Abstracts are listed in the order of presentations.
9:00 am | Traditional Talks
Predators in the water: What’s an isopod to do?
Elizabeth Long*, Dr. Erika Iyengar (faculty advisor); Muhlenberg College
The ability to detect predators using chemical cues is often essential for prey in ponds where visual cues are largely precluded by light limitations. Isopods are relatively large benthic potential prey that can be important food resources for fish, which are predominantly visually-oriented predators. We predicted that isopods (Caecidotea communis) would decrease their rate of movements to avoid detection when exposed to sunfish cues (Lepomis spp.), but only in daytime hours because the darkness of night would hide them, but that they would increase their rates of movements in the presence of cues from invertebrate predators, which typically employ sit-and-wait strategies. We used time-lapse photography to track isopod movement and calculated their movement rates and the proportion of time spent moving when exposed to either dechlorinated tap water or dechlorinated tap water containing sunfish cue. We viewed trials utilizing fish cues in the morning, afternoon, and nighttime separately, using infrared light to illuminate night photos as crustaceans cannot see red light. Trials using invertebrate predators were only conducted during the day. Surprisingly, no significant difference was seen in rates of movement or proportion of time spent moving across any of the treatments.
Effect of habitat fragmentation by roads on soil salinity & abundance of terrestrial salamanders
Nikki Morley*, Dr. Megan Rothenberger, Lafayette College
The microclimate conditions of forest edges are altered by habitat fragmentation, threatening the regularity of many forest processes and native species. Conservation biologists use bioindicator species as tools to evaluate forest health because of their relation to many forest processes. Due to their relative abundance in forest habitats, sensitivity to environmental disturbance, and mid-level position in the food web, Plethodon cinereus was evaluated as a sensitive indicator of habitat fragmentation by roads using a multiyear monitoring study in a state park (2014 and ongoing). Monitoring takes place at an unfragmented and road-fragmented site with biweekly collection of soil pH, canopy cover, leaf litter depth, soil moisture, soil conductivity and salamander abundance from March – November using the artificial cover object (ACO) method. The abundance of P. cinereus, is significantly higher at the unfragmented site where the nearest road is greater than 1000 m away. At the fragmented site, which is approximately 100 m from two roads, salamander abundance increases significantly with distance from the road. Our results also indicate that P. cinereus is sensitive to microhabitat change, and their abundance is significantly correlated with higher soil pH, lower leaf litter depth, and lower soil conductivity.
Do metabolic interactions structure the endosymbiotic communities of the pea aphid, Acyrthosiphon pisum?
Jessica Hoban*, Linyao Peng, Drexel University
Bacterial endosymbionts can form distinct community structures within their hosts, with certain pairs of species found predominantly together and others apart. While molecular screening can elucidate trends of community structure, it cannot identify the underlying causative mechanisms. For this, researchers often use genomic inference, focusing on the inferred metabolic properties of co-occurring and co-excluding microorganisms. The pea aphid, Acyrthosiphon pisum, is a model for studies on animal microbiomes, and harbors various combinations of seven non-essential, protective, maternally transferred symbiont species. At least five are comprised of multiple strains, as identified through sequence differences in house-keeping genes. Using a combination of genomes generated for
five of the seven species, genomes of the obligate symbiont Buchnera (found in all aphids), and the genome of the pea aphid itself, we reconstructed metabolic networks for co-occurring and co-excluding symbiotic partners. Incorporating substantial data engineering, we expanded upon two published tools: NetSeed, which infers exogenously acquired metabolites based on network topology, and NetCooperate, which calculates a metabolic complementarity index (MCI) score, estimating possible levels of symbiont cross-feeding. Our preliminary results suggest that, out of five strains from the prevalent Hamiltonella defensa symbiont, the two with the strongest tendencies to live with other symbionts exhibit increased metabolic dependency. There are also symmetrically high levels of support between two co-occurring species, Serratia symbiotica and Rickettsiella viridis. Future work includes broader tests of the relationship between co-occurrence and MCI scores, thereby using genomic inference to understand the forces behind symbiont community structure in the cosmopolitan pea aphid pest.
Testing the center-periphery hypothesis in red cornsnakes (Pantherophis guttatus) at the edge of their range
Karan Singh1*, Alexander Milano1, Howard K. Reinert2, John Bunnell3, Lauretta M. Bushar1
1Arcadia University, 2The College of New Jersey, 3New Jersey Pinelands Commission
The center-periphery hypothesis (CPH) states that genetic diversity, gene flow, and species abundance is lowest at the edge of their range. The northernmost edge of the range of red cornsnakes, Pantherophis guttatus, is the New Jersey Pine Barrens. In order to test the CPH in red cornsnakes, we screened 22 primers for microsatellite loci identified in eastern and gray ratsnakes, Pantherophis alleghaniensis and Pantherophis spiloides, (Bloiun-Demers and Gibbs 2003) and eastern foxsnakes, Pantherophis gloydi (Row et al. 2008) for use in red cornsnakes. Twelve loci were useful in analyzing population genetic structure of red cornsnakes from two populations of red cornsnakes in the New Jersey Pine Barrens, Berkely (n=8) and Woodland (n=38). We found evidence of null alleles at one locus. Because this is the first study of the genetic structure of red cornsnakes, we compared measures of genetic diversity for the red cornsnake populations with data for a population of eastern foxsnakes from southwestern Ontario (Row et al 2008) and for gray and eastern ratsnakes (Blouin-Demers and Gibbs 2003). We found no difference in observed or expected heterozygosity among the populations. Although there were more alleles in the gray and eastern foxsnakes, this is most likely due to the larger sample size and the sample including two different species sampled across their range. There was no evidence for population subdivision or isolation by distance in the Woodland population of red cornsnakes. Future studies should be directed at obtaining data for additional red cornsnake populations across their range.
Variable flowering phenology dependence on climate change by native and non-native plants
Cole Geissler*, Dr. Allison Davidson, and Dr. Richard Niesenbaum, Muhlenberg College
We tested the hypothesis that rising temperatures associated with climate change impact plant flowering phenology, and that trends varied between native and non-native species. We ran regressions using herbarium records of 20 native and 16 non-native species and NOAA temperature data occurring in Eastern Pennsylvania counties from 1884 to 2015. Responses varied, with some species having no significant shift, some flowering earlier, and others flowering later; the variability of these trends also shows some dependence on temperature averages from various time intervals, including the year of collection, early months, and the onset of spring. However, in general, plants in the counties of interest bloom earlier with rising temperatures. Variable responses reflect climate change’s significant relationship with flowering phenology shifts but also the possible presence of other influencing factors.
10:30 am | Traditional Talks
Fish are friends? Lack of predator threat recognition in aquatic isopods
Austin Hoffman, Dr. Erika Iyengar (faculty advisor), Muhlenberg College
In the Northeastern United States, aquatic isopods are often abundant detritivores that serve critical roles in nutrient cycling and lower trophic levels of the food webs of both lentic and lotic aquatic ecosystems. Predatory fish commonly feed on isopods, and these invertebrates can be an important food source for some game fish. As such, we expected isopods to demonstrate inducible defenses in response to fish predators. In a naturally fish-less pond in Autumn 2020, I deployed leaf packs, nestled within the local detritus, underneath a cage that either was empty or contained two fish (a sunfish and a golden shiner, both of which can consume isopods) that were in proximity but prevented from accessing the leaf packs. After either six or two days, I retrieved the leaf packs and counted the number of isopods within. Surprisingly, no significant difference in population densities was observed between the treatments, suggesting that isopods do not actively avoid areas with fish as an imminent potential threat.
Invasive Asian shore crabs and Chinese mitten crabs: Current response, best management practices, and competition dynamics with native blue crabs
Katie Kavanagh* and Dr. Megan Rothenberger, Lafayette College
The Asian shore crab (Hemigrapsus sanguineus) and Chinese mitten crab (Eriocheir sinensis) are two invasive species with emerging populations on the eastern coast of the U.S. that have raised concern among scientists and conservation managers because of the environmental and economic harm they have caused in aquatic ecosystems in Western Europe and along western coast of the U.S. The objective of this research study was to explore what is being done, what is missing, and what ought to be done to improve management responses to the Asian shore crab and Chinese mitten crab invasions. To address this overall goal, we performed a competition experiment between the Asian shore crab and the blue crab (Callinectes sapidus), an economically important native species. We also conducted interviews with conservation managers to understand where gaps between published management plans and on-the-ground management of the crabs occur and to generate recommendations for their improved management. Preliminary results from laboratory competition experiments indicate the potential of Asian shore crabs to compete with blue crabs for food, signaling the importance in managing the growth and spread of already-established Asian shore crab populations. Management responses to the Asian shore crab and Chinese mitten crab, however, have been limited due to constraints in coordination, funding, time, and human resources.
Ecosystem service trade-offs within coral reefs: A global analysis
Megan Keene* and Natasha Gownaris, Gettysburg College
Coral reefs are biodiversity hotspots that provide humans with extractive ecosystem services like fisheries and non-extractive services like tourism. Though no studies have examined these trade-offs among these services at a global scale, there are now large, open datasets that make this possible. Using these datasets, we asked whether spatial protection and the level of protection (World Database on Protected Areas) impacted coral reef tourism value (Atlas of Ocean Wealth). We also examined whether proximity to regions of high fishing effort, defined as the top 25th percentile of the average annual effort from Global Fishing Watch, impacted tourism values. Since our data were zero-inflated, we used a two-step modeling approach for statistical analysis, examining predictors of tourism presence/absence then predictors of tourism value magnitude. We found that protected coral reefs are more likely to have a tourism value than those that are not. Among reefs with tourism value, protected areas had a higher average value than unprotected areas. In addition, the level of protection influenced the likelihood and magnitude of tourism value, though in some instances in unexpected ways, possibly due to restrictions on tourism in strongly protected reefs. Coral reefs in closer proximity to high fishing
effort had a lower chance of having tourism value, but in areas that did have tourism value, areas closer to high fishing effort had a higher average value. Using large, global datasets of ecosystem services, our study informs management trade-offs in coral reef ecosystems.
Effects of the American toad (Anaxyrus americanus) on the agricultural ground-dwelling insect community
Valerie Kuppek*, Maddie Duboyce, Abby Marich, Dr. Scott Boback, Dr. Maggie Douglas, Dickinson College
Ecological pest management within agricultural settings often incorporates pest predators in lieu of harmful pesticide application to crops. While generalist predator species can contribute to pest suppression, complex and potentially conflicting effects can occur when predators eat both pest and beneficial species. While many different integrated pest management approaches have been explored over time, little is known about the efficacy of amphibian predators as biological control agents within temperate agricultural systems. We created habitat enclosures at the Dickinson College Farm with varying densities of the American toad (Anaxyrus americanus) to measure the influence of this species on the insect community coinciding with the key crop plant, kale (Brassica oleracea). The ground-dwelling insect community was sampled, processed, and statistically analyzed. Results from this study contribute to understanding the dietary preferences of amphibian predators, informing further design of ecological pest management.
Effect of habitat quality on aggression in convict cichlid (Amatitlania nigrofasciata) pairs
Cole Bower*, Timothy Cruz* and Dr. Joseph Leese, DeSales University
For many animals, habitat quality is one of the most significant factors in determining access to resources and general safety, and becomes even more important when the habitat serves as a potential breeding ground. As a result, many animals invest a great deal of time and energy defending their territories from conspecific and heterospecific intruders that compete for suitable habitats. The convict cichlid Amatitlania nigrofasciata is an aggressive member of the Cichlidae family in which monogamous pairs defend territories that include nest sites by chasing and harassing intruders. As such, we hypothesized that pairs may be sensitive to the quality of a given habitat and capable of altering their defensive behavior in response. To test our hypothesis, two different environments were created in experimental aquaria. A ‘high-quality’ tank contained an opaque PVC nest site that hid individuals and eggs/fry inside while a ‘low-quality’ tank had a clear PVC nest site with a visible interior. Subjects were given time to form pairs, and then assessed for their levels of aggression in one of the two habitat treatments by introducing a juvenile conspecific intruder. The number of aggressive behaviors (bites, chases, displays) demonstrated from each pair was monitored and recorded. Preliminary data suggests that convict cichlid pairs can adjust their defensive behavior and will invest less in defending a lower quality habitat than a higher quality one.
1:00 pm | Lightning Round Talks
Pesticide contamination in wetlands: Impacts of pesticides on anuran diversity and abundance
Janniry Cabrera Belen, Dr. Sara McClelland (faculty advisor), Moravian College
Amphibians are one of the most endangered classes of the Animal Kingdom. However, a lack of amphibian research has resulted in a disparity of available data to address their decline. One of the many factors affecting amphibian populations are pesticides. Due to their permeable skin, these chemicals pose a serious threat to anuran health. Pesticides have been shown to affect physiology, reproduction, immune system function, and behavior. My research project aims to survey local frog habitats to determine which areas may be contaminated by pesticides, and then to analyze whether the level of contamination is correlated with the diversity and abundance of anurans in these areas. Local frog habitats were found through the U.S. Fish and Wildlife Service Wetlands Mapper, and site visits were conducted to choose the most accessible sites. At each site, I will use frog calls to identify the species present, and calling intensity to estimate frog abundance. Soil and water samples will also be taken and sent to an outside lab that specializes in low dose pesticide analysis to determine the chemicals (if any) that are present at each location. I would hypothesize that the contaminated ponds will most likely be located near agricultural fields or roadways where pesticides are typically applied, and that these ponds will have decreased frog abundance and diversity when compared to uncontaminated ponds. Understanding how the quality of frog habitat is impacting frog populations is key to being able to conserve amphibian populations throughout the Lehigh Valley.
Testing the center-periphery hypothesis of reduced genetic variation in eastern kingsnakes (Lampropeltis getula getula) at the edge of their range
Tyler Paul1*, Howard K. Reinert2, John Bunnell3, Lauretta M. Bushar1; 1Arcadia University, 2The College of New Jersey, 3New Jersey Pinelands Commission
The central peripheral hypothesis (CPH) predicts that populations on the edge of their geographic range will have reduced genetic variation compared to more centrally located populations. Eastern kingsnakes, Lampropeltis getula getula, in the New Jersey Pine Barrens are at the northernmost edge of their range. In order to test the CPH in these snakes, primers for 13 microsatellite loci, Lge 1, 2, 3, 5, 6, 9, 14, 15, 16, 21, 23, 25, and 26, identified in California kingsnakes, Lampropeltis californiae (Monzón Argüello et al 2015), were screened in eastern kingsnakes. Lge 2, 6, 9, 14, 15, and 25 were useful for analyzing population genetic structure in a population of eastern kingsnakes in the Pine Barrens. There was evidence for null alleles at Lge 2, 14, and 25, with frequencies <25%. There are no other known studies of genetic diversity within populations of eastern kingsnakes; thus measures of genetic variation for this population of eastern kingsnakes were compared to those for two populations of recently (<25 years) introduced California kingsnakes in Grand Canary Island off the coast of northwestern Africa (Monzón Argüello et al 2015). There were no differences in observed heterozygosity, expected heterozygosity, or number of alleles. Genetic diversity measures were comparable to other members of the tribe Lampropeltini. There was no evidence in support of decreased genetic variation in eastern kingsnakes in the New Jersey Pine Barrens. Data for additional populations in the Pine Barrens and more centrally located populations is needed.
Development of sexually dimorphic branchiae in Streblospio benedicti
Caitlin Segarra*, Dr. Elizabeth McCain, Muhlenberg College
All polychaetes utilize integumentary respiration and gas exchange but many have evolved vascularized external extensions of the body called gills or branchiae. Development of the branchiae has never been documented and there are few thorough descriptions of adult branchial anatomy. I used the scanning electron microscopy (SEM) to understand the morphological changes taking place during the development and maturation of the spionid marine worm S. benedicti, and its branchiae. I also
assessed the possibility that branchiae may have functions that are not respiratory. In the process of examining the adults, I discovered S. benedicti exhibits sexual dimorphism of the branchiae. The males have unique, and more complex cilial patterns on their branchiae compared to females. These findings are striking, considering less than ten of over 450 spionid species exhibit any form of documented sexual dimorphism beyond the reproductive difference.
Gut bacterial symbionts of turtle ants express genes for pollen digestion
Richard Lu*, Dharman Anandarajan, Yi Hu, Jacob A. Russell, and Benoit Bechade, Drexel University
Symbiotic bacteria can promote digestion of plant complex carbohydrates and lignins (i.e. “fibers”) for the development and survival of their animal hosts. The symbiosis between turtle ants (genus Cephalotes) and their gut bacteria provides an ideal model to explore bacterial fiber digestion and study the nature of insect-bacteria symbioses. Cephalotes adult workers host abundant and diverse gut bacteria, that are conserved across Cephalotes species and recycle nitrogen. These ants feed substantially on pollen, but unlike honeybees, bacterial degradation of pollen-derived fibers has never been demonstrated. Moreover, recent exploratory data from shotgun metagenomics has shown that across Cephalotes species, several bacterial symbionts encode enzymes to initiate the degradation of typical plant fibers including hemicelluloses, lignin, starch and pectins. To explore bacterial contributions toward host digestion, we used metatranscriptomics on Cephalotes varians guts from colonies fed with different diets. We then used bioinformatics to assess the expression level of genes encoding enzymes to degrade fibers. Our metatranscriptomic analyses reveal that in Cephalotes varians feeding on a pollen-rich diet, members of the Rhizobiales are more active while members of the Sphingobacteriales and Xanthomonadales express genes coding for arabinofuranosidase, an enzyme degrading side-chains of pollen-derived fibers, like hemicelluloses and pectins. This activation of digestive enzyme suggests symbiont-enhanced catabolism of pollen-derived fibers in turtle ants. Such digestive function was likely kept by conserved symbionts of different Cephalotes species for ~45 million years, and may have been key to the ecological success of this diverse ant group.
1:30 pm | Lightning Round Talks
Habitat use of red cornsnakes (Pantherophis guttatus) in the New Jersey Pine Barrens
Patricia Nguyen* and Howard Reinert, The College of New Jersey
The red cornsnake (Pantherophis guttatus) in the New Jersey Pine Barrens is thought to be facing an increasing risk of population decline due to forest changes and habitat fragmentation. Pantherophis guttatus is also prized in the international pet trade, resulting in increased illegal poaching in the region. To provide information to support conservation management programs, a multi-year study was conducted to examine the habitat preference of P. guttatus. From 2016 to 2019, 35 P. guttatus (18 female/17 male) were tracked using radio telemetry to assess habitat use. We measured 11 structural environmental variables at snake-selected sites and at comparative, randomly selected locations within the study area. Univariate analysis (ANOVA) indicated that male and female P. guttatus did not differ in their structural habitat use for any of the measured variables. However, both sexes differed from randomly selected locations for most of the measured habitat parameters. A principal components analysis (PCA) illustrated the similarity and broad overlap of the structural habitat used by males and females. This analysis also showed that snakes generally used habitat with a more open canopy and surface structure than the more heavily wooded habitat measured at random sites. PCA also illustrated that large fallen logs in open habitat were potentially important environmental features for these snakes. Creating and maintaining a diversity of forest habitat structure and maintaining surface log cover may be useful habitat management strategies for maintaining and improving habitat for P. guttatus populations in the Pine Barrens.
Measuring color change as a non-invasive method to monitor stress levels in amphibians
Midelys Franceschini*, Dr. Sara McClelland (faculty advisor), Moravian College
Amphibian populations worldwide are in danger of extinction due to numerous ecological threats such as invasive predators, climate change, habitat destruction, pollution and diseases. These threats can activate the stress-axis causing an increase in stress hormones. Monitoring the concentration of corticosterone, the main stress hormone in amphibians, can provide important information on environmental stressors and the health of amphibian populations. The traditional ways that stress levels have been studied in amphibians are lethal or invasive, which can impact already declining population numbers. Thus, it is imperative to find non-invasive methods to monitor stress to aid in conservation efforts. Previous studies in birds and fish have shown a change in pigmentation due to chronic stress. The purpose of this study was to investigate if the color of the skin also changes in tadpoles when they are chronically stressed. I hypothesized that tadpoles that were chronically stressed would be lighter in color. Tadpoles were exposed to either exogenous corticosterone or a vehicle control for three weeks. To determine if stress levels were associated with color change in tadpoles, I measured the brightness of tadpole bodies using ImageJ. Amphibians provide beneficial services for humanity: they consume insects, thereby controlling disease vector populations. Their skin secretions have also been used to develop new pharmaceuticals. This novel research project is the first step in enabling us to use coloration to monitor the health of these important animals, and to ensure that future generations of frogs recover.
Assessment of microplastic presence, type, and concentration in drinking water on the Cedar Crest College campus
Lauren Crispina and Dr. John Cigliano, Cedar Crest College
Microplastic production is increasing rapidly in our world and very little is known about the effects that they have on humans and the environment. Microplastics are plastic fragments, beads, and fibers ranging in size from 100nm to 5mm. It is estimated that every year 8 million tons of plastic are dispersed into the ocean. Microplastics have been found not only in aquatic environments but also in bottled drinking water, beer, sugar, and air. The purpose of my study is to determine the presence and concentration of microplastics in drinking water at Cedar Crest College, Allentown, PA. Samples were taken from sinks and water fountains located on campus, as well as bottle water sold on campus. 1000 L samples were vacuum filtered through mixed cellulose nitrate filters (Whatman, 47 mm diameter, 0.45 um pore size) and examined under a dissecting microscope to determine the size, shape, color, and abundance of microplastics. This is the first study to determine the amount of direct exposure to microplastics to the Cedar Crest College Community and will add to our understanding of the extent of microplastic pollution in the environment.