Past CSUR-REU Research at the Calder Center

Project Title: Invertebrate grazing effects on diatom ecological guilds and species composition

Mentors: Dr. John Wehr, Madelaine Wrey

Abstract: A study assessed the invertebrate grazing effects on diatom ecological guilds and species composition in the Colorado River below Glen Canyon Dam, Arizona, USA. Invasive species often negatively impact the pre-existing food base of the ecosystems they colonize. This study compared the grazing patterns of two contrasting invertebrate taxa; the invasive New Zealand Mud Snail (Potamopyrgus antipodarum) and the native amphipod Gammarus lacustris, collected in November 2021. Goals were to assess whether either invertebrate selectively consumed specific diatom species or guilds, and to contrast the potential impacts of an invasive with a native consumer in this system. P. antipodarum consumed significantly more low-profile than high-profile diatoms at both study locations (RM-2: M-W U = 599, p < 0.001; RM-12: M-W U = 413, p < 0.001). These data suggest the recent snail invasion may accelerate the consumption of low-profile diatoms within the food web. However, snails did increase their consumption of high-profile species downstream (M-W U = 518, p < 0.001). P. antipodarum may therefore be well-adapted to physical differences within this system. The proportions specific to diatom taxa in snail guts were similar to that measured in the river in 2020 at a downstream location (RM-2), but differed significantly from in situ diatom abundances upstream (RM-12). These outcomes may indicate selectivity, although 2020 data may not accurately describe in situ composition present in 2021. The study also revealed that native G. lacustris fed on high-profile diatoms to a greater degree than P. antipodarum (M-W U =1134, p < 0.05) but no significant difference was found between their consumption of low-profile species. These results likely reflect differences in feeding mechanisms and morphology of the two species, as well as differential impacts on the epiphytic diatom flora of the river.

Project Title: River macrophytes harbor differing epiphytic diatom associations

Mentors: Dr. John Wehr, Madelaine Wrey

Abstract: Aquatic macrophytes and epiphytic diatoms form the base of the Colorado River food web. Diatoms attach to macrophytes and are grazed by invertebrate consumers. Their means of attachment vary: some are a closely-adhering low-profile guild; others form a high-profile guild. Previously, Cladophora was the dominant macrophyte in the river, but altered water release patterns from Glen Canyon Dam transformed the once turbulent system into a more stable flow system, allowing other macrophyte species to proliferate: Chara vulgaris, Fontinalis hypnoides (moss), and Potamogeton sp. I predicted that a new macrophyte flora would alter diatom species composition and ecological guilds. This study focused on the ratio of high- and low-profile diatoms (H:L) across different macrophytes in winter (2021-2022). In each sample, 18 species were counted (2 invasives) and ranked in order of abundance. Relative proportions of the two most abundant species werecompared for each macrophyte. High-profile Gomphonema pumilum [1] and Rhoicosphenia abbreviata [2] were more abundant on Chara (0.225) and moss (0.057), respectively. Low-profile Cocconeis pediculus [1] and Cocconeis placentula [2] were more abundant on moss (0.544 and 0.183) and Potamogeton (0.531 and 0.217), suggesting an association between low-profile diatoms and these macrophytes. To test if the ratios of the two guilds were equal (H:L = 1.0) or suggested a preference (H:L > or < 1.0), a comparison was conducted for each macrophyte. H:L on moss and Potamogeton averaged significantly less than 1.0 (0.2017 and 0.2070, respectively), strongly suggesting low-profile diatoms were more common on these plants. Pairwise comparisons identified significantly different epiphyte compositions between Chara vs moss (t = 2.397, p = 0.050) and Chara vs Potamogeton (t = 2.471, p = 0.044). These data indicate that the food base changed in response to a new macrophyte composition of the Colorado River, which may have implications for the river food web.

Project Title: Assessing the Influence of Organic and Synthetic Fertilizers on Tomato Growth

Mentors: Dr. JD Lewis

Abstract: This study highlights the significance of organic fertilizer in optimizing tomato growth while aligning with sustainable agricultural practices. As Earth's climate warms, extreme heat and humidity are increasing, thus making it crucial to understand the effects of different fertilizers in enhancing plant resilience. The study aimed to assess the morphological responses of Tiny Tim Tomatoes (Solanum lycopersicum) to different organic and synthetic fertilizer treatments and determine the most suitable fertilizer type for promoting tomato growth and productivity. A greenhouse block design was used for ten weeks with ten replicates and six treatments totaling sixty plants. The three organic fertilizers used were fish emulsion, worm castings, and bio-fertilizer, and the two synthetic fertilizers used were Epsom salt and Miracle-Gro, as well as one control with no treatments. After measuring the pH of the soil, stem height, the number of true leaves, and leaf diameter, the plants treated with worm castings had the most significant growth rate because the fertilizer has a primarily nitrogen and calcium content and a vital microbiome ideal for the nitrogen-deficient soil. The Epsom salt had the opposite effect and killed nine of the ten plants treated with it, potentially due to the added magnesium preventing calcium uptake and harmful high exposure to sodium. The Miracle-Gro was the only fertilizer to cause leaf scorch because it had the highest chemical concentration. This study found that organic fertilizer consistently led to healthier and more robust tomato plants and improved soil structure, promoting long-term soil health and sustainability.

Project Title: Exploring within-season changes in aggression and territory defense in the Gray Catbird (Dumetella carolinesis)

Mentors: Ar Kornriech and J. Alan Clark

Abstract: The Gray Catbird is a songbird species in the Mimidae family named for its characteristic catlike mew call. Although this species is territorial, the Gray Catbird’s usage of common signals of avian aggression in territory defense remains relatively unknown. Even less is known about its usage of song complexity in territorial defense and mate attraction. A sample of Gray Catbirds (N = 13) with known territories was exposed to two identical field playback experiments to gain insight into within-season aggression and song complexity changes. The first set of experiments was conducted between May 16th and June 1st, when Gray Catbirds usually establish territories and mate pairings. The second set was conducted between June 30th and July 1st, when nestlings usually fledge. Friedman and Wilcoxon signed-rank tests trended towards the usage of common signals of aggression in territory defense. However, behavior did not differ significantly between early and late playbacks. Song complexity could not be studied due to time restraints and will be examined in the coming months. We will additionally continue exploring this dataset with other statistical models, such as linear mixed models.

Project Title: Exploring the habitat and history of the invasive tick, Haemaphysalis longicornis

Mentors: Dr. Thomas Daniels and Dr. Richard Falco

Abstract: The invasion of the Asian Longhorned Tick, Haemaphysalis longicornis, is sweeping the United States. First identified in the year 2017, this tick has already established populations in nineteen states to date. Although its vector status in the United States is currently unknown, it is a known vector in Asia and the South Pacific. The presence of this tick poses concerns for public health, including the possibility of it becoming a vector for disease. The presence of H. longicornis is also poses a threat to I. scapularis ticks, as competition between the two in the woods could drive out I. scpaularis entirely.  The aim of this research is to determine what environmental factors affect the survivability of this tick and how densely this tick populates different habitat types. This study hopes to gain insight into what the future of Northeastern America will look like as the invasion of H. longicornis continues. To assess the survivability of H. longicornis and I. scapularis, survival cages were dispersed across 250 m² edge and woodland sites.  In two-week intervals, cages were collected, and the ticks that remained alive were placed into humidity chambers to be monitored for survival. Environmental factors like weather data, percent canopy cover, leaf litter depth and vegetation diversity were assessed at each plot in order to determine if one or more of these factors affected tick survival. In order to determine tick density in various habitats, drag sampling was conducted at field, edge, and woods sites. Results demonstrated that H. longicornis exhibited superior survivability to I. scapularis in both the edge and woods sites. Weather and habitat data collected on the two sites suggest that the difference in survivability is due to tick biology rather than environmental factors. Additionally, drag sampling showed that H. longicornis is not only present in the edge and woods sites of LCC, but also in fields. It is clear that the invasion of the Asian Longhorned tick will continue to unfold, and should be monitored for public health.

Project Title: Seasonal changes in the abundance and lipid content of insect species consumed by Little Brown Bats (Myotis lucifugus)

Mentors: Dr. Craig Frank

Abstract: White Nose Syndrome, a condition caused by the fungus Pseudogymnoascus destructans, disrupts torpor in bats causing an overwinter mortality rate of 75-95% among North American bat populations. According to past research, polyunsaturated fats (PUFAs) found in dietary insects commonly consumed by bats play a significant role in increasing the resistance of bat populations to P. Destructans by increasing torpor bout length and propensity. In our research, we collected data on the abundance and lipid content of dietary insects at Fordham’s Louis Calder Center to see if they varied by species, date, and collection location. To collect the data, we used Townes Style Malaise Traps. Two were set up close to Calder Lake (semi-aquatic) and one was set up in a field (terrestrial) farther away from the lake. Insects collected were predominantly from the orders Diptera, Hymenoptera, Lepidoptera, Hemiptera, Coleoptera, and Homoptera. We found that insect abundance initially decreased from late spring into early summer and then leveled out for the duration of the summer. Of the six orders collected, Diptera and Hymenoptera were the most abundant, followed by Lepidoptera and Coleoptera. Regarding lipid content, there was only enough sample to conduct lipid tests for the Dipterans, Lepidopterans, Coleopterans, and Hymenopterans. According to these tests, there was not enough variation between the lipid contents of the four orders to suggest any significant difference in lipid content based on order. The four orders all had a mean crude lipid content between 11.9 and 18.4 %.There was also not enough variation between the lipid content of the insects collected at the terrestrial and semi-aquatic sites to suggest any significant difference between the two. We plan to conduct further research on collected samples to see if the fatty acid composition of the lipids from semi-aquatic insects is significantly different from the lipids of terrestrial insects of the same Order.

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

Mentors: Dr. Thomas Daniels, Dr. Richard Falco, and Ms. Morgan Kelly

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