Animal Sciences Commons^™

Population Dynamics Of Feral House Mice And Meadow Voles On A Dredge Disposal Site, Georgia E. Kratimenos

Biological Sciences Theses & Dissertations

The population dynamics of two species was studied for one year on Craney Island in Portsmouth, Virginia. This dredge disposal site provided good habitat for the house mouse, Mus musculus, whose opportunistic behaviors can withstand the sudden changes in a dynamic environment. Although the site was not optimal habitat, a population of Microtus pennsylvanicus, the meadow vole, was sustained there. Of the seven species of small mammals captured, 65% were house mice and 28% were meadow voles. Meadow voles were more successful at establishing short periods of residency than were house mice; on average, each meadow vole was …

Computer Simulation Techniques To Assess Bias And Precision In The Roving Creel Survey Estimator, David L. Wade

Biological Sciences Theses & Dissertations

Fisheries scientists use roving creel survey methods to estimate total catch and total effort of recreational fisheries. Bias in the roving creel estimators had been known to the scientific community, but it had not been quantified. I developed a roving-creel-survey computer simulation model to investigate the bias and precision of roving creel estimators, and estimated parameters for the model based on field observations from the blue crab (Callinectes sapidus) fishery of the Chesapeake Bay. The computer model was used to identify bias in roving-creel effort and catch estimators and to demonstrate survey methods that will reduce this bias. …

A Laboratory Study Of Predation On The Trinidadian Guppy, Poecilia Reticulata, By Two Natural Piscine Predators: Effects Of Predator Size, Prey Size, And Habitat Complexity, Hayden Thomas Mattingly

Biological Sciences Theses & Dissertations

Test populations of different-sized guppies, Poecilia reticulata, were exposed to individuals of two natural predatory species, the pike cichlid Crenicichla a/ta and the killifish Rivulus harti, under conditions of varying prey (guppy) density and habitat complexity in the laboratory. Rivulus fed most frequently on newborn and juvenile guppies < 14 mm. Crenicichla consumed more and larger guppies than did Rivulus. The mean guppy size eaten by Crenicichla was dependent on the length of the individual predator, but as a group, the 15 Crenicichla tested were non-selective with respect to guppy size and gender. The prey gender preference of Rivulus could not he determined …

The Identification, Distribution, And Status Of The Threatened Dismal Swamp Shrew (Sorex Longirostris Fisheri), Thomas M. Padgett

Biological Sciences Theses & Dissertations

Southeastern shrews (Sorex longirostris) were trapped throughout southeastern Virginia and northeastern North Carolina to determine if any morphological characters could

be identified that would aid in the identification and distribution of the threatened subspecies Sorex l._ fisheri, endemic to the Great Dismal Swamp, the more upland nominate subspecies Sorex l. longirostris, and possible intergrades between the two subspecies. Animals were classified a priori into three groups, based on their location of capture. Animals collected from the Great Dismal Swamp National Wildlife Refuge (GDSNWR) and associated bottomland habitats were designated as "fisheri", animals collected farthest from the Swamp as "longirostris", and …

Age Growth And Reproduction Of Black Drum, Pogonias Cromis, In Virginia, Stephen J. Bobko

Biological Sciences Theses & Dissertations

The black drum, Pogonias cromis, is of great economic importance to the communities of the lower Eastern Shore of Virginia. Fish are sought both commercially and recreationally during their yearly spring spawning run. Although the number of fish caught each year does not rival other exploited species, it is a directed fishery that partially supports many local fishermen, seafood distributors, marinas, motel owners, and restauranteurs.

Black drum were collected during the fall of 1989 and the spring of 1990 to investigate the population dynamics of fish found in Virginia's Chesapeake Bay and surrounding coastal waters. A total of 235 fish …

The Effects Of Two Polycyclic Aromatic Hydrocarbons Benzo[A]Pyrene And Naphthalene On Reproductive Success Embryological Development Larval Physiology And Mortality Of The Mud Crab Rhithropanopeus Harisii (Gould), Gregory V. White

OES Theses and Dissertations

Polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap) and benzo[a]pyrene (B[a]P) are common in the water column and sediments of estuarine and coastal areas. The mud crab Rhithropanopeus harrisii was exposed to varying concentrations of Nap or B[a]P to determine the effects on reproductive success, embryological development, larval physiology and mortality. Nap and B[a]P decreased hatching success and prolonged embryological development. Both pollutants produced high abnormality frequencies for egg exposed larvae. Molt frequency and respiratory rates of larvae from non-exposed eggs were more chronically affected by these pollutants than were egg exposed larvae. The EC₅₀ concentrations were determined for …

Small Mammals In The Great Dismal Swamp Of Virginia And North Carolina, Robert K. Rose, Roger K. Everton, Jean F. Stankavich

Biological Sciences Faculty Publications

Small" mammals were surveyed in a range of habitats in the Great Dismal Swamp of Virginia and North Carolina. The survey is based on three chronologically overlapping studies, each lasting 15-18 months and for which the results have been reported separately. A different trapping method was used in each of the three studies: nest boxes, Fitch live traps, or pitfall traps. Only two species of mammals, both arboreal, were taken in nest boxes, compared with 10 and 9 species in Fitch live traps and pitfall traps, respectively. The Fitch live traps had a much higher catch rate per 1,000 trap-nights …

Reproduction In The Hispid Cotton Rat, Sigmodon-Hispidus Say And Ord (Rodentia: Muridae), In Southeastern Virginia, Robert K. Rose, Michael H. Mitchell

Biological Sciences Faculty Publications

The hispid cotton rat, Sigmodon hispidus Say and Ord, a species of the southwestern United States that has been moving northward and eastward in this century, was first observed in Virginia in 1940. In this study of the cotton rat in southeastern Virginia, most males were reproductively competent from February through November, embryos were recorded from March through October, and litter sizes were comparable to those from other locations except Kansas. Also unlike the cotton rat in Kansas, animals grew at substantial rates during the winter in Virginia. The hispid cotton rat seems to have adjusted its breeding season in …

An Analysis Of External Features As Predictors Of Reproductive Status In Small Mammals, Kenneth Wayne Mccravy

Biological Sciences Theses & Dissertations

Reproductive status in specimens of nine populations of seven species of small mammals was evaluated by examining the external reproductive features of nipple size, condition of the pubic symphysis, and vaginal condition and, in males, testis position. Usefulness of these external features in predicting true monthly breeding rates was evaluated by comparing predictions of breeding rates with true rates based on necropsy. Accuracy of predictions of reproductive status of individuals based on single external features and combinations of external features and body measurements was then analyzed at a finer level by comparing those predictions with results of necropsy of the …

Comparison Of The Protein Content In Selected Tissues At Different Feeding Stages In The American Dog Tick Dermacentor Variabilis (Say), Mark John Beveridge

Biological Sciences Theses & Dissertations

Selected tissues from Dermacentor yariabilis (Say) were collected at different feeding stages (unfed, part-fed, and replete) and examined by several different protein analyses to determine soluble protein content, protein or polypeptide molecular weights, and pI values. Results showed a relationship between the salivary gland, ovary and hemolymph and evidence indicates the synganglion produces and secretes substances that may control oocyte development.

Investigations Of The Trophic Relationships, Feeding Ecology And Feeding Behavior Of Larval Spot, Leiostomus Xanthurus Lacepede, And Atlantic Croaker, Micropogonias Undulatus (Linnaeus) (Pisces:Sciaenidae), Dirk Edward Peterson

Biological Sciences Theses & Dissertations

The feeding ecology of preflexion and flexion-postflexion spot (Leiostomus xanthurus) and Atlantic croaker (Micropogonias undulatus) larvae was evaluated and compared. Nutritional condition of spot larvae from the Gulf of Mexico was high, with no larvae classified as starving. This was probably due to an inability to sample starving larvae at sea because of predation pressure or was indicative of favorable feeding conditions and an absence of starvation in the collection area. In spite of morphological similarities between the species, significant differences in body shape existed.

The diets of the two species converged with age and interspecific dietary overlap was relatively …

Fecundity Of Blue Crab, Callinectes Sapidus, In Chesapeake Bay: Biological, Statistical And Management Considerations, Michael H. Prager, John R. Mcconaugha, Cynthia M. Jones, Patrick J. Geer

OES Faculty Publications

Ovigerous blue crabs were collected from the mouth of Chesapeake Bay during the 1986 and 1987 spawning seasons. Mean carapace width was 14.7 cm; mean fecundity was 3.2×106 eggs. Fecundity was significantly related to carapace width, and did not vary significantly with developmental stage of the eggs. Mean fecundities were 2.6×106 eggs in 1986, and 4.0×106 eggs in 1987. An additive model with year and size effects described the observed fecundities reasonably well, was compact, and was easier to interpret than a multiplicative model. To fit a more general model without year effects, the authors took the mean of 1986 …

Estimates Of Spawning Stock Size Of Blue Crab, Callinectes Sapidus, In Chesapeake Bay, 1986-1987, Cynthia M. Jones, John R. Mcconaugha, Patrick J. Geer, Michael H. Prager

OES Faculty Publications

The 1986 spawning stock exhibited a single abundance peak, increasing from 1.0×105 individuals in early July to 9.3×106 in late July, maintaining high levels throughout the summer, and declining in the fall to 7.4×105 individuals. The 1987 spawning stock showed 2 peaks of abundance. The population reached the lesser peak, 1.0×106 individuals, in late July; the greater peak, 1.5×106, in late August. By late September, the population had declined to 6.5×105 individuals. The peak abundance of the 1987 female spawning stock was only 16% as great as the peak abundance in 1986; the 1987 spawning stock size in 1986. Variability …

The Temporal And Spatial Distribution Of Blue Crab Larvae On The Mid-Atlantic Bight Adjacent To The Chesapeake Bay, 1982-1983, Lyle Michael Varnell

OES Theses and Dissertations

Recruitment processes are important information for the management of commercially and recreationally exploited marine species. Recruitment processes of the Chesapeake Bay's most important commercial and recreational species, the blue crab, are unknown, due in part to the lack of knowledge of the processes directly preceeding recruitment.

The present study was undertaken to investigate and explain the movement and developmental patterns of blue crab larvae while offshore. Interannual and intraseasonal variations of these patterns were also examined.

Sampling occurred from May to November during 1982 and 1983. Larvae were collected at three depths (neuston layer (upper 10 cm), one meter and …

The Development And Comparative Morphology Of The Mandibular Symphysis In Salamanders, Jennifer Lorenz Elwood

Biological Sciences Theses & Dissertations

Despite the extensive literature on salamander cranial morphology, few authors mention the structure or development of the mandibular symphysis. Adult specimens representing eight caudate families and larval Ambystoma opacum, representing nine developmental stages, were evaluated histologically to determine the structure and development of the mandibular symphysis.

From this analysis it was determined that early in the ontogeny of the mandibular symphysis Meckel's cartilages are separated by a band of undifferentiated cartilage. As development progresses, this band of undifferentiated cartilage gradually transforms into a wedge of fibrocartilage which fuses to Meckel's cartilages.

Symphyseal morphologies of the adult caudates could be broken …

A Review Of The Pacific Members Of The Gobiid Fish Genus Bollmannia Jordan, Robin L. Bedenbaugh

Biological Sciences Theses & Dissertations

The Pacific members of the genus Bollmannia Jordan 1890 comprise seven species of gobies distributed from Baja California to Peru and west to the Galapagos Archipelago.

Previous authors recognized nine nominal species, all known only from their brief original accounts. Those accounts do not allow for proper discrimination of the species. All nominal species were re­ examined using meristic, morphometric, and pigment-pattern characteristics. Three of the nine nominal species are herein considered synonymous with previously described forms. The six valid nominal species are redescribed, a new species is described, and a key and illustrations are provided for the seven valid …

A Light And Electron Microscopic Study Of The Rat Olfactory Tubercle: Normal Morphology And Acetylcholinesterase Localization, James Curtis Woodley

Biological Sciences Theses & Dissertations

A cytoarchitectural analysis of the rat olfactory tubercle using Nissl-stained coronal sections revealed that the dense cell layer (DCL) consisted of medium sized striatal cells in the cortical regions and small sized "granule" cells in the cap regions. Also delineated from this experiment was a rim of neuropil, nearly devoid of neurons as well as neuronal processes, outlining the islands of Calleja. Acetylcholinesterase (AChE) localization utilizing light microscopy revealed that the olfactory tubercles (OT) contained AChE-positive fibers that were orientated dorsoventrally in the molecular and multiform layers. The DCL consisted of only fibers en passant and putative terminals. Diisopropylfluorophosphate (DFP) …

Comparative Analysis Of The Effects Of Visual And Auditory Stimuli On Avian Mobbing Behavior, C. Ray Chandler, Robert K. Rose

Biological Sciences Faculty Publications

Both visual and auditory stimuli elicit avian mobbing behavior, but there is little comparative information on their isolated and additive effects. Using three combinations of two experimental stimuli (mount and tape of an Eastern Screech-Owl, Otus asio) we tested the effects of stimuli on the frequency, intensity, and duration of avian mobbing behavior. Of 169 mount-only trials, only 11 (6.5%) were successful in attracting birds. Tape-only (n = 169) and mount-and-tape (n = 170) were equally successful in attracting birds (approximately 85% of all trials), but mount-and-tape trials were more likely to initiate mobbing behavior. Birds responding …

Age And Growth Of The Tautog, Tautoga Onitis (Pisces: Labridae), From Lower Chesapeake Bay And Coastal Waters Of Virginia, E. Brian Hostetter

Biological Sciences Theses & Dissertations

The tautog, Tautoga onitis (Pisces: Labridae), is rapidly gaining popularity in Virginia by anglers, spearfishermen and specialized commercial interests. In Virginia, tautog are seasonally abundant on hard bottom substrates in nearshore (ca. 2-10 m) habitats and inhabit offshore wrecks and reef areas (ca. 10-30 m) year round. Habitat restriction and slow growth of the species coupled with recent technological advances in marine electronics which simplify locating tautog populations by user groups may contribute to overexploitation of tautog within the region.

Tautog were collected over a two year period from the lower Chesapeake Bay and nearshore waters of the Atlantic Ocean …

Use Of Woody Vegetation By Beavers In Southeastern Virginia, John L. Echternach, Robert K. Rose

Biological Sciences Faculty Publications

Nonbreeding and sometimes transient beavers, Castor canadensis, cut a variety of woody plants throughout the year during a 15-month study at three sites in southeastern Virginia. Ten species of trees were cut in proportions greater than would be expected according to their availabilities. Beavers heavily used viburnum, alder, ironwood, bayberry, tulip poplar, and dogwood. Winter food caches were constructed but were only lightly used.

Growth Potential Of Young Black Sea Bass, Centropristis Striata, In Artificial Environments, Joung Won Kim

OES Theses and Dissertations

The growth potential of the commercially important marine finfish, black sea bass (Centropristis striata), was examined for aquaculture under controlled conditions. The effect of food and body weight on growth was evaluated using juveniles and young black sea bass cultured with a natural diet and a commercial diet at various feeding levels.

Growth was affected by type of food, food consumption rate, and fish body weight. For fish having positive weight gain, absolute growth rate (gram/day) increased exponentially as food consumption rate (percent of body weight per day) and/or body weight increased. Instantaneous growth rate (percent of body weight per …

A Comparison Of Potential Fishing Methods Associated With Fish Aggregating Devices Off The Northeast Coast Of Puerto Rico, Alan M. Friedlander

OES Theses and Dissertations

Six fish aggregating devices (FADs) were deployed in June and monitored through December 1986. Emphasis was placed on trolling, live-bait handlining and longlining.

There was a significant difference (x2 = 7.815, pCoryphaena hippurus) which made up 64.2% of the catch.

Handlining at night around inshore buoys for one boat yielded 82.7 kg per trip. Pelagic fish comprised 83.9% of the catch, with the majority (81.4%) being kingfish (Scomberomorous cavalla). Catch rates were 50% higher and the species diversity much greater on the FADs versus control during experimental nightfishing, but the difference was not significant.

Longlining resulted in 3.4 …

The Identification Of The Threatened Southeastern Shrew Using Multivariate Statistical Techniques, Thomas M. Padgett, Roger K. Everton, Robert K. Rose

Biological Sciences Faculty Publications

The threatened subspecies of the southeastern shrew, Sorex longirostris fisheri, is endemic to the Great Dismal Swamp of southeastern Virginia. Previous studies based on discriminant analysis of external measurements determined that intergrades with the upland form, Sorex l. longirostris, exist along the periphery of the Swamp. To better discriminate among these populations, a study of cranial morphology was initiated. Fifteen cranial measurements were taken, using 59 specimens of Sorex collected previously form southeastern Virginia, including the Dismal Swamp. Both Principal Component and Cluster Analyses revealed no significant cranial variation or morphometric patterns within the specimens examined, but a …

Distribution And Current Status Of The Threatened Dismal Swamp Southeastern Shrew, Sorex Longirostris Fisheri, Robert K. Rose, Roger K. Everton, Thomas M. Padgett

Biological Sciences Faculty Publications

The Dismal Swamp southeastern shrew, Sorex longirostris fisheri, was given "Threatened" status by the U.S. Fish and Wildlife Service in 1986 because of its limited distribution and the potential threat of interbreeding with the nearby upland subspecies, Sorex l. longirostris. Known from about 20 specimens collected before 1980 and a few dozen taken since then, "fisheri" seems to have morphologically diverged from the smaller upland "longirostris" in association with the development of the Dismal Swamp. The detection of southeastern shrews that are intermediate in size between the two subspecies, coupled with the location of these collection sites on …

Validation Of The Otolith Increment Aging Technique For Striped Bass, Morone Saxatilis, Larvae Reared Under Suboptimal Feeding Conditions, Cynthia Jones, Edward B. Brothers

OES Faculty Publications

Striped bass, Morone saxatilis, larvae were reared in the laboratory for 97 days to validate the otolith increment aging technique for this species. Otolith-increment deposition rates were determined under optimal laboratory conditions for growth and under three conditions of restricted feeding and using both light and scanning electron microscopy (SEM). Under optimal laboratory conditions. increments were deposited daily from the fourth day after hatching through the first 2 months of life and were discernible with the light microscope. For larvae reared under restricted feeding regimes and readings done with the light microscope, counts did not reflect true age. Counts …

Environmental Factors Affecting Nocturnal Migrations Of Macrobenthos, C. Timothy Morris

Biological Sciences Theses & Dissertations

Nocturnally dispersing macrobenthic invertebrates of the Lafayette River, Norfolk, Virginia were collected from September 4 to October 4, 1982 to determine environmental factors affecting migrations. A total of 55 taxa were identified from 325 surface and bottom nocturnal plankton tows. Peracaridan crustaceans were the dominant (99.0% of the total density) group collected. Six of the commonly collected species showed a significant (P

Late Prehistoric And Protohistoric Large Mammal Zoogeography Of Virginia, Robert K. Rose

Biological Sciences Faculty Publications

Evidence derived from18late prehistoric (middle and late Woodland Period) archeological sites, from several early historical accounts, and from the current understanding of the distribution of Virginia mammals indicates that the large mammal fauna of the Commonwealth has not changed substantially within the past 4,000 yrs. Some species (e.g., bison, elk, timber wolf, and mountain lion) have been extirpated since the settlement of Virginia by Europeans; some previously extirpated species (e.g., porcupine, coyote, and beaver) have been naturally or artificially reintroduced during the historical period, and others (e.g., woodchuck and red fox) probably have expanded their distributions as a result of …

Reproductive Strategies Of Meadow Voles, Hispid Cotton Rats, And Eastern Harvest Mice In Virginia, Robert K. Rose

Biological Sciences Faculty Publications

Patterns of reproduction in small mammals in Virginia were examined by autopsying samples of meadow voles (Microtus pennsylvanicus) collected for 23 months near Charlottesville, of hispid cotton rats (Sigmodon hispidus) collected for 14 months in Portsmouth, and by evaluating live-caught eastern harvest mice (Reithrodontomys humulis) trapped for 15 months in Suffolk and for 12 months in Chesapeake. The meadow vole, a microtine rodent with a north temperate and sub-arctic distribution throughout North America, suspended breeding during the winter of peak density but not of declining density. High metabolic rates and other adaptations for winter …

The Relationship Between Habitat Structure And Small Mammal Communities In Southeastern Virginia And Northeastern North Carolina, Roger Keith Everton

Biological Sciences Theses & Dissertations

A variety of terrestrial habitats was pitfall trapped in the vicinity of the Great Dismal Swamp of eastern Virginia and North Carolina to evaluate the small mammal community within the region. Habitat variables were measured at the end of the growing season on 21 0.25 ha grids. Four multivariate tests were used to examine the small mammal communities, their relationship with habitat structure, and the role of habitat selection in community structure.

Cluster and ordination analysis revealed the existence of two distinct associations of small mammals, and their habitat types, within the region. The small mammal associations were interpreted as …

Community Ecology, Robert K. Rose, Elmer C. Birney

Biological Sciences Faculty Publications

COMMUNITIES with Microtus tend to be structurally simple, usually grasslands or tundra, and to have no more than two species of Microtus and rarely more than six species of small mammals. Microtus often dominates both numerically and in total small mammal biomass, especially at higher latitudes. The small mammal community is most influenced by Microtus through its fluctuations in density, and thus also in biomass, by its relatively high level of diurnal activity, and by its year-round activity. Other species of small mammals may be adversely affected because Microtus usually is larger and behaviorally dominant and also because the mere …