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Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev
The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev
Electronic Thesis and Dissertation Repository
There is a collective prediction among ecologists that climate change will enhance phytoplankton biomass in temperate lakes. Yet there is noteworthy variation in the structure and regulating functions of lakes to make this statement challengeable and, perhaps, inaccurate. To generate a common understanding on the trophic transition of lakes, I examined the interactive effects of climate change and landscape properties on phytoplankton biomass in 12,644 lakes located in relatively intact forested landscapes. Chlorophyll-a (Chl-a) concentration was used as a proxy for phytoplankton biomass. Chl-a concentration was obtained via analyzing Landsat satellite imagery data over a 28-year period (1984-2011) and using …
Climate Change And Dissolved Organic Matter In Subarctic Lakes: Relevance To Methylmercury Bioavailability, Kyra Lyn Simone
Climate Change And Dissolved Organic Matter In Subarctic Lakes: Relevance To Methylmercury Bioavailability, Kyra Lyn Simone
Electronic Thesis and Dissertation Repository
One of the first steps of methylmercury (MeHg) bioaccumulation, uptake by phytoplankton, is regulated by dissolved organic matter (DOM). Methylmercury binds strongly with DOM, especially high-molecular weight (HMW) compounds containing reduced sulphur; this binding decreases MeHg bioavailability. Climate-induced changes were measured at the landscape level using ArcGIS; land-cover changes between 2005-2010 were assessed around lakes in Mackenzie Valley, NWT. The observed changes, a 10% increase in forest-classified area and up to 15% decrease in wetland area, will likely increase delivery of HMW DOM and MeHg to lakes. Partitioning experiments were conducted to examine effects of DOM ligand quality on MeHg …
Future Changes Of Hydroclimatic Extremes In Western North America Using A Large Ensemble: The Role Of Internal Variability, Mohammad Hasan Mahmoudi
Future Changes Of Hydroclimatic Extremes In Western North America Using A Large Ensemble: The Role Of Internal Variability, Mohammad Hasan Mahmoudi
Electronic Thesis and Dissertation Repository
Increases in the intensity and frequency of extreme events in Western North America (WNA) can cause significant socioeconomic problems and threaten existing infrastructure. In this study we analyze the impacts of climate change on hydroclimatic extremes and assess the role of internal variability over WNA, which collectively drain an area of about 1 million km2. We used gridded observations and downscaled precipitation, maximum and minimum temperature from seven General Circulation Models (GCMs) that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and a large ensemble of CanESM2 model simulations (CanESM2-LE; 50 members) for this analysis. Spatial …
Evaluating Restoration Success By Tracking The Structural And Functional Recovery Of Restored, Drained, And Intact Wetlands, Renee C. Howard
Evaluating Restoration Success By Tracking The Structural And Functional Recovery Of Restored, Drained, And Intact Wetlands, Renee C. Howard
Electronic Thesis and Dissertation Repository
Wetland restoration efforts have increased on the Canadian prairies to compensate for widespread loss of wetland area, form, and function. Restoration activity presumes a direct replacement for natural wetlands, where restored wetlands provide equivalent ecological functions and services. However, restoration projects often show limited recovery success in biological structure and biogeochemical function. Using plant functional traits is an emerging approach to assessing ecological process and may provide a better indicator of wetland functional recovery than vegetation structural indicators alone. Here, I tracked vegetation structural metrics (i.e., species richness, composition, and cover) and plant functional traits over a chronosequence of restored …
Optimal Algorithms For Deriving Estimates Of Phytoplankton Biomass In Lakes From Landsat Satellite Imagery, Michael A. Dallosch
Optimal Algorithms For Deriving Estimates Of Phytoplankton Biomass In Lakes From Landsat Satellite Imagery, Michael A. Dallosch
Electronic Thesis and Dissertation Repository
The frequency, intensity, and geographical distribution of harmful phytoplankton blooms are on the rise globally. There is a scientific need for estimates of historical and current phytoplankton data. This research develops mathematical algorithms for accurate assessment of surface chlorophyll-a (chl-a), a proxy for phytoplankton biomass, within freshwater lakes. Landsat satellite images (4-5 TM, 7 ETM and 8 OLI) were used to create predictive models (from 1984 to 2017) for seven ecoregions (ranging from the tropics to arctic). Correlation tests for 82 algorithms were conducted to establish the best fit models (linear, exponential, logarithmic, power) for chl-a …