Paper No. 38-10
Presentation Time: 8:30 AM-2:30 PM
TEMPORAL AND GEOGRAPHIC TRENDS OF PREDATION TRACES AND TAPHONOMIC ATTRIBUTES IN LIVE, DEATH, AND FOSSIL MOLLUSCAN ASSEMBLAGES OF FLORIDA FRESHWATER SYSTEMS
KNOWLES, Jaiden1, FREDERICKS, Andrew1, GROSS, Lilianna1, MOSES, Kaitlyn1, PRATT, Jay1, ROUTH, Ainsley1, WILLIAMS, Claire1, DURAN, Keeley1, KANNAI, Alshina2, WEINSTEIN, Sofia3, KOWALEWSKI, Michał2, MEANS, Guy H.4, MEANS, Ryan5, PORTELL, Roger W.2 and KUSNERIK, Kristopher1, (1)Geosciences Department, Hamilton College, 198 College Hill Road, Clinton, NY 13323, (2)Division of Invertebrate Paleontology, Florida Museum of Natural History, University of Florida, 288 Dickinson Hall, 1659 Museum Road, Gainesville, FL 32611, (3)Department of Geosciences, Georgia State University, Atlanta, GA 30303, (4)Florida Department of Environmental Protection, Florida Geological Survey, 3000 Commonwealth Boulevard, Tallahassee, FL 32304, (5)Coastal Plains Institute, 46 Kinsey Road, Crawfordville, FL 32327
Recent environmental disturbances from climate change, human activity, invasive species, sea level rise, and habitat degradation have increasingly threatened freshwater species. Taphonomic characteristics of molluscan assemblages can provide key historical insights into ecological, environmental, and biological changes in freshwater ecosystems. This study involves taphonomic scoring and predation trace identification in three assemblage types: live (living specimens), death (loosely accumulated shells), and fossil (from Late Pleistocene-Holocene sediments) gastropods from the Wakulla, Silver, and Ocklawaha Rivers in Florida. We scored 9521 specimens of six freshwater species: Elimia floridensis (n = 2976), Melanoides tuberculata (n = 307), Pomacea paludosa (n = 469), Callinina georgiana (n = 1523), Planorbella trivolvis (n=650), and Planorbella duryi (n = 3596). Scored traits include aperture damage, fragmentation, color, abrasion, spire condition, and exterior luster. Predation traces such as repair scars, holes, or scrapes were also noted. Individual trait values were then combined into a z-standardized Total Taphonomic Score (TTS) representing a degree of alteration to each specimen.
Fossil specimens have the highest TTS (mean = 0.45) reflecting greatest alternation. Live gastropod specimens were least altered (mean = -6.92), while death assemblage specimens were only slightly less altered than fossils (mean = 0.36). These trends suggest death and fossil assemblages undergo significant taphonomic change, with death assemblage likely containing high proportions of reworked fossils. Live specimens exhibit the highest rate of predation traces (60%, mostly repair scars), compared to death (22%) and fossil (28%) specimens, potentially reflecting more recent increases in predation related to introduced species. These trends suggest fossil, death, and live assemblages record a history of ecological, environmental, and taphonomic processes operating in freshwater ecosystems.
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