GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 162-54
Presentation Time: 9:00 AM-6:30 PM


DITMAR, Jolene M., Fullerton, CA 92382 and BONUSO, Nicole, Geological Sciences, California State University, Fullerton, 800 N. State College Blvd, Fullerton, CA 92831,

Oyster diversity steadily declined from four species in the Cenozoic to two oyster species in the Pleistocene. Currently only one native species remains: Ostrea lurida. Biologists attribute the decline of oyster beds to industrialization and urbanization of southern California. Restoration efforts continue within southern California but researchers lack the deep-time perspective of oyster bed community history. Here we examine Pleistocene oyster populations and ecology to better understand pre-human oyster habitats. We examined sediments and documented fossil content from the Late Pleistocene Palos Verdes Sands on Knoll Hill, San Pedro, California. The samples were wet sieved, sorted and all fossils were identified to the species level and counted. Length and width measurements of all oyster fossils were recorded and growth lines along the oyster shells were used to determine the oysters’ age. Salinity and temperature ranges were estimated using modern data ranges of particular gastropods and bivalves. The data collected will provide an image of species abundance and diversity in the region prior to urbanization. This data has the potential to help guide current restoration efforts.