Physical Sciences and Mathematics Commons^™

Regenerative Ionic Currents And Bistability, Gregory D. Conradi Smith

Arts & Sciences Book Chapters

What every neuroscientist should know about the mathematical modeling of excitable cells. Combining empirical physiology and nonlinear dynamics, this text provides an introduction to the simulation and modeling of dynamic phenomena in cell biology and neuroscience. It introduces mathematical modeling techniques alongside cellular electrophysiology. Topics include membrane transport and diffusion, the biophysics of excitable membranes, the gating of voltage and ligand-gated ion channels, intracellular calcium signalling, and electrical bursting in neurons and other excitable cell types. It introduces mathematical modeling techniques such as ordinary differential equations, phase plane, and bifurcation analysis of single-compartment neuron models. With analytical and computational problem …

Six Fish And 600,000 Thirsty Folks—A Fishing Moratorium On American Shad Thwarts A Controversial Municipal Reservoir Project In Virginia, Usa, J. E. Olney, Donna M. Bilkovic, Carl Hershner, Lyle M. Varnell, Harry V. Wang, Roger L. Mann

VIMS Books and Book Chapters

Moratoria on fishing directly impact fishers, distributors and marketers of product and can have serious socio-economic implications. Moratoria can impact communities but usually populations closely linked to the banned activity. In an unprecedented example, a moratorium on fishing in Virginia has directly impacted a nonfishing citizenry by thwarting plans for a public utility. In May 2003, a panel empowered to regulate marine resources denied permission to withdraw raw water from a pristine freshwater river, the Mattaponi. The controversial action spoiled a multi-million dollar plan to establish the King William Reservoir, a water source considered essential to future growth and development …

Can We Predict Joint Effects Of Hypoxia And Metals On Fish Survival?, Michael C. Newman

VIMS Books and Book Chapters

Fish are suddenly exposed to hypoxic conditions during diverse events such as seiche- or turnover-related water movements, bottom water release from reservoirs, ice-over of eutrophic arctic lakes, and rapid shifts in respiration: photosynthesis associated with cultural eutrophication. In each case, chemical equilibria established under hypoxic conditions that result in metal dissolution and accumulation suddenly shift toward chemical equilibria of oxic conditions. Critical changes in speciation include those determining the free ion activity that, as expressed by the Free Ion Activity Model (FIAM), is often the most bioactive form of a dissolved metal. Metal phase can also change rapidly and, in …

Evidence For A Relation Between A White Perch Young-Of-The-Year Index And Indices Of Later Life Stages, Thomas C. Mosca Iii, Herbert M. Austin, David M. Plotner

VIMS Books and Book Chapters

Juvenile indices are employed in fisheries management to predict the future abundance of harvestable adults. Frequently, regulations on the utilization of the resource, and a lack of fishery independent abundance data, make verification of the prediction accuracy impossible. In the case of white perch in Virginia, this is not so. Using the weighting system developed for a Chesapeake Bay-wide index of juvenile striped bass abundance based on summertime beach seine data collected in nursery ground waters, we developed a similar index for white perch in the Virginia portion of the Bay. Regressions against Virginia Institute of Marine Science otter trawl …

The Precarious State Of The Chesapeake Public Oyster Resource, William J. Hargis Jr., Dexter S. Haven

VIMS Books and Book Chapters

The 243,000 acres of Virginia's public oyster reefs (a.k.a. the Baylor Grounds) have been extremely productive of usable and saleable (market .md seed) oysters (Crassostrea virginica), oyster shells and oyster shell by-products. Archaeological remains and historical records show that they have yielded great numbers of whole oysters, oyster meats, oyster "seed" and shell since the 01esapeake was formed some 3,000 years BP. In the last century their natural productivity, as indicated by commercial harvest records (the only long-term data available), has declined markedly. In 1904, Vrrginia's total market (adult) oyster harvest was about 7.6 million bushels (mostly from public grounds). …

Chesapeake Bay Fisheries: An Overview, Herbert M. Austin

VIMS Books and Book Chapters

The value of the marine resources of the Chesapeake Bay is second only to its value as a transportation corridor. The oyster, blue crab and striped bass or rock fish, along with the sailboat, epitomize our vision of the Bay. Nowhere else do such important renewable natural resources co-exist so closely to man's residential and industrial activities.

Over time, all natural resource distribution and abundance fluctuates in response to a normally fluctuating environment. Man's harvest adds an additional pressure, and in some cases recruitment levels cannot keep pace with consumer demand. In the Bay, pollutants, both intentional point source discharge, …

A Socio-Economic Overview Of The Chesapeake Bay Fisheries, James E. Kirkley

VIMS Books and Book Chapters

The marine resources of the Chesapeake Bay are believed to provide substantial benefit to residents of the State of Maryland and Virginia. However, the possibility of overfishing and degradation of the marine environment seriously jeopardizes the possible benefit . In thsi section, a brief overview of the economic importance and characteristics of the Chesapeake Bay marine resources is presented. The potential for economic lossee are discussed relative to observed economic values.

Submerged And Emergent Aquatic Vegetation Of The Chesapeake Bay, Carl Hershner, Richard L. Wetzel

VIMS Books and Book Chapters

Chesapeake Bay supports a diverse assemblage of submerged and emergent aquatic vegetation. The distribution of species of each kind of vegetation is governed largely by salinity. The functions of both submerged and emergent vegetation in the Bay ecosystem includes contributing to total net primary production, service a habitat and performance in both water quality and sedimentation processes. Research on submerged aquatic vegetation is focused on its role in the estuarine system and determinants of its distribution and abundance. Research on emergent vegetation still concerns basic questions of structure and function, but has also branched into methodologies for utilization by man …

Contaminant Effects On Chesapeake Bay Finfishes, Ronald J. Klauda, Michael E. Bender

VIMS Books and Book Chapters

Habitat deterioration is consistent with perceived population declines for several resident and anadromous finfish species in Chesapeake Bay that are subjected to different levels of fishing pressure (e.g., striped bass versus blueback herring). Diminution of habitat quality has natural and anthropogenic roots that are difficult to separate. Recent contaminant effects studies focused on Chesapeake Bay fishes can be grouped as follows: (a) mathematical and statistical modeling studies aimed at elucidating contaminant and stock trend relationships using extant data and theoretical insights, (b) biological and chemical field surveys in selected areas to demonstrate spatio-temporal associations between levels of toxic organic and …

Contaminants In Chesapeake Bay: The Regional Perspective, George R. Helz, Robert J. Huggett

VIMS Books and Book Chapters

Industrial and municipal point sources of contaminants are scattered along the shores of Chesapeake Bay and its tributaries, but reach especially high density at Norfolk, Va., and Baltimore, Md. Sedimentation and various chemical processes in many cases conspire to restrict the water-borne transport of contaminant away from point source . Kepone, residual chlorine, volatile halogenated hydrocarbons, and anthropogenic trace metals are well-studied example of point-source contaminants. For the most part, their concentration in water and sediment drop to nearly immeasurable values within a distance of a few kilometers, or sometimes a few tens of kilometers, from their source .

On …

Effects Of Contaminants On Estuarine Zooplankton, Brian P. Bradley, Morrris H. Roberts Jr.

VIMS Books and Book Chapters

The objectives of the chapter are (1) to evaluate laboratory studies concerning effects of heavy metals, pesticides and oxidants on copepods, mysids, bivalve and decapod larvae (2) access field studies (mainly with copepods) on these and other contaminants which when coupled with laboratory data provide information on known and potential hazards of contaminants to zooplankton and (3) briefly review some bioassay methods used in these studies.

Mercury is the most toxic heavy metal by weight, followed by copper, silver and cadmium. Pesticides have been tested much less extensively than heavy metals. In general, bivalve larvae seem less sensitive than the …

Mollusk Culture For The Chesapeake Bay, Michael Castagna

VIMS Books and Book Chapters

The water quality of the Chesapeake Bay has suffered a decline over the last 5 decades due to anthropomorphic activities. Insidious additions of industrial and farm pollutant to the Bay have created a situation where in many areas there are periodic sub lethal levels of chemicals. Although the juveniles and adults seem to survive these levels, they are obviously interfering with some early life stage of the living organisms that make up the bay fauna. Species whose early life history takes place out of the Bay (i.e. Cal!inectes sapidus) are less affected by this problem than those species whose eggs, …

Toxic Substances, R. Bieri, O. Bricker, R. Byrne, R. J. Diaz, Et Al

VIMS Books and Book Chapters

This part of the CBP Synthesis Report summarizes and integrates the research findings and reconnnendations of 13 projects of the Chesapeake Bay Toxic Substances Program performed between July 1978 and October 1981. The following sections describe research on potentially toxic substances, or toxicants, in water-sediments and selected biota. The subjects considered include a brief review of metals, their sources, distribution and behavior, and then a review of sources and distribution of organic chemicals. Finally, information concerning the significance of toxicants in the- Bay and their pattern of enrichment is provided. Most information synthesized in this report can be traced to …

Light And Submerged Macrophyte Communities In Chesapeake Bay: A Scientific Summary, Richard L. Wetzel, Robin F. Van Tine, Polly A. Penhale

VIMS Books and Book Chapters

The initial focus of submerged aquatic vegetation (SAV) research in the U.S. Environmental Protection Agency (EPA), Chesapeake Bay Program (CBP) was evaluation of the structural and functional ecology of these communities. In the upper Bay, Myriophyllum spicatum and Potamogeton perfoliatus are the dominant species; the dominant species in the lower Bay are Zostera marina and Ruppia maritima. Studies centered on various aspects of productivity (both primary and secondary), trophic structure, and resource utilization by both ecologically and economically important species. Much of the initial research was descriptively oriented because of a general lack of information on Chesapeake Bay submerged plant …

Kepone® Residues In Chesapeake Bay Biota, M. E. Bender, R. J. Huggett, W. J. Hargis Jr.

VIMS Books and Book Chapters

Oysters from the James displayed variations in Kepone residue levels related to water temperature and their spawning cycle. Oyster depuralion rates were related to temperature. In summer the "biological half. life" of Kepone in oysters was about one week, while during the winter about 40 days were required for residue levels to decline by 50 per cent. Residues in blue crabs varied as a function of sex, males having considerably higher residues than females. Fin fish levels from the James varied greatly, with residue levels being dependent on species and length of residence for migratory fishes .. Average Kepone residues …

Changes In Salinity Structure Of The James, York And Rappahannock Estuaries Resulting From The Effects Of Tropical Storm Agnes, Paul V. Hyer, Evon P. Ruzecki

VIMS Books and Book Chapters

The peak effect of the flood waters produced by Tropical Storm Agnes was seen on June 25 in the James, June 26 in the Rappahannock, and June 30 in the York. Recovery toward normal salinity conditions after the high runoffs proceeded discontinuously, with alternating periods of vertical stratification and destratification. During strongly stratified stages, saline water advanced upstream along the bottom. In the York and James Rivers, the most dramatic stratification occurred about July 20- 25. This event resulted in bottom salinity values exceeding normal ambient values and, at the river mouths, reaching values hitherto unobserved. This event was apparently …

Public Health Aspects Of Tropical Storm Agnes In Virginia's Portion Of Chesapeake Bay And Its Tributaries, M. P. Lynch, J. Claiborne Jones

VIMS Books and Book Chapters

All Virginia waters within Chesapeake Bay were closed for the taking of shellfish for direct consumption on 23 June 1972. This initial closing was in anticipation of high microorganism levels accompanying flood waters moving downstream. Various areas beginning with the lower portion of Chesapeake Bay were reopened beginning )n 20 July 1972. By 5 October 1972 all areas closed as a result )f Tropical Storm Agnes were reopened. No increased incidents of infectious diseases caused by waterborne microorganisms were noted in Virginia which could be attributed to Tropical Storm Agnes.