10-7 Paleoecology of Molluscan Assemblages from North and Central Florida across the Plio-Pleistocene

Session: Undergraduate and Graduate Geoscience Student Showcase (Posters)

Poster Booth No.: 64

Presenting Author:

Kayla Hira

Authors:

Hira, Kayla N.¹, Acosta, Kaitlyn A.², Hou, Alexie³, Kelly, Charlise⁴, Horvath, Shannon M.⁵, Visaggi, Christy C.⁶, Portell, Roger W.⁷

(1) Environmental Sciences, Georgia State University, Atlanta, GA, USA, (2) Environmental Sciences, Georgia State University, Atlanta, GA, USA, (3) Physics, Georgia State University, Atlanta, GA, USA, (4) Geosciences, Georgia State University, 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:

Ecological shifts in marine communities are important to study in the fossil record. Because the sixth mass extinction is greatly influenced by anthropogenic factors, examining changes due to extinction episodes over the last few million years prior to human impact is valuable. This research examines differences in the paleoecology of molluscan communities from the understudied Nashua and Anastasia Formations from localities in north and central Florida. Existing data from this research incorporates 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). One more sample of the Nashua Formation is currently being processed from Dickerson Rucks Pit of Okeechobee County, FL. All samples were sieved and sorted with shells retained that were greater than 5mm and included the apex (gastropods) or umbo (bivalves). Shells were organized into groups of whole (> 85% intact) and fragmented specimens and identified to genus level. Different ecological life modes were determined for feeding, mobility, attachment, and substrate types. Nearly all samples analyzed contain abundant and diverse bivalves. The most common life modes represented for bivalves are unattached, actively mobile, infaunal suspension feeders. Carnivores dominated gastropods in most samples but with suspension feeders more prominent in a few samples. Data processing is ongoing for the new sample of the Nashua Formation added from Dickerson Rucks Pit, but preliminary results indicate similar patterns to previous samples studied. Once specimen identification is complete, more detailed analysis of variation in molluscan ecology in space and time will be conducted.

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

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