Past CSUR-REU Research at the Calder Center
Project Title: Do impounded streams in the Croton Watershed harbor Didymosphenia geminata?
Mentors: Dr. John Wehr, Madelaine Wrey, Michael Kausch
Abstract: The freshwater diatom Didymosphenia geminata (AKA “Didymo”) has received increasing concern over the past several decades as an invasive species and a source of benthic algal blooms. Didymo blooms are caused by the secretion of extracellular polysaccharide stalks, which grow to cover streambeds as mats of stalk material. The presence of a dam or other impoundment in a stream has been hypothesized to affect water conditions in ways favorable to Didymo blooms. To explore this hypothesis, we conducted an observational study focusing on the prevalence of D. geminata within the Croton Watershed in southeastern NY state. Between Jun 10 - Jul 15 2022, we sampled four sites in three rivers in which frequent fishing activity occurs and were downstream from a different dam: Muscoot River, Titicus River, and two sites on the West Branch River (u/s - d/s). We periodically visited the four sites to check for visible blooms and collect diatom samples, which were mounted on slides for D. geminata valves (silica cell walls) to be counted in proportion to the estimated total number of diatoms per slide. Although we did not observe any blooms that could be observed macroscopically in the field, D. geminata valves were detected in multiple samples from three sites on two of the three rivers, West Branch of the Croton and the Titicus River; the latter location was previously not known to contain this diatom. D. geminata was most abundant in the upstream West Branch River location at more than 10,000 valves / 10 million total diatom valves. When present in two other systems, quantities ranged between 20 - 100 valves per 10 million total. We did not detect D. geminata in the Muscoot River on any date. Our data suggest that low and stable flow conditions may favor the establishment and spread of this potentially invasive species in the region.
Project Title: Extending entomopathogenic fungal spore viability to control vector ticks
Abstract: Not available
Project Title: A-mew-sed? An exploration of Gray Catbird calling.
Mentors: Dr. J. Alan Clark and Ar Kornreich
Abstract: Gray Catbirds are an abundant migratory species named after their most common call, a catlike mew. Not much is known about the function of this call as earlier conclusions fail to explain the various contexts of mews, and do not address the variations of mews observed in the field. To gain insight into mew function, mews recorded from wild individuals were clustered based on acoustic parameters. Cluster results showed mews can be separated into distinct clusters that also exhibit several overlaps, suggesting that mew types may not be distinct but rather reflect continuous differences on a spectrum. The acoustic structure of mews were not found to be reliably sexually dimorphic. Mew acoustic parameters varied widely between individuals. The general variation within mew structure possibly accounts for the inability for cluster analyses to determine the optimal number of clusters, suggesting that variation may be continuous. Mew function was unable to be studied due to time restraints, and will be more deeply explored in future studies. We also intend to increase our sample size and include other acoustic parameters in future analyses.
Project Title: Stenotrophomonas rhizophila bacterium as an effective growth promoter and inhibitor of disease in tomato.
Mentor: Dr. JD Lewis
Abstract: Due to demand for crop plants such as the tomato (Solanum lycopersicum) growing exponentially, the environmental impact of growing crop plants as well as its potential harm to human health must be considered. Harmful fungicides and chemicals used to curb the growth of phytopathogens and support plant growth are unsustainable for use on a large scale; however, many farmers are desperate for solutions to widespread plant diseases such as Fusarium wilt. The bacterial species Stenotrophomonas rhizophila, which is closely associated with plants and found naturally in both plant tissue and the rhizosphere, is a viable candidate to replace these chemicals due to its plant growth promoting and antifungal properties. In this study, an isolate of S. rhizophila was grown for use in non-sterile soil in order to imitate agricultural conditions. In order to account for differences in responsiveness between genetic types, both heirloom and hybrid cultivars were grown for a total of six weeks in a greenhouse setting. Inoculation with varying densities of the bacterium resulted in differences between plant growth as well as susceptibility to infection. Furthermore, significant differences between cultivars and treatments in leaf number, leaf mass, and stem mass were determined using ANOVA. The presence of Fusarium oxysporum f.sp. lycopersicum was confirmed by plating leaf disc samples on Fusarium-specific agar. Average diameter of fungal growth was used to determine the effectiveness of S. rhizophila as an antifungal agent. These results suggest that S. rhizophila could be used as a replacement for harmful chemicals in agriculture.
Project Title: Legacy Effects of Drought on Plant Soil Feedback with Bohemian Knotweed
Mentors: Dr. Steve Franks and Jospeh Jaros
Abstract: Various microbial communities within soil develop relationships with plants. These relationships create feedback loops that can positively or negatively influence a plant’s fitness. Mutualistic microbes can help break down nutrients in soil in exchange for food, but parasitic microbes can cause harm through disease. These interactions can be influenced by abiotic factors like droughts or flooding. Previous research has shown that Bohemian Knotweed, an invasive species, creates negative feedback loops in drought conditions. This experiment explored how prior drought can affect the plant soil feedbacks of a contemporary drought. Bohemian knotweed was planted in sterile, invaded, and uninvaded soil. The three types of soil represented the control without microbes, soil microbes conditioned by Knotweed, and microbe communities conditioned by other species, respectively. The plants experiencing the drought were watered half as much as the regularly watered condition for two weeks. This process was repeated for the second drought. No significant differences were found in plant traits among soil treatments or between plants exposed to prior watered treatments or drought. However, the total PSF, a comparison between microbial relationships in sterile and invaded pots, showed a significant difference between the two conditions. The largest positive effect was shown in plants that were historically watered. This points to a stronger relationship between mutualistic microbes with the Bohemian Knotweed in pots that started with live invaded soil. Those in sterile pots showed a positive total PSF to a lesser extent pointing to a weaker feedback loop between the microbes and the plant.
Project Title: The Role of Dietary Fatty Acids in the Susceptibility of Bats to Cutaneous Fungal Infections
Mentor: Dr. Craig L. Frank
Abstract: White Nose Syndrome (WNS) is a fungal infection characterized by the growth of Pseudogymnoascus destructans (Pd) on the ears, snout, and wings of bats. Upon infection with Pd, hibernating bats experience shortened bouts of torpor, resulting from damage caused to the epidermis and dermis by fungal hyphae. Shortened bouts of torpor increase energy expenditure, causing premature depletion of fat deposits, and ultimately death. The mammalian epidermis serves as the primary means of defense against infection, and is composed of a variety of lipid classes, including free fatty acids, wax esters, and triacylglycerols. Certain lipids of the mammalian epidermis have been found to aid in resistance to WNS, particularly oleic acid and linoleic acid. Oleic acid is an monounsaturated fatty acid that is synthesized in the mammalian epidermis, however, linoleic acid is a polyunsaturated fatty acid (PUFA) that must be obtained by the diet. We hypothesized that the composition of the wing epidermis of a bat species highly resistant to WNS (E. fuscus) would contain a greater proportion of oleic acid and linoleic acid compared to a highly susceptible species (M. lucifugus). Additionally, we hypothesized that the diet of E. fuscus would contain a greater proportion of PUFAs compared to M. lucifugus. By evaluating the wing tissue and feces of both species, it was found that 1) the epidermal lipids of E. fuscus contained significantly more oleic and linoleic acid than those of M, lucifugus, and 2) PUFAs account for »20% of all fatty acids in the diet of E. fuscus. Thus, indicating the important role of epidermal lipids in the defense against cutaneous infection.
Project Title: A landscape analysis of scat deposition among New York carnivores
Mentors: Dr. Jason Munshi-South and Kimberly Hughes
Abstract: Not Available