Importance du régime de dénudation sur la structure et la succession des communautés intertidales de substrat rocheux en milieu subarctique

1983 ◽  
Vol 40 (8) ◽  
pp. 1278-1292 ◽  
Author(s):  
Diane Archambault ◽  
Edwin Bourget
Keyword(s):  
Early Stage ◽  
Ascophyllum Nodosum ◽  
Fucus Vesiculosus ◽  
Tidal Level ◽  
Developmental Patterns ◽  
Lawrence Estuary ◽  
Long Period ◽  
Study Sites ◽  
St Lawrence Estuary ◽  
Balanus Balanoides

Developmental patterns were studied following natural (abrasion by ice) and experimental disturbances (total or partial clearings) in intertidal rocky communities. Four semi-exposed communities along the St. Lawrence Estuary and Gulf were studied from May 1977 to May 1979. In the spring, when free space becomes available, annual algae, mainly Ulothricales and Ulvales, rapidly colonize areas denuded by ice abrasion. This early stage is soon followed by an abundant fucoid growth, largely Fucus vesiculosus but also some Ascophyllum nodosum, and a large number of Balanus balanoides, along with some Mytilus edulis. Opportunists, F. vesiculosus and B. balanoides, dominate where ice disturbances are severe and regular but where the community is not severely disturbed, initial differences in the abundance of F. vesiculosus and A. nodosum are reduced, and the community becomes closer to the mature one dominated by A. nodosum. The period of disturbance influences the species' settling and their abundance. The earlier the disturbance in the spring, the greater will be the colonization by the opportunists Ulothricales, Ulvales, and B. balanoides, but when the disturbance occurs later, F. vesiculosus and M. edulis are the main settlers. The tidal level influences mainly the establishment of dominance. In the mid zone, few species are present, densities are low, competition is not an important controlling factor, and Balanus dominate. In the low zone, barnacles are replaced by mussels, the number of species and densities are high, and competition is greater. Exclosure and enclosure experiments using cages have shown that littorinid grazers have a negligible influence on the reduction of the dominant annual alga Ulothrix flacca. Its reduction in midsummer appears to be related to its life cycle. Predators were rarely observed at the study sites. Structural and developmental patterns of intertidal rocky communities were slow and the monopolization of space by A. nodosum and M. edulis, as observed in the mature, less disturbed community, must result from a long period [Formula: see text] without major disturbances.

scholarly journals Green extraction of proteins, umami and other free amino acids from brown macroalgae Ascophyllum nodosum and Fucus vesiculosus

2021 ◽  
Author(s):  
Viruja Ummat ◽  
Marco Garcia-Vaquero ◽  
Mahesha M. Poojary ◽  
Marianne N. Lund ◽  
Colm O’Donnell ◽  
...  
Keyword(s):  
Amino Acids ◽  
Citric Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Food Industry ◽  
Ascophyllum Nodosum ◽  
Fucus Vesiculosus ◽  
Green Solvents ◽  
Brown Macroalgae ◽  
Extraction Solvent

AbstractSeaweeds are a valuable potential source of protein, as well as free amino acids (FAAs) with umami flavour which are in high demand by the food industry. The most commonly used flavouring agents in the food industry are chemically synthesised and therefore are subject to concerns regarding their safety and associated consumer resistance. This study focuses on the effects of extraction time (1 and 2 h) and solvents (0.1 M HCl, 1% citric acid and deionised water) on the extraction of protein and FAAs including umami FAAs from Irish brown seaweeds (Ascophyllum nodosum and Fucus vesiculosus). Extraction yields were influenced by both the extraction solvent and time, and also varied according to the seaweed used. Both seaweeds investigated were found to be good sources of protein, FAAs including umami FAAs, demonstrating potential application as flavouring agents in the food industry. Overall, the use of green solvents (deionised water and citric acid) resulted in higher recoveries of compounds compared to HCl. The results of this study will facilitate the use of more sustainable solvents in industry for the extraction of proteins and flavouring agents from seaweed.

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

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.

A biophysical model of the interaction between vertical migration of crustacean zooplankton and circulation in the Lower St. Lawrence Estuary

1999 ◽  
Vol 56 (12) ◽  
pp. 2420-2432 ◽  
Author(s):  
Bruno A Zakardjian ◽  
Jeffrey A Runge ◽  
Stephane Plourde ◽  
Yves Gratton
Keyword(s):  
Population Dynamics ◽  
Vertical Migration ◽  
Horizontal Distribution ◽  
Calanus Finmarchicus ◽  
Biophysical Model ◽  
Crustacean Zooplankton ◽  
Simple Formulation ◽  
Lawrence Estuary ◽  
Circulation Patterns ◽  
St Lawrence Estuary

As an essential step in modeling the influence of circulation on the population dynamics of marine planktonic copepods, we define a simple formulation of swimming behavior that can be used in both Eulerian and Lagrangian models. This formulation forces aggregation of the population toward a preferential depth and can be stage specific and time varying, thus allowing description of either diurnal or seasonal vertical migration. We use the formulation to examine the interaction between the circulation and vertical distribution in controlling horizontal distribution of the common planktonic copepod Calanus finmarchicus in the Lower St. Lawrence Estuary, Canada. We first introduce diel migration into a simple one-dimensional model and then into a model of residual two-dimensional circulation patterns representative of conditions encountered in the Lower St. Lawrence Estuary. Results from the latter indicate that interactions between circulation and stage-specific swimming behaviors are the main mechanisms for aggregation of planktonic crustaceans at the head of the Laurentian Channel and highlight the implications of flushing of the surface-dwelling young stages for the population dynamics of C. finmarchicus in the Lower St. Lawrence Estuary.

scholarly journals Clinical Efficacy of Brown Seaweeds Ascophyllum nodosum and Fucus vesiculosus in the Prevention or Delay Progression of the Metabolic Syndrome: A Review of Clinical Trials

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 714
Author(s):  
Enver Keleszade ◽  
Michael Patterson ◽  
Steven Trangmar ◽  
Kieran J. Guinan ◽  
Adele Costabile
Keyword(s):  
Metabolic Syndrome ◽  
Clinical Trials ◽  
Brown Seaweed ◽  
Public Health Problem ◽  
Ascophyllum Nodosum ◽  
Fucus Vesiculosus ◽  
Total Phenolic ◽  
World Population ◽  
Brown Seaweeds ◽  
The Metabolic Syndrome

Metabolic syndrome (MetS) is a global public health problem affecting nearly 25.9% of the world population characterised by a cluster of disorders dominated by abdominal obesity, high blood pressure, high fasting plasma glucose, hypertriacylglycerolaemia and low HDL-cholesterol. In recent years, marine organisms, especially seaweeds, have been highlighted as potential natural sources of bioactive compounds and useful metabolites, with many biological and physiological activities to be used in functional foods or in human nutraceuticals for the management of MetS and related disorders. Of the three groups of seaweeds, brown seaweeds are known to contain more bioactive components than either red and green seaweeds. Among the different brown seaweed species, Ascophyllum nodosum and Fucus vesiculosus have the highest antioxidant values and highest total phenolic content. However, the evidence base relies mainly on cell line and small animal models, with few studies to date involving humans. This review intends to provide an overview of the potential of brown seaweed extracts Ascophyllum nodosum and Fucus vesiculosus for the management and prevention of MetS and related conditions, based on the available evidence obtained from clinical trials.

Surface pulses in the lower St. Lawrence Estuary

1998 ◽  
Vol 36 (3) ◽  
pp. 271-295 ◽  
Author(s):  
R.F. Marsden ◽  
Y. Gratton
Keyword(s):  
Lawrence Estuary ◽  
St Lawrence Estuary
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