Since the larvae's first dip into Gloucester's tanks on May 7th, these youngsters have been quite busy! After three days of swimming around in heated tanks in order to induce setting, the larvae were able to set (or attach to) two substrates- reef balls and shell. Under a microscope, we were able to confirm a healthy spat set.
For the next week and a half, the VA Oyster Team (Tommy Leggett, Jackie Shannon, and Tracy Weidert) monitored the temperature and salinity of the water in the tank, which gave the "�spat' time to securely attach themselves to their permanent homes: reef balls or shell.
To measure the number of larvae that successfully set on shell, VA Oyster Volunteers counted the number of spat on shell using a predetermined sample size of shells from each tank and a square grid to determine the sample surface area on reef balls.
Finally, on May 21st, the once free-swimming larvae, now three week old "�spat' (set on reef balls and shell), were deployed in their final destination in the Piankatank River at Palace's Bar Reef.
The Virginia Oyster Team also recently acquired a new land-based upweller. This system uses individual cylinders or boxes, called silos, to harbor the oyster seeds while they are growing. The silos are set in a large tank, with a pipe running along the tops of the silos, and the bottom of the silo is covered by mesh. Water is pumped into the tank, moving up through the mesh and exiting out of the pipes. The cycling estuary water provides the oyster seeds with nutrients and plankton to feed on, and the constant flow of water pushes waste to the surface.
The new upweller system is operational just in time for the 2012 oyster restoration season. After working out a few kinks, the system is running smoothly with 200,000 cultchless oyster seeds growing rapidly. The Virginia Oyster Team sieved the seed to separate the oysters by size, and then placed them back into the upweller. Everyday the seed needs to be stirred, as the oysters are constantly feeding and producing waste. The oysters, once they have grown, will be used for Virginia's demonstration oyster farm and given to volunteers in their oyster gardening cages.
(First photo: Close-up shot of spat on a low pro reef ball. Courtesy of VA Oyster Team. Third photo: A volunteer holding cultchless oysters growing in the upweller system. Courtesy of VA Oyster Team. Fourth Photo: CBF's Dan Johannes standing next to the new upweller. Photo by Meghan Hoffman/CBF. Fifth Photo: Members of the VA Oyster Team sort out oyster seeds from the upweller system. Courtesy of VA Oyster Team.)