Microbial Community Analysis of a Floating Island System in a Stormwater Wet Detention Basin Danielle Winter, Dessy Owiti, François Birgand, Terrence Gardner, and Bryan Maxwell Methods ` Introduction Floating Islands: An Emerging Water Quality Tool Weekly Discrete Sampling Vegetated Mats Methods of Treatment Chemical analysis: surface water sample & sediment Microbial community analysis: solution from mats, root wash from composite root sample, and sediment Microbial assimilation Nutrient treatment Nitrogen Phosphorus Filtration and sedimentation of suspended solids Increases in dissolved oxygen Reduction in water temperature Pathogen treatment Improved aesthetic Provision of habitat and nutrition Treatment of heavy metals Improved microbial diversity Reduced biochemical oxygen demand (BOD) Predation within microbial communities Filtration and sedimentation via root systems Mats Only Control Treatment by Floating Islands Sample of water within mats and of attached biofilms Example of an Established Island Microbial mineralization Plant uptake (phytoremediation) Island Prototype Utilized for Sampling Objectives of this Study Microbial dissimilatory reductions Adsorption to plant roots and matting Characterize microbial community structure in a floating island system to better understand treatment mechanisms and capabilities of these systems. Analyze coincidence of changes in the wet detention basin environment and changes in microbial community structure. Investigate spatial and temporal variations in microbial communities in floating island systems. Develop reliable, replicable methods for sampling microbes in floating island systems. Chelation of metals via organic compounds extruded by plants Composite root sample from 3 plant species Sample of surface water Sample from upper layer of sediment Visual of the Sampling Scheme Results ` PCA Analysis Microbial Community Analyses Mat environment appears to strongly influences all FAME indicators. Potential explanations: Aerobic and anaerobic conditions in mats Substrate quality Surfaces available for attachment Efficacies of different sampling techniques Presence of a distinct cluster for each sampling location suggests unique community structures. Bacterial signals are dominated by gram-positive bacteria Resistant to environmental change Few are pathogenic FAME Analysis Analyzed Fatty Acids Correlations among Biomarkers (p<0.05) FAME (fatty acid methyl ester) analysis involves extracting fatty acids from living and dead cells. Certain fatty acids are specific to cell membranes of certain organisms [See Table]. Analyses performed with an Agilent 780B Gas Chromatography system. FAME Results Many positive correlations among and between fungi and bacteria across locations may suggest overlap of favored environmental conditions and/or mutualistic relationships (PCA analysis also suggests this). Fungal biomarkers 16:0, 18:2ω6, 18:1ω6 may have an overlap of favored environmental conditions and/or mutualistic relationships. 18:3ω6 appears to behave differently from other fungal biomarkers, warranting further investigation to ascertain if this biomarker can identify constituents of the fungal community at a higher resolution. *17:1ω6, 20:0, 16:0, 18:1ω5, i19:0, and a19:0 not included Gram-negative bacteria and actinomycetes biomarkers may overlap in favored environmental conditions and/or respond similarly to certain sampling methods. Actinomyces (genus of actinomycetes)= facultative anaerobes Gram-negative signals (cy17:0 & cy19:0) = anaerobes Correlations with Environmental Conditions (p<0.05) Sediment appears to provide the most conducive environment for biomarkers of Bacteria (except for 17:1ω6 and i19:0) Fungi Actinomycetes Roots likely provide Root zone and mat samples tended to exhibit more variability. Dynamic communities Shorter establishment period Ineffective sampling methods Fungal biomarkers were observed in all locations and in substantial concentrations, indicating potential for floating islands to degrade a variety of organic compounds, such as PAHs, EDCs, and pesticides. Sulfate-reducing bacteria (17:1ω6) were observed in all three locations, suggesting potential for floating islands to treat sulfate, other oxidized forms of sulfur, and hydrocarbons. If the most robust microbial community is in sediment, sedimentation is a key treatment mechanism of floating islands. (this should be a conclusion!) Figure F-1 Many correlations between water properties and sediment biomarkers may suggest significant exchange between the water column and upper sediment layers. Figure F-2 Only a few correlations were found between chemical properties of the wet detention basin environment and the mat and root zone environments. This result is likely related to elevated variability of FAME results at these locations. Figure F-3 Figure F-4 Future Work Conclusions Continuation of microbial community composition monitoring for a full year. Monitoring of chlorophyll-a concentrations for a full year. Deep sequencing of microbes in pond sediment prior to floating island installation and after one year of floating island treatment.