Microbiologically Influenced Corrosion (MIC) occurs in environments where microbial attachment and biofilm formation occurs. The microbial metabolic activities which cause MIC affect materials in a wide variety of industries. Although MIC has not traditionally been a major durability concern for Florida coastal and inland bridges, a recent finding by the Florida Department of Transportation (FDOT) of severe corrosion of steel bridge piles with strong evidence of microbial activity, has motivated the present study. As a preliminary research, identify the possible susceptibility of a case study marine bridge infrastructure to MIC is the main objective. This will be supported by determining the bacteria, nutrient levels, environmental conditions and other factors that could support MIC. A site visit to a bridge was carried out in 2016 and water samples (close to the site) at varying depths, as well as underwater pictures of the bridge steel piles were taken. The chemical composition including pH, total organic nitrogen, nitrate, phosphate, sulfate, chloride, ammonia and microbiological content of the samples were determined. Sulfate Reducing Bacteria (SRB), Slime Forming Bacteria (SFB), Iron Reducing Bacteria (IRB), and Acid Producing Bacteria (APB) were found in water samples. The presence of carbon, sulfate, nitrogen, phosphorus, as well as Ca, K, Na, Mg in water samples of the case study could provide the necessary nutrient to support large bacteria colonization. Site visit results (water chemistry and microorganism content) were compared with database information of water management districts of Florida, in order to find similar conditions that could support MIC. As a result, many sites with similar characteristics as the case study were found that may support MIC.
