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Reconstructing Cyclical Browning In A Subtropical Lake From Diatoms, Meredith Emery

FIU Electronic Theses and Dissertations

Lakes are browning globally from increased inputs of colored dissolved organic carbon (cDOC) driven by climate and land-use change. Browning changes lake ecosystems, especially through reductions in water transparency. I used long-term limnological and plankton records and upper surface sediment diatom assemblages to infer a ~1600-year history of browning from diatom assemblages in a 166 cm core from a subtropical, oligotrophic lake known to experience cyclical browning related to climate oscillations. Diatom assemblages were strongly regulated by cDOC-driven transparency fluctuations in a 14-year plankton dataset (modern model, R² = 0.62) and in the upper 35 cm of sediments corresponding …

Comparison Of Modern And Mid-Holocene Benthic Foraminifera To Assess Recent Environmental Change In Almirante Bay, Caribbean Panama, Maria N. Gudnitz

FIU Electronic Theses and Dissertations

This study used the diversity and distribution of benthic foraminiferal assemblages of Almirante Bay, Caribbean Panama, as environmental proxies to compare modern coral, seagrass and mangrove habitats to mid-Holocene coral reef facies on the island of Isla Colón, to investigate both natural and human-influenced changes.

The modern study associated species and assemblage characteristics with environmental conditions related to degraded water quality. Assemblages were fairly similar among neighboring habitats but differed in species proportions, while several stress-tolerant taxa might indicate eutrophic conditions. Diversity appeared to be regionally controlled by freshwater input irrespective of habitat type, was generally lower near the mainland …

Evidence Of Climate Variability And Tropical Cyclone Activity From Diatom Assemblage Dynamics In Coastal Southwest Florida, Emily R. Nodine

FIU Electronic Theses and Dissertations

Estuaries are dynamic on many spatial and temporal scales. Distinguishing effects of unpredictable events from cyclical patterns can be challenging but important to predict the influence of press and pulse drivers in the face of climate change. Diatom assemblages respond rapidly to changing environmental conditions and characterize change on multiple time scales. The goals of this research were to 1) characterize diatom assemblages in the Charlotte Harbor watershed, their relationships with water quality parameters, and how they change in response to climate; and 2) use assemblages in sediment cores to interpret past climate changes and tropical cyclone activity.

Diatom assemblages …