80 Paleontology II, Mesozoic and Cenozoic (Posters)

Tuesday, 16 March 2010
1:30 PM - 5:35 PM
International ABCDF

EFFECTS OF PLIO-PLEISTOCENE EXTINCTION IN NORTH CAROLINA ON MOLLUSCAN TROPHIC ECOLOGY: A PROGRESS REPORT

Paper number: 80-9
Program: Technical Sessions
Time: 1:30 PM – 5:35 PM

Authors

Abstract

The Plio-Pleistocene was a time of turnover for molluscan faunas in the western Atlantic, but the ecological consequences of the extinction and nature of recovery are not well understood, especially for the Carolinas. As part of a Research Experiences for Undergraduates study, we compared the trophic ecology for the Duplin Formation (prior to the extinction), the lower Waccamaw Formation (following an initial turnover pulse), and the upper James City Formation (following a second turnover pulse). Bulk samples were collected from a Duplin exposure along the Lumber River near Lumberton, NC, and the classic Natural Well exposure in Magnolia, NC, the Waccamaw at Register Quarry near Old Dock, NC, and the upper James City on the Neuse River, near James City, NC. Samples were sieved through a quarter-inch mesh and specimens picked, sorted and identified to genus level; life modes were assigned using the NMITA molluscan life modes database.

Our previous results (Kelley et al. 2009) for the Lumber River and Old Dock localities indicated that most measures of trophic structure did not change significantly between the Duplin and the lower Waccamaw. The addition of the Natural Well and Neuse River localities strengthens this interpretation; the percent of suspension feeding genera (43-53%) and suspension feeding individuals (77-92%) was similar for the three formations. Suspension feeding bivalves represented 72-80 % of bivalve genera and 94-99% of Duplin, 95% of lower Waccamaw, and 81% of upper James City bivalve individuals. Predators constituted 24-36% of all genera for the three formations, and 5% of Duplin, 7% of lower Waccamaw, and 4% of upper James City individuals. Predatory gastropods included 61-70% of Duplin gastropod genera (28% of gastropod individuals), 68% of lower Waccamaw gastropod genera (42% of gastropod individuals), and 63% of upper James City gastropod genera (28% of gastropod individuals). Future work will examine samples from additional localities to test the robustness of the pattern.