Life Sciences Commons^™

Comparative Taphonomy And Paleoecology Of A Glaciomarine Fauna, Carboniferous (Westphalian- Namurian) La Capilla Fm., Argentina, Rex A. Hanger, Mohutsiwa Gabadirwe

Virginia Journal of Science

The Carboniferous La Capilla Fm. of the Calingasta-Uspallata basin of western Argentina contains a low diversity fauna inhabiting a continental shelf under glacial ice fronts advancing from the east. Distal glaciomarine sediments on these ice-influenced shelves of Gondwana are most commonly interpreted as being deposited under quiet, low-energy conditions. Ta­phonomic and paleoecologic analysis of a sample of the fauna reveals the following: low species richness, yet comparable equitability to coeval, tropi­cal faunas; low articulation ratios and high pedicle valve dominance for brachiopods; diverse corrasion modes, about half relatively high categories; one hundred percent fracturing of brachiopod shells, with carinate fracture …

The Impact Of Resident And Transient Predators On The Popultation Dynamics Of Juvenile Caribbean Spiny Lobster (Panulirus Argus) In Florida Bay, Florida, Jason Edward Schratwieser

Biological Sciences Theses & Dissertations

There has been a considerable amount of research devoted to exploring the relationship between predators and prey, but many of these studies fail to address how predation can vary over spatial and temporal scales. The tendency of ecologists to model predation as a static entity often masks its capacity for creating distinctive effects in prey populations and communities. Most predation studies also focus on the effect of a single species of predator on a prey population, an unrealistic situation in nature. In the Florida Keys, juvenile spiny lobsters are subjected to two general classes of predators: i) "resident" predators such …

A Study Of The Seasonal Composition And Abundance Of Phytoplankton And Autotrophic Picoplankton In A Brackish Water Lake In Portsmouth Virginia, Jennifer Leigh Wolny

Biological Sciences Theses & Dissertations

The phytoplankton and autotrophic picoplankton populations of Hoffler Lake, a brackish-water lake in Portsmouth, Virginia, were monitored from May 1997 through May 1998, Analyses of the phytoplankton community using the Utennohl method showed a dominance of Chlorophytes (61-88% of the total abundance) throughout the year, including a winter bloom of Chlamydomonas snowii (maximum concentration of 2.5 x 101 cells/L). Subdominants were Cyanobacteria (10-33% of the total abundance) whose composition included several species of Anabaena, Lyngbya, and a fall bloom of Microcoleus sp. Diatoms, dinoflagellates, and cryptophytes played a secondary role in the phytoplankton community of Hoffler Lake. …

Use Of Extractable Lipofuscin For Age Determination Of Blue Crab Callinectes Sapidus, Se-Jong Ju, David H. Secor, H. Rodger Harvey

OES Faculty Publications

The blue crab Callinectes sapidus is an economically and ecologically important species in many temperate estuaries, yet stock assessments have been limited to length-based methods for demographic analyses. We evaluated the potential of age pigments (lipofuscins) sequestered in neural tissue of eye-stalks and brains to estimate the age of blue crabs collected from Chesapeake Bay and Chincoteague Bay. The rate of lipofuscin accumulation was determined using crabs of known age reared in the laboratory. Age pigments were extracted from neural tissues (eye-stalk or brain), quantified, and normalized to protein content to allow comparisons across tissue types and crab sizes. Field-collected …

Adaptive Strategies That Reduce Predation On Caribbean Spiny Lobster Postlarvae During Onshore Transport, Charles A. Acosta, Mark J. Butler Iv

Biological Sciences Faculty Publications

Like many marine species with meroplanktonic larvae, the Caribbean spiny lobster (Panulirus argus) has a postlarval stage that moves from the oceanic plankton to inshore nurseries only under specific environmental conditions (i.e., at night, in the surface water layer, on the flood tide, and during new moon), presumably to avoid predation or to enhance onshore transport. Using held and mesocosm experiments, we compared predation on planktonic postlarvae swimming at night near the surface and bottom over coastal habitats along typical offshore-inshore transport paths and determined whether predation rates differed between lunar periods (new moon vs, full moon) and with prey …

Conservation Status Of The Southern Appalachian Herpetofauna, Joseph C. Mitchell, Thomas K. Pauley, David I. Withers, Steven M. Roble, Brian T. Miller, Alvin L. Braswell, Paul V. Cupp Jr., Christopher S. Hobson

Virginia Journal of Science

Seventy one species of amphibians (55 salamanders, 16 anurans) and 46 species of reptiles (15 turtles, 8 lizards, 23 snakes) inhabit a five state area (Kentucky, North Carolina, Tennessee, Virginia, West Virginia) in the southern Appalachian region bordered by the Potomac River, the Blue Ridge Mountains, and the western margin of the Appalachian Plateau. Of these, 47.9 % of the amphibian fauna and 52.2 % of the reptilian fauna are listed as being of conservation concern by federal, state, and Natural Heritage programs in all or a portion of their ranges of this region. The Shenandoah salamander (Plethodon Shenandoah …

Possible Predation Scars On Rectithyris Subdepressa (Stoliczka, 1872), Late Cretaceous (Maastrichtian) Kallankurichi Fm., India, Rex Alan Hanger, Rama Krishnaswamy

Virginia Journal of Science

A single specimen of the terebratulid brachiopod, Rectithyris subdepressa (Stoliczka, 1872) from the Late Cretaceous (Maastrichtian) Kallankurichi Fonnation of southern India was found with durophagous predation traces. This occurrence is significant as it is possibly the first documentation of elasmobranch shark predation on brachiopods from the Mesozoic.

Benthic Community Analysis Of Hog Island Bay, Virginia, David James Lewis

Biological Sciences Theses & Dissertations

The benthic infaunal macroinvertebrate communities of Hog Island Bay of the Virginia Eastern Shore were quantitatively sampled at 30 locations on August 31 and September 1, 1995. The primary objectives of this study were: (1) to characterize the subtidal macroinfaunal benthic communities of Hog Island Bay, (2) to examine relationships between abiotic factors and the macroinfaunal communities and (3) to characterize the environmental condition of the system using the Benthic Index of Biotic Integrity (B-IBI) (Weisburg et al. 1997) and the EMAP Benthic Index for the Virginian Province (Strobel et al. 1995).

The ecological condition of Hog Island Bay appears …

Monitoring Results For Pfiesteria Piscidida And Pfiesteria-Like Organisms From Virginia Waters In 1998, Harold G. Marshall, David W. Seaborn, Jennifer Wolny

Virginia Journal of Science

Results of an extensive 1998 monitoring program for the presence of Pfiesteria-like organisms (PLO) in Virginia estuaries indicate these dinoflagellates are widely distributed in both the water column, and as cysts in the sediment, however Pfiesteria piscicida was not detected at this time. The highest concentrations of PLO were in estuaries along the Virginia shore line of the Potomac River, and in western Chesapeake Bay estuaries from the Little Wicomico River to the Rappahannock River. The most common PLO included Cryptoperidiniopsis sp. and Gymnodinium galatheanum. The lowest PLO concentrations were at ocean side locations. PLO were also …

The Impacts Of External Nutrient Sources On Marine Phytoplankton In An Eastern Shore Sea-Side Estuary, Claudette Lajoie Jenkins

OES Theses and Dissertations

The Eastern Shore of Virginia (Greens Creek) as well as a large portion of the North Atlantic coastline is characterized by estuarine systems not dominated by large river systems. Instead, small freshwater creeks influence many coastal systems yet little information has been documented on their ecological significance. The focus of this research is to identify the biogeochemical and physical interactions within an estuarine water-column and understand the importance of freshwater sources in governing phytoplankton production. The hypothesis of this research is that increases in external nutrient loading into Greens Creek will not result in an increase in primary production. The …

Growth And Yield-Per-Recruit Modeling Of Spot (Leiostomus Xanthurus) In The Chesapeake Bay, And A Comparison Of Biological Reference Points, Kevin Ray Piner

Biological Sciences Theses & Dissertations

Spot were sampled from the Chesapeake Bay commercial fishery from 1993–1995 to determine if spot are overfished. Transversely sectioned otoliths were determined to be the most appropriate structure for ageing spot. It was determined that spot have a high natural mortality rate (M = 0.9) and fast growth (K = 0.6). This combination of M and K makes spot relatively impervious to growth overfishing as determined by yield-per-recruit modeling. Because spot are nearly impervious to growth overfishing, management thresholds based on yield-per-recruit modeling may be inappropriate. In addition, the combination of high M and fast K makes it possible to …

Monitoring Results For Pfiesteria Piscidida And Pfiesteria-Like Organisms From Virginia Waters In 1998, Harold G. Marshall, David W. Seaborn, Jennifer Wolny

Biological Sciences Faculty Publications

Results of an extensive 1998 monitoring program for the presence of Pfiesteria-like organisms (PLO) in Virginia estuaries indicate these dinoflagellates are widely distributed in both the water column, and as cysts in the sediment, however Pfiesteria piscicida was not detected at this time. The highest concentrations of PLO were in estuaries along the Virginia shore line of the Potomac River, and in western Chesapeake Bay estuaries from the Little Wicomico River to the Rappahannock River. The most common PLO included Cryptoperidiniopsis sp. and Gymnodinium galatheanum. The lowest PLO concentrations were at ocean side locations. PLO were also …

Pfiesteria Piscicida And Dinoflagellates Similar To Pfiesteria, Harold G. Marshall

Biological Sciences Faculty Publications

Pfiesteria pisiccida is a microscopic, unicellular organism that is classified as both a mixotrophic and heterotrophic dinoflagellate, which has been associated with both fish deaths and a cause of human illness (Burkholder et al., 1992; Glasglow et al., 1995; Burkholder and Glasgow, 1997). This species possesses a complex life cycle that includes motile forms (e.g. zoospores, gametes, amoebae) and a cyst stage that may remain dormant in the sediment (Burkholder et al, 1995b). Pfiesteria piscicida is known to have toxin and non-toxin producing populations, where cyst transformation into the toxic motile zoospores may be initiated by the presence of certain …