The biology of Gammarus (Crustacea, Amphipoda) in the northwestern Atlantic. VI. Gammarus tigrinus Sexton

1972 ◽  
Vol 50 (8) ◽  
pp. 1063-1068 ◽  
Author(s):  
D. H. Steele ◽  
V. J. Steele
Keyword(s):  
Life Cycle ◽  
Late Summer ◽  
Lawrence Estuary ◽  
Gammarus Tigrinus ◽  
Estuarine Species ◽  
St Lawrence Estuary

Gammarus tigrinus is an endemic estuarine species of the northwestern Atlantic found from the St. Lawrence estuary south to Florida. At St. Andrews, N.B., 50% maturity occurs at 6.1 mm in the female. Females produce a series of broods between April and September at which time they enter the resting stage. The oogonia begin to enlarge in February, but are not fertilized until April. The young hatched in the spring probably enter the resting stage in late summer before producing the first brood. The older generation disappears in the summer and the life cycle is annual.

Life cycle of Calanus finmarchicus in the lower St. Lawrence Estuary: the imprint of circulation and late timing of the spring phytoplankton bloom

2001 ◽  
Vol 58 (4) ◽  
pp. 647-658 ◽  
Author(s):  
Stéphane Plourde ◽  
Pierre Joly ◽  
Jeffrey A Runge ◽  
Bruno Zakardjian ◽  
Julian J Dodson
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Production Rate ◽  
Egg Production ◽  
Phytoplankton Bloom ◽  
Food Limitation ◽  
Calanus Finmarchicus ◽  
Lawrence Estuary ◽  
Egg Production Rate ◽  
St Lawrence Estuary

The life cycle of Calanus finmarchicus in the lower St. Lawrence estuary is described based on observations of female egg production rate, population stage abundance, and chlorophyll a biomass collected over 7 years (1991–1997) at a centrally located monitoring station. The mean seasonal pattern shows maximum abundance of females in May, but peak population egg production rate and naupliar (N3–N6) abundance occur in early July just after onset of the late spring – early summer phytoplankton bloom. The population stage structure is characterized by low summer abundance of early copepodite stages C1–C3 and high stage C5 abundance in autumn. Between 1994 and 1997, there was important interannual variation in both timing (up to 1 month) and amplitude (five- to eight-fold) of population reproduction. Patterns of seasonal increase of C5 abundance in autumn suggest interannual variations of both timing and magnitude of deep upstream advection of this overwintering stage. Thus, the main features of C. finmarchicus population dynamics in the central lower St. Lawrence Estuary are (i) late reproduction resulting from food limitation prior to the onset of the summer phytoplankton bloom, (ii) probable export of early developmental stages during summer, and (iii) advection into the central lower St. Lawrence Estuary of overwintering stage C5 in autumn from downstream regions. These results support the hypothesis that circulation, mainly driven by discharge from the St. Lawrence River and its tributaries, is a key factor governing population dynamics of C. finmarchicus in this region.

Cycle de développement, écologie et succès d'Hippomedon propinquus (Amphipoda, Gammaridea) dans deux écosystèmes du golfe du Saint-Laurent

1987 ◽  
Vol 65 (12) ◽  
pp. 3116-3132 ◽  
Author(s):  
Gabriel Lamarche ◽  
Pierre Brunel
Keyword(s):  
Life Cycle ◽  
Life Expectancy ◽  
Primary Production ◽  
Food Web ◽  
Adult Stage ◽  
Monitoring Station ◽  
Lawrence Estuary ◽  
Crustacean Species ◽  
Average Size ◽  
St Lawrence Estuary

Bimonthly quantitative day and night samples from one monitoring station located in the St. Lawrence Estuary (in silt–clay, at a depth of 119 m), with a constant yearly temperature (1–4 °C), reveal that densities of the detrivorous and necrophagous lysianassid amphipod Hippomedon propinquus were similar (0.4–9.7 individuals/100 m3 in 1970, 1971, and 1973) to densities at another station in Chaleur Bay with comparable sediments, temperature, and depth (4.2–7.5 individuals/100 m3 in 1969 and 1971). However, its rank among the gammaridean community (10th to 15th in the bay, 3rd to 5th in the estuary) and a faster growth in the estuary suggest better "success" in the latter. Vertical migrations are mainly diurnal and of higher amplitude in the bay than in the estuary, where these are mostly nocturnal, except in June and July. Life expectancy is over 2 years with a maximum of 13 molts, 4 to 5 of which occur in the adult stage. Growth is slower, life expectancy is shorter, but rank is higher (third) at another Chaleur Bay station where H. propinquus also displays increased swimming activity. In both ecosystems, reproduction is mostly a continuous, year-round process, but juvenile recruitment is more important in spring and summer, conforming to our prediction that life cycle is more independent of primary production and seasonal sestonic fallout when species occupy higher positions in the food web. Average size of ovigerous females decreases while fecundity increases in summer. Females produce larger eggs in Chaleur Bay. Poorer and less predictable primary production in the St. Lawrence Estuary gives opportunistic species like H. propinquus an advantage over more strictly detrivorous crustacean species.

The effects of drought and waterlogging conditions on the performance of an endemic annual plant, Aster laurentianus

2000 ◽  
Vol 78 (1) ◽  
pp. 40-46 ◽  
Author(s):  
Gilles Houle ◽  
Annie Belleau
Keyword(s):  
Salt Marshes ◽  
Carbon Assimilation ◽  
Late Summer ◽  
Annual Plant ◽  
Endemic Plant ◽  
Lawrence Estuary ◽  
Negative Effect ◽  
Effects Of Drought ◽  
Interannual Fluctuations ◽  
St Lawrence Estuary

Aster laurentianus Fernald is an annual plant endemic to the St. Lawrence estuary. It typically grows in salt marshes at the periphery of shallow lagoons. In this habitat, the water level fluctuates greatly both within and between years. Such fluctuations may induce significant interannual variations in marsh-plant populations. In this study, we experimentally determined the effects of different water availability conditions, imposed at various stages of plant development, on the performance of A. laurentianus. Waterlogging had no significant effect on net carbon assimilation rate, plant growth, and biomass allocation. However, a drought stress at the time of reproductive-bud differentiation had a negative effect on flower-head production. We propose that occasional reproductive failures resulting from late-summer droughts may cause significant interannual fluctuations in the size of A. laurentianus populations, potentially making them more susceptible to local extinction.Key words: Aster laurentianus, endemic plant, Îles-de-la-Madeleine, rare plant, salt marshes, water stress.

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

Preliminary investigations into the life cycle of Ventruia inaequalis (Cooke) WINT. in South Australia.

1953 ◽  
Vol 4 (4) ◽  
pp. 415 ◽  
Author(s):  
MW Jeffery
Keyword(s):  
Life Cycle ◽  
Primary Infection ◽  
South Australia ◽  
Late Summer ◽  
Relative Importance ◽  
New Information ◽  
One Year

Investigation into the possible sources of primary infection by the fungus Ventruia inaequalis (Cooke) Wint. in spring has been carried out. The results present new information on the life cycle of the pathogen under South Australian conditions. Sources of primary infection, such 'as lesions on one-year-old wood or overwintering superficial conidia on the trees, do not appear important. Bud-scale infection of dormant buds has been shown, and its relative importance is discussed. Ascospores are the most important source of primary infection. Their period of discharge extends to a later date than previously reported for South Australia and is considered in relation to leader shoot and late summer spot infection.

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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