◽  
Author(s):  
Violaine Nicolas ◽  
Patrick Barrière ◽  
Marc Colyn
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Dominant Species ◽  
Abundant Species ◽  
Dry Season ◽  
Reproductive Phenology ◽  
Ecological Constraints ◽  
Species Dominance ◽  
Composition Structure ◽  
Over Time

The composition, structure and reproductive phenology of a shrew community were investigated for 1 y at two neighbouring sites in an undisturbed African forest of south-western Gabon. We captured 717 shrews, belonging to four genera and 10 species. The data were analysed to answer three main questions: (1) to what extent does the shrew abundance vary seasonally? (2) is there a shift in species dominance over time? and (3) does the intensity of breeding activity vary seasonally? The number of species captured varied seasonally and tended to be least during the period of minimal trap success. Trap success for the four most abundant species (Sylvisorex johnstoni, Crocidura batesi, Paracrocidura schoutedeni and Sylvisorex ollula) varied seasonally with a minimum around the long dry season. Sylvisorex johnstoni remained the dominant species throughout the year. Seasonal variation in trap success of shrews might be related, at least partly, to their reproductive characteristics. Litter size, based on embryo counts, ranged from 1–4 among the species. Breeding occurred throughout the year, but its intensity was lower during the long dry season corresponding with the period of higher ecological constraints for shrews.

Étude du benthos d'eau douce dans le haut-estuaire du Saint-Laurent (Québec)

1979 ◽  
Vol 57 (11) ◽  
pp. 2171-2182 ◽  
Author(s):  
B. Vincent
Keyword(s):  
Dominant Species ◽  
Gradual Change ◽  
Lower Section ◽  
St Lawrence River

Benthos samples collected in 37 sites interspersed along a 230 km stretch of the St. Lawrence River, between Lake St. Pierre and Ile aux Oies, were analyzed. The distribution of the main taxa shows the downstream succession of many of the dominant species. Benthic groups of the upstream and downstream sections of the upper estuary are characterized by the hydrobiid B. tentaculata and the viviparid V. georgianus, respectively. The structure of the benthic groups undergoes a gradual change downstream from Gentilly and the samples collected in the lower section add up to a much more heterogeneous community than the samples collected in the upper or the middle reaches of the estuary.[Journal Translation]

La périodicité de la croissance chez la femelle de l'esturgeon jaune (Acipenser fulvescens) du fleuve Saint-Laurent est-elle reliée à la périodicité de la reproduction?

1992 ◽  
Vol 49 (7) ◽  
pp. 1336-1342 ◽  
Author(s):  
Sylvie Guénette ◽  
Daniel Goyette ◽  
Réjean Fortin ◽  
Jean Leclerc ◽  
Nelson Fournier ◽  
...  
Keyword(s):  
Cross Sections ◽  
Growth Patterns ◽  
The State ◽  
Lake Sturgeon ◽  
Acipenser Fulvescens ◽  
Ottawa River ◽  
First Ray ◽  
The Mean ◽  
Narrow Annuli ◽  
St Lawrence River

Measurements of annual increments on cross-sections of the first ray of the pectoral fin of 125 St. Lawrence River female lake sturgeon (Acipenser fulvescens) aged 24 yr and older were used to test the correspondance between growth patterns at the margin of the sections and the state of maturity of the fish. For each of the 21 females aged 34 yr and older, and for the upper Ottawa River specimens presented by Roussow (1957. J. Fish. Res. Board Can. 14: 553–572), annual increments were treated as a temporal series and analysed with the contingency periodogram. The mean age at first spawning was determined using the age at the end of the first belt of crowded annuli, following Roussow. Only 3 of the 21 females aged 34 yr and older showed a typical succession of belts of large and narrow annuli. The most frequent periods were 5–11 yr, using the periodogram, as compared with 6–9 yr for Roussow' specimens. No significant correspondance was found between the pattern of the last five annual increments and the state of maturity. The mean age at first spawning, estimated at 19 yr by this technique, is lower than the mean age of sexual maturity determined for St. Lawrence River females based on the examination of the gonads (26 yr).

Lake Ontario: the predominant source of triazine herbicides in the St. Lawrence River

2000 ◽  
Vol 57 (S1) ◽  
pp. 78-85 ◽  
Author(s):  
T -T Pham ◽  
B Rondeau ◽  
H Sabik ◽  
S Proulx ◽  
D Cossa
Keyword(s):  
Lake Ontario ◽  
Quebec City ◽  
Triazine Herbicides ◽  
Triazine Herbicide ◽  
Ottawa River ◽  
River Water Samples ◽  
The Difference ◽  
High Concentrations ◽  
Dissolved Phase ◽  
St Lawrence River

To estimate triazine herbicide concentrations and sources in the St. Lawrence River, water samples were collected at its two major inlets (from the Great Lakes, Cornwall station, and from the Ottawa River, Carillon station) and at the outlet (Quebec City station) of the fluvial section. Sampling was carried out over an 18-month period between 1995 and 1996. Triazines were detected only in the dissolved phase at concentrations ranging from 2 to 91, from <0.4 to 15, and from <0.4 to 13 ng·L-1 for atrazine, cyanazine, and simazine, respectively. Dilution models show that, despite the presence of sporadically high concentrations of herbicides in St. Lawrence tributaries during periods of their application, loading from the tributaries is minor. Mass balance calculations show that Lake Ontario is clearly the main source of triazines (~90%) to the St. Lawrence River. During the 1995-1996 hydrological year, Lake Ontario contributed 15.1 × 103 of the 16.6 × 103 kg of atrazine outflowing the St. Lawrence River to the estuary. The difference (1.5 × 103 kg·year-1) can be attributed to tributaries in Quebec, which represent 0.75% of the amount of atrazine spread on farmlands. There is no evidence of the degradation of triazine compounds during their transit time in the river.

Effects of 3,3′,4,4′-tetrachlorobiphenyl on the dynamics of vitamin A in brook trout (Salvelinus fontinalis) and intestinal retinoid concentrations in lake sturgeon (Acipenser fulvescens)

1995 ◽  
Vol 52 (3) ◽  
pp. 512-520 ◽  
Author(s):  
Aristocle Ndayibagira ◽  
Marie-Josée Cloutier ◽  
Perry D. Anderson ◽  
Philip A. Spear
Keyword(s):  
Vitamin A ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Retinyl Palmitate ◽  
Lake Sturgeon ◽  
Contaminated Site ◽  
Acipenser Fulvescens ◽  
River Population ◽  
Ottawa River ◽  
St Lawrence River

A single i.p. injection of 5 μg 3,3′,4,4′-tetrachlorobiphenyl (TCBP)/g body mass in adult brook trout (Salvelinus fontinalis) resulted in decreased (p < 0.0001) growth rate despite pair feeding. Plasma retinol decreased (p < 0.0037). Intestinal retinyl palmitate (RP) and 3,4-dehydroretinyl palmitate (DRP) concentrations decreased in TCBP-injected males (RP, p < 0.0143; DRP, p < 0.0009), whereas retinoid levels did not decrease significantly in TCBP-injected females. The RP:DRP ratio in trout liver increased (p < 0.0001). These results suggested that DRP is more sensitive than RP to the effects of TCBP. No significant differences in ovarian retinoids occurred in post-spawning trout. Field validation of the effects on intestinal retinoids was conducted with lake sturgeon (Acipenser fulvescens) caught at a contaminated site on the Des Prairies River near Montréal (St. Lawrence River population) and reference sturgeon taken from a site near the origin of the Ottawa River in LaVerendrye Park. Intestinal retinoid concentrations were lower (RP, p < 0.0008; DRP, p < 0.0004) in the St. Lawrence River sturgeon. Our results demonstrate that a coplanar PCB is capable of altering vitamin A dynamics in several tissues and organs, and may cause a lowering of retinoids in the intestine.

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