Vegetation patterns in James Bay coastal marshes. I. Environmental factors on the south coast

1986 ◽  
Vol 64 (1) ◽  
pp. 217-226 ◽  
Author(s):  
Kern Ewing ◽  
K. A. Kershaw
Keyword(s):  
Land Surface ◽  
Salinity Gradient ◽  
Detrended Correspondence Analysis ◽  
Hudson Bay ◽  
James Bay ◽  
Surface Salinity ◽  
Vegetation Development ◽  
Community Types ◽  
Freshwater Inputs ◽  
Peat Formation

Coastal wetlands of the Hudson Bay Lowlands along southern James Bay are generated by a positive water balance, low relief, and a rising land surface. Marshes, dominated by sedges and grasses, and separated by beach ridges, occur between unvegetated intertidal flats and the inland boreal forest. Bay waters, affected by currents, shallow depths, and large freshwater inputs from major rivers in the Hudson Bay drainage, are brackish. Off the coast at the Harricanaw River, surface salinity in the bay is <4 ppt while soil water salinities in the adjacent marsh are higher. Standing water and tidal water in contact with vegetation often measure 0 ppt salinity. Plant communities adapted to brackish water have developed. Using two-way indicator species analysis classification, twelve widespread community types were recognized. Ordination using detrended correspondence analysis revealed gradients of salinity, elevation, drainage, vegetation development, complexity, and peat formation, and separated coastal from estuarine communities. An inverse salinity gradient, which has been reported elsewhere in James Bay, was not found; explanations are proposed for isolated areas of high salinity.

Vegetation patterns in James Bay coastal marshes. III. Salinity and elevation as factors influencing plant zonations

1989 ◽  
Vol 67 (10) ◽  
pp. 2967-2974 ◽  
Author(s):  
J. C. Earle ◽  
K. A. Kershaw
Keyword(s):  
Salt Marsh ◽  
Salinity Gradient ◽  
Detrended Correspondence Analysis ◽  
Distribution Patterns ◽  
Environmental Data ◽  
Plant Distribution ◽  
Coastal Marsh ◽  
James Bay ◽  
Factors Influencing ◽  
Community Types

Plant zonations and selected environmental variables were studied in a subarctic coastal marsh at Ekwan Point, James Bay, Ont. Eight distinct community types were identified using two-way indicator species analysis classification (TWINSPAN). These were interpreted as a primary successional sequence. The eight communities were found to conform closely to the classical marsh zonations based on elevation and tidal influence: (1) lower salt marsh, (2) middle salt marsh, (3) upper salt marsh, (4) saline meadow, (5) freshwater meadow, and (6) freshwater fen. Environmental data collected along the vegetation transects indicated that changes in elevation and soil-water salinity probably influence species distributions. A species ordination using detrended correspondence analysis (DECORANA) revealed several trends in plant distribution patterns. Consideration of the environmental affinities of species separated along three ordination axes suggested that salinity and elevation, water content, and soil texture were probably important factors influencing successional processes in the marsh during at least the last century. An inverse salinity gradient, which has been reported at many sites along the west coast of Hudson and James bays, was not found at Ekwan Point.

Vegetation patterns in James Bay coastal marshes. II. Effects of hydrology on salinity and vegetation

1988 ◽  
Vol 66 (12) ◽  
pp. 2586-2594 ◽  
Author(s):  
Jonathan S. Price ◽  
Kern Ewing ◽  
Ming-ko Woo ◽  
Kenneth A. Kershaw
Keyword(s):  
Salt Marshes ◽  
Saline Water ◽  
Coastal Marsh ◽  
Hudson Bay ◽  
James Bay ◽  
Stream Channels ◽  
Surface Salinity ◽  
Rooting Zone ◽  
Hydrologic Gradients ◽  
Freshwater Budget

The vegetation of a coastal marsh in southern James Bay was examined in reference to the salinity and hydrological processes. Regional hydrologic influences related to the freshwater budget of James Bay reduce the local salinity so that the vegetation typifies that of a fresh to brackish marsh system, in contrast to the Hudson Bay salt marshes reported in the literature. Thus species that thrive in areas of higher salinity have only limited occurrence at the study site. Infrequent tidal inundation of low salinity bay water diminishes surface salinity, which is primarily controlled by the interaction of marsh hydrology with fossil salt diffusing upward from postglacial deposits. The soil water salinity increases with depth and distance inland. However, local hydrologic gradients near raised beach ridges and incised stream channels affect surface runoff and groundwater recharge and discharge, producing further distinct spatial variations in salinity. These processes thus control the distribution of saline water in the rooting zone and hence the patterns of vegetation.

Morphological and isozyme variation in Salicornia europaea (s.l.) (Chenopodiaceae) in northeastern North America

1987 ◽  
Vol 65 (7) ◽  
pp. 1410-1419 ◽  
Author(s):  
S. L. Wolff ◽  
R. L. Jefferies
Keyword(s):  
North America ◽  
Atlantic Coast ◽  
Hudson Bay ◽  
Salicornia Europaea ◽  
Electrophoretic Variation ◽  
James Bay ◽  
Northeastern North America ◽  
Electrophoretic Patterns ◽  
Anther Length ◽  
Vegetative Characters

Morphological and electrophoretic variation has been documented within and among populations of Salicornia europaea L. (s.l.) in northeastern North America. Univariate and multivariate analyses (discriminant analyses) of measurements of floral and vegetative characters delimited three morphologically distinct groups of populations: Atlantic coast tetraploids (2n = 36), Hudson Bay diploids, and Atlantic coast and James Bay diploids (2n = 18). The two diploid groups were morphologically distinct from the midwestern diploid, S. rubra Nels., based on anther length, width of the scarious border of the fertile segment, and the overall width of the fertile segment. Electrophoretic evidence supported the delimitation of the three distinct morphological groups of populations of S. europaea with the exception of the population from James Bay, which had electrophoretic patterns identical with those of plants from Hudson Bay but resembled the Atlantic coast diploids morphologically. Most enzyme systems assayed were monomorphic. Only homozygous banding patterns were detected in diploid plants and electrophoretic variation was not observed within populations of S. europaea or S. rubra but was detected between groups of populations. Four multilocus phenotypes were evident; these corresponded to the major groups recognized on the basis of ploidy level and morphology. Reasons that may account for the paucity of isozymic variation are discussed.

Grass phytoliths in surface sediments of the Sunderbans, India and their implications in reconstructing past deltaic environmental changes

The Holocene ◽  
2021 ◽  
pp. 095968362110417
Author(s):  
Madhab Naskar ◽  
Ruby Ghosh ◽  
Sayantani Das ◽  
Dipak Kumar Paruya ◽  
Binod Saradar ◽  
...  
Keyword(s):  
Surface Sediments ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Salinity Gradient ◽  
Detrended Correspondence Analysis ◽  
Mangrove Ecosystem ◽  
Sea Level Changes ◽  
Tidal Influence ◽  
Mangrove Environment ◽  
Mangrove Associate

Reliability of grass phytoliths for discriminating different deltaic sub-environments has been assessed on the modern surface sediments collected along the salinity gradient of the Sunderbans delta, India. It has been observed that grass phytolith assemblages can successfully distinguish different deltaic sub-environments especially the true mangrove zones from the mangrove associate and non-mangrove zones with minor overlaps, which further corroborated with the results of discriminant analysis (DA). Detrended correspondence analysis (DCA) and redundancy analysis (RDA) performed on the surface grass phytolith data show that salinity is the most crucial environmental parameter influencing grass phytolith distribution in the deltaic sub-environments. The potential of modern grass phytolith data in reconstructing past deltaic environmental changes has been further assessed on a late Quaternary fossil phytolith spectra from the Sunderbans spanning a sedimentary record for the last ~13.6 ka. A true mangrove environment with discernible tidal influence has been revealed between 13.6 and 3.9 ka. Absence of true mangrove–indicator grass phytoliths between ~3.9 and 2.2 ka further suggests disappearance of mangrove vegetation from this part of the Sunderbans which might have recolonized during ~2.2–0.8 ka. A mangrove associated or non-mangrove environment with little or no tidal influence came into existence in the study area since 0.8 ka onwards. A comparison with some earlier records suggests that the present grass phytolith-based palaeoenvironmental data shows conformity with the past dynamics in mangrove ecosystem in the east coast of India in respect to relative sea level changes.

Impact of mesoscale eddies on salinity and CO2 ocean parameters in the western tropical Atlantic in February 2020

2021 ◽  
Author(s):  
Léa Olivier ◽  
Jacqueline Boutin ◽  
Nathalie Lefèvre ◽  
Gilles Reverdin ◽  
Peter Landschützer ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Salinity Gradient ◽  
Sea Surface Salinity ◽  
Amazon River ◽  
Tropical Atlantic ◽  
Surface Salinity ◽  
The North ◽  
Brazil Current ◽  
North Brazil

&lt;p&gt;Large oceanic eddies are formed by the retroflection of the North Brazil Current (NBC) near 8&amp;#176;N in the western tropical Atlantic. The EUREC&lt;sup&gt;4&lt;/sup&gt;A-OA/Atomic cruise took place in January - February 2020, and extensively documented two NBC rings. The NBC flows northward across the Equator and pass the mouth of the Amazon River, entraining fresh and nutrient-rich water along its nearshore edge. From December to March, the Amazon river discharge is low but a freshwater filament stirred by a NBC ring was nevertheless observed. The strong salinity gradient can be used to delineate the NBC ring during its initial phase and its westward propagation. Using satellite sea surface salinity and ocean color associated to in-situ measurements of salinity, temperature, dissolved inorganic carbon, alkalinity and fugacity of CO&lt;sub&gt;2&lt;/sub&gt; we characterize the salinity and biogeochemical signature of NBC rings.&lt;/p&gt;

Chapter 18 Marine and Coastal Birds of James Bay, Hudson Bay and Foxe Basin

1986 ◽  
pp. 355-386 ◽  
Author(s):  
R.I.G. Morrison ◽  
A.J. Gaston
Keyword(s):  
Hudson Bay ◽  
James Bay ◽  
Foxe Basin ◽  
Coastal Birds

BIOLOGICAL AND OCEANOGRAPHIC CONDITIONS IN HUDSON BAY: 6. THE GENERAL HYDROGRAPHY AND HYDRODYNAMICS OF THE WATERS OF THE HUDSON BAY REGION

1932 ◽  
Vol 7 (1) ◽  
pp. 91-118 ◽  
Author(s):  
H. B. HACHEY
Keyword(s):  
Fresh Water ◽  
Water Movement ◽  
Open Ocean ◽  
Hudson Bay ◽  
Water Drainage ◽  
James Bay ◽  
Bay Area ◽  
Hydrographic Conditions ◽  
The Many ◽  
Oceanographic Conditions

The waters of Hudson bay differ markedly from the waters of Hudson strait and the waters of the open ocean. Intense stratification in the upper twenty-five metres, decreasing as the waters of the open ocean are approached, gives Hudson bay the character of a large estuary. Below fifty metres the waters are for all purposes dynamically dead, thus resulting in a cold saline body of water which probably undergoes very little change from season to season. The movements of the waters at various levels are dealt with to show that the inflow of waters from Fox channel and the many fresh-water drainage areas control the hydrographic conditions as found. The main water movement is from the James bay area to Hudson strait and thence to the open ocean.

scholarly journals Cholera Risk: A Machine Learning Approach Applied to Essential Climate Variables

2020 ◽  
Vol 17 (24) ◽  
pp. 9378
Author(s):  
Amy Marie Campbell ◽  
Marie-Fanny Racault ◽  
Stephen Goult ◽  
Angus Laurenson
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Land Surface ◽  
Environmental Changes ◽  
Random Forest Classifier ◽  
Sea Surface Salinity ◽  
Learning Approach ◽  
Climate Variables ◽  
Surface Salinity ◽  
Machine Learning Approach

Oceanic and coastal ecosystems have undergone complex environmental changes in recent years, amid a context of climate change. These changes are also reflected in the dynamics of water-borne diseases as some of the causative agents of these illnesses are ubiquitous in the aquatic environment and their survival rates are impacted by changes in climatic conditions. Previous studies have established strong relationships between essential climate variables and the coastal distribution and seasonal dynamics of the bacteria Vibrio cholerae, pathogenic types of which are responsible for human cholera disease. In this study we provide a novel exploration of the potential of a machine learning approach to forecast environmental cholera risk in coastal India, home to more than 200 million inhabitants, utilising atmospheric, terrestrial and oceanic satellite-derived essential climate variables. A Random Forest classifier model is developed, trained and tested on a cholera outbreak dataset over the period 2010–2018 for districts along coastal India. The random forest classifier model has an Accuracy of 0.99, an F1 Score of 0.942 and a Sensitivity score of 0.895, meaning that 89.5% of outbreaks are correctly identified. Spatio-temporal patterns emerged in terms of the model’s performance based on seasons and coastal locations. Further analysis of the specific contribution of each Essential Climate Variable to the model outputs shows that chlorophyll-a concentration, sea surface salinity and land surface temperature are the strongest predictors of the cholera outbreaks in the dataset used. The study reveals promising potential of the use of random forest classifiers and remotely-sensed essential climate variables for the development of environmental cholera-risk applications. Further exploration of the present random forest model and associated essential climate variables is encouraged on cholera surveillance datasets in other coastal areas affected by the disease to determine the model’s transferability potential and applicative value for cholera forecasting systems.

Sign in / Sign up

Export Citation Format

Share Document