Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 5 of 5
Full-Text Articles in Life Sciences
Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. I. Model Development, Implementation, And Verification, Susan Ford, Eric Powell, John Klinck, Eileen Hofmann
Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. I. Model Development, Implementation, And Verification, Susan Ford, Eric Powell, John Klinck, Eileen Hofmann
CCPO Publications
A mathematical model simulating the host-parasite-environmental interactions of eastern oysters (Crassostrea virginica) and the pathogen, Haplosporidium nelsoni, which causes MSX disease, has been developed. The model has 2 components. One replicates the infection process within the oyster and the other simulates transmission. The infection-development component relies on basic physiological processes of both host and parasite, modified by the environment, to reproduce the observed annual prevalence cycle of H. nelsoni. Equations describing these rates were constructed using data from long-term field observations, and field and laboratory experiments. In the model, salinity and temperature have direct effects upon …
Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. Iii. Regional Application And The Problem Of Transmission, Eric N. Powell, John M. Klinck, Susan E. Ford, Eileen E. Hofmann, Stephen J. Jordon
Modeling The Msx Parasite In Eastern Oyster (Crassostrea Virginica) Populations. Iii. Regional Application And The Problem Of Transmission, Eric N. Powell, John M. Klinck, Susan E. Ford, Eileen E. Hofmann, Stephen J. Jordon
CCPO Publications
A model of transmission for Haplosporidium nelsoni, the disease agent for MSX disease, is developed and applied to sites in Delaware Bay and Chesapeake Bay. The environmental factors that force the oyster population- H. nelsoni model are salinity, temperature, food, and total suspended solids. The simulated development of MSX disease was verified using 3 time series of disease prevalence and intensity: 1960 to 1970 and 1980 to 1990 for Delaware Bay, and 1980 to 1994 for Chesapeake Bay, and for a series of sites covering the salinity gradient in each bay. Additional simulations consider the implications of assumptions made …
Understanding The Success And Failure Of Oyster Populations: The Importance Of Sampled Variables And Sample Timing, Thomas M. Soniat, Eric N. Powell, Eileen E. Hofmann, John M. Klinck
Understanding The Success And Failure Of Oyster Populations: The Importance Of Sampled Variables And Sample Timing, Thomas M. Soniat, Eric N. Powell, Eileen E. Hofmann, John M. Klinck
CCPO Publications
One of the primary obstacles to understanding why some oyster populations are successful and others are not is the complex interaction of environmental variables with oyster physiology and with such population variables as the rates of recruitment and juvenile mortality. A numerical model is useful in investigating how population structure originates out of this complexity. We have monitored a suite of environmental conditions over an environmental gradient to document the importance of short time-scale variations in such variables as food supply, turbidity, and salinity. Then, using a coupled oyster disease population dynamics model, we examine the need for short rime-scale …
Modeling Oyster Populations Ii. Adult Size And Reproductive Effort, E. E. Hofmann, J. M. Klinck, E. N. Powell, S. Boyles, M. Ellis
Modeling Oyster Populations Ii. Adult Size And Reproductive Effort, E. E. Hofmann, J. M. Klinck, E. N. Powell, S. Boyles, M. Ellis
CCPO Publications
A time-dependent model of energy flow in post-settlement oyster populations is used to examine the factors that influence adult size and reproductive effort in a particular habitat, Galveston Bay, Texas, and in habitats that extend from Laguna Madre, Texas to Chesapeake Bay. The simulated populations show that adult size and reproductive effort are determined by the allocation of net production to somatic or reproductive tissue development and the rate of food acquisition, both of which are temperature dependent. For similar food conditions, increased temperature reduces the allocation of net production to somatic tissue and increases the rate of food acquisition. …
Environmental Effects On The Growth And Development Of Eastern Oyster, Crassostrea Virginica (Gmelin, 1791), Larvae: A Modeling Study, Margaret M. Dekshenieks, Eileen E. Hofmann, Eric N. Powell
Environmental Effects On The Growth And Development Of Eastern Oyster, Crassostrea Virginica (Gmelin, 1791), Larvae: A Modeling Study, Margaret M. Dekshenieks, Eileen E. Hofmann, Eric N. Powell
CCPO Publications
The effects of temperature, food concentration, salinity and turbidity on the growth and development of Crassostrea virginica larvae were investigated with a time-dependent mathematical model. Formulations used in the model for larval growth are based upon laboratory data. Simulations were done using temperature conditions characteristic of Laguna Madre, Galveston Bay, Apalachicola Bay, North Inlet and Chesapeake Bay. These simulations show that the duration of the planktonic larval phase, which is determined by larval growth rate, decreases at lower latitudes in response to warmer water temperatures. Also, oysters in the more southern locations have a longer spawning season during which the …