Estimating above- and below-ground macrophyte production in Scirpus tidal marshes

1988 ◽  
Vol 66 (2) ◽  
pp. 368-374 ◽  
Author(s):  
Jean-François Giroux ◽  
Jean Bédard
Keyword(s):  
Standing Crop ◽  
Belowground Biomass ◽  
Tidal Marshes ◽  
Optimal Size ◽  
Lawrence Estuary ◽  
Plant Parts ◽  
Peak Standing Crop ◽  
Below Ground ◽  
The Difference ◽  
St Lawrence Estuary

Different methods to estimate primary production of Scirpus marshes of the St. Lawrence estuary were compared. Quadrats 25 × 25 cm and cores 10 cm in diameter were found to be the optimal size to sample above- and below-ground standing crops, respectively. Ash content for different plant parts of various species was measured to obtain more accurate estimates of organic matter. A series of allometric equations relating stem height and mass were developed to estimate aerial standing crop from permanent nondestructively sampled plots. This method, however, overestimated standing crop compared with the destructive (harvest) method. The relationship between the above- and below-ground standing crop was also determined for the dominant species and used to predict belowground biomass without destructive sampling. Finally, the Smalley method provided the best estimates of net annual above- and below-ground production when losses attributed to decomposition were not considered. For less intensive studies, however, the methods based on peak standing crop and on the difference between maximum and minimum biomass would yield good approximations of above- and below-ground production.

Above- and below-ground macrophyte production in Scirpus tidal marshes of the St. Lawrence estuary, Quebec

1988 ◽  
Vol 66 (5) ◽  
pp. 955-962 ◽  
Author(s):  
Jean-François Giroux ◽  
Jean Bédard
Keyword(s):  
Standing Crop ◽  
River Estuary ◽  
Dry Mass ◽  
Tidal Marshes ◽  
Lawrence Estuary ◽  
Aboveground Production ◽  
History Of ◽  
Below Ground ◽  
South Shore ◽  
St Lawrence Estuary

Above- and below-ground standing crops as well as primary production of several macrophytes were estimated in Scirpus marshes along the south shore of the St. Lawrence River estuary in Quebec. Aboveground standing crop was measured by clipping vegetation, while belowground standing crop was estimated by soil coring. Seasonal variation of live and dead standing crops was first determined for different plant species. The root:shoot mass ratio was then examined and related to the life history of each species. Total aboveground production varied from 74 to 627 g ash-free dry mass∙m−2∙year−1 among different plant communities, whereas belowground production was lower, with estimates varying between 38 and 244 g∙m−2∙year−1. Production was lower along the St. Lawrence estuary than in other types of marshes located farther south.

Flock composition and foraging behavior of greater snow geese (Chen caerulescens atlantica)

1992 ◽  
Vol 70 (12) ◽  
pp. 2410-2415 ◽  
Author(s):  
Luc Bélanger ◽  
Jean Bédard
Keyword(s):  
Social Status ◽  
Foraging Behavior ◽  
Foraging Strategy ◽  
Behavioral Differences ◽  
Lawrence Estuary ◽  
Chen Caerulescens ◽  
Plant Parts ◽  
Snow Geese ◽  
Chen Caerulescens Atlantica ◽  
St Lawrence Estuary

We studied the foraging behavior of greater snow geese (Chen caerulescens atlantica) staging in a Scirpus tidal marsh along the St. Lawrence Estuary in Quebec during fall 1985 and 1986 and spring 1986 and 1987. Among all foraging activities, grubbing (feeding on underground plant parts) ranked first (>50%), but important seasonal differences were observed. Geese spent less time grubbing and more time searching and grazing on newly emerging shoots in spring than in fall. Our study also revealed differences in the foraging behaviors of birds of differing social status. We found that juveniles spent more time searching for food than adults, particularly in fall. Males also spent more time alert than females, at least in fall. We also observed behavioral differences among adults of different social status (member of a family, paired bird, and unpaired bird). Solitary unpaired birds devoted less time grubbing and, consequently, more time searching for food, than paired birds in fall. Finally, paired and family-member adult birds adopted a similar foraging strategy, spending more time searching and grazing in spring than in fall.

The Effects of Grazing by Greater Snow Geese on the Vegetation of Tidal Marshes in the St Lawrence Estuary

1987 ◽  
Vol 24 (3) ◽  
pp. 773 ◽  
Author(s):  
J.-F. Giroux ◽  
J. Bedard
Keyword(s):  
Tidal Marshes ◽  
Lawrence Estuary ◽  
Snow Geese ◽  
St Lawrence Estuary

Behaviour of dissolved iodine in the upper St. Lawrence Estuary

1985 ◽  
Vol 22 (4) ◽  
pp. 644-646 ◽  
Author(s):  
Kazufumi Takayanagi ◽  
Daniel Cossa
Keyword(s):  
Water Samples ◽  
Total Iodine ◽  
Lawrence Estuary ◽  
Major Species ◽  
The Difference ◽  
St Lawrence Estuary

The concentrations of dissolved total iodine and iodate were determined in the water samples collected from various depths at 14 stations located in the upper St. Lawrence Estuary. The concentrations of total iodine and iodate ranged from undetectable (< 0.008 μM) to 0.40 μM and from undetectable to 0.36 μM, respectively, and salinities ranged from 0 to 33.9‰. The concentrations of total iodine and iodate increased with increasing salinity, and they correlated linearly with salinity. This implies that both total iodine and iodate behave conservatively in the estuary. The concentration of iodide, calculated as the difference in the concentrations of total iodine and iodate, was low throughout the estuary. Iodate was the major species of dissolved iodine in the upper St. Lawrence Estuary.

scholarly journals Tidally induced variations of pH at the head of the Laurentian Channel

2018 ◽  
Vol 75 (7) ◽  
pp. 1128-1141 ◽  
Author(s):  
Alfonso Mucci ◽  
Maurice Levasseur ◽  
Yves Gratton ◽  
Chloé Martias ◽  
Michael Scarratt ◽  
...  
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Field Measurements ◽  
Tidal Mixing ◽  
Lawrence Estuary ◽  
Saguenay Fjord ◽  
Physical And Chemical Variables ◽  
The Difference ◽  
St Lawrence Estuary ◽  
The Impact

The head of the Laurentian Channel is a very dynamic region of exceptional biological richness. To evaluate the impact of freshwater discharge, tidal mixing, and biological activity on the pH of surface waters in this region, a suite of physical and chemical variables was measured throughout the water column over two tidal cycles. The relative contributions to the water column of the four source-water types that converge in this region were evaluated using an optimum multiparameter algorithm (OMP). Results of the OMP analysis were used to reconstruct the water column properties assuming conservative mixing, and the difference between the model properties and field measurements served to identify factors that control the pH of the surface waters. These surface waters are generally undersaturated with respect to aragonite, mostly due to the intrusion of waters from the Upper St. Lawrence Estuary and the Saguenay Fjord. The presence of a cold intermediate layer impedes the upwelling of the deeper, hypoxic, lower pH and aragonite-undersaturated waters of the Lower St. Lawrence Estuary to depths shallower than 50 m.

scholarly journals Benthic fluxes of dissolved organic nitrogen in the lower St. Lawrence estuary and implications for selective organic matter degradation

2013 ◽  
Vol 10 (11) ◽  
pp. 7609-7622 ◽  
Author(s):  
M. Alkhatib ◽  
P. A. del Giorgio ◽  
Y. Gelinas ◽  
M. F. Lehmann
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Bottom Water ◽  
Estuarine Sediments ◽  
Internal Source ◽  
Lawrence Estuary ◽  
Element Partitioning ◽  
Sediment Porewaters ◽  
St Lawrence Estuary

Abstract. The distribution of dissolved organic nitrogen (DON) and carbon (DOC) in sediment porewaters was determined at nine locations along the St. Lawrence estuary and in the gulf of St. Lawrence. In a previous manuscript (Alkhatib et al., 2012a), we have shown that this study area is characterized by gradients in the sedimentary particulate organic matter (POM) reactivity, bottom water oxygen concentrations, and benthic respiration rates. Based on the porewater profiles, we estimated the benthic diffusive fluxes of DON and DOC in the same area. Our results show that DON fluxed out of the sediments at significant rates (110 to 430 μmol m−2 d−1). DON fluxes were positively correlated with sedimentary POM reactivity and varied inversely with sediment oxygen exposure time (OET), suggesting direct links between POM quality, aerobic remineralization and the release of DON to the water column. DON fluxes were on the order of 30 to 64% of the total benthic inorganic fixed N loss due to denitrification, and often exceeded the diffusive nitrate fluxes into the sediments. Hence they represented a large fraction of the total benthic N exchange, a result that is particularly important in light of the fact that DON fluxes are usually not accounted for in estuarine and coastal zone nutrient budgets. In contrast to DON, DOC fluxes out of the sediments did not show any significant spatial variation along the Laurentian Channel (LC) between the estuary and the gulf (2100 ± 100 μmol m−2 d−1). The molar C / N ratio of dissolved organic matter (DOM) in porewater and the overlying bottom water varied significantly along the transect, with lowest C / N in the lower estuary (5–6) and highest C / N (> 10) in the gulf. Large differences between the C / N ratios of porewater DOM and POM are mainly attributed to a combination of selective POM hydrolysis and elemental fractionation during subsequent DOM mineralization, but selective adsorption of DOM to mineral phases could not be excluded as a potential C / N fractionating process. The extent of this C- versus N- element partitioning seems to be linked to POM reactivity and redox conditions in the sediment porewaters. Our results thus highlight the variable effects selective organic matter (OM) preservation can have on bulk sedimentary C / N ratios, decoupling the primary source C / N signatures from those in sedimentary paleoenvironmental archives. Our study further underscores that the role of estuarine sediments as efficient sinks of bioavailable nitrogen is strongly influenced by the release of DON during early diagenetic reactions, and that DON fluxes from continental margin sediments represent an important internal source of N to the ocean.

Pre-exposure to Cu2+ and CuO NPs leads to infection of caged blue mussels, Mytilus edulis L., by pathogenic microalga: Pilot study in the Lower St. Lawrence Estuary (Québec, Canada)

2021 ◽  
Vol 166 ◽  
pp. 112180
Author(s):  
Michael Zuykov ◽  
Galina Kolyuchkina ◽  
Graeme Spiers ◽  
Michel Gosselin ◽  
Philippe Archambault ◽  
...  
Keyword(s):  
Pilot Study ◽  
Mytilus Edulis ◽  
Lawrence Estuary ◽  
Blue Mussels ◽  
Cuo Nps ◽  
St Lawrence Estuary

Movement of sturgeons ( Acipenser oxyrinchus oxyrinchus and A. fulvescens ) in the St. Lawrence Estuary: A 35‐year tagging study

2021 ◽  
Author(s):  
Yves Paradis ◽  
Marc Pépino ◽  
Simon Bernatchez ◽  
Denis Fournier ◽  
Léon L’Italien ◽  
...  
Keyword(s):  
Lawrence Estuary ◽  
St Lawrence Estuary ◽  
Acipenser Oxyrinchus

A Current-Induced Ekman Spiral in the St. Lawrence Estuary

1983 ◽  
Vol 13 (8) ◽  
pp. 1540-1543 ◽  
Author(s):  
Clifford L. Trump
Keyword(s):  
Lawrence Estuary ◽  
St Lawrence Estuary ◽  
A Current

Marine tube-dwelling diatoms of eastern Canada: descriptions, checklist, and illustrated key

1984 ◽  
Vol 62 (4) ◽  
pp. 778-794 ◽  
Author(s):  
Christopher S. Lobban
Keyword(s):  
New Species ◽  
Northwest Territories ◽  
Common Species ◽  
Bay Of Fundy ◽  
Eastern Canada ◽  
Lawrence Estuary ◽  
The Common ◽  
Living Material ◽  
St Lawrence Estuary ◽  
A New Species

From a study of living materials and specimens in several regional herbaria, a list has been drawn up of all the common and several of the rarer tube-dwelling diatoms of eastern Canada. Descriptions, illustrations of living material and acid-cleaned valves, and a key to the species are provided. Most specimens were from the Atlantic Provinces and the St. Lawrence estuary, but a few were from the Northwest Territories. By far the most common species is Berkeleya rutilans. Other species occurring commonly in the Quoddy Region of the Bay of Fundy, and sporadically in space and time elsewhere, arc Navicula delognei (two forms), Nav. pseudocomoides, Nav. smithii, Haslea crucigera, and a new species, Nav.rusticensis. Navicula ramosissima and Nav. mollis in eastern Canada are usually found as scattered cohabitants in tubes of other species. Nitzschia tubicola and Nz. fontifuga also occur sporadically as cohabitants.

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