Anomalous localized corrosion of submerged steel H-piles was detected in a Florida bridge spanning over a brackish river. Microbiological and chemical analysis of the waters samples showed high population of sulfate reducing bacteria (SRB) and high concentration of sulfate ions. The steel piles had noticeable heavy marine growth which were thought to have an effect on corrosion process by supporting biofilm development, creating localized corrosion and differential aeration cells. As part of ongoing research to identify the role of physical properties of macrofouling on the aggravation of microbiologically influences corrosion(MIC) of submerged steel bridge, the objective of the work presented here was to identify the influence of microbe availability to promote SRB proliferation under occluded and porous fouling spaces and development of MIC there. Both laboratory and field exposure tests were conducted. Laboratory experiments were carried out in nutrient-rich environments inoculated with SRB, with both occluded and porous crevice conditions characteristic of hard and soft marine fouling. Field exposure tests included long term exposure of steel coupons subjected to varying submersion depths in the river at the Florida bridge site. Electrochemical tests included the measurement of open circuit potential (OCP), linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). It was confirmed that SRB proliferation can occur as the macroorganism can accommodate different environmental condition. Occurrence of severe corrosion conditions was shown to be possible in the presence of macrofoulers and SRB.