RSS 1.0Brockport Environmental Science and Ecology Theses
Recent Submissions
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Great Lakes Lake Trout Thiamine Status and Influencing Factors in Lake OntarioChapter 1: Though stocking lake trout (Salvelinus namaycush) in the Great Lakes has found success in establishing some self-sustaining populations, a return of consistent natural recruitment of lake trout in Lakes Michigan, Erie and Ontario remains unachieved. A major impediment has been thiamine deficiency complex (TDC). Insufficient maternal deposition of thiamine (vitamin B1) into eggs during development is a major consequence of TDC and leads to mass mortality of fry prior to their first feeding. Monitoring of egg thiamine concentrations is a critical indicator for TDC impacts on lake trout populations. Since 2001, the USGS Great Lakes Science Center in cooperation with partner agencies has monitored egg thiamine concentrations in lake trout eggs throughout the Great Lakes region. Our analysis of the resulting dataset reinforces prior findings connecting the presence of alewife (Alosa pseudoharengus) in the diet with reduced egg thiamine concentrations. Relationships between total length of egg producing females and total egg thiamine concentrations of lake trout eggs in Lake Ontario suggest that a shift in diet from a round goby (Neogobius melanostomus) dominated diet, to an alewife dominated diet, results in lower total egg thiamine concentrations among larger lake trout. Long-term trends in lake trout egg thiamine concentrations are closely linked to changes in prey base composition. Following the crash of the alewife population in Lake Huron, lake trout egg thiamine concentrations increased considerably. Similarly, reductions in site specific alewife abundance preceded lake trout egg thiamine increases in Lake Michigan and may have helped to facilitate a recent trend of increasing natural recruitment. The introduction of alewife to Lake Champlain in 2004 lead to large declines in lake trout egg thiamine concentrations in the lake, but also appears to have facilitated natural recruitment of the same lake trout population. Egg thiamine concentration from Cayuga Lake lake trout increased following the 2013 introduction of round goby, presumably offering lake trout an alternative to alewife as prey, however, lake trout egg thiamine concentrations in Cayuga Lake have returned to pre-introduction concentrations. Chapter 2: The specific mechanism behind the induction of TDC by a diet rich in alewife is yet to be fully explained. The thiamine degrading enzyme thiaminase I is present in the visceral organs of alewife and represents the leading hypothesized cause of TDC. However, oxidative stress in the form of lipid peroxidation and the consumption of thiamine through its role as an antioxidant is thought to be the mechanism behind thiamine deficiency in Atlantic Salmon (Salmo salar) in Northern Europe. In this chapter we explored relationships among lake trout egg thiamine concentrations, belly flap fatty acid compositions and concentrations of the primary lipid peroxidation disrupting antioxidant, α-tocopherol (vitamin E), in lake trout livers and eggs. α-tocopherol concentrations in lake trout eggs appeared to be driven by diet and have a negative relationship with length in both Lake Ontario and Lake Superior. Egg and liver α-tocopherol concentrations did not appear to have a direct impact on egg thiamine concentrations. Integrating recent findings on the roles of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in cellular antioxidant defense activation into a calculation of peroxidation potential, led to an improved negative relationship between belly flap unsaturation index and lake trout egg thiamine concentrations, potentially implicating lipid peroxidation as a source of thiamine consumption.
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Assessing how invasive cattail treatment affects methane emissions in Lake Ontario meadow marshesWetlands sequester carbon and buffer extreme weather events; however, they are also the largest natural source of methane, a potent greenhouse gas (GHG). We assessed the effects of invasive cattail (Typha spp.) removal on methane emissions and carbon storage at the Braddock Bay Wildlife Management Area on the southern coast of Lake Ontario. We measured methane fluxes in two restored marshes and an uninvaded meadow marsh using a backpack cavity ring-down analyzer, logged belowground environmental conditions to model methane fluxes over time, and estimated carbon storage of the different sites. In 2019, data were collected during a record high flood event in Lake Ontario, and we did not find a significant difference in methane fluxes among the control, treatment, and uninvaded areas. However, under lower water conditions in 2020, the cattail monoculture (control) emitted more methane than areas with cattail removal with replanting, and the uninvaded wet meadow had the lowest average flux during the growing season. Soil moisture (and water levels) decreased over the growing season, while temperatures and biomass increased. Areas where cattail had invaded (whether removed or not) had greater percent soil organic carbon than the uninvaded meadow marsh. The control sites had greater carbon stored aboveground than replanted sites. Our results indicate that methane emissions may be mitigated through plant community restoration; however, ensuring that the native plant community establishes will be important to long-term carbon sequestration. In addition, a mesocosm experiment was conducted to investigate methane emissions when substrate and plant community were manipulated. The experiment included six treatments with two different substrate types and three plant community types. The two substrate types were the top five cm from cattail monocultures, “cattail substrate”, and the next layer below the layer of organic matter, “topsoil removed substrate”. There were three levels of planting treatments: no plants, cattail (Typha x glauca), and native grass, Calamagrostis canadensis. The findings indicated that mesocosms with the topsoil removed had significantly lower methane emissions than those with topsoil. Moreover, no significant differences in emissions were observed between Canada bluejoint (Calamagrostis canadensis) and Typha x glauca. However, it is important to note that this was a limited experiment, and more data is required for comprehensive analysis. Our results show that substrate type appears to be a more important factor contributing to methane emissions than plant identity.
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Quantifying Waterfowl Use and Habitat Characteristics Following Wetland Restoration in Lake Ontario Coastal Wetlands at Braddock Bay Wildlife ManagementThe coastal wetlands of Braddock Bay Wildlife Management Area (WMA) on the southern coast of Lake Ontario provide migratory spring-stopover habitat that is important for a variety of pre-breeding season waterfowl. Cattail (Typha sp.) invasion can degrade these spring-stopover wetlands, and directly decrease the amount of open-water interspersion within a wetland. One of the targets of restoration is to increase the amount of open-water area interspersed within marshes to improve waterfowl habitat. This study aimed to assess the effects that dredging various size and shape ponds within a cattail marsh has on the abundance, diversity, and composition of waterfowl within Braddock Bay WMA during late winter into spring. We used a combination of point-count and trail camera surveys to estimate spring waterfowl abundance and composition of dredged ponds, undredged, natural ponds, and large open-water areas occurring throughout the Braddock Bay WMA. We also assessed differences in vegetation, invertebrates, and physical habitat characteristics among the different habitat types of Braddock Bay WMA. We found that waterfowl area-corrected cumulative use days, species, richness, and species diversity were similar or greater in dredged ponds than natural ponds. We also found that vegetation species richness, percentage vegetated, invertebrate order richness, and invertebrate abundance/cubic meter within dredged ponds was similar or greater than natural ponds in Braddock Bay WMA, in each year of sampling. These findings suggest that dredging treatments to increase interspersion within Braddock Bay WMA provide additional open-water habitat that offers comparable food and cover resources supports similar waterfowl diversity, richness, and use to pre-existing natural ponds. We found that shoreline development index and interspersion were significant explanatory variables for predicting square root transformed waterfowl cumulative use days per hectare for dredged and natural ponds. Using trail cameras proved to be an efficient, non-nonintrusive method for the long-term monitoring of waterfowl in areas that were inaccessible to point-count surveys. Trail camera data provide an estimate of waterfowl use and diversity within the dredged and natural ponds of Braddock Bay WMA. The multivariate relationships we found between wetland habitat characteristics and waterfowl use and diversity can be used to help influence future wetland restoration and waterfowl management efforts within Braddock Bay WMA and other coastal wetlands throughout the Great Lakes region.
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Joining interdisciplinary modeling and field-based methods to document riparian forests in eastern New YorkRiparian floodplain forests persist in a small fraction of their historical extent in the United States with estimated cumulative losses as high as 95% for some regions. Many remaining occurrences are also degraded due to changes to local flood dynamics, disturbance pressure from adjacent land use, and exotic species invasions. Yet these communities are disproportionally valuable for the area they occupy as they provide vital ecosystem services such as flood mitigation, erosion control, runoff interception, and wildlife habitat. To strengthen their protection and management, we present a novel approach for identifying riparian forests in eastern New York using low-complexity flood modeling and land cover analysis. We enlisted the Height Above Nearest Drainage method to compute ten-year floodplains for rivers and streams in the Mohawk River Watershed of eastern New York. We then extracted the forested portions of these floodplains using the National Land Cover Dataset Tree Canopy Cover. This process produced approximately 21,500 acres of predicted riparian forest spread across 1,063 occurrences. Our field verification surveys took us to 17 modeled locations where we successfully captured examples of riparian forests at 76% of sites and correctly predicted overbank flood occurrence, though not necessarily extent, at 88%. Our model also outperformed several other publicly available datasets in remotely identifying floodplains illustrating that this method shows promise for identifying community occurrences unrepresented in other datasets. In the field, we documented a diverse set of riparian forests with varied ecological condition and species composition. Our cluster analysis produced three compositional groups adding weight to ongoing efforts to formally recognize distinct riparian forest types in the Northeast. As predicted, our disturbance metrics were negatively correlated with floristic quality and percent native species. Yet contrary to our hypothesis, larger model occurrences typically had lower floristic quality and higher disturbance scores though this was the result of overestimated polygon extent in heavily modified areas rather than a true phenomenon. Our results demonstrate the power of blending remote and field methods while presenting an approach for the rapid and inexpensive identification of some of our most valuable and threatened natural communities.
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Assessing diets of California salmonines using fatty acid signatures and its impact on observed thiamine deficiencyCalifornia Central Valley (CCV) Chinook Salmon (Oncorhynchus tshawytscha) hatchery fry were diagnosed with thiamine (vitamin B1) deficiency complex (TDC) in 2020, launching a statewide monitoring program to evaluate egg thiamine concentrations in populations of Chinook Salmon, Coho Salmon (O. kisutch), and Steelhead Trout (O. mykiss). There have been two proposed hypotheses for the drivers of thiamine deficiency: consumption of prey with increased thiaminase activity or with a high lipid content. Limited Chinook Salmon stomach content analysis showed a dominance of Northern Anchovy, a prey species with high thiaminase activity and a high lipid content, preceding the observation of thiamine deficiency. Therefore, the objective of this research was to identify the diet of Chinook Salmon, Coho Salmon, and Steelhead Trout using fatty acid signature (FAS) analysis and link their diet to the observed TDC. From 2020-2022, eggs from female Chinook Salmon, Coho Salmon, and Steelhead Trout were collected from CCV and northern California (NC) hatcheries. Main historical salmonine forage species were also collected from the Pacific Ocean. Fatty acid signatures and thiamine concentrations were quantified from eggs and prey using gas chromatography/mass spectrometry and high performance liquid chromatography, respectively. Chinook Salmon egg FASs differed significantly between CCV and NC populations suggesting NC Chinook Salmon were predominantly reliant on Pacific Herring, characterized by greater proportions of oleic acid (18:1n-9) and greater thiamine reserves. However, CCV Chinook Salmon populations appeared to consume mostly Northern Anchovy, characterized by high proportions of eicosapentaenoic acid (20:5n-3) and decreased thiamine reserves. Chinook Salmon egg FASs were also significantly different among seasonal run (fall, late fall, winter, and spring), with the winter-run and late fall-run Chinook Salmon being the most impacted by thiamine deficiency. Coho Salmon eggs from NC hatcheries had variable FASs; those indicative of Northern Anchovy consumption were thiamine deficient, while those indicative of a larger reliance on Pacific Herring had greater thiamine reserves. Steelhead Trout egg FASs presented variation among hatcheries; Trinity River Hatchery eggs were mostly rich in 18:1n-9 indicating Pacific Herring in the diet and Nimbus River Hatchery eggs were rich in 22:6n-3 which indicated consumption of Market Squid. Steelhead Trout eggs collected from Mokelumne River, Feather River, and Coleman National Fish hatcheries were generally rich in 20:5n-3 which corresponds to a diet of Northern Anchovy. Interestingly, Nimbus Steelhead Trout eggs had the greatest presence of thiamine deficiency, followed by eggs rich in 20:5n-3. Egg lipid content was not strongly correlated with decreased thiamine concentrations, but polyunsaturated fatty acid proportions were. The egg unsaturation index had a strong negative correlation with egg thiamine concentration, indicating the importance of lipid quality over quantity when considering drivers of TDC. This study highlights how FASs can be used to track the effect of changing ocean regimes on complex food webs and how diet shifts can impact salmonine health.
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Traits and control of invasive mile-a-minute (Persicaria perfoliata) in western New YorkInvasive and nuisance species are recognized as a major threat to natural ecosystems and a leading threat to biodiversity. Mile-a-minute, Persicaria perfoliata, is an invasive species in North America and is native to Asia and the Philippines. It was introduced in the United States in the late 1800s and has become a serious invasive species in the eastern United States. Herbicides, biological control, and mechanical control methods have been effective for controlling mile-a-minute, but their relative efficacy is not known. I evaluated herbicide, mechanical and combined treatments for mile-a-minute over three years at two sites. All methods were effective at reducing mile-a-minute percent cover. Treatment type affected mile-a-minute percent cover in the first year of my study, when the mechanical-only treatment was less effective than herbicide treatments at the first resample. However, there were no significant differences among treatments in the second or third year of the project. My results indicate that mechanical, herbicide, or combined treatments can effectively manage mile-a-minute. However, because germination continues through October revisits are needed after initial treatment applications regardless of methods chosen. I also found that there was inter-year variability in the phenology of mile-a-minute and was an important indicator that control methods need to be applied before flowering occurs. To further evaluate how phenology and plant phenotypes vary among mile-a-minute populations, I conducted a greenhouse experiment. I grew mile-a-minute plants from seeds of regional and local populations under varying environmental conditions. I observed that mile-a-minute grew faster, larger, and was phenologically 2 advanced under warmer, wetter, and sunnier conditions. However, mile-a-minute survival and growth was still high under low resource conditions, and plants in low resource conditions began to reproduce by the eighth week of the experiment. Seed source was a significant predictor of growth and plant traits, indicating genetic differences among populations and among seed collection times. Surprisingly, differences among seed sources from the same populations collected at different times were similar to differences among populations. Mile-a-minute is primed to continue invading many habitats given its phenotypic plasticity and trait diversity produced by sexual reproduction. Although typically found in sunny, high light edge environments, mile-a-minute grows well in many environmental conditions, which means it can continue to spread to new environments. Since mile-a-minute can survive in low resource environments, land managers must survey deep into forests near infestations for plants as they may potentially seed.
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Evaluating annual recruitment of sea duck populations in the Atlantic Flyway using harvest and photo survey juvenile proportionsChapter 1: Sea duck (tribe mergini) populations in the Atlantic Flyway have experienced significant declines in recent years, though underlying causes are poorly understood. Information on population demographic parameters may provide insight for wildlife managers seeking to maintain sustainable harvest. However, population monitoring capacity for sea ducks is limited relative to other migratory bird species due to their remote breeding distribution. The U.S. Fish and Wildlife Service organizes a Parts Collection Survey (PCS) which estimates recruitment in sea duck populations using age ratios (juveniles/adult), though estimates are biased due to differential harvest vulnerability between age-cohorts. I used a direct-count photo survey to calculate improved estimates of annual recruitment for long-tailed duck, black scoter, surf scoter, and white-winged scoter (hereafter sea ducks) populations in the Atlantic Flyway. I and other surveyors collected photos of flighted sea ducks from shore and by boat in 11 states from October 15-December 15 annually in 2019-2022. We classified photographed birds according to age and sex and calculated juvenile proportions of each species using a Bayesian binomial model. To compare photo survey estimates with PCS estimates, I used a paired t-test organized by year. I found that PCS estimates of juvenile proportions were significantly greater than photo survey estimates for three sea duck species, indicating a consistent positive bias in PCS driven by harvest vulnerability. I also derived novel estimates of juvenile harvest vulnerability using the mean difference between within-year estimates. My work demonstrated the photo survey methodology used in this study produced reliable and precise annual recruitment estimates for four poorly monitored waterfowl populations; I recommend managers continue to adopt this approach in future years with additional consideration given for spatial representation and refinement of image classification procedures for long-tailed duck estimates. Chapter 2: Components of breeding productivity and survival rates in avian populations respond to dynamic environmental stressors across the annual cycle, which therein shape population dynamics over time. In sea ducks (tribe mergini), few studies have characterized the ecological factors that drive annual recruitment trends at the population level over time due to scarce scalable population information. Here, I leveraged historic harvest survey recruitment estimates (juvenile proportions) and indicators of environmental conditions at breeding, staging, and wintering areas from 1980-2017 to investigate factors influencing annual recruitment rates in eastern North American populations of long-tailed ducks (Clangula hyemalis), black scoters (Melanitta americana), white-winged scoters (M. delgandi) and surf scoters (M. perspicilatta). Recruitment rates in multiple species were positively associated with mean ambient temperatures at staging and breeding areas during spring. This supported my hypothesis that pre-nesting ice cover in key habitats limits breeding productivity by delaying breeding phenology and causing declines in female body condition. Surf scoter recruitment had a strong negative association with great gray owl irruptive migrations, suggesting surf scoters experience intensified predation pressure during low phases of vole population cycles and incur lower nest and brood survival rates. North Atlantic Oscillation patterns and staging area mean ambient temperatures in autumn showed associations with sea duck recruitment, suggesting harsh weather conditions post-fledging may precipitate early migratory movements that reduce juvenile survival rates or elicit greater proportions of adult sea ducks in subsequent harvests. My findings highlight important relationships between sea duck annual recruitment and ecological factors that may have considerable consequences for sea duck populations as ecosystems and climatic patterns undergo significant changes in the future.
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Assessing floating treatment wetland effects on water quality at two scales and their potential to restore meadow marsh habitatsFreshwater wetlands are important ecological habitats that are often degraded by water quality issues from runoff events. Floating treatment wetlands (FTWs) can be an effective method to reduce and retain excess phosphorus in watersheds through plant and microbial uptake. This study aims to support the literature on FTWs and fill gaps in knowledge by testing specific plant and substrate treatments on phosphorus reduction and investigating the sustainability of FTWs. I examined changes in phosphorus concentrations in mesocosms and retention ponds using wetland plant species native to northeastern North America: Carex stricta (tussock sedge), Iris versicolor (northern blue flag), Juncus effusus (common rush), and Eleocharis palustris (common spikerush), as well as with coconut coir substrate and no substrate. Plant combinations of the FTWs included tussock species (tussock sedge/northern blue flag), reed species (common rush/common spikerush), and a mixture of reed and tussock species. I measured the percent change in concentrations for total phosphorus (TP), orthophosphate, chlorophyll-a, dissolved oxygen, specific conductivity, and pH. I also looked at extending FTW lifecycles by investigating overwintering and establishment success of FTW plants for reuse in future projects. The mesocosm study was conducted as two separate experiments during the 2020 and 2021 summer field seasons. The 2020 mesocosm study investigated changes in phosphorus and water quality metrics between soaked coconut coir substrate and no-substrate FTWs, as well as between no-substrate planted FTWs and unplanted controls. I found that FTWs with coconut coir substrate had significantly greater orthophosphate reduction than FTWs with no substrate, but no significant differences in phosphorus reduction between no-substrate plant treatments and controls. The 2021 mesocosm study investigated changes in phosphorus and water quality metrics between FTW functional groups with unsoaked coconut coir substrate. I saw an increase in TP and orthophosphate concentrations, and no significant differences between the plant treatments due to phosphorus leaching from the unsoaked coconut coir substrate. For the retention pond study, I did not find any significant differences in changes in phosphorus concentrations between FTW plant treatment ponds and FTW control ponds due to the low FTW coverage ratio and sample size. During the establishment study, I found that tussock species were most effective in overwintering and establishment, while reed species had the greatest number of flowering individuals when planted in soil following the end of the experiment. The findings suggest that FTW studies and applications should use coconut coir substrate since it significantly reduced orthophosphate in mesocosms and improved overall growth of plants, though researchers should be sure to flush out any phosphorus that may leach from the coir. Floating treatment wetland applications can also use any native wetland plant species since no real differences were found in TP or orthophosphate concentrations between reed species, tussock species, or mixtures. Any FTW study conducted on larger scales should be sure to have FTW coverage ratios of at least 5% or greater to see any contribution of FTW plants to changes in phosphorus concentrations or impact on water quality metrics. Lastly, it is encouraged that any FTW study or application take into consideration the sustainability of the FTWs, and reuse plants for future applications or for wetland restoration efforts.
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Movement and life history diversity of Yellow Perch (Perca flavescens) between Lake Ontario and two barrier beach wetlands in the Braddock Bay Wildlife Management AreaYellow Perch (Perca flavescens) utilize both nearshore and coastal wetland habitats of the Laurentian Great Lakes during their lifetime and are known to exhibit different movement life histories. However, uncertainty persists in quantifying variability in the duration of habitat use and whether such variation manifests as morphometric differences depending on the degree of nearshore use. To explore these uncertainties, I used a multi-metric approach that included water and otolith microchemistry, tissue stable isotopes (𝛿15N, 𝛿13C), and body morphometric analysis. Manganese was useful for identifying movements between wetland and lake habitats while carbon and nitrogen tissue isotopes revealed variable duration of wetland use related to ontogeny. Morphometrically, Yellow Perch caught in Lake Ontario had smaller features relative to wetland caught Yellow Perch. My research suggests that otolith microchemistry is a useful tool for describing habitat transitions of Yellow Perch between these two habitat types. Tissue stable isotopes indicate that some Yellow Perch spend more time in coastal wetland habitats than others, which may influence their susceptibility to recreational harvest. Body morphometrics appear to reflect either use of more open habitats (e.g., Lake Ontario), or use of more complex habitats (e.g., coastal wetland).
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Flight call response and energetics: two case studies analyzing migratory biology in select passerines on the south shore of Lake OntarioPasserine migration is an energy-intensive behavior that occurs during spring and autumn, often between distant breeding and wintering grounds. Stopover sites provide places to rest and refuel. This two-part collaborative thesis studied extrinsic and intrinsic factors that affected the behavior and energetics of migratory passerines that visited Braddock Bay Bird Observatory (BBBO), located on the south shore of Lake Ontario. First, we compared the conspecific flight-call response of 2 parulid species captured spring 2018 and 2019 during the day and at dusk. Responsiveness was much lower at dusk, which suggests flight-call communication is likely not an important feature of dusk departure in parulids. Second, we constructed seasonal path models using BBBO bird banding data from 1999-2016 to examine the impacts of extrinsic (i.e., capture date and hour captured) and intrinsic (i.e., age and sex) factors on the energetic condition of 3 Catharus thrushes. Capture date was the most important predictor of condition followed by age and hour, except when sex was included in our models. However, analyses of sex were limited (and potentially inflated) because we could only determine the sex of the largest and smallest individuals in one species, the Swainson’s Thrush (C. ustulatus). Both studies showed that extrinsic and intrinsic factors have important implications on passerine migration behavior and physiology and that migratory behavior is complex and worthy of additional investigation.
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The potential use of filamentous bacterial growth on stream macroinvertebrates as an indicator of nutrient enrichmentThe influence of environmental stressors, such as nutrient enrichment and physical habitat degradation, can lead to a loss of biological integrity in streams. Nutrient enrichment in streams is a major concern in agriculturally dominated watersheds as fertilizers and animal waste runoff contaminate and pollute these systems through non-point source means. The impacts of nutrient enrichment on stream health requires further attention as well as the methods used to determine the source of contamination. One of the notable effects of nutrient addition in streams is the increased growth of aquatic, filamentous bacteria such as Sphaerotilus and Leptothrix. These bacteria have been known to colonize and grow on aquatic insects in nutrient enriched streams, and cases of high coverage on the insect have been found to be fatal. This study aims to analyze the differences in stream macroinvertebrate communities by looking at community composition, diversity, taxa richness, and biomass in nutrient enriched and non-enriched streams as well as evaluating the growth of filamentous bacteria on macroinvertebrates and its potential use as a bioindicator for nutrient pollution that is beyond extreme levels. Seasonal field measurements were taken of macroinvertebrate abundances, nutrient concentrations, and degree of bacterial growth on insects in six streams located in Western New York that were categorized as nutrient enriched or not based on nitrogen and phosphorus concentrations. Using non-metric multi-dimensional scaling (NMDS), analysis of similarities (ANOSIM), and similarity percentages (SIMPER), macroinvertebrate abundances in the enriched streams were compared to the non-enriched streams. The enriched and non-enriched streams were found to have significantly different macroinvertebrate communities, where the enriched streams had an abundance of pollution- tolerant organisms such as oligochaetes and leeches, while the nonenriched streams were mainly composed of pollution-sensitive insect species, and the non- Edwards 2 enriched streams were also significantly more diverse and had higher family richness. While the biological data indicate significant differences in stream integrity between the enriched and the non-enriched sites, bacterial growth and coverage did not follow similar expectations. There was no difference in the presence of bacteria between the enriched and non-enriched sites and the percentage of colonization was not greater in the enriched sites. Based on the data in this study, the use of filamentous bacteria growth on aquatic macroinvertebrates as a rapid bioindicator for nutrient enrichment in streams should be re-evaluated as nutrient levels in streams may not be the only contributing factor for bacterial growth to occur, and interpretation may not be broadly valid compared with traditional monitoring techniques
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Abundance and composition of microplastics in surface waters and sediments of five south-central Lake Ontario tributariesMore than 10,000 metric tons of plastic enter the Great Lakes every year. Most of this is microplastic, tiny plastic particles less than five millimeters in length or diameter. Microplastic pollution is a growing environmental concern in the Great Lakes where these particles can affect aquatic life as well as humans if ingested. To better understand potential sources of microplastics in Lake Ontario, we surveyed microplastic concentration in five tributaries within the south-central Lake Ontario basin in both surface waters and sediments. We analyzed the microplastic morphologies and polymer types and compared the results to three sites in nearshore south-central Lake Ontario. Tributaries surface samples had significantly higher microplastic concentrations (4.9 microplastics/m³) compared to lake sites (1.3 microplastics/m³). Tributary sediments had an average concentration of 0.16 microplastics/g dry weight. Fibers were the most common particle morphologies in tributary surface waters (49%) and sediments (52%) while fragments were the most common morphology found in lake surface waters (73%). These morphologies are harder for aquatic life to pass if ingested and are more likely to remain in the gut, leading to potential health issues and bioaccumulation in the food web. Polyethylene (recycling types two and four) and Other polymers (recycling type 7) accounted for over 90% of microplastics captured. Tributaries are important sources of microplastic pollution in south-central Lake Ontario and should be included in plastic prevention strategies. Furthermore, knowing the most prevalent morphologies and polymers may help to pinpoint sources of plastic and contribute to targeted prevention
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Factors influencing thiamin concentrations in lake troutFirstly, I would like to thank my major advisor Dr. Jacques Rinchard, for his dedication, time and commitment to his students. He has pushed me both academically and intellectually to become a better version of myself. Next, I would like to thank the rest of my graduate committee Drs. Brian Lantry, Donald Tillitt, and Matthew Altenritter who contributed to the conceptualization and execution of this thesis. Special thanks to the dedicated professionals at the United States Geological Survey - Lake Ontario Biological Station including Dr. Brian Weidel and Scott Minikiem, Dr. Michael Connerton from the New York State Department of Environmental Conservation, all those who assisted with annual lake trout and prey fish surveys, and finally to the staff at the Allegheny National Fish Hatchery for providing lake trout on short notice. This work would not be possible without their hard work and perseverance. The undergraduate laboratory assistants in Dr. Rinchard’s lab, including Jarrod Ludwig and Lillian Denecke deserved recognition for their dependability and diligence in assisting with laboratory work. Finally, financial assistance was provided by the Brockport Distinguished Professor Award, the Department of Environmental Science and Ecology, and the Great Lakes Research Consortium. On a personal note, I would like to thank my friends Kylee Wilson, Kyle Morton and the rest of the Altenritter’s lab for providing substantial moral support, thoughtful conversations and fond memories that made my time at Brockport special. Lastly, I would like to thank my parents Kim and Chris Heisey for the sacrifices they ii made to make my educational journey a reality. Their love and support made this thesis possible and for that I have immense gratitude.
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Effects of an exotic invasive plant and microtopography on terrestrial salamander populationsPlant invasions can have strong, negative effects on some amphibians and represent a substantial challenge to conserving native biodiversity. However, invasive plant species do not always impose an immediate threat to amphibian populations and in some cases may facilitate increased abundance and provide additional habitat. The objective of my study was to determine how habitats invaded with pale swallowwort (Vincetoxicum rossicum) affected Plethodon cinereus and P. glutinosus salamander populations, their forest floor microclimate, and prey availability, and to determine if these parameters differed across a microtopographic gradient. I focused on these two plethodontid species because they were the most abundant within my study area at Oatka Creek County Park in Wheatland, New York during 2019 and 2020, and their many important roles within forested ecosystems have been widely studied. Plethodon glutinosus relative abundance peaked early during late summer 2019, while P. cinereus peaked during early fall. In 2020 P. cinereus relative abundance peaked in early April and late August, while P. glutinosus peaked in late summer. Peaks in the surface activity of both species corresponded to their documented life history patterns. P. cinereus relative abundance was significantly higher in uninvaded habitat during 2019 but did not differ between habitat types in 2020. There was no difference in P. glutinosus abundance between habitat types in either year. Plethodon cinereus relative abundance was highest in uphill topography types during both years, but P. glutinosus differed only during 2019. Generalized linear models predicting relative abundance showed positive relationships with the presence of the other Plethodon species, leaf litter depth, relative humidity, soil moisture, swallowwort cover, and arthropod abundance. There was also a negative relationship with temperature. Topography was an important factor in predicting relative salamander abundance, with more of an effect on P. cinereus relative to P. glutinosus, which may result from differences in microhabitat preference and morphology. Patterns in relative salamander abundance and distribution, as well as variation in abiotic parameters may be related to indirect effects of plant cover and microtopography. Ultimately, my findings suggest that swallowwort invasion does not directly and negatively impact P. cinereus and P. glutinosus and instead, may provide favorable microclimate and habitat features during periods of extreme weather, especially as dry spells and elevated temperatures become increasingly prevalent.
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An investigation into the presence of slender false brome (Brachypodium sylvaticum) and its relationship with plant communities in New York StateGlobalization has led to an increased frequency of biological introductions. These introductions have the potential to progress into invasions that negatively impact the recipient communities. However, not all species may have large impacts on native species or community assembly patterns. By understanding where invaders are likely to establish and their impacts, we can better allocate resources for early detection and rapid response to prevent future invasion. Brachypodium sylvaticum is an invasive grass in North America that is native to Eurasia and North Africa. First introduced in the Pacific Northwest, it has since made its way to the East Coast and western New York. As a relatively new invader, little is known about its environmental preferences, potential impact on communities, and its competitive ability. My study investigated these questions. In the first portion of my study I conducted vegetation surveys and environmental measurements in eight invaded and three uninvaded communities that varied in B. sylvaticum population size, environmental conditions, and forest types. As predicted, I found that water content and canopy cover determined B. sylvaticum abundance. It preferred drier soils within wetter sites, and wetter soil within drier sites. Contrary to my expectations, I found that B. sylvaticum abundance was not dependent on canopy type. Brachypodium is associated with lower species richness, which provides evidence that the invader is negatively impacting communities. However, impacts on recipient communities are limited to changes in richness as I did not find significant difference in community structure or assembly patterns between invaded and uninvaded quadrats. In the second portion of my study, I conducted a greenhouse competition experiment in which I selected species from my co-occurrence analyses to grow in competition with B. sylvaticum. I found that B. sylvaticum is not a strong competitor against another exotic grass Combined, my studies indicate that B. sylvaticum may not be a strong competitor on the east coast and may instead be a passenger of already degraded communities.
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Acoustic telemetry data characterizes movement behaviors of yearling and sub-adult Lake Sturgeon (Acipenser fulvescens) within the Genesee River, NYIn the Laurentian Great Lakes basin, Lake Sturgeon (Acipenser fulvescens) populations were decimated by the turn of the 20th century, but in some areas are beginning to rebound after decades of ongoing rehabilitation efforts. In the Genesee River of Lake Ontario, hatchery-raised Lake Sturgeon have been stocked in hopes of re-establishing a healthy and self-sustaining population. To understand the efficacy of these efforts and to build an understanding of how these stocked individuals use the Genesee River and Lake Ontario habitats, ninety-nine juvenile lake sturgeon (30 sub-adults, 69 yearlings) were tagged with acoustic transmitters and tracked for approximately two years. Water quality parameters were monitored with the combined use of a USGS stream gauge and passive dissolved oxygen monitors. A multi-state model created to estimate survival and transitions from the Genesee River to Lake Ontario revealed that sub-adults had higher survival rate compared to yearlings. Yearling survival estimates were higher than previously estimated with capture-mark-recapture techniques, likely a result of being able to account for emigration. Sub-adults used both lake and river habitats more than yearlings, although both life stages frequently utilized both habitats. Seven sub-adults made large scale migrations (>100km) to either the Lower Niagara River or the St. Lawrence River. Hypoxic conditions that relate to discharge formed during the summer months within the Genesee River and appeared to limit Lake Sturgeon movements. The use of and survival in the Genesee River indicates that stocked juvenile Lake Sturgeon are using it as a nursery habitat. This has important implications when considering the efficacy of this management approach with implications for supplementing population abundance, understanding habitat use, and directing management efforts. Patterns of large-scale movements and nearshore habitat use exhibited by sub-adults should continue to be monitored as they could prove to influence vital rates (i.e., survival, recruitment, growth) and inform the degree of connectivity among populations throughout the Lake Ontario basin.
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The effects of invasive slender false-brome (Brachypodium sylvaticum) on forest ecosystem function in western New YorkThe interconnectedness of the modern world has led to the spread of species outside of their normal range. Some species become invasive and can impact ecosystems by changing soil, water, and nutrient dynamics. Disrupting these important ecosystem processes can facilitate further invasion. Slender false-brome (Brachypodium sylvaticum) is an exotic bunchgrass that is invasive in North America. Its encroachment into forest understories may have implications for ecosystem processes and characteristics. The goal of this study was to understand the impacts of slender false-brome on forest ecosystem function. This study took place within two forests in western New York, one at Taughannock Falls State Park (TFSP), Trumansburg, and one in Danby State Forest (DSF), Danby. Replicate paired plots with and without B. sylvaticum were selected in each forest; each pair was matched by canopy cover and canopy type. In plots I measured vegetation, soil physical and chemical characteristics, soil moisture, soil respiration, and decomposition of leaf litter. I used generalized linear mixed models to determine variables that were the strongest predictors of soil nutrients, soil respiration, and leaf litter decomposition. All soil characteristics measured were significantly different between invaded and uninvaded plots except bulk density. At TFSP, invaded plots were enriched with organic matter (OM) and total nitrogen (TN). At DSF, invaded plots were enriched with phosphorus (P). Invaded plots at both sites had greater cation (Mg, Ca, K) concentrations, pH, and bulk density, and soil respiration and decomposition rates also increased in response to B. sylvaticum invasion. My results demonstrate that Brachypodium sylvaticum invasion significantly alters ecosystem processes, although initial site conditions do affect the magnitude and trend of some changes. Overall, B. sylvaticum has impacts on ecosystem processes like other flagship invasive species, however the impacts seem to change based on initial site conditions. I found that sites like Danby State Forest and Taughannock Falls State Park are at risk of changes in soil nutrients, soil respiration, and decomposition. A greater diversity of sites needs to be investigated to determine if other types of ecosystems are at risk from Brachypodium sylvaticum.
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Effective control methods and the genetic and phenetic differences of European dewberry (Rubus caesius) among locations in the Finger Lakes Region of New YorkThe colonization of invasive species is rapidly increasing due to human travel, trade, and disturbance. An area of focus in invasive species control efforts is in riparian zones, which are often highly invaded and disturbed systems. Rubus caesius (European dewberry) is a nonnative invasive woody shrub that has recently been observed to grow densely and spread through riparian ecosystems in western New York. Multiple locations have been noted, but it is not clear if all locations of Rubus caseius are correctly identified, as morphological and reproductive characteristics vary among them. Rubus caeisus is a relatively understudied invasive plant and it is not known how R. caesius is dispersing or how to effectively control extant locations. To understand the dispersal mechanisms of R. caesius I conducted a greenhouse cutting experiment and quantified the fruiting characteristics among six locations across western New York. I found that R. caesius is capable of reproducing via fragmentation regardless of source location, while only some locations produce large numbers of seeds. I investigated location differences through vegetative morphometrics and microsatellite fragment analysis. I found that all locations are identified correctly as R. caesius but there is some evidence for differentiation among the locations. Contrary to my expectations the most similar locations are not always the closest geographically. To evaluate effective control measures, I conducted a control experiment in a randomized block design at one located at Ganondagan State Historic Site in Victor, NY. I compared mechanical and herbicide treatments in different combinations of frequency, control method, and herbicide type. Treatments using chemicals were most effective in reducing the cover of R. caesius across a variety of environmental conditions. I also provide tentative evidence that repeated mechanical treatments are effective in reducing the cover of R. caesius. My determination of potential dispersal mechanisms and effective control methods will be useful for land managers as management strategies may need to differ based on reproductive traits among locations.
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Post-implementation re-assessment of agricultural best management practices on watersheds of Conesus Lake: Effects on stream water chemistry and aquatic macroinvertebrate communitiesNutrient pollution is the third largest source of impairment of water quality in rivers and second largest in lakes in the US according to the Environmental Protection Agency (EPA). Agricultural best management practices (BMPs) are intended to improve water quality, reduce sediment and nutrient runoff, and remediate the effects of altered hydrology. BMPs were installed in the early 2000s in the Conesus Lake watershed and have shown initial success in reducing nutrient runoff in agricultural watersheds; however, continued monitoring of watersheds was recommended to determine if the BMPs remained effective over time. We compared water quality of agricultural BMP streams to non-BMP and reference streams in the Conesus Lake watershed to determine if BMP streams have better water quality than non-BMP streams. We also determined if there are differences in water quality in the BMP tributaries compared to prior pre- and post-BMP implementation monitoring periods. In addition, we performed an aquatic invertebrate diversity and biotic index study to determine if BMP streams have healthier populations of aquatic macroinvertebrates than non-BMP streams. We observed higher nutrient concentrations and loss of nutrients in the agricultural streams rather than the reference streams. However, our hypothesis that BMP streams would be significantly better in terms of water quality than non-BMP streams was generally not supported. In our analyses of parameters over time for the BMP streams, we observed that concentrations and loss per hectare were some of the highest we have recorded for many analytes in most streams. We also observed that BMP streams in the Conesus watershed do not have healthier invertebrate communities than the agricultural non-BMP steams. In some cases, this is likely driven by BMPs no longer implemented (or changes in land use). This could also be driven by climate change, more frequent storm events, greater storm intensity, and due to the timing of these storms. Previous studies have shown mixed results on whether BMP practices remain effective over time. BMPs should be made available throughout watersheds due to how effective they can be in reducing nutrient pollution, but they should not be considered “the be all end all” as they only provide partial solutions to watershed issues.
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Benthic Macroinvertebrate Community Changes Following Zebra Mussel Colonization of Southwestern Lake OntarioChanges in abundance and diversity of benthic macroinvertebrates inhabiting a natural cobble and artificial reef substrate in southwestern Lake Ontario were quantified following invasion of the zebra mussel, Dreissena polymorpha. Post-zebra mussel invasion data (1991-92) were statistically compared with pre-invasion data (1983) from the same sites. By 1991-92 zebra mussels comprised 73% and 90% of cobble and artificial reef macroinvertebrates, respectively, replacing the amphipod Gammarus fasciatus as the numerically dominant taxon at both sites. Overall abundance of non-zebra mussel taxa was significantly greater (p < 0.05) at cobble and artificial reef sites in 1991-92, than in 1983 before zebra mussels were present. Taxa exhibiting significant population increases at the cobble site during the time period separating the two studies were the annelids Manayunkia speciosa, Spirosperma ferox and unidentified tubificids; the gastropods Helisoma anceps,Physa heterostropha, Stagnicola catascopium, Valvata tricarinata, Goniobasis livescens and Amnicola limosa; and the arthropods Gammarus fasciatus and Orconectes propinquis. Significant population increases of Physa heterostropha, Goniobasis livescens, Amnicola limosa, Gammarus fasciatus and the trichopteran Polycentropus were observed at the artificial reef site. Although a few taxa sampled infrequently in 1983 were not collected in 1991-92, no taxa have decreased significantly since 1983. Comparisons of community composition in 1983 and 1991-92 suggest the cobble community has changed more than the artificial reef community. These changes are likely positive, as species richness was greater at cobble and artificial reef sites in 1991-92 relative to 1983, and Simpson's Diversity showed no decline. Though other factors may have contributed to observed native macroinvertebrate community changes, my results support theories that zebra mussels are facilitating energy transfer to the benthos by filter-feeding, and that mussel shoals are providing additional habitat for native invertebrate taxa.
