10-9 Predation in Molluscan Assemblages from North and Central Florida across the Plio-Pleistocene

Session: Undergraduate and Graduate Geoscience Student Showcase (Posters)

Poster Booth No.: 66

Presenting Author:

Eleanor Godsey

Authors:

Godsey, Eleanor G.¹, Gibbs, Cameron², Boardman, Eliza J.³, Albright, Katherine M.⁴, Horvath, Shannon M.⁵, Visaggi, Christy C.⁶, Portell, Roger W.⁷

(1) The New School, Atlanta, GA, USA, (2) Geosciences, Georgia State University, Atlanta, GA, USA, (3) The New School, Atlanta, GA, USA, (4) Midtown High School, Atlanta, GA, USA, (5) Biology, Georgia State University, Atlanta, GA, USA, (6) Geosciences, Georgia State University, Atlanta, GA, USA; Center for Excellence in Teaching, Learning, and Online Education, Georgia State University, Atlanta, GA, USA, (7) Florida Museum of Natural History, Gainesville, FL, USA,

Abstract:

Extinction episodes in marine communities across the Plio-Pleistocene led to changes in molluscan assemblages along the U.S. Atlantic and Gulf Coastal Plains. Previous research has focused mostly on understanding shifts in biota from the Carolinas and south Florida, but less is known about how communities responded in north and central Florida near the biogeographic boundary between the Carolinian and Gulf provinces. This study focuses on documenting predation in assemblages from the understudied Nashua and Anastasia Formations including adding new data from a sample in process from Dickerson Rucks Pit of Okeechobee County, FL. Existing data included float samples from East Coast Aggregates (Hastings, FL) as well as in-situ samples from Buck Hammock Materials (Deer Park, FL) and World Golf Village (St. Augustine, FL).

All samples were sieved and shells greater than 5 mm were retained. Shells containing an umbo (bivalves) or apex (gastropods) were pulled for analysis, separated into whole (>85% of the shell intact) or fragmented specimens, and identified to genus. Whole shells were examined for the presence of complete and incomplete drillholes. Complete drillholes indicate successful predation events, whereas incomplete drillholes imply failed attacks. Most drillholes documented appear to be beveled and likely reflect predation by naticid gastropods, which were also observed in multiple samples.

The new sample from Dickerson Rucks Pit contains evidence of both complete and incomplete drilling predation. So far, complete drillholes are recorded in Mulinia, Glycymeris, and Anadara for bivalves, with an incomplete drillhole documented in Diplodonta. Complete drillholes are additionally observed in the gastropods Olivella, and also Neverita suggesting cannibalism among naticids. Data analysis is ongoing; more in-depth comparisons of predation will be completed upon further sample processing for multiple localities across the geographic region. These data will be used to evaluate changes in predator-prey interactions across the Plio-Pleistocene providing new insight on how molluscan communities responded to environmental change and extinction events in Florida’s coastal ecosystems.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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