Taphonomic Processes Affecting Peat Accumulation in Mangroves, Barnes Sound, Florida, United States

Abstract

This dissertation explores taphonomic processes affecting leaf mat formation, peat accumulation, and leaf litter decomposition within mangrove communities in Barnes Sound, Florida. My research takes a novel paleobiological approach by using plant organ- and taxon-based measures to describe the influence of the taphonomically active zone on the decomposition of mangrove peat with depth. This research allows us to understand the taphonomic processes imposed on mangrove peat as it is sequestered in the depth of final burial and provides us with the paleoecological context to better interpret preserved peats and reconstruct past mangrove sub-habitats from peat cores. By comparing the proportional abundance of mangrove peat constituents in surficial mangrove peat samples, I was able to establish a modern analog needed to interpret changes in depositional environment of historical mangrove peats found in sediment cores, which is critical for understanding shoreline responses to sea-level rise and anthropogenic change. Further, my research investigates the influence of detritivory by the coffee bean snail Melampus coffea (Linnaeus, 1758), and bioturbation by the fiddler crab Leptuca speciosa (Ives, 1891) on leaf litter decomposition within mangroves. I found there are no differences in decomposition rates between sites when M. coffea is excluded, suggesting that detritivory plays a role in leaf litter decomposition and the formation of leaf mats. Burrowing by fiddler crabs enhances aerobic peat decomposition and extends the depth of the taphonomically active zone, and their foraging changes the quality, bioavailability, and distribution of organic matter in surficial sediments but does not alter the composition of the peat.