I was formerly a marine invertebrate ecologist now working as a freshwater aquatic ecologist in the R.K. Mellon Freshwater Research Initiative Laboratory with research interests centered around macroinvertebrate and fish communities in a variety of watersheds.
More specifically, I have spent the past several years studying the invasive rusty crayfish (Orconectes rusticus) populations and their impacts on the native crayfish (Cambarus b. bartonii) populations within the mainstem Susquehanna River and selected tributaries, as well as the feeding behaviors and diets of both species.
Another focus of mine involves an assessment of stream restoration practices and best management practices (BMPs) and the effects on aquatic communities both pre- and post- construction.
Other project participations with Susquehanna colleagues and students includes terrestrial macroinvertebrates and salamander diets with Tanya Matlaga; large river ecosystem and headwater ecosystem research particularly involving water quality, diatoms and macroinvertebrates with Jack Holt and Ahmed Lacchab; and unassessed waters research on brook trout with Jonathan Niles. Individual research topics concentrate on the taxonomy of macroinvertebrate and fish species mostly in the rivers and streams of the Northeastern and Mid-Atlantic U.S.
Our lab has been involved in three large projects through the summer, two on the main stem of the Susquehanna River and one on five headwater streams.
Although the students in my lab have particular responsibilities, we all work together as a team on days when multiple hands and backs are needed.
Eighth Year of the Byers Island Monitoring Project
We continue to monitor diatom biofilm communities and benthic macroinvertebrate communities at four sites on the Byers Island transect. Sites 1 and 2 are on the west side of Byers Island, and sites 3 and 4 are on the east side.
For both communities, we use passive sampling (rock baskets and Hester-Dendy Multiplate samplers for the macroinvertebrate communities and diatometers for the diatom biofilms; deployed on June 9) and active sampling (kicks and stone collections for macroinvertebrates and diatoms, respectively).
Active samples are taken at 100 meter intervals upstream from sites 1 and 2 for 500 meters. Site 1 is in the west branch plume while sites 2-4 are in the north branch plume. Still, each of the north branch plume sites show individual characteristics, especially during this low flow summer.
Diatom Community Monitoring for Young-of-Year Small Mouth Bass Project
The diatom community monitoring is a portion of a larger project that includes fish, macroinvertebrates and diatom biofilms at specified locations on the lower west branch, upper main stem, and tributaries of the Susquehanna River—11 sites in all.
Headwater Stream Multicommunity Project
This is the second year that we have studied the macroinvertebrate communities, diatom communities and water chemistry of five headwater streams that flow down the north face of Penns Creek Mountain into Penns Creek.
Last year we found that, although the chemistry is quite similar from one stream to the next, the macroinvertebrate and diatom communities are quite different from each other.
This summer we set out to repeat the samples and methods of last year. In addition to examining the upper reaches of the respective streams, we chose one stream, Green Gap, to examine in a longitudinal study to its confluence with Weikert Run.
Although we examined diatom communities on stone, sediment and plants in the summer of 2015, this summer we are restricting our investigation to diatom biofilms on stones.
Through live capture-release and recapture studies of small mammals, stomach content analyses of carnivores (coyote, foxes, minks), owls feeding ecology work (barn and long-eared) and quaternary vertebrate faunal reconstructions, my research interest has focused on the natural history, ecology, conservation and evolution of vertebrates (past and present) in the area.
My students help me develop new lines of research constantly and ways to ask questions and define hypotheses. Students in my lab start doing research during their sophomore year, first assisting juniors and seniors and later defining their own protocols and questions.
Eventually, we invest enough time in research to warrant the writing and presentation of results in local, regional, state, national and even international scientific meetings. I work side-by-side with every one of my research students in the long and tedious process of applying to graduate schools. And, when merited, we submit our final manuscripts to be considered for publication in a peer-review scientific journal.
As a scientist I love to combine the intellectual challenge of forming hypotheses with the physical challenge of testing these hypotheses using experiments and computer models.
Research in my lab focuses on answering the overarching question—why are invasive plants successful and what are the ecological consequences of their success?
There are dozens of invasive plants here in the Mid-Atlantic and many utilize a similar reproductive strategy. This strategy allows new individuals to be produced sexually by seed and asexually by belowground rhizomes.
Despite much research we still do not know if this mixed reproductive strategy is directly responsible for the tremendous success of these plants. Results from our research shed light on which biotic and abiotic conditions influence the success of sexual and clonal offspring.
Recently we have begun to investigate the invasive shrub Japanese knotweed (Fallopia japonica), which is quickly spreading throughout riparian forest along the Susquehanna River. I am excited to have students of any stage and experience participate in my lab. If you are interested, please contact me.
I am an ecologist broadly focused on how human activities affect the life histories of animals, primarily amphibians. My research has examined core ecological questions concerning how populations are impacted by natural abiotic and biotic variation, as well as human-caused changes in land use, disease, chemical contamination and climate change in North and Central America.
I love to share my enthusiasm for biology with students by using the scientific process, from making those essential first observations to interpreting the final graphs that illustrate the answer to a question.
The questions I currently examine with my students include "How will climate change impact terrestrial salamanders and their invertebrate food sources?" and "How do roads and streams impact salamander movement across the landscape?"
We employ a variety of methods to answer these questions, including cover board arrays to find salamanders, marking techniques to identify individuals and berlese funnels to extract invertebrates from leaf litter samples.
Please contact me if you have any questions.
I an aquatic ecologist whose research centers on the biology and ecology of fish. In particular, I study native cold water fishes like the brook trout (Salvelinus fontinalis). My research interests and projects focus on how human activities (development, agriculture, forestry, energy development, climate change) affect various life histories of fish species. In addition to these research interests, I also have research projects in aspects of applied aquatic ecology including habitat enhancement, watershed protection, watershed restoration and natural resources management.
Students in our Freshwater Research Initiative lab work on a variety of research projects in conjunction with governmental agencies, non-profit groups and other academic institutions.
Projects in our lab focus on four areas (brook trout in headwater streams, smallmouth bass in the Susquehanna River,sStream restoration in agricultural systems and aquatic invasive species). Current projects in our lab include:
- The Unassessed Waters Initiative with PA Fish and Boat Commission to proactively identify and properly classify the most at-risk streams which support naturally reproducing brook trout populations in order to protect, conserve and enhance those waters as wild trout streams.
- Response of brook trout populations to catastrophic flooding.
- Population genetic structure of brook trout in the Loyalsock Creek watershed.
- Long-term brook trout population and benthic macroinvertebrate assessments of Loyalsock Creek watershed.
- Importance of Un-named tributaries to brook trout populations.
- Phenotype-specific Gene Expression in Brook Trout in the Loyalsock Creek Watershed
- Assessing potential impacts of unconventional natural gas extraction and mercury concentrations on trophic food webs of headwater streams.
- Vulnerability assessment of unconventional oil and gas (UOG) development on brook trout and other aquatic resources in the Susquehanna River Basin.
- Elemental analysis of brook trout otoliths, fin rays and scales to determine exposure to metals associated with unconventional oil and gas extraction.
- Investigating the genetic population structure and movement dynamics of smallmouth bass in the Susquehanna River.
- The role of groundwater as a point source of emerging contaminants to smallmouth bass.
- YOY smallmouth bass health and diets across various sites in the Susquehanna River.
Restoration of agricultural streams
- Biological Effectiveness of Instream Restoration
- Implementing Precision Conservation in the Susquehanna River Basin
Aquatic Invasive Species
- Rusty Crayfish and Smallmouth Bass Dynamics in the Susquehanna River: who is eating whom
- Assessment of density and diet of crayfish in the Middle Creek watershed above and below reservoirs
Students with an interest in fisheries/aquatic ecology are encouraged to visit the Freshwater Research Initiative page and see how they can become involved.
Trained as a plant ecologist, I am interested in understanding the biotic and abiotic factors that determine the abundance and distribution of plants in their natural environments.
Research in my lab primarily focuses on the ways in which biotic factors impact the growth, reproduction and survival of plants. Earlier research in my lab explored the role soil pathogens played in shaping seedling recruitment patterns near black cherry (Prunus serotina) trees. I found that mature trees fostered the growth of host-specific pathogens that reduced survival of black cherry seedlings beneath mature trees, but did not have a similar effect on seedlings of other species. Distance- and/or density-dependent seedling survival has the power to shape species distributions, but also to impact community-level patterns of species diversity.
More recent research in my lab has explored the effect of plant-animal interactions on plant growth, reproduction and survival. In particular, we have looked at plant allocation to defense, growth and reproduction in both bean species and Prunus species.
These two groups both have multiple defenses against herbivory, including the ability to release hydrogen cyanide (HCN) in response to damage and the production of extrafloral nectaries (EFNs). While HCN offers plants a means of directly defending themselves against enemies, extrafloral nectaries provide defense to the plants indirectly—by rewarding, with nectar, those visitors that attack the plants' natural enemies.
Further, EFNs are often an induced defense—meaning the plant responds to damage by investing in additional EFNs. My lab has explored the effect that herbivory, resource availability and the soil microbial community has on plant allocation to defense, growth and reproduction. Current work being done in collaboration with Dr. Matlaga, examines the effects of simulated herbivory on the goldenrod/gall fly interaction.
As a developmental biologist, my lab is interested in learning more about the ways in which cell communication and signaling are used to determine cell fate as an animal embryo develops from an unfertilized egg.
Our model system is the sea urchin embryo, which is easy to grow in the lab and is beautiful transparent, making observation of development very easy.
We are currently studying several different signaling pathways, one of which is the planar cell polarity (PCP) pathway. We have shown that a protein in this pathway, c-jun N-Terminal kinase, is needed for the formation of the archenteron, which is the embryonic digestive system (Long et al., 2015, genesis 53:762-769).
We are currently examining other roles for this protein during development, such as formation of the spindle during early mitosis. We have also recently initiated studies on the Hippo pathway, which is known in other systems to be a regulator of cell proliferation but has not been characterized in the sea urchin.
Using small molecule inhibitors of the Hippo pathway effector protein YAP, we are conducting loss-of-function studies to determine the role of YAP in the sea urchin embryo.
My current research is focused on adipogenesis, the process of cell differentiation from preadipocytes, which are relatively undifferentiated cells, into mature white adipose tissue adipocytes (fat cells). We use the 3T3-L1 cell line as a model system to study the process of adipogenesis. The conversion of the fibroblastic phenotype to a rounded phenotype is stimulated with treatments of insulin, dexamethasone, and 3-isobutyl-1-methylxanthine (IBMX) over a two-week period.
While reviewing the literature on the 3T3-L1 cell system, one of my research students became interested in an article that showed that artificial sweeteners stimulate 3T3-L1 differentiation into adipose cells. Even though artificial sweeteners contain fewer calories than traditional sugars, it is possible that they could stimulate development of new fat tissue, since fat cell precursors (preadipocytes) have been shown to express sweet taste receptors on their surface.
We have been using the 3T3-L1 cell model system to determine if fat cell development is stimulated by artificial sweeteners. In our research, we have investigated whether a variety of artificial sweeteners (saccharine, sucralose, stevia) stimulate adipogenesis. We determine the amount of adipogenesis by measuring lipid accumulation using Oil Red O staining, and measure the expression of key proteins involved in the adiopogenesis process by Western blotting. This research may help explain why some people continue to gain weight even though they consume artificially sweetened beverages.
Mature adipocytes are surrounded by an extracellular matrix (ECM) that contains collagen IV as a major component, and several other ECM proteins such as fibronectin and laminin. We are interested in observing the effects of these ECM proteins (collagen IV, fibronectin, and laminin) on the growth and differentiation of 3T3-L1 preadipocytes, and in particular the interaction between various ECM components and artificial sweeteners.
As a behavioral ecologist, I'm interested in understanding how animal communication and information use influences survival and reproductive success.
We use spiders as a model organism to ask questions about female mate choice, predator-prey interactions and kin-recognition. Our lab also uses spiders to address questions in the areas of chemical, physiological and community ecology, as well as neuroscience.
Current projects include:
- Measuring mercury accumulation in spiders and other arthropods near power plants, uncontrolled mine fire sites and mining-impacted rivers. Spiders are extremely efficient at concentrating mercury and mobilizing it across food webs but we don't understand why.
- Identifying how wolf spiders learn to recognize predators even before they are born.
- Testing the tactics used by poor quality male wolf spiders to find a mate. Paradoxically, one strategy may be to seek out spider pairs that are already mating.
- Measuring the behavioral and physiological adaptations spiders use to respond to periodic flooding. Our work is identifying how many spiders can stay alive for hours underwater.
- Identifying the chemical composition of spider pheromones. While thousands of insect pheromones have been identified, only six spider pheromones have been characterized.
- Testing the role of octopamine in shaping spider personalities. Octopamine is an arthropod "fight or flight" hormone that functions like norepinephrine in vertebrates. We are examining how increased levels of octopamine modify spider aggression level across multiple contexts including diet choice, courtship, predator avoidance and prey capture tactics. Some wolf spiders show seemingly maladaptive levels of aggression-like killing prey they don't eat or killing all their prospective mates and dying unmated. Octopamine regulation may be a key to understanding why these behaviors persist.
I study a problem that was first identified more than 60 years ago but remains unsolved. Thalidomide can be considered the most notorious teratogenic (causing birth defects) drug ever. The drug was promoted as a safe alternative to many of the therapeutic alternatives at the time. When researchers realized that it caused birth defects, it was immediately removed from the market and stayed off the market for decades.
Thalidomide returned to the market place because it provides many significant therapeutic solutions for several diseases due to its immunomodulatory and anti-inflammatory properties. The exact mechanism whereby the drug harms the developing fetus has never been completely understood, although over 30 theories have been put forth.
One of the problems associated with understanding thalidomide is that it does not seem to have same effects in pregnant laboratory rodents as it does in humans, making the search for a teratogenic mechanism of action more complicated.
Our laboratory found that thalidomide affects developing sea urchin embryos and started using them as a model organism for trying to uncover the drug's mechanism of action in embryos. We use techniques such as embryo culture, immunohistochemistry, in situ hybridization, light microscopy and other cell biology techniques to try to unravel the drug's mechanism of action.
Recently, we started looking at the epigenetic effects thalidomide may have when thalidomide treated sperm fertilize the sea urchin eggs.
The research in my laboratory is focused on the impact of developmental environment on the physiology and behavior of adult offspring.
A wide array of experimental studies in species from fish to humans have convincingly demonstrated that the early developmental environment has a significant and long-lasting effect on offspring as adults.
The long-term consequences of one's developmental environment have been termed gestational programming or maternal effects.
One of the initial findings to support the existence of gestational programming was from humans exposed to famine during gestation during the Dutch hunger winter in 1944-45.
These offspring were born with low birth weight and had a much higher rate of developing obesity, diabetes, heart disease and a number of other pathologies.
Findings from this and subsequent studies showed that low birth weight could be used as a marker for impaired gestational environment.
In my research, we use a gestational nutrient restriction rodent model to produce low birth weight offspring. The low birth weight offspring are used to study the effects of impaired gestational environment on the brain, reproduction and motivated behaviors.
Information gained from this research should have a significant impact on our understanding of the underlying mechanisms responsible for gestational programming and will hopefully provide insight into new potential interventions for low birth weight humans.
The role of the endocrine system in the development of eggs in insects represents an important gap in our understanding of these processes.
Previous work suggests that the production and deposition of yolk into developing oocytes relies upon a balance between the ecdysteroids, the insect-specific juvenile hormones (JHs) and the insulin-signaling (ILS) pathway. Furthermore, egg development arrests when insulin signaling is disrupted by mutation, such that the trafficking of yolk proteins across the oocyte membrane is disrupted. Interestingly, these mutants are also smaller than wild-type animals and live considerably longer, indicating links between cell division and growth, fecundity, carbohydrate intake, and oxidation and aging.
Recently, I have become interested in the effects of oxygen levels on biological systems. Exposure to low partial pressures of oxygen induces the expression of hypoxia-inducible transcription factors (HIFs) that then appear to regulate a wide range of pathways including those associated with aging, growth and insulin signaling.
My hypothesis is that the exposure of insects to low partial pressures of oxygen will affect egg development by stimulating HIF production, thus disrupting the ILS pathway and the expression of yolk protein genes and those genes involved in protein trafficking.
In addition, we hypothesize that reduced ambient pressure (simulating changes in altitude) will affect the expression of these genes and downstream egg development. Anecdotal observations in the Himalayas suggest that the geographical range of some insect species is extending to higher altitudes, possibly as a result of climate change in the region.
Given that some insects in low-lying areas of Asia are vectors for diseases such as malaria and dengue fever, an understanding of the effects of altitude and oxygen availability on insect reproduction may inform our understanding of the possible outcomes of climate change.
Microbial Ecology of the Centralia, Pa., Mine Fire
In 1962, a trash fire in an abandoned anthracite coal mine ignited a near-surface coal seam. The fire has been burning ever since. It currently covers 300 acres and has resulted in the evacuation of the town of Centralia, Pa.
Ultimately, the fire is expected to impact 3,000 acres. Since the fire is a recent phenomenon, with easily-defined boundaries that ebb and flow with time, my students and I have a unique ability to monitor microbial adaptations to this geothermal event as it happens.
We are interested in the roles that the resident bacteria are playing in the biogeochemical cycling of nitrogen and sulfur in the mine fire area and in isolating new species of antibiotic-producing bacteria. Our interdisciplinary research uses metagenomic, metatranscriptomic and traditional culture-based assays and we currently collaborate with faculty at Michigan State University, as well as with members of the Susquehanna University departments of chemistry and earth and environmental sciences.
There are two main research projects currently underway in my laboratory.
One project aims to understand how different cell types are specified in multicellular organism. We are focusing our attention on dissecting the molecular mechanisms that regulate the differentiation of glial cells within the central nervous system (CNS) of Drosophila.
The CNS of Drosophila, like that of vertebrates, is bilaterally symmetrical and consists of two major cell types-neurons and glia. Glial cells are required for establishment of the blood-brain barrier, for neuronal proliferation, survival, insulation and axon pathfinding. Improper functioning of glial cells is implicated in human disorders such as multiple sclerosis, schizophrenia and Alzheimer's disease.
Understanding how they develop and function, therefore, is critical. We are investigating whether pointed and repo function together to regulate the expression of genes in longitudinal glial cells. Longitudinal glial cells perform analogous functions to mammalian oligodendrocytes.
The second project focuses on using RNA mediated interference (RNAi) to investigate the function of the ETS family of transcription factors. ETS transcription factors are evolutionary conserved and regulate diverse cellular processes such as proliferation, differentiation, migration and angiogeneisis.
Misregulation of several ETS proteins are implicated in human cancers. We have used RNAi to knockdown pointed (Pnt), an ETS family transcriptional activator. We effectively produced a range of phenotypes when we targeted Pnt RNA during oogenesis, eye development and cardiac muscle cell development. We are currently investigating the effect of knocking down other ETS transcription factors using RNAi.