Summer Plankton Distributions Associated with the Physical and Nutrient Properties of the Northwestern Gulf of St. Lawrence

1979 ◽  
Vol 36 (2) ◽  
pp. 187-203 ◽  
Author(s):  
J.-M. Sevigny ◽  
M. Sinclair ◽  
M. I. El-Sabh ◽  
Serge Poulet ◽  
A. Coote
Keyword(s):  
Species Composition ◽  
Primary Production ◽  
Physical Properties ◽  
Nutrient Limitation ◽  
Physiological State ◽  
Copepod Species ◽  
Total Biomass ◽  
Surface Mixed Layer ◽  
North Shore ◽  
The North

Two transects, north–south and east–west, through the Anticosti gyre and the Gaspé current were sampled for physical properties, nutrient and plankton concentrations over a 5-d period during July 1976. Temperature, salinity, σt and nutrient isolines formed a dome characteristic of cyclonic circulation with the apex within the Anticosti gyre, but a strong shallow thermocline prevented nutrient enrichment of the surface mixed layer. Surface nitrate and silicate concentrations were very low, except for two anomalies, throughout the region sampled, with phosphate concentrations higher. Phytoplankton biomass was uniformly low and dominated by nannoplankton (< 15 μm) at all stations except that in the Gaspé current at which netplankton (15–202 μm) was important and the total biomass considerably higher. The higher biomass and importance of larger celled species suggest higher nutrient turnover in the Gaspé current. Nitzschia delicatissima dominated the species composition in the Gaspé current, dinoflagellates and microflagellates being of more importance within the gyre and along the north shore. Zooplankton biomass was distributed fairly uniformly over the entire region but species composition at the shallower stations was characterized by small copepod species (Pseudocalanus sp., Acartia sp.) and fish larvae, the gyre stations being characterized by larger copepod species (Calanus sp.), euphausids, and decapod larvae. Physical properties, nutrients, and plankton were distributed quite uniformly except for the marked variability in the measurements made in the strongly advective Gaspé current station. Distributions of derived parameters that were estimated at 5 m depth suggest nutrient limitation at most stations within the gyre, with the exception of the two stations at which surface nutrient anomalies were detected, while at the nearshore stations, in the Gaspé current and along the north shore, better physiological state and lack of nutrient limitation were observed. Short-term variability in these parameters complicate geographic interpretation, but trends were discernable. Estimated daily primary production was an order of magnitude less than that reported previously. Key words: Anticosti gyre, Gaspé current, primary production, nutrient limited growth

Impact of acidification on structural organization of phytoplankton community in the forest lakes of the north-western Russia

1996 ◽  
Vol 33 (4-5) ◽  
pp. 291-296 ◽  
Author(s):  
L. G. Korneva
Keyword(s):  
Phytoplankton Community ◽  
Diversity Index ◽  
Structural Characteristics ◽  
Total Biomass ◽  
North Shore ◽  
The North ◽  
Forest Lakes ◽  
Ph Range ◽  
North Western ◽  
The Rybinsk Reservoir

The response of the phytoplankton to different degree of pH was studied by the example of 7 shallow weakly mineralized forest lakes located in the Darwin National reserve on the north shore of the Rybinsk reservoir (north-western Russia). With a decrease of pH the number of phytoplankton species decreased especially among centric diatoms,blue-greens and Euglenophyta, total biomass of phytoplankton and its seasonal dispersion declined. Green algae, chrysomonades and cryptomonades biomass correlated negatively with pH but diatoms and blue-greens biomass were related positively to pH. The drop in pH produced a decrease of Shannon-Weaver diversity index, obtained from biomass and cell volume of algae, increase of Simpson index and algae size. The growth of phytoplankton did not correspond the total phosphorus. The necessary modifications to the structural characteristics of phytoplankton by the acidification came about in the pH range from 6 to 5.

On Riccia marginata and related species (Ricciaceae, Marchantiophyta)

2012 ◽  
Vol 46 ◽  
pp. 298-305 ◽  
Author(s):  
A. D. Potemkin ◽  
T. Ahti
Keyword(s):  
Related Species ◽  
Lake Ladoga ◽  
Leningrad Region ◽  
Sem Images ◽  
North Shore ◽  
The North ◽  
Molecular Studies ◽  
The Future ◽  
The Town

Riccia marginata Lindb. was described by S. O. Lindberg (1877) from the outskirts of the town of Sortavala near the north shore of Lake Ladoga, Republic of Karelia, Russia. The species has been forgotten in most recent liverwort accounts of Europe, including Russia. Lectotypification of R. marginata is provided. R. marginata shares most characters with R. beyrichiana Hampe ex Lehm. It differs from “typical” plants of R. beyrichiana in having smaller spores, with ± distinctly finely areolate to roughly papillose proximal surfaces and a narrower and shorter thallus, as well as in scarcity or absence of marginal hairs. It may represent continental populations of the suboceanic-submediterranean R. beyrichiana, known in Russia from the Leningrad Region and Karelia only. The variability of spore surfaces in R. beyrichiana is discussed and illustrated by SEM images. A comparison with the spores of R. bifurca Hoffm. is provided. The question how distinct R. marginata is from R. beyrichiana needs to be clarified by molecular studies in the future, when adequate material is available. R. marginata is for the time being, provisionally, included in R. beyrichiana.

The Marine Environment

2017 ◽  
Author(s):  
N. Penny Holliday ◽  
Stephanie Henson
Keyword(s):  
Primary Production ◽  
North Atlantic ◽  
Physical Environment ◽  
Seasonal Cycle ◽  
Physical Processes ◽  
The North ◽  
Basin Scale ◽  
The North Atlantic ◽  
Physical Features ◽  
Growth Distribution

The growth, distribution, and variability of phytoplankton populations in the North Atlantic are primarily controlled by the physical environment. This chapter provides an overview of the regional circulation of the North Atlantic, and an introduction to the key physical features and processes that affect ecosystems, and especially plankton, via the availability of light and nutrients. There is a natural seasonal cycle in primary production driven by physical processes that determine the light and nutrient levels, but the pattern has strong regional variations. The variations are determined by persistent features on the basin scale (e.g. the main currents and mixed layer regimes of the subtropical and subpolar gyres), as well as transient mesoscale features such as eddies and meanders of fronts.

Conflict, Population Movement, and Microscale Social Networks in Northern Iroquoian Archaeology

2021 ◽  
Vol 86 (2) ◽  
pp. 350-367
Author(s):  
Jennifer Birch ◽  
John P. Hart
Keyword(s):  
Social Networks ◽  
Sixteenth Century ◽  
Lake Ontario ◽  
Population Movement ◽  
Network Ties ◽  
The West ◽  
Local Networks ◽  
North Shore ◽  
The North ◽  
Specific Sequences

We employ social network analysis of collar decoration on Iroquoian vessels to conduct a multiscalar analysis of signaling practices among ancestral Huron-Wendat communities on the north shore of Lake Ontario. Our analysis focuses on the microscale of the West Duffins Creek community relocation sequence as well as the mesoscale, incorporating several populations to the west. The data demonstrate that network ties were stronger among populations in adjacent drainages as opposed to within drainage-specific sequences, providing evidence for west-to-east population movement, especially as conflict between Wendat and Haudenosaunee populations escalated in the sixteenth century. These results suggest that although coalescence may have initially involved the incorporation of peoples from microscale (local) networks, populations originating among wider mesoscale (subregional) networks contributed to later coalescent communities. These findings challenge previous models of village relocation and settlement aggregation that oversimplified these processes.

Seismicity and faulting in the Charlevoix zone of the St. Lawrence Valley

1984 ◽  
Vol 74 (2) ◽  
pp. 595-603
Author(s):  
F. M. Anglin
Keyword(s):  
Active Zone ◽  
Continuous Monitoring ◽  
North Shore ◽  
The North ◽  
Earthquake Zone ◽  
St Lawrence River

Abstract Continuous monitoring of the seismically active Charlevoix zone since late 1977 has delineated the boundaries of the earthquake zone under the north shore and has enabled an association to be made with surface mapped faults that strike along the St. Lawrence Valley and dip to the southeast. Within the active zone, aseismic volumes are found under parts of the St. Lawrence River and another elongated zone of activity is found to the southeast on unmapped faults dipping under the river. The previous suggestions that the activity is related to old rift faults, which have been later weakened by a meteor impact, would seem to be upheld.

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