2007 REU Research Projects
- Aylmer Bourke Lambert Collection in the Philadelphia Herbarium
- Cost-Effective Extraction of Diapause Eggs from Sediment
- Investigation of the freshwater diatom Reimeria
- Mass Mortality of Late Devonian Placoderms
- Migration and Growth Rates of Anguilla rostrata
- Molecular Investigations of Swartzia
- Online Identification Guide of Crane Fly Turfgrass Pests
- Trophic Transfer of in a Freshwater Marsh Ecosystem
The Aylmer Bourke Lambert Collection in the Philadelphia Herbarium at the Academy of Natural Sciences
Kristian D. Jones, Salem College
Mentor: Alina Freire-Fierro
The Herbarium of Aylmer Bourke Lambert (1761-1842) deposited at PH (Philadelphia Herbarium) is a compilation of botanical specimens from 20 different collectors including Frederick Pursh, John Fraser, William Baldwin, and Thomas Nuttall. Upon his death, his estate was divided into 317 lots and was bought by 16 buyers, one of which being Edward Tuckerman, Jr. The collection was then passed along to The Academy of Natural Sciences, where it is housed in the Types room. Since the Lambert collection has been obtained, previous curators including James Mears have examined the specimens for types and have tried to update the specimens to present herbarium status. In this study, the Lambert collection was curated, entered into The Collections database of The Academy of Natural Sciences, and imaged. A website was created featuring the 521 specimens, including their systematic information, annotations from the database, and a visual image. The website also includes information, images and handwriting about A. B. Lambert, the collectors found in his herbarium, as well as a description of the project.
Cost-Effective Extraction of Diapause Eggs from Sediment
Tiffany Liu, Princeton University
Mentor: Dr. Scott Mills
We conducted two Analyses of Variance (ANOVAs) to determine the efficiency of sucrose floatation for the recovery of ashable material as a proxy for diapause eggs. Utilizing centrifugation and bench-top separation treatments on both dry and wet sediment (Lost Lake, CT, -72.707°, 41.268°), the first analysis was conducted under conditions of equivalent force (1g for 500 min, 100g for 5 min) in a two-way experimental design. Results indicated that centrifugation retained more sediment in the supernatant than with bench-top treatments (Ashable F=283.69 p<0.05, Inorganic F=1150.97 p<0.05); wet sediments similarly retained more material in the supernatant than in dry treatments (Ashable F = 201.10 p<0.05, Inorganic F=410.54 p<0.05). Our second analysis examined the effect of sucrose molarity (1.15 M to 2.20 M in increments of 0.15 M) on the extraction of ashable material from sediment (New Jersey salt marsh -74.265°, 39.611°) set on the bench-top at 1 g for 24 hours. Resultsindicated that higher molarities recovered more ashable and inorganic material (F=33.2102 p<0.05). These results are discussed in light of optimizing a cost-effective filtering kit that can be posted worldwide for the recovery of diapause eggs. The efficacy of the filtering kit has been demonstrated in Australia, Greece and Mexico.
An investigation of the freshwater diatom genus Reimeria: distinctions between Reimeria sinuata and Reimeria uniseriata
Kelly Hondula, University of Virginia
Mentor: Dr. Don Charles
R. sinuata was originally described in 1856 by Gregory as Cymbella sinuata, and was transferred to a new genus in 1987 by Kociolek and Stoermer. In 1993, Sala et al. separated two distinct morphologies into the species R. sinuata and R. uniseriata based on differences in the type of straie found in populations of several South American rivers.
Samples from the USGS NAWQA project were studied with the aim of determining autecological information about these species. Both R. sinuata and R. uniseriata were found to have wide geographic distributions in the United States, frequently appearing together. Analysis of water chemistry parameters where the species were found revealed significantly higher ecological preferences for R. uniseriata in pH, conductivity, calcium concentration, and magnesium concentration. SEM images showed differences between these two species in pore structure and position of apical pore fields. Recognizing R. uniseriata distinctly from R. sinuata in diatom studies could lead to new insights and clearer interpretation about the occurrence of these species.
Investigation of a mass mortality of Late Devonian Placoderms
Katharine Criswell, Shippensburg University
Mentors:
Dr. Jason P. Downs and Dr. Edward B. Daeschler
The antiarch placoderm Bothriolepis is commonly encountered in the Upper Devonian Catskill Formation in Pennsylvania. During road construction in Tioga County in 2004, 2005, and again in June of 2007, several hundred small, articulated individuals of Bothriolepis sp. were collected on numerous slabs of red siltstone. This large sample of small individuals came from a single site and the specimens are situated closely together but do not overlap. These circumstances generate questions concerning the nature of death and preservation of the sample and whether these are actually juveniles rather than a species with small-sized adults. The combined head and trunk shield lengths range from 20 to 52 mm with an average of 28 mm, and depict certain juvenile characteristics that were previously documented in Bothriolepis canadensis such as a relatively large orbital fenestra and head shield and a relatively narrow anterior median dorsal plate. These specimens also lack a median ventral plate that until now has been unreported in any species of Bothriolepis. Based on these characteristics, along with the orientation of the individuals and proof of over thirty specimens on a single bedding plane, we document this occurrence as a mass mortality in an ephemeral aquatic setting, perhaps the drying of a marginal stream environment.
Migration and Growth Rates of A. rostrata Young-of-Years: A Case Study of Eel Ecology in Ridley Creek, PA
Cassie Ornell, Colby College
Mentor: Dr. Richard Horwitz
American Eels (Anguilla rostrata) are a unique fish species whose life cycle and behaviors remain largely unknown. Despite the species’ widespread occurrence, their recruitment to freshwater bodies in North America has markedly decreased in recent years. This study focused on tracking young-of-year eel migration and growth rates in Ridley Creek, PA, during the summer to gain an understanding of their presence in the water body in order to better protect them. All eels, caught at seven sampling sites with backpack electroshockers, were measured, and most were weighed. A subsample of eels from these sites was taken back to lab for otolith analysis. Young-of-year eels were determined to be between 5 and 7 cm total length in the early sampling times, and between 6 and 8 cm in the later weeks. These eels grew an average of 0.2557 cm per day. Young-of-year eels dispersed slowly from downstream sampling sites, but had been found 1.63 km upstream 42 days after initial sampling, suggesting 38.8 m of daily migration, assuming a linear rate. Otolith measurements and aging methods confirmed the separation point between young-of-year and yearling yellow eels; however, more work is needed to better understand the data gathered in this study.
Molecular Investigation of Swartzia; a phylogeographic anaylsis of the possiroid clade
Claire Addis, Luther College
Mentor: Dr. Benjamin Torke
Tropical rainforests hold much of the world's tree diversity, yet very little is known about the genetic variation and speciation in tropical trees. Some authors have suggested that hybridization is rare in tropical trees, but very few studies have explored this theory. This study examines the evolutionary history and species boundaries within the Central American distribution of the possiroid clade of Swartzia. DNA sequence data were collected from the chloroplast trnT-D spacer and the nuclear ncpGSI gene. Sequence variation was used to identify phylogenetic and genealogical relationships among four putative species of the possiroid clade: S. guatemalensis, S. myrtifolia, S. standleyi, and S. simplex. Molecular data were analyzed phylogenetically with maximum parsimony and Bayesian criteria, and haplotype networks were generated using statistical parsimony. Morphometric data were collected and analyzed using a Principle Components Analysis. Substantial congruence was noted among the three datasets; each recovered at least two distinct lineages. Correlated discontinuities in morphological and genetic variation were at least partially in agreement with previous taxonomic species designations. Very little haplotype sharing was observed across species, but there is some evidence, however, for reticulation and/or lineage sorting.
Online Identification Guide to Crane Fly Pests of Turfgrass in the Eastern United States
Paul Rhine, Temple University
Mentor: Dr. Jon K. Gelhaus
Two species of European craneflies, Tipula (Tipula) paludosa and Tipula (Tipula) oleracea, have been migrating into the United States and pose a potential threat to golf courses, lawns, pastures, and crops. These are established in the Pacific Northwest and Canadian Maritimes provinces as the leading insect pests of turfgrass, and have recently been documented in central Canada and the Northeastern U.S. These pest species spread through flight in the adult stage or can be carried in soil or turfgrass transported for benign reasons. The appearance of these two species is similar to some harmless native species that occupy similar habitats.
This guide will be helpful for agricultural extension experts, golf courses, and homeowners to identify these invasive pest species and avoid unnecessary application of pesticides. This project was accomplished by examining the anatomical characteristics of 21 crane fly species of similar habitat and appearance and developing the corresponding character states into an online interactive guide using 20q software produced by the Discover Life project. These characteristics were illustrated with photographs taken with the microscope digital imaging system and Automontage software. When the correct characteristics for a specimen are selected, the guide narrows the potential species to those that match, allowing identification.
Tropic transfer of PCBs and PBDEs within a freshwater tidal marsh ecosystem
Marcell Vasquez, Philadelphia University
Mentors: Dr. Jeffrey Ashley and Dr. David Velinsky
Polybrominated diphenyl ethers (PBDEs) are chemicals currently added to various manufactured materials to act as flame retardants. Polychlorinated biphenyls (PCBs), banned from production in the mid-1970s, were mainly used as dielectric fluids in capacitors and transformers. These two classes of chemicals have similar physicochemical properties, accumulate in the environment, and are known endocrine disruptors and/or carcinogens. Although PCB levels have been well-studied since their ban, much less is known about PBDEs and their distribution patterns. The goal of this study was to quantify the extent of PCB and PBDE contamination in the freshwater tidal ecosystem at the John Heinz National Wildlife Refuge at Tinicum, PA, by comparing the sources and accumulation paths of these two classes of chemicals. Organisms from key trophic levels characteristic of this shallow, contaminated system were collected and analyzed. Biological concentrations of PCBs ranged from 90 to 1810 ng/g wet weight while PBDEs concentrations were an order of magnitude less. Both PCBs and PBDEs concentrations were highly correlated with lipid content suggesting it is a large determining factor to contaminant body burden. In general, concentrations increased with increasing trophic level revealing that both these chemical classes biomagnify up the food web.