scholarly journals Mercury Distribution in an Upper St. Lawrence River Wetland Dominated by Cattail (Typha Angustifolia)

2021 ◽  
Author(s):  
Evie S Brahmstedt ◽  
Carla N Ayala Crespo ◽  
Thomas M Holsen ◽  
Michael Twiss
Keyword(s):  
Water Level ◽  
Plant Biomass ◽  
Management Plan ◽  
Hydric Soils ◽  
Water Level Fluctuations ◽  
Organic Detritus ◽  
Riparian Wetland ◽  
Water Level Management ◽  
Living Tissues ◽  
St Lawrence River

Abstract Legacy mercury (Hg) exists in Upper St. Lawrence River wetland hydric soils and is impacted by a new water level management plan (established in 2017) implemented to restore biodiversity and reduce the monotypic nature of riparian wetlands, currently dominated by Typha spp.. The distribution of Hg within the various components of a riparian wetland provides insight into potential impacts of water level fluctuations. Hydric soil represents 83% of the wetland Hg burden while wetland plant biomass contributed 17%, mostly due to organic detritus (13%). Although Typha roots had a bioconcentration factor of 1.2 (relative to hydric soils) and had the highest total Hg among living tissues (25 ± 9.3 ng/g dry wt.), detritus had the highest overall Hg content (110 ± 53 ng/g dry wt.). While root tissue Hg correlated significantly with soil Hg (p = 0.045), it was determined here that Typha spp. has limited use as a biomonitor in wetlands with low levels of Hg contamination, as in this ecosystem. Hg contained within the organic detritus contributed more to the overall Hg burden in these monotypic Typha wetlands than any other tissue or biomass component analyzed. Consequently, shifts in the plant community that are expected to result from a new water level management plan may alter Hg storage within these wetlands and affect its mobility in this ecosystem.

Impact of water level fluctuations on St. Lawrence River aquatic vegetation

1997 ◽  
Vol 54 (12) ◽  
pp. 2853-2865 ◽  
Author(s):  
Christiane Hudon
Keyword(s):  
Water Level ◽  
Aquatic Vegetation ◽  
Plant Biomass ◽  
Plant Cover ◽  
Negative Relationship ◽  
Climatic Conditions ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Vertical Range ◽  
St Lawrence River

Historical records of average seasonal water levels in the St. Lawrence River over the past 80 years reveal cyclic variations of up to 1 m above (1976) and 1 m below (1965) present levels. These variations are probably related to climatic conditions in the basin. Over the same period, the vertical range of seasonal water levels decreased from 2.2 to 1.5 m because of discharge regulation. Exposure of new substrate during periods of extreme low water levels may facilitate the invasion of aggressive and (or) exotic species. In Lake Saint-Pierre, a strong negative relationship was observed between seasonal water level and the percentage of emergent plant cover. Under low water levels, the lake becomes a large (387 km2) marshland that could support a high plant biomass (286 times 103 t) whereas under high water levels, the lake shifts to a vast (501 km2) open-water body with a lower predicted plant biomass (117 times 103 t). A model of the major anthropic and climatic forces acting on water levels is also presented; it describes aquatic plant biomass allocation and species diversity under different water level conditions.

From pristine to present state: hydrology evolution of Lake Saint-François, St. Lawrence River

1998 ◽  
Vol 25 (5) ◽  
pp. 864-879 ◽  
Author(s):  
Jean Morin ◽  
Michel Leclerc
Keyword(s):  
Water Level ◽  
Plant Biomass ◽  
Seasonal Pattern ◽  
Water Levels ◽  
Ship Traffic ◽  
Water Level Rise ◽  
Hydropower Production ◽  
Discharge Regulation ◽  
The Impact ◽  
St Lawrence River

Lake Saint-François is a relatively shallow fluvial lake of the St. Lawrence River with numerous deep channels. This complex system has been considerably altered from its pristine state 150 years ago. Currently, the water level is stabilized and the flow is regulated; important areas have been dredged and the major part of its outflow is diverted through the Beauharnois canal. The evolution of water levels shows a trend towards stabilization as required for ship traffic in the St. Lawrence Seaway and for hydropower production. With the construction of the Moses-Saunders dam in 1960, the flow of the river could be regulated; changes occur in the seasonal pattern of the flow. Ancient stage-discharge relationships were recreated to describe the impact of the 1849 damming and of the present level stabilization. Stabilization of the water level has favored the growth of submerged plants. Manning's friction coefficient was used to show that plant biomass has doubled since 1920; the onset of biomass increases corresponds to a water level stabilization event. The distribution of wetlands in the Lake Saint-François area was drastically modified by the water level rise caused by the 1849 damming. New wetlands were created and pre-1849 wetlands, located on what are currently shoals in the central part of the lake, have totally disappeared.Key words: Lake Saint-François, St. Lawrence River, impact of civil works, flow discharge regulation, water level regulation, wetland flooding cycle, submerged macrophyte, ecosystem reaction, civil work history.

Tree-ring analysis of wetlands of the upper St. Lawrence River, Quebec: response to hydrology and climate

1996 ◽  
Vol 26 (3) ◽  
pp. 482-491 ◽  
Author(s):  
Martin Jean ◽  
André Bouchard
Keyword(s):  
Water Level ◽  
Tree Growth ◽  
Significant Relationship ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Climatic Fluctuations ◽  
Climatic Variations ◽  
Temperature And Precipitation ◽  
Growth Variation ◽  
St Lawrence River

A dendrochronological analysis of three tree species colonizing a swamp along the St. Lawrence River was undertaken to (a) study the extent to which water-level fluctuations have an impact on tree growth in comparison to climatic variations; (b) compare the responses of three species (Acerrubrum L., Larixlaricina (Du Roi) K. Koch, and Thujaoccidentalis L.) with hydrologic and climatic variations; and (c) examine the duration of the influence of water-level fluctuations on tree growth. Tree cores from 78 stands were cross-dated and verified with COFECHA and a master chronology for each species was produced using ARSTAN. Response function analyses were used to measure the influence of climate (temperature and precipitation) and water level on tree growth. Water-level fluctuations have a significant influence on A. rubrum growth, accounting for 30% of the tree growth variation. A significant relationship exists between L. laricina and water-level fluctuations, but only 9% of the tree growth is explained by hydrology. No significant relationship was found between water levels and T. occidentalis growth. Climatic fluctuations are a more important influence on growth for all three species, accounting for 46% to 51% of the tree growth variation not explained by water levels.

Shift in wetland plant composition and biomass following low-level episodes in the St. Lawrence River: looking into the future

2004 ◽  
Vol 61 (4) ◽  
pp. 603-617 ◽  
Author(s):  
Christiane Hudon
Keyword(s):  
Plant Biomass ◽  
Lythrum Salicaria ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Terrestrial Plants ◽  
Hydrologic Variability ◽  
Najas Flexilis ◽  
Average Water ◽  
Similar Episode ◽  
St Lawrence River

The effects of a 1-m drop in average water levels in 1999 on species composition and biomass were documented for a St. Lawrence River wetland and compared with a similar episode in 1931. These observations highlight the manifold effects of past and future water level fluctuations on St. Lawrence River wetlands and faunal habitats, resulting from natural hydrologic variability, climate change, and (or) human intervention. In 1931 and 1999, waters were 2–3 °C warmer than the previous 10-year average. Low water levels markedly altered wetland vegetation: various Graminea (including Phalaris arundinacea and Phragmites australis) and facultative annual species invaded previously marshy areas. Submerged species previously found in shallow waters were replaced on dry ground by annual terrestrial plants; Alisma gramineum colonized emergent waterlogged mudflats. The low water levels of 1999 induced a spatially discontinuous plant biomass that was richer in terrestrial material than in previous years (1993–1994). In comparison with the 1930s, recent surveys indicate a decline of assemblages dominated by Equisetum spp. and Najas flexilis and a rise of those dominated by Lythrum salicaria, Potamogeton spp., and filamentous algae. These shifts reveal the additional effects of nutrient enrichment, alien species, and shoreline alteration accompanying a change from a mostly agricultural to a mostly urbanized and industrialized landscape.

6. An Investigation of the Spatial Differences in Mercury Burdens of Small Fish in a St-Lawrence River Impoundment Reservoir: the Role of Water Level Fluctuations

2016 ◽  
Author(s):  
Michele Parisien
Keyword(s):  
Water Level ◽  
High Water ◽  
Water Level Fluctuations ◽  
Small Fish ◽  
Water Reservoirs ◽  
Hydroelectric Reservoirs ◽  
Spatial Differences ◽  
Reducing Bacteria ◽  
St Lawrence River

In many hydroelectric reservoirs across Canada, fish exhibit elevated mercury burdens. This is thought to occur due to the flooding of soil with water level fluctuations. Periods ofhigh water level may cause mercury from shoreline soil to be released into the water, which may make it available for methylation by sulfur-reducing bacteria in the sedimentand phytoplankton on plants. The amount of methylmercury produced during periods of high water level may depend on the topography of the shoreline; if the shoreline has agentle slope, more of its surface area would be covered during rises in water level than if the shoreline has a steep slope. I hypothesize that bays within a reservoir that have a gentle slope and a relatively large amount of vegetation (vegetation provides habitat for periphyton) will have more mercury than steeply-sloped bays with little vegetation. Totest this hypothesis, I have collected 10 each of the 3 most abundant fish (≤100 mm) from 3 bays in eastern Lake St. Lawrence (an impoundment reservoir with water fluctuations ≤2meters throughout the year) at Massena, NY. I will use stable isotopes to infer the trophic level and food web of each fish in order to determine spatial patterns of mercurydistribution. This study may improve our knowledge of mercury methylation patters in water reservoirs, and provide us with information necessary to properly manage the StLawrenceRiver water reservoirs.   

scholarly journals Characteristics and Management Plan for the Distribution of Nelumbo nucifera community in Junam Wetland

2021 ◽  
Vol 24 (5) ◽  
pp. 469-483
Author(s):  
Soo-Dong Lee ◽  
Han Kim ◽  
Bong-Gyo Cho ◽  
Gwang-Gyu Lee
Keyword(s):  
Environmental Factors ◽  
Water Level ◽  
Soil Depth ◽  
Weather Conditions ◽  
Physicochemical Characteristics ◽  
Management Plan ◽  
Wildlife Habitat ◽  
Nelumbo Nucifera ◽  
Quality Analysis ◽  
Water Level Management

Background and objective: If the Nelumbo nucifera spreads in a wetland at a high density, it can have considerable positive and negative ecological effects on habitats. For this reason, it is necessary to precisely investigate the impacts of its rapid proliferation. This study was conducted to propose the distribution and management of N. nucifera, which can cause the degradation of wildlife habitats due to the rapid spread of internal and external environmental factors that may affect the Junam wetland ecosystem. Methods: For the investigation and analysis of physical and ecological characteristics, factors of the abiotic environment such as general weather conditions, topography and water depth structure, and soil and water quality analysis, and bioenvironment characteristics such as changes in the N. nucifera community distribution were evaluated. To assess whether the differences in the soil depth and physicochemical characteristics between the N. nucifera community and the aquatic plant community are statistically significant, a One-way ANOVA was executed. Results: N. nucifera was presumably introduced in approximately 2007 and observed at a prevalence of only 0.8% in 2009, but had expanded to 11.1% in 2014. After that, the area was increased to 19.3% in 2015 and 40.0% in 2017, about twice that of the previous survey year. The rapid diffusion of an N. nucifera colony can have adverse effects on wildlife habitats and biodiversity at Junam Wetland. To solve these problems, four management methods can be proposed; water level management, mowing management, installation of posts and removal of lotus roots. Control of the N. nucifera community using these methods was judged to be suitable for cutting and water level management when considering expansion rate, water level variation, and wildlife habitat impacts. Conclusion: As the biotic and abiotic environmental factors are different for each wetland, it is necessary to determine the timing and method of management through a detailed investigation.

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