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Climate change models for continental regions of North America include reduced growing season precipitation and a “repackaging” of rainfall into fewer but larger events. Water and nutrients (NPK) have individually been proven to be a limiting resource on plant growth and determinants of competition in many grassland systems, however their interacting effects remain relatively unknown. My study will examine the effects of water and nutrient availability alone, and their combined influences on above-ground biomass production and functional group composition which could provide fundamental insight into the functioning of a mesic temperate old field meadow in southeastern Ontario. Total and graminoid above-ground biomass was significantly higher in the reduced precipitation treatment compared to the added and ambient precipitation treatments, whereas legumes and other forbs had the highest above-ground biomass in the added precipitation treatment. Below-ground processes such as microbial activity and root systems may have been enhanced under rainout shelters for graminoids, compared to legumes which were possibly able to fix nitrogen more efficiently in added water plots. Rainout shelters acting as microclimates, such as by reducing wind speed, may have created ideal conditions for the point-frame method, which could explain the highest above-ground biomass in the reduced water treatment. Soil moisture was significantly lower in the reduced precipitation treatment compared to added and ambient precipitation treatments. Nutrient addition, as well as the interacting effects of water and nutrients insignificantly affected plant above-ground biomass production and composition. Therefore, nutrient addition may not be a major limiting factor to plant productivity or composition in this community, and water addition only seems to enhance legume and other forb productivity.

A number of lakes across North America are experiencing a shift from unicellular to colonial species of scaled chrysophytes, which in some cases, is creating water-quality issues. In this study, the timing and the rate of the shift from unicellular Mallomonas taxa to colonial Synura petersenii was assessed in two lakes in the Adirondacks, NY in order to identify potential driver(s) of this shift. Lakes which have been minimally impacted by local disturbances were chosen in order to assess regional stressors such as climate change and acid deposition in driving this shift. Eagles Nest Lake displayed a single shift from unicellular Mallomonas species to colonial S. petersenii which began in the early 1960’s and intensified in the 1980’s, while Copperas Pond displayed two abrupt shifts. The first shift in Copperas Pond was from unicellular Mallomonas to colonial S. curtispina prior to the 1900’s and the second was from S. curtispina to S. petersenii which occurred in the 1990’s. The pre-1990’s shift in Copperas Pond is unusual and warrants further investigation in order to determine if a regional or local driver is at play. The shift in Eagles Nest Lake in the 1980’s and the second shift in Copperas Pond in the 1990’s corresponded with the intensification of the rise in temperatures in the Adirondack region in the 1980’s. However, as multiple regional disturbances are occurring within same time period, it was difficult to completely isolate regional drivers of change. As a result, it is also possible that both recent climate changes and/or oligotrophication resulting from long-term acid deposition played a role in causing the shift towards S. petersenii dominance in the study lakes.

Microalgae biodiesel provides an alternative to crude oil extraction and petroleum diesel production. However, for efficient large scale algae based biodiesel production there needs to be an increased understanding of the enzymes involved in the glycerol metabolism and triacylglycerol (TAG) synthesis. This study focuses on understanding the role of GLYCEROL 3-PHOSPHATE DEHYDROGENASE (GPDH) in TAG synthesis and glycerol metabolism from the environmentally robust oleaginous microalgae species Chlorella vulgaris. Using the known GPDH sequences in other algal species, degenerate primers were designed for amplification of C. vulgaris GPDH. The amplified region was sequenced and new gene specific primers were designed for Rapid Amplification of cDNA Ends (RACE). The amplified region was sequenced and identified to contain the GPDH open reading frame (ORF) from C. vulgaris. The ORF was then ligated into the expression vector pET-30a(+) to determine if the identified ORF encoded for GPDH through heterologous expression and protein expression in E. coli. Additionally, the ORF was then ligated into the Chlamydomonas protein expression vector pChlamy_4 so future studies could transform Chlamydomonas reinhardtii to determine if GPDH expression increases the TAG yield and enabled glycerol metabolism through heterologous expression. Restriction digests reveal successful ligation of the GPDH ORF into pET-30a(+) and pChlamy_4. Western blot analysis using His6-Tag antibodies reveals production of heterologous GPDH in transformed E. coli. Identification of C. vulgaris GPDH allows future studies to determine its role in the TAG yield and extracellular glycerol metabolism to potentially develop transgenic strains for cost effective commercial application.

There has been consistent debate since the 1970s regarding what variables control community biomass in a natural plant community. Many hypotheses have arisen to explain these controllers, including the sampling effect hypothesis, which states that the biomass of an assemblage trends to increase with species richness because of the chance of containing larger, more productive species. However, the question whether the most productive species are large and less abundant or small and more abundant is still unknown. The “size advantage” hypothesis states that larger species are better competitors and in turn should be the main predictor of community biomass. Alternatively, the “reproductive economy advantage hypothesis” states that smaller species (not larger species) should be more successful because of their increased reproductive capabilities (they have a smaller minimum reproductive threshold size). My study aimed to explain the controls on community biomass on a between-plot and between-species level: is community biomass controlled by large, less abundant species (“size advantage” hypothesis) or smaller, more abundant species (“reproductive economy advantage” hypothesis)? My project’s results do not completely support the “size advantage” hypothesis, which opens a dialogue for alternative explanations and theories, one of which being the “reproductive economy advantage” hypothesis. The “reproductive economy advantage” hypothesis is supported in both of my between-plot and between-species levels of biomass measurement and analysis. These results and conclusions suggest that traditional theory stating that “bigger is better” needs further questioning and experimentation to prove its applicability.

Climate change is expected to have profound effects on species behaviour, persistence, and distributions. Amphibians are especially sensitive to environmental change as their biphasic lifestyles rely heavily on both aquatic and terrestrial habitats and degradation of either will compromise their persistence. Anurans use temperature as an important developmental and behavioural cue, and temperature changes in the spring trigger the initiation of mating calls in many temperate species. Not all anuran species respond similarly to temperature in changing climates, and not all populations within species will respond the same way. This high variability in behavioural responses has sparked interest in monitoring anuran call phenology through time. I examine how the onset of temperate anuran vocalizations in the spring have changed between 2009 and 2021 at three marshes in eastern Ontario. Automated recording data were used to collect information on local species present and the date of first calling and peak calling for each species as a proxy to estimate the initiation of the breeding season. Contrary to my predictions, the onset of anuran calling appears to have shifted later in the year with increasing ambient spring air temperatures. Local average spring air temperatures have risen by approximately 0.2℃ between 2000 and 2021, correlating with a shift of both the initiation of vocalization and peak calling activity in spring peepers (Pseudacris crucifer) to later in the season. Northern leopard frogs (Lithobates pipiens), wood frogs (Lithobates sylvaticus), and chorus frogs (Pseudacris sp.) are also trending towards later call times under increased spring temperatures. These shifts in spring-calling anuran phenology may result in increased competition for food resources and breeding sites if the breeding season overlaps with those of late-spring- or early-summer-calling anuran species, and may place additional developmental and predation pressures on offspring.

Lithium is used in the cathode and electrolyte of rechargeable batteries in many portable electronics and electric vehicles, and is thus seen as a critical component of modern technology (Gruber et al., 2011). Electric vehicles are promoted as a way to reduce carbon emissions associated with the transportation sector, which accounts for 14.3% of anthropogenic greenhouse gas emissions (OECD International Transport Forum, 2010). However, the sustainability of lithium procurement will influence the overall environmental impact of this proposed “green” solution. It is estimated that 66% of the world’s lithium resource is contained in natural brines, 24% in pegmatites, and 8% in sedimentary rocks such as hectorite clays (Gruber et al., 2011). It has been shown that “[r]ecycling of lithium from Li-ion batteries may be a critical factor in balancing the supply of lithium with future demand” (Gruber et al., 2011). In an attempt to quantify energy and materials consumption associated with production of a unit of useful lithium compounds, industry reports and peer-reviewed scientific literature concerning lithium mining and lithium recycling were reviewed and compared. Other aspects of sustainability, such as waste or by-products produced in the production of a unit of useful lithium, were also explored. Thus, this paper will serve to further the evaluation of the comparative environmental consequences associated with lithium production via extraction versus recycling. Efficiencies must be made in both processes to maximize productivity while minimizing ecological harm.

Energy production is a prominent issue facing society today, largely due to the highly unstable costs of fossil fuels, as well as the impact that the mining/transportation and consumption of these fuels has on the environment, including the contribution to increasing global atmospheric CO2 levels. Currently the use of microalgae as a platform for the production of biofuels is limited by high costs associated with harvest/lipid extraction, wasteful co-production, and a lack of understanding of these systems on a metabolic level necessary for engineering. Degenerate primers were designed to clone Chlorella Vulgaris’ GLYCEROL KINASE (GlyK) sequence. These primers were used to PCR Chlorella cDNA resulting in a product which when run on a 1% Agarose gel resulted in a band of the expected size for the region of GlyK being cloned. This region will be sequenced, and used to amplify the peripheral regions of the gene via a rapid amplification of cDNA ends cloning reaction. Once these regions are sequenced, the full gene can be cloned. This sequence will be used to transform Chlamydomonas reinhardtii, and changes in triacylglycerol (TAG) accumulation measured. The impact on glycerol consumption and TAG accumulation that the transformation has, will demonstrate the role of GlyK in lipid metabolism. The goal of this research is to develop a better understanding of TAG assembly metabolism in microalgae, so that highly efficient TAG accumulating strains can be developed for use in producing biodiesel.

Arctic regions around the world have been experiencing greater pressures from environmental disturbances. Rapid climate warming and increasing human encroachment due to intensified resource extraction activities pose considerable risks to sensitive Arctic ecosystems. Previous work has noted the significant impacts of calcareous road dust from gravel roads on surrounding vegetation and permafrost layers. In the Peel Plateau region, the Dempster Highway represents a potential source of road dust since its construction in the mid-1970s. At the same time, regional air temperature records indicate that the period of greatest warming began around ~1970. Due to an absence of historical data on these Sub-Arctic lakes, it is unclear what the extent of road dust impacts has been. This study aims to employ paleolimnological methods to examine road dust effects on the biota of lakes close to the highway, and to tease apart the potential role of concurrent regional warming. Sediment cores were collected from two impact lakes adjacent to the road (FM-2, FM-4) and one reference lake (FM-6) located at a distance that is outside the range of dust transport. Analyses of diatoms, chlorophyll-a and chrysophyte scales preserved in dated sediment cores revealed negligible impacts from road dust on the two impact lakes. Trends over the past ~100 years were more consistent with regional warming. The biological proxies from the reference lake exhibited a clear warming response consistent with increased thermal stratification. Further work may expand on this research by surveying a wider range of lakes in the region.

White sucker are a ubiquitous fish composing a high biomass in many North American lakes and rivers. However, how their movements in lakes are impacted by temperature has not yet been studied, with research on this specific species and how they are being impacted by warming waters has been severely lacking. Using novel telemetry data collected over multiple years in a boreal study lake, both horizontal and vertical movement were measured to predict how white sucker use the space throughout different water temperatures. Monthly data showed a significantly shallower depth during the months of May or June, likely for spawning, before moving back to deeper depths in the summer, and remaining at these depths during the winter months. White sucker did show seasonal patterns in spatial use: in the spring, white sucker would remain close to the edge of the lake, and would move towards the center of the lake during the summer in order to increase their depth. During the winter, white sucker would spend most of their time in a significantly smaller core area. These findings were reflected in swim speed trends, with winter showing a significantly less movement than in the spring or summer. Analyzing trends between years, white sucker did also move to significantly deeper depths during years where water temperatures are warmer, strengthening the idea that movements towards deeper waters during warmer times of the year is likely impacted by temperature. Depth preferences were also much more consistent between individuals during the spring and summer months, as these periods have a critical range of temperatures that white sucker prefer to remain within; however, individual depth preferences were significantly different in the winter, suggesting that these months have few factors which drive white sucker depth. This study shows that white sucker do base their horizontal and vertical movements in part on temperature differences in their environment, and suggests that white sucker will continue to occupy deeper waters as global temperatures increase.

The widespread recent expansion of deciduous shrubs across much of the Arctic has been attributed largely to climate warming. Increases in net shrub growth have the potential to create large-scale climate feedbacks, including enhanced CO2 release from Arctic soils (due to shrubs trapping snow and insulating soils over the winter). Understanding the intensity and distribution of Arctic shrub expansion is therefore necessary to predict future climate patterns. This study examines growth-rates of a deciduous shrub (Dwarf Birch, Betula glandulosa) at a central low Arctic site (Daring Lake, NWT). Direct measurements of shrub land-cover and stature in 2016 were compared with corresponding 2006 data for five representative birch habitat-types across the landscape. These growth-rates, as well as dendrochronologically-based annual growth-rates, were evaluated in relation to habitat-type environmental characteristics and 20-year climate data. Birch height, dimensions, and land-cover all increased 20-25% over the last decade, in all habitat-types. However, a lack of correlation between annual climate and annual secondary growth, limited warming at this site, and uniformity in growth-rates among habitat-types, together indicate that warming is not the driving factor. Instead, it is likely a release from herbivory following recent caribou herd declines driving shrub expansion at this site. Individual shrub growth was correlated to soil nutrient flux (particularly of ammonium), but the latter was highly variable within and across habitat-types, suggesting that fine-scale variability in nutrient supply is more important than habitat-scale variability in determining birch growth-rates following herbivory release. This observed net shrub growth indicates that caribou herd declines may be driving shrub expansion in lieu of strong warming in the Canadian central low Arctic.