Life Sciences Commons^™

Effects Of Phosphorus On Benthic Diatom Assemblage Network Structure, Eric M. Massa

FIU Electronic Theses and Dissertations

Ecological network analysis helps identify how relationships among species differ over time and across sets of species. Microbial assemblages are ideal for evaluating changes in species interactions due to environmental changes because they are speciose and respond at multiple scales. To determine how phosphorus limitation influences diatom network structure, I analyzed relationships among 257 species of diatoms from benthic microbial (periphyton) mats from 10 years of annual samples from 136 sites. Expected evidence of changes in network structure in response to periphyton TP were not found, likely due to species replacement with increased TP. Analysis of species connection distributions and …

Diatoms As Tools For Inferring Changing Environmental Gradients In Coastal, Freshwater Wetlands Threatened By Saltwater Intrusion, Viviana Mazzei

FIU Electronic Theses and Dissertations

Saltwater intrusion alters the natural salinity and phosphorus (P) gradients in the oligotrophic, freshwater wetlands located near coastlines of the Caribbean Basin with important consequences to the structure and function of key ecosystem components, including plants, soil microbes, and periphyton. Periphyton communities, particularly diatoms, are extremely sensitive to water quality changes and can serve as excellent bioindicators; however, little is known about their use in detecting novel rates of saltwater intrusion into coastal, freshwater wetlands. I examined the individual and combined effects of elevated salinity and P on periphyton functional processes and diatom composition by conducting transect surveys along salinity …

Controls On Benthic Microbial Community Structure And Assembly In A Karstic Coastal Wetland, Nicholas O. Schulte

FIU Electronic Theses and Dissertations

The assembly mechanisms underlying microbial community abundance, biotic interactions, and diversity over space and time are unresolved, particularly in benthic microbial mats distributed along environmental gradients. Experimental enrichment of nutrient-limited microbial mats from the Florida Everglades along a nutrient subsidy-salinity stress gradient stimulated autotrophic and heterotrophic metabolism, growth, and diversity independent of autotroph-heterotroph interactions across treatments and space. These results suggest spatial segregation of autotrophic and heterotrophic components within mats. Considering only the diatom component of Everglades mats over space and time, the subsidy-stress gradient controlled diatom compositional turnover at broad spatial scales while environmental and dispersal-based processes structured diatom …

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 …

Mechanisms Of Diatom Assembly In A Hydrologically-Managed Subtropical Wetland, Sylvia S. Lee

FIU Electronic Theses and Dissertations

Diatoms are useful indicators of ecological conditions but the mechanisms driving assemblage distribution are not clearly defined. Understanding the mechanisms underlying assemblage distribution is necessary to make accurate predictions about the effects of environmental change, such as hydrologic management, restoration, and climate change. The examination of diatom distribution and key drivers across a large wetland over several years can provide a resolved spatio-temporal framework for determining the relative importance of environmental and spatial factors influencing assemblage patterns. I examined a 6-year record of diatom distribution across the Everglades, a large hydrologically-managed subtropical wetland. Successful restoration of this ecosystem depends on …