The Brazilian brachiopods are the best modern analogy for the life and times of the critter that was so pervasive over 250 million years ago, says David Rodland, Ph.D. student in geological sciences at Virginia Tech. He has been studying the population since July 2000.
Rodland is studying the encrustation, or colonization, of the modern brachiopods by oysters, bryozoans -- or "moss animals," and, in particular, worm tubes. There has been no large-scale study of modern brachiopod encrustation, he says. The study results might allow scientists to estimate such things as the water depth at which Paleozoic brachiopods lived and the productivity of plankton populations, of the earth's waters at that time.
He will present his findings at the Geological Society of America's 114th annual meeting in Denver October 27-30.
Rodland is looking at "every scale, from shell to shelf," he says. Factors affecting encrustation are water depth, nutrients in the water, and shell surface.
Some findings are that encrustation is highest in shallower water and in deep water where upwelling delivers nutrients." The brachiopods appear to be concentrated in nutrient rich water and the variations in the abundance of encrusters suggest a link to productivity," Rodland says.
Below 100 meters, encrustation drops to about 2 percent for all brachiopods combined, although it varies by species. About 9 percent of the grooved Argyrotheca are encrusted at depths of 100 to 500 meters, while fewer than 1 percent of the spiny Platidia are still colonized."Similar patterns are found on Paleozoic brachiopods," Rodland says. "Shell ornamentation affects colonization by encrusters. Gro
Contact: David Rodland