Ecology and Evolutionary Biology Commons^™

Dinoflagellate Cysts Within Sediment Collections From The Southern Chesapeake Bay, And Tidal Regions Of The James, York, And Rappahannock Rivers, Virginia, David W. Seaborn, Harold G. Marshall

Virginia Journal of Science

The upper 2 cm of sediment core samples from 70 stations in the tidal waters of three Virginia rivers and at 23 stations in the lower Chesapeake Bay were sampled for dinoflagellate cysts. The river sediment cysts were dominated by three common bloom producing species (Heterocapsa triquetra, Scrippsiella trochoidea, and Cochlodinium polykrikoides), whereas these were in low concentration on the Chesapeake Bay sediments which contained mainly dinoflagellate cysts of neritic and oceanic taxa. The mean sediment concentrations from stations in the James, York, and Rappahannock rivers were respectively 1174.8, 536.2, and 323.6 cysts g^-1. The mean …

Induction Of Winter Breeding In Small Mammals By 6-Mboa, Robert K. Rose, Roger K. Everton, Gregory E. Glass

Virginia Journal of Science

A plant-derived cyclic carbamate, 6-methoxybenzoxazolinone (6-MBOA), is

known to initiate reproductive activity in Microtus montanus. We studied

overwintering populations of four other rodent species, and observed increased

reproduction in experimental populations of two herbivorous species, Microtus

pennsylvanicus and Sigmodon hispidus, but not in two omnivorous species,

Oryzomys palustris and Mus musculus. These results suggest that low

concentrations of 6-MBOA may trigger seasonal breeding primarily in

herbivorous small mammals.

Spatial Analyses And Repletion Of Gargathy Coastal Lagoon, Loreto Herraiz Gomez

OES Theses and Dissertations

Coastal lagoons and bays vary in shape and size in response to antecedent topography, geologic processes and sea level rise. Variations in shape and environmental conditions of coastal basins are believed to influence the distribution of benthic sub-environments and the exchange of water with the ocean and other adjacent coastal systems. Gargathy Inlet and its coastal lagoon vary spatially from the inlet, where the greatest depths are observed, to the mainland, dominated by shallow intertidal areas, colonized by marsh. Hypsographic and hydro-hypsographic analyses of Gargathy's coastal lagoon were the primary techniques applied to understand the relative distribution of the benthic …

A Phylogeny Of The Snappers (Lutjanidae; Percoidei) Inferred From Cytochrome B Sequence Data, Matthew R. Semcheski

Biological Sciences Theses & Dissertations

The Lutjanidae are economically and ecologically important fishes commonly known as snappers. A morphological study of Lutjanidae concluded that it contained four subfamilies and that together with the family Caesionidae, form the superfamily Lutjanoidea. Although this view was supported elsewhere in the literature, it was later contradicted, treating the caesionids as members of the Lutjanidae. In order to infer a phylogeny of genera within Lutjanidae, the complete cytochrome b gene (1140bp) of 21 lutjanid taxa was sequenced and analyzed along with 19 lutjanid, caesionid, and outgroup sequences obtained from GenBank. Data were analyzed for base composition stationarity and saturation. Phylogenetic …

New Records, Biogeography, And Habitat Protection Needs Of Four Species Of Potamon (Decapoda: Brachyura) In Greece, Eugene G. Maurakis, David V. Grimes

Virginia Journal of Science

Objectives are to determine the occurrence of species of Potamon in eastern Crete and the Aegean Islands (Chios, Naxos, Paros, Mykonos, Tinos and Andros); generate phylogenetic relationships among species to propose a biogeographic hypothesis relative to current distributions of the four species of the freshwater crab genus, Potamon, in Greece; and comment on the need to protect habitat suitable for the survival of species of Potamon in the country. Our collections, made in areas not previously sampled by researchers, indicate the presence of Potamon fluviatile on Tinos, N axos, and Andros, and Potamon potamios from central to eastern Crete; …

Influences Of The Loggerhead Sponge (Spheciospongia Vesparium) And The Vase Sponge (Ircinia Campana) On Nearshore Hard-Bottom Community Development In The Florida Keys, Scott Donahue

Biological Sciences Theses & Dissertations

Sponges, octocorals, and stony corals are the dominant sessile fauna within shallow, hard-bottom communities in the Florida Keys, FL (USA). The sponge component of these communities is not well studied and has been cyclically decimated from as early as 1844, most recently in south-central Florida Bay in 1991 and 1992, in apparent association with phytoplankton blooms. The purpose of this research was to examine ways in which sponges may contribute to the maintenance of hard-bottom communities. Specifically, I investigated: 1) the effect of sponges and physical structures on local sea floor scouring and thus the potential for maintenance of hard-bottom; …

Spatial And Trophic Dynamics Of A Macrofaunal Community On A High Energy Intertidal Sandflat, Sharon Ann Tatem

Biological Sciences Theses & Dissertations

Spatial and trophic interactions between macrofaunal species were studied in a high energy intertidal system during spring-summer low tides. Bioturbation by the enteropneust hemichordate, Balanoglossus aurantiacus (Girad), as evidenced by large fecal mounds, was a conspicuous feature on the sandflat Sediment characteristics were compared between ambient (non-fecal) and B. aurantiacus fecal mound types (fresh-oxidized, fresh-reduced, aged-oxidized, and aged-reduced). Fecal material was differentiated by age based on the presence or absence of mucus and the time of fecal deposition. The color of fecal material was used to assign oxidative state. Multiple isotopes (carbon, nitrogen, sulfur) were used to determine the origins …

Food Limitation In Larval Fish: Ontogenetic Variation In Feeding Scope And Its Potential Effect On Survival, Alexander B. Bochdansky, Peter Grønkjær, Pierre Pepin, William C. Leggett

OES Faculty Publications

We used the radiated shanny Ulvaria subbifurcataas a model species to explore the relative gut fullness from hatch to metamorphosis of wild larvae, and compared these values with those of laboratory-reared larvae fed at maximum rates. Ingestion rates of most wild larvae were above starvation levels but below the maximum feeding levels of laboratory-reared larvae. Twenty-six percent of freshly-hatched wild larvae and 11% of large, pre-settlement wild larvae had insufficient food in their stomach to satisfy metabolic requirements. These results, taken on their own, are consistent with the much hypothesized increased foraging performance and survival of larger larvae relative …

Low-Density Rodent Communities In Eastern Virginia, Robert K. Rose, Jean F. Stankavich

Virginia Journal of Science

Two communities of small mammals were live trapped every other week for 15 months in linear oilfield habitat bordered by forested swampland in eastern Virginia. All nine species of the rodent community were present, mostly in low numbers and often intermittently. All species were characterized by high transiency, with a minority of marked animals becoming resident. Despite high trappability, all but two species in these communities had extremely low densities, suggesting that most species could not sustain populations via in situ reproduction.

Microspore Wall Morphogenesis And Orbicule Ultrastructure Of Isoetes, Khalid Alarid

Biological Sciences Theses & Dissertations

The microspore wall morphogenesis and orbicule ultrastructure of Isoetes were studied using electron microscopy. Microspore wall morphogenesis in five species of Isoetes (I. appalachiana, I. engelmannii, I. hyemalis, I. piedmontana, and an undescribed species from York Co., VA, USA) was studied using scanning and transmission electron microscopy. Results show that they generally have the same developmental stages in terms of microspore wall morphogenesis. The mature microspore wall consisted of four layers: perispore, paraexospore, exospore and endospore. Paraexospore formation began during the tetrad stage. The exospore was then formed between the paraexospore and the plasma membrane. During the free spore …

Interactions Between Changing Pco2, N2 Fixation, And Fe Limitation In The Marine Unicellular Cyanobacterium Crocosphaera, Fei-Xue Fu, Margaret R. Mulholland, Nathan S. Garcia, Aaron Beck, Mark E. Warner, Sergio A. Sañudo, David A. Hutchins

OES Faculty Publications

We examined the physiological responses of steady-state iron (Fe)-replete and Fe-limited cultures of the biogeochemically critical marine unicellular diazotrophic cyanobacterium Crocosphaera at glacial (19 Pa; 190 ppm), current (39 Pa; 380 ppm), and projected year 2100 (76 Pa; 750 ppm) CO₂ levels. Rates of N₂ and CO₂ fixation and growth increased in step with increasing partial pressure of CO₂ (pCO₂), but only under Fe- replete conditions. N₂) and carbon fixation rates at 75 Pa CO₂ were 1.4-1.8-fold and 1.2-2.0-fold higher, respectively, relative to those at present day and glacial pCO_{2 …}

Mycobacteriosis-Associated Mortality In Wild Striped Bass (Morone Saxatilis) From Chesapeake Bay, Usa, D. T. Gauthier, R. J. Latour, D. M. Heisey, C. F. Bonzek, J. Gartland, E. J. Burge, W. K. Vogelbein

Biological Sciences Faculty Publications

The striped bass (Morone saxatilis) is an economically and ecologically important finfish species along the Atlantic seaboard of the United States. Recent stock assessments in Chesapeake Bay (USA) indicate that non-fishing mortality in striped bass has increased since 1999, concomitant with very high (>50%) prevalence of visceral and dermal disease caused by Mycobacterium spp. Current fishery assessment models do not differentiate between disease and other components of non-fishing mortality (e. g., senescence, predation); therefore, disease impact on the striped bass population has not been established. Specific measurement of mortality associated with mycobacteriosis in wild striped bass is …

Ancient Dna Identification Of Early 20th Century Simian T-Cell Leukemia Virus Type 1, Sebastien Calvignac, Jean-Michel Terme, Shannon M. Hensley, Pierre Jalinot, Alex D. Greenwood, Catherine Hanni

Biological Sciences Faculty Publications

The molecular identification of proviruses from ancient tissues (and particularly from bones) remains a contentious issue. It can be expected that the copy number of proviruses will be low, which magnifies the risk of contamination with retroviruses from exogenous sources. To assess the feasibility of paleoretrovirological studies, we attempted to identify proviruses from early 20th century bones of museum specimens while following a strict ancient DNA methodology. Simian T-cell leukemia virus type 1 sequences were successfully obtained and authenticated from a Chlorocebus pygerythrus specimen. This represents the first clear evidence that it will be possible to use museum specimens to …

Oviposition Behavior Partitions Aquatic Landscapes Along Predation And Nutrient Gradients, C. A. Binckley, W. J. Resetarits Jr.

Biological Sciences Faculty Publications

That individuals attempt to minimize the ratio of mortality risk/growth rate (μ/g) when foraging within individual habitat patches is well established. Do species partition among spatially discrete communities embedded in complex landscapes in a similar manner? We investigated how 3 ovipositing species (2 Hyla treefrogs and a hydrophilid beetle, Tropisternus lateralis) responded to simultaneous gradients of nutrients and predation risk. Species partitioned our experimental metacommunity primarily by reducing oviposition with fish. Tropisternus positively responded to increased nutrients, but the effect decreased with increasing risk, as predicted by μ/g theory. Use of fish habitats by Tropisternus was unrelated to breeding …

Population Ecology Of The Golden Mouse, Robert K. Rose

Biological Sciences Faculty Publications

An understanding of the population dynamics of a species requires knowledge of the major life-history parameters of a population, including age at maturity, distribution of age classes, and lifetime reproductive contribution of the sexes, sex ratio, length of the breeding season, mean litter size, rates of growth and survival, and life span. Because few long-term studies have been conducted with Ochrotomys nuttalli as the focal species of investigation, only fragmentary information is available for many population parameters. As importantly, densities of golden mice often are low, making them difficult to evaluate statistically. Little has been published on age at maturity …