REU 2005 Projects
- Saltwater Intrusion into Freshwater Tidal Marshes
- Microsatellite loci for Culex restuans
- Pandanaceae website for the Academy's Herbarium
- Larval black fly drift
- Soil Organic Matter Storage in Hovsgol, Mongolia
- Bothriolepid Placoderms from Nunavut
- Impact of grazing on aquatic insects in Mongolia
- Research in Ichthyology
- Scientific Illustration
Saltwater Intrusion into Freshwater Tidal Marshes
Ashley Smyth
University of North Carolina
Mentors: Drs. Melanie Vile and David Velinsky
Tidal freshwater marshes play a valuable role in the river ecosystem. They act as a medium of exchange between terrestrial and estuarine aquatic ecosystems by combining features of salt marshes and freshwater inland marshes. Unfortunately, the advent of recent global climate change has resulted in sea level rise and a loss of tidal freshwater marshes. Thus, depending on many factors such as river sediment fluxes and the organic matter accumulation rates within marsh ecosystems, seawater encroachment can trigger a change in the structure and function of freshwater tidal marshes.
As sea level rises, salt water begins to intrude in the freshwater zone, affecting the biogeochemical cycling of nutrients within the system as well as the sustainability of the ecosystem. An increase in salt water will also affect the flora and fauna of the river system and thus alter the system’s physical and chemical properties. The purpose of this study is to determine how biogeochemical processes change across a salinity gradient in the Delaware estuary, specifically to examine the role of increasing salinity on rates of sulfate reduction via production of CO2 from sediments. We hypothesize that salt marshes (or high sulfate marshes) have higher fluxes of CO2 than freshwater marshes (or low sulfate marshes). This study works towards establishing the relationship between SO4 -2 and CO2 production by manipulating sulfate concentrations in freshwater sediments. Information concerning the adaptation of freshwater marshes to salt-water intrusion will help determine the effect of climate change and sea level rise on the biogeochemical processes of tidal marshes.
Microsatellite loci for Culex restuans, potential vector of West Nile virus
Tarannum Jaleel
University of Alabama
Mentor: Dina Fonseca
While thirty species of mosquitoes have been found positive for the West Nile virus (WNV), Kilpatrick et.al (2005) suggest that Culex pipiens L. and Culex restuans Theobald may be responsible for up to 80% of human WNV infections in the northeastern United States. Since Cx. Restuans starts its activity earlier in the year compared to Cx. pipiens, it has been proposed to be an important vector of WNV early in the transmission season (Andreadis et al. 2001) Cx. restuans occurs from California to North Carolina, from southern Canada to Honduras, however, locally adapted populations may differ in epidemiologically significant traits. The examination of the genetic variability will allow for more informed exchange of information across epidemiological studies. In order to perform population genetic analysis, microsatellite loci serve as good markers because of their relative ease of use, hypervariablity, and low cost compared to sequencing (Zhang & Hewitt 2003). Microsatellite loci were isolated using a modified version of the enrichment protocols described by Hamilton et al. (1999) and Glenn & Schable (2005).
A Website for the Pandanaceae Types for the Academy's Herbarium
Bryan A. Niedenberger
High Point University
Mentor: Dr. James Macklin
Among the historically important collections housed in herbarium of The Academy of Natural Sciences (PH) is the type collection of Pandanaceae. A type refers to a specimen designated to serve as a reference point to a scientific name. Pandanaceae (screw pines) is a paleotropical family of monocots. Many of the Pandanaceae were collected by Benjamin C. Stone (1933-1994) during his tenure at the University of Malaya from 1963-1994. When Dr. Stone served as department chair of the botany department of the Academy of Natural sciences from 1984-1989, many of his collections were brought to PH. As this is a particularly important collection, it is necessary to make it more easily available to those who are interested in it. To accomplish this, a website was created using label information from a preexisting database. The website was created “on the fly” using PHP script with the help of Dr. Paul Morris. Each specimen on the website was imaged using a Nikkon coolpix 5000 camera. A map of the country where each specimen was collected was created using OMC (online map creation). Such a website may serve to generate future interest Pandanaceae.
Patterns of larval black fly drift
Tracy Hill
Clemson University
Mentor: Jonathan Fingerut
The aquatic larvae of black flies (Diptera: Simuliidae) live in moderately fast flowing waters of streams and rivers. While they are able to move themselves around a limited amount on the stream bottom, they rely on the stream current for long-range dispersal; however, when a larva chooses to detach from the stream bed and enter the water column, it is taking a great risk because nothing ensures that the larva will end up in a favorable location. We investigated what aspects of the stream influence a larva's chance of ending up in a favorable location after entering the water column. We hypothesized that stream morphology, particularly the location of slow-moving pools, affects a larva's likelihood of being deposited by the current in a favorable microhabitat. We worked in Neshaminy Creek, a stream north of Philadelphia, PA. We chose two stretches of the stream that we considered pools (long, slow-moving reaches that larvae cannot drift through.) We measured the local velocity, depth, and density of larvae in the water column upstream and downstream of each pool. We found that pools can act as sinks for larvae, but the relationship between the structure of the pool and the density of larvae flowing through it is complex, depending heavily on the shape of the reach, the depth, the presence of shelves or backwaters, and other factors. In the lab, we looked more closely at the behavior of the larvae in pool-like conditions, and we found that first-instar larvae can drift at much slower speeds than previously assumed using silk drag lines. Together, our field and lab results suggest that previous assumptions about what makes an area act as a sink to drifting organisms may need to be revised.
Soil Organic Matter Storage in Hovsgol, Mongolia: Permafrost and Land-Use Effects
Noam Ross
Brown University
Mentor: Clyde Goulden
I studied the effects of permafrost and land use on the quantity and quality of soil organic matter at Hovsgol Lake Global Environmental Facility, Mongolia. Hovsgol Lake lies at the border of the Mongolian steppe and Siberian taiga ecosystems, and is experiencing rapid climate warming as well as increases in grazing pressure from pastoral land-use. I hypothesized that soil underlain by permafrost would have greater amounts and quality of carbon due to low decomposition rates, and that grazing would reduce the quantity of carbon by influencing the depth of the permafrost. I dug soil pits at four sites: lightly grazed steppe both with and without permafrost, and heavily grazed steppe with and without permafrost. 3 pits were dug at each site, quantitatively sampling 0.5 m2 quadrats in 20-cm layers extending to 1 meter depth or to frozen soil. Soil samples will be tested for total carbon, carbon mineralized under incubation, and carbon in particulate organic matter pools. These data will be used to estimate potential change in soil organic matter storage under different land-use and climate change scenarios.
Bothriolepid Placoderms from the Nunavut Paleontological Expeditions: A Comparative Analysis
Jessica Walz
Ohio Wesleyan University
Mentor: Dr. Ted Daeschler
Expeditions to the Canadian Artic in 1999, 2000, and 2002 involved the excavation of vertebrate fossil material. During 1999, various work sites were established on Melville Ile Vanier Islands, and in 2000 and 2002 excavation sites were established on Ellesmere Islands. Fossil material included placoderm fish fragments from the Frasnian and Famennian ages, divisions of the Late Devonian Period. Previous stratigraphy indicated that those fossils collected in 1999 were derived from the early and middle Famennian deposits of the Parry Islands Group, as well as from the early Frasnian deposits of the Beverly Inlet Formation. Fossils collected in 2000 and 2002 were derived from the middle and late Frasnian deposits of the Okse Bay Group. The primary family of Placodermi fish fossils that were collected throughout the Nunavut Expeditions belonged to the family Bothreolipidae. Fragmentary pieces of head and trunk armor were identified through comparison to previously named elements. In order to document the diversity of Bothriolepid forms within the Nunavut region, a catalog was created consisting of an analysis of the various elements’ unique characteristics. Elements within a specific site from on of the expedition years were grouped together and given informal names, which were than used to make correlations between field sites. Based on similarities in plate characteristics, those forms that correlated indicate the necessity to redefine the previously excepted stratigraphy. More specifically, results indicate that some forms from Parry Islands’ Cap Fortune Formation, mapped as early Famennian age, may belong lower in the geologic time scale, the Middle Frasnian age. Also, some forms from Parry Islands’ Consett Head Formation of the Middle Famennian age may belong lower in geologic time scale, the Late Frasnian age. However certain correlations simply confirmed the accuracy of the previously accepted stratigraphy. This was indicated based on the correlation of lower Beverly Inlet formation and Fram formation across a wide geographic area. Finally, it was demonstrated that certain Nunavut forms also correlate with species from Eastern Europe. Some of the smallest Nunavut forms have similar plate characteristics to B. prima and B. evaldi of Eastern Europe. Finally it was determined that the largest form, excavated from the Nunavut expeditions, most likely is a different species than B. maxima, the largest named European form, based on significant differences in plate size and thickness. However, more detailed comparative analysis between Nunavut and East European forms is necessary to confirm preliminary analysis.
Mongolian Aquatic Insect Survey: Grazing Impact and Impairment of Aquatic Insects of the Selenge River Drainage Basin, Mongolia
Katie Hopp
Luther College
Mentor: Dr. Jon Gelhaus
Offsite Mentor: Dr. Barbara Hayford, University of California at Davis
Over-grazing of livestock is a potential impact on the aquatic insect communities in the Selenge River Basin of north central Mongolia. As part of a larger survey of macroinvertebrate diversity in the basin, we collected insects, physical, and habitat data using a modified version of the EPA’s Rapid Bioassessment Protocol. From these samples 2,249 insects from 31 families were examined and analysis of standard metrics and indices used in biological assessment indicated an impact from grazing. Percent Chironomidae decreased with increased grazing, percent Ephemeroptera increased with increased grazing and percent Plecoptera and Trichoptera were not responsive to changes in grazing intensity. Currently, the impact of grazing on aquatic insect communities may not be as evident as in the past because grazing of livestock has been practiced for thousands of years. However, future studies will focus on genus level identifications to further test whether intensive grazing practices are impacting stream biota in the Selenge River Basin.
Research in Ichthyology
Tiffany Jones
Eastern Michigan University
Mentor: Dr. John Lundberg and Dr. Mark Sabaj
Research was conducted on the ontogeny of and phylogentic influences upon Doradid swim bladder morphology.
Scientific Illustration
Amanda Labadie
Arcadia University
Mentors: Multiple scientists from the Center for Systematic Biology and Evolution
Work was done on the purposes and procedures of scientific illustration.