Environment & Sustainability Honors Theses
Permanent URI for this collection
The Environment & Sustainability major is a collaboration between the College of Agriculture & Life Sciences and the College of Arts & Sciences. Undergraduate honors theses posted here are also cross-listed in the College of Agriculture and Life Sciences Theses collection.
Browse
Recent Submissions
Item Differences in Longevity and Oviposition between Two Silver Fly Species, Leucotaraxis argenticollis and Leucotaraxis piniperda, Specialist Predators of Adelges tsugaeMahecha Rios, Linda (2024)Since the introduction of the hemlock woolly adelgid (HWA, Adelges tsugae) in the 1950s, eastern and Carolina hemlock (Tsuga canadensis, T. caroliniana) stands have greatly declined throughout eastern North America. Because of the importance of hemlocks, much research has been done to manage this pest. Currently, the use of biocontrol predators is a priority for research as it would naturally control HWA populations without the use of insecticides; insecticides, while effective, are costly and cannot be applied across large landscapes. Two potential biocontrols are silver fly species native to the Northwestern US, Leucotaraxis argenticollis and Leucotaraxis piniperda, as they are natural predators of HWA found in that region. Due to many similarities between the two species and difficulty of identification, especially for immatures, they have historically been lumped together, but currently, there is research looking into the differences between the two species. This paper looks specifically at the differences in longevity, length of their pre-oviposition period, oviposition, and impact that availability of live HWA has on their oviposition. It was found that L. piniperda lived longer than L. argenticollis (48.4 days compared to 25.7 days), that the length of pre-oviposition period for L. piniperda was greater than that of L. argenticollis (23 days compared to 14 days), and that there was a positive correlation between the number of live HWA on a twig and the number of eggs laid for L. argenticollis but not for L. piniperda. Understanding these differences helps us further understand the biology of these two species which is important in the context of using them as biocontrols for HWA.Item Comparing Lake Sturgeon Growth Across Water Bodies in NYS Using Size-at-Age Comparisons, von Bertalanffy Growth Curves, and Age-Length KeysDixon, Krystal (2024-05-31)Lake Sturgeon (Acipenser fulvescens) are a threatened fish in New York State due to historical overfishing and habitat loss. Despite conservation efforts, significant knowledge gaps persist regarding population abundances, age structure, and growth rates. This study helps to address these gaps by developing an age-length key for Lake Sturgeon in New York State. Long-term Lake Sturgeon monitoring data from Oneida Lake, Genesee River, and the Niagara River were analyzed to compare population growth and determine if population specific age-length keys were needed. Size-at-age analyses and von Bertalanffy growth curves were used to assess differences among populations. Results showed significant differences in size-at-age among populations, with the Genesee River population exhibiting the smallest mean lengths at comparable ages. Von Bertalanffy growth curves further highlighted population-specific growth. Age-length keys were found to have varying degrees of accuracy in predicting fish ages. While age-length keys offer a time-efficient and cost-effective alternative to traditional aging methods, caution is advised in their application for Lake Sturgeon in New York.Item CAN RESTORATION OYSTERS SUSTAIN THEMSELVES IN HUDSON RIVER PARK? A GENOMIC TEST FOR LOCAL RECRUITMENTHua, Henry (2024-04-15)Eastern oyster (Crassostrea virginica) populations are sparse and fragmented throughout the Hudson River Estuary (HRE). For oyster restoration efforts to collectively build a self-sustaining population, larval connectivity between isolated breeding populations is required. This study analyzes patterns of spat settlement at two spatial scales: the entire upper estuary and more intensively in Hudson River Park (HRP), Manhattan where there is a relatively new restoration site. Oyster sampling sites were located in both fresh or brackish water (upstream near Mario Cuomo Bridge) and near-oceanic salinities (downstream near lower Manhattan). Two breeding populations exist along this gradient: remnant native oysters in the Tappan Zee/Haverstraw Bay (TZHB) area near Tarrytown, and aquaculture oysters used for restoration in HRP. Native oysters are genetically distinct from domesticated aquaculture oysters, which provided a means to distinguish spat and adult reference samples by genotyping 243 DNA variants in reference adult samples and each spat. At a large scale, spat settlement abundances were analyzed in 2022 and 2023 to map the temporal and spatial distribution of recruitment. Connectivity patterns between populations were inferred with genomic assays. Spat abundances were highest upstream in 2022 and flipped to be highest downstream near HRP in 2023. Almost all of the 2095 spat genotyped in both years were genetically more similar to TZHB native oysters, indicating they originated from parents in the upstream population. This suggests that recruitment contributions from the HRP oysters were below detection power in this study or occurred in unsampled portions of the estuary. Histological gonad analyses confirm that adult restoration oysters in HRP spawned in 2023, so finding where their offspring disperse remains an important challenge. At a small scale, spat abundance was compared among 2023 HRP sites to test whether altered river flow at certain piers (baffle effects) increases larval recruitment. Baffle affected piers did not show a significantly greater amount of spat when compared to controls, though a significantly higher number of spat/shell were found at piers at the northern end of HRP relative to the south. Further study to confirm a baffle mechanism can be leveraged to enhance settlement.