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Arnoldo Valle-Levinson, Center for Coastal Physical Oceanography, Old Dominion University
The Chesapeake Bay, where a number of rivers including the James, Potomac, Susquehanna empty into the Atlantic Ocean near the capital of the United States, is the country's largest estuary. (An estuary is a semi-enclosed coastal body of water where the ocean's salt water meets fresh water). A complex and dynamic ecosystem, the Chesapeake Bay is affected by seasonal changes, river discharge, tides, and winds. More recently its finely-balanced ecology has also been altered by dredging and urban pollutants.
How do all of these changes affect the life of the Bay? The Chesapeake Bay is the nursery and spawning ground to a number of species, including the commercially valuable blue crab. But the numbers of blue crabs, along with oysters and other sea life, are decreasing.
No one knows why. Enter Glen Wheless and his colleagues at Old Dominion University in Norfolk, Virginia, who are working with NCSA to build a Chesapeake Bay Virtual Ecosystem that will help them understand the changing ecosystem. Using the CAVE (Cave Automatic Virtual Environment), a virtual reality environment they'll be able to "walk" through a simulated Chesapeake Bay, observing first-hand the complex interactions of many environmental variables.
At SIGGRAPH '94 Wheless demonstrated a three-dimensional circulation model of the Chesapeake Bay in a virtual reality room (VROOM). Users could navigate the 3-D environment of the Bay, viewing semi-transparent 3-D surfaces showing the seasonal change of salinity throughout the bay.
Glen Wheless, Old Dominion University
JPEG Image (51 KB)
The virtual ecosystem model, demonstrated this year on the ImmersaDesk (a scaled-down version of the CAVE) at Supercomputing '95, builds upon the 3-D circulation model of the Chesapeake Bay. It incorporates a number of other 3-D fields of data, including the movement of larval fish in response to circulation patterns, and salinity and temperature gradients (if a hum at middle C indicates 55 degrees F, then a visitor working his or her way toward a colder section of the ecosystem might perceive a steady decrease in pitch). The user can wave a wand that triggers the release of "virtual" crab larvae (tracer particles) into the environment. By changing the model parameters (winds, tides, or river runoff) which affect the circulation patterns of the bay, they can observe how alterations in each variable affects the movement of the larvae.
Wheless aims to link two CAVEs over the I-Way, such that distant collaborators could watch an identical simulation unfold. He and his colleagues also plan to install the virtual ecosystem onto an interactive World Wide Web site, making it easy for anyone with access to the Web and the appropriate software to run their own simulations of life in the Chesapeake Bay.
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