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.

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.

scholarly journals Experimental assessment of the sensitivity of an estuarine phytoplankton fall bloom to acidification and warming

2018 ◽  
Vol 15 (16) ◽  
pp. 4883-4904 ◽  
Author(s):  
Robin Bénard ◽  
Maurice Levasseur ◽  
Michael Scarratt ◽  
Marie-Amélie Blais ◽  
Alfonso Mucci ◽  
...  
Keyword(s):  
Growth Rate ◽  
Primary Production ◽  
Net Primary Production ◽  
Skeletonema Costatum ◽  
Potential Effect ◽  
Lawrence Estuary ◽  
Chl A ◽  
Wide Range ◽  
To Come ◽  
St Lawrence Estuary

Abstract. We investigated the combined effect of ocean acidification and warming on the dynamics of the phytoplankton fall bloom in the Lower St. Lawrence Estuary (LSLE), Canada. Twelve 2600 L mesocosms were set to initially cover a wide range of pHT (pH on the total proton scale) from 8.0 to 7.2 corresponding to a range of pCO2 from 440 to 2900 µatm, and two temperatures (in situ and +5 ∘C). The 13-day experiment captured the development and decline of a nanophytoplankton bloom dominated by the chain-forming diatom Skeletonema costatum. During the development phase of the bloom, increasing pCO2 influenced neither the magnitude nor the net growth rate of the nanophytoplankton bloom, whereas increasing the temperature by 5 ∘C stimulated the chlorophyll a (Chl a) growth rate and maximal particulate primary production (PP) by 76 % and 63 %, respectively. During the declining phase of the bloom, warming accelerated the loss of diatom cells, paralleled by a gradual decrease in the abundance of photosynthetic picoeukaryotes and a bloom of picocyanobacteria. Increasing pCO2 and warming did not influence the abundance of picoeukaryotes, while picocyanobacteria abundance was reduced by the increase in pCO2 when combined with warming in the latter phase of the experiment. Over the full duration of the experiment, the time-integrated net primary production was not significantly affected by the pCO2 treatments or warming. Overall, our results suggest that warming, rather than acidification, is more likely to alter phytoplankton autumnal bloom development in the LSLE in the decades to come. Future studies examining a broader gradient of temperatures should be conducted over a larger seasonal window in order to better constrain the potential effect of warming on the development of blooms in the LSLE and its impact on the fate of primary production.

Seasonal Distribution, Abundance, and Growth of Larval Capelin (Mallotus villosus) in the St. Lawrence Estuary and Northwestern Gulf of St. Lawrence

1977 ◽  
Vol 34 (11) ◽  
pp. 2008-2014 ◽  
Author(s):  
Bernadette Jacquaz ◽  
Kenneth W. Able ◽  
William C. Leggett
Keyword(s):  
Primary Production ◽  
Larval Transport ◽  
Larval Abundance ◽  
Mallotus Villosus ◽  
Daily Growth ◽  
Lawrence Estuary ◽  
Capelin Mallotus Villosus ◽  
Feeding Area ◽  
Anticosti Island ◽  
St Lawrence Estuary

Capelin (Mallotus villosus) larvae in the St. Lawrence estuary and northwestern Gulf of St. Lawrence were most abundant in 1974 and 1975 in the upper estuary in early June; this coincided with the spring peak in primary production. A spectacular decline (>99%) in larval abundance between June and September resulted principally from their downstream transport by currents. In October and November larval capelin were concentrated in a large counterclockwise gyre located in the northwestern Gulf between Anticosti Island and Pointe des Monts. This region is within the area of maximum primary production in the estuary and Gulf and may serve as an important feeding area for larval capelin. Length of capelin larvae at the end of the first growing season in the estuary and northwestern Gulf was greater than that of capelin from Newfoundland, Labrador, and Greenland. However, this difference may have resulted from sampling biases. Daily growth rates of capelin larvae from these areas were similar. Key words: capelin, Mallotus villosus, St. Lawrence, seasonal distributions, larval transport, growth, vertical distribution

scholarly journals Experimental assessment of the sensitivity of an estuarine phytoplankton fall bloom to acidification and warming

2018 ◽  
Author(s):  
Robin Bénard ◽  
Maurice Levasseur ◽  
Michael Grant Scarratt ◽  
Marie-Amélie Blais ◽  
Alfonso Mucci ◽  
...  
Keyword(s):  
Growth Rate ◽  
Primary Production ◽  
Skeletonema Costatum ◽  
Potential Effect ◽  
Lawrence Estuary ◽  
Chl A ◽  
Wide Range ◽  
To Come ◽  
Two Phases ◽  
St Lawrence Estuary

Abstract. We investigated the combined effect of ocean acidification and warming on the dynamics of the phytoplankton fall bloom in the Lower St. Lawrence Estuary (LSLE), Canada. Twelve 2600 L mesocosms were set to initially cover a wide range of pHT (pH on the total proton scale) from 8.0 to 7.2 corresponding to a range of pCO2 from 440 to 2900 µatm, and two temperatures (in situ and +5 °C). The 13-day experiment captured the development and decline of a nanophytoplankton bloom dominated by the chain-forming diatom Skeletonema costatum. During the development phase of the bloom, increasing pCO2 influenced neither the magnitude nor the net growth rate of the nanophytoplankton bloom whereas increasing the temperature by 5 °C stimulated the chlorophyll a (Chl a) growth rate and particulate primary production (PP) by 50 % and 160 %, respectively. During the declining phase of the bloom, warming accelerated the loss of diatom cells and negatively affected PP. Due to the countervailing responses of the plankton community to warming during the two phases of the experiment, the time-integrated primary production was not significantly affected over the full duration of the study. The diatom bloom was paralleled by a gradual decrease in the abundance of photosynthetic picoeukaryotes and followed by a bloom of picocyanobacteria. Increasing pCO2 and warming did not influence the abundance of picoeukaryotes, but warming stimulated picocyanobacteria proliferation. Overall, our results suggest that warming, rather than acidification, is more likely to alter phytoplankton autumnal bloom development in the LSLE in the decades to come. Future studies examining a broader gradient of temperatures should be conducted over a larger seasonal window in order to better constrain the potential effect of warming on the development of blooms in the LSLE and its impact on the fate of primary production.

scholarly journals Life cycle, survivorship and life expectancy of foliage spider (Marpissa bengalensis) in citrus orchard

2018 ◽  
Vol 48 (3) ◽  
Author(s):  
Muhammad Nawab ◽  
Mushtaq Hussain Lashari
Keyword(s):  
Life Cycle ◽  
Life Expectancy ◽  
Incubation Period ◽  
Developmental Stages ◽  
Adult Stage ◽  
Average Duration ◽  
Gravid Female ◽  
Citrus Orchard ◽  
Laboratory Conditions

ABSTRACT: The post embryonic developmental stages of Marpissa bengalensis (Araneae; Salticidac), the 2nd most abundant predatory species in citrus orchard were collected from the experimental fruit garden, department of Horticulture, located at the campus of University of Agriculture Faisalabad andstudied. Life cycle was observed in the laboratory, which started from egg sac collected from the field along with gravid female and released into the spider cages. The incubation period ranged from 5-15 days. The average eggs hatched were 23.8 eggs/cocoon and hatching % under laboratory conditions was recorded as 73.18%. The average duration of spiderlings span on their mothers back was 7 days. An overall, mean duration of 3rd spiderling stage was of 7.46 days. All spiderlings hatched from 8 cocoons. At the 4th spiderling stage, the average duration was of 10.23 days. In the 5th spiderling stage, the spiderling spent an average of 19.82 days. The 6th and 7th spiderlings stages lasted a total of 23.14 days and 25.86 days respectively. During 8th spiderling stage, the duration was maximum and it was recorded in 28.08 days. On average, from hatching to adult stage, the spiderlings lasted 137 days to attained maturity. Greater mortality was observed in the 3rd and 4th spiderling stages, decreasing thereafter and reaching zero in the 8th spiderling stage.

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.

Protozooplankton: Ciliates

2017 ◽  
Author(s):  
Alex Kraberg ◽  
Rowena Stern ◽  
Michaela Strüder-Kypke
Keyword(s):  
Life Cycle ◽  
Nutrient Cycling ◽  
Food Web ◽  
Tree Of Life ◽  
Family Level ◽  
Freshwater Habitats

This chapter describes the taxonomy of ciliates. Ciliates can be found in almost every environment; the majority of species, however, are aquatic and occur in marine, brackish, and freshwater habitats. They play a major role in nutrient cycling in the food web; some are also capable of photosynthesis through acquisition of chloroplasts from their prey. The chapter covers their life cycle, generalized morphology, and ecology and distribution. It includes a section that indicates the systematic placement of the taxon described within the tree of life, and lists the key marine representative illustrated in the chapter (usually to genus or family level). This section also provides information on the taxonomic authorities responsible for the classification adopted, recent changes which might have occurred, and lists relevant taxonomic sources.

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
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