EFFECTS OF NATURAL AND ANTHROPOGENIC IMPACTS ON THE MICROBIOME OF THE INDIAN RIVER LAGOON, FL, USA

The Indian River Lagoon (IRL) FL, USA, is an Estuary of National Significance due to its economic and high biodiversity. Microbial populations are understudied in the IRL despite their numerous ecological services. A two-year, nineteen-site Lagoon-Wide Survey (LWS) was conducted to provide the first 16S rRNA amplicon sequencing data on the microbiome of the sediment in the IRL and determine how the microbiome changed in response to environmental and anthropogenic factors. The most influential variables that explained the variability between microbiomes were porewater salinity, total organic matter (TOM), and copper (Cu). These results correlated with some of the anthropogenic pressures the IRL faces such as freshwater discharges from St. Lucie Estuary (SLE), trace metal contamination, and the accumulation of fine-grained, highly organic sediment known as “IRL muck” (muck). Research then focused on determining the microbial differences between three sets of sample types: sediment from the IRL versus the SLE; sediment that had three muck characteristics versus those with zero; and high TOM sediment that had high Cu versus high TOM sediment that had low Cu. Differentially abundant prokaryotes between sample types were determined with novel indicator analysis techniques. One technique tested the effectiveness of an indicator list to separate samples based upon the product of the sensitivity and specificity of partitioning around medoids clustering in comparison to metadata classifications. The other technique allowed for the tracking of changes in the entire indicator microbiome. These new indicator analysis techniques were created using the original LWS data and tested to determine how sediment microbiomes responded during two opportunistic surveys: dredging of muck from an IRL tributary (Eau Gallie River) and Hurricane Irma. These studies have filled the knowledge gap regarding the unknown microbiome of the IRL and how sediment microbiomes respond to extreme events such as dredging and a hurricane. They also led to the development of new indicator analysis techniques that can be used by to track changes in the entire indicator microbiome.