Forty Years of Change in the Bulrush Marshes of the St. Lawrence Estuary and The Impact of the Greater Snow Goose

AbstractOn the north shore of the St Lawrence Estuary (Québec, Canada), near the Betsiamites river delta, a large sub-aerial submarine landslide complex was mapped using multi-beam bathymetry and light detection and ranging (LiDAR) data. Previous analysis of this landslide complex revealed that, since 7250 cal years BP, at least four different landsliding events occurred to form the present morphology, in which over 2 km3 of material have been mobilized. The 7.25 cal ka BP landslide is of particular interest here: this landslide is entirely submarine and mobilized about 1.3 km3 of material, deposited over an area of 54 km2, which make this landslide the largest identified on the St Lawrence estuary seafloor. This landslide showed a runout distance of about 15 km. Landslide-generated tsunamis may be triggered by such a landslide, where a large volume of material is mobilized in a short time. Kinematic analysis of this landslide was previously performed, and here we use these analyses in order to perform tsunami wave generation and propagation modelling. It is shown in this analysis that, even if the mobilized volume is very high and there is a long runout, the tsunami generated is small with tsunami wave amplitudes of <1.5 m, except in the vicinity of the landslide. The highest tide elevation in this part of the St Lawrence Estuary is about 5.5 m, so the impact of such a tsunami wave may be limited.

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Caractéristiques hydrodynamiques d'un estran à forte sédimentation

Canadian Journal of Civil Engineering ◽

10.1139/l90-019 ◽

1990 ◽

Vol 17 (2) ◽

pp. 148-155 ◽

Cited By ~ 5

Author(s):

Jean-Pierre Troude ◽

Jean-Baptiste Sérodes

Keyword(s):

Tidal Marsh ◽

Drainage System ◽

High Energy ◽

Tidal Flats ◽

Tidal Creeks ◽

Lawrence Estuary ◽

Strong Winds ◽

St Lawrence Estuary ◽

The Impact ◽

The Mathematical Model

In the St. Lawrence estuary (Canada), tidal flats localized in the area of saline intrusion are covered with up to 30 cm of fine sedimentation during July, August, and September. This sedimentation is the result of waters coming from the turbidity zone. The upper half of the tidal flats are covered with a tidal marsh. This vegetation is very important in preventing the sediments from eroding. In the tidal marsh, measurements with automatic current meters were taken during periods longer than a month. These showed that, among the vegetation, currents are weak and steady during spring tides and neap tides, whereas next to the drainage systems, currents are heavily dependant on the range of the tide. Close to the shore, currents decrease significantly, thus helping fine sedimentation to occur. A mathematical simulation of the currents made on a line perpendicular to the shore shows the impact of the vegetation on the formation of the drainage system in the tidal flats. Water entrapment by the vegetation at the end of the flood initiates the creation of creeks and insures their continuity throughout the summer. As soon as the vegetation is destroyed, creeks fill up with sediments and disappear from the surface of the tidal marsh. Contrary to what could be assumed, the mathematical model also shows that spring tides, even though associated with strong currents, promote a very active sedimentation on the tidal marsh. In the St. Lawrence estuary, erosion of the mud flats deposits is observed during short periods of strong winds in summer. This high energy and high variability do explain the strong year to year variation in sedimentation observed in the tidal flats. Key words: currents, intertidal sedimentation, tidal creeks, tidal flats.

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The effect of postural adjustment on the thermal environment of greater snow goose goslings

Canadian Journal of Zoology ◽

10.1139/z00-002 ◽

2000 ◽

Vol 78 (5) ◽

pp. 817-821 ◽

Cited By ~ 4

Author(s):

Daniel Fortin ◽

Gilles Gauthier

Keyword(s):

Wind Speed ◽

Convective Heat ◽

Thermal Environment ◽

Postural Adjustment ◽

Operative Temperature ◽

Snow Goose ◽

Wind Speeds ◽

Postural Changes ◽

Greater Snow Goose ◽

The Impact

This study examines how changing from a standing to a sitting posture influences the thermal environment of greater snow goose goslings (Chen caerulescens atlantica). This was investigated by estimating the standard operative temperature of four heated taxidermic mounts (3, 10, 20, and 30 d old) exposed to various wind velocities (0-5 m/s) and ground (16-23°C) and air (0-15°C) temperatures, in three orientations (head, flank, or tail toward the wind) and two postures (sitting and standing). Changes in posture influenced both conductive and convective heat exchanges. At low wind speeds, sitting on the sand reduced the standard operative temperature of goslings, while at high wind speeds sitting enhanced this temperature index. We calculated that a net thermal gain would be obtained by sitting on cold sand at air temperatures of 5, 10, and 15°C when the wind speed exceeded 3 m/s for most orientations toward the incoming wind. However, this critical wind speed would be 23% lower following a 7°C increase in ground temperature. Our study suggests that postural changes can have important consequences on goslings' thermal environment. It also stresses the importance of considering the synergistic impact of conductive and convective heat transfer processes, when studying the impact of postural changes on thermal environments.

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2017-0007 ◽

2018 ◽

Vol 75 (7) ◽

pp. 1128-1141 ◽

Cited By ~ 10

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.

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Impact of anthropogenic pH perturbation on dimethyl sulfide cycling

Elem Sci Anth ◽

10.1525/elementa.2021.00043 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Robin Bénard ◽

Martine Lizotte ◽

Maurice Levasseur ◽

Michael Scarratt ◽

Sonia Michaud ◽

...

Keyword(s):

Chlorophyll A ◽

Atmospheric Chemistry ◽

Dimethyl Sulfide ◽

Phytoplankton Bloom ◽

Lawrence Estuary ◽

Chlorophyll A Concentration ◽

Pco2 Treatment ◽

St Lawrence Estuary ◽

Scavenging Efficiency ◽

The Impact

The objective of this study was to assess experimentally the potential impact of anthropogenic pH perturbation (ApHP) on concentrations of dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP), as well as processes governing the microbial cycling of sulfur compounds. A summer planktonic community from surface waters of the Lower St. Lawrence Estuary was monitored in microcosms over 12 days under three pCO2 targets: 1 × pCO2 (775 µatm), 2 × pCO2 (1,850 µatm), and 3 × pCO2 (2,700 µatm). A mixed phytoplankton bloom comprised of diatoms and unidentified flagellates developed over the course of the experiment. The magnitude and timing of biomass buildup, measured by chlorophyll a concentration, changed in the 3 × pCO2 treatment, reaching about half the peak chlorophyll a concentration measured in the 1 × pCO2 treatment, with a 2-day lag. Doubling and tripling the pCO2 resulted in a 15% and 40% decline in average concentrations of DMS compared to the control. Results from 35S-DMSPd uptake assays indicated that neither concentrations nor microbial scavenging efficiency of dissolved DMSP was affected by increased pCO2. However, our results show a reduction of the mean microbial yield of DMS by 34% and 61% in the 2 × pCO2 and 3 × pCO2 treatments, respectively. DMS concentrations correlated positively with microbial yields of DMS (Spearman’s ρ = 0.65; P < 0.001), suggesting that the impact of ApHP on concentrations of DMS in diatom-dominated systems may be strongly linked with alterations of the microbial breakdown of dissolved DMSP. Findings from this study provide further empirical evidence of the sensitivity of the microbial DMSP switch under ApHP. Because even small modifications in microbial regulatory mechanisms of DMSP can elicit changes in atmospheric chemistry via dampened efflux of DMS, results from this study may contribute to a better comprehension of Earth’s future climate.

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

Biogeosciences ◽

10.5194/bg-10-7609-2013 ◽

2013 ◽

Vol 10 (11) ◽

pp. 7609-7622 ◽

Cited By ~ 13

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.

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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)

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2021.112180 ◽

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

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

Journal of Applied Ichthyology ◽

10.1111/jai.14234 ◽

2021 ◽

Author(s):

Yves Paradis ◽

Marc Pépino ◽

Simon Bernatchez ◽

Denis Fournier ◽

Léon L’Italien ◽

...

Keyword(s):

Lawrence Estuary ◽

St Lawrence Estuary ◽

Acipenser Oxyrinchus

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

Journal of Physical Oceanography ◽

10.1175/1520-0485(1983)013<1540:aciesi>2.0.co;2 ◽

1983 ◽

Vol 13 (8) ◽

pp. 1540-1543 ◽

Cited By ~ 4

Author(s):

Clifford L. Trump

Keyword(s):

Lawrence Estuary ◽

St Lawrence Estuary ◽

A Current

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

Canadian Journal of Botany ◽

10.1139/b84-114 ◽

1984 ◽

Vol 62 (4) ◽

pp. 778-794 ◽

Cited By ~ 19

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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