The application of bioremediation to marine oil spills is limited due to dilution of either nutrients or hydrocarbonoclastic organisms. This study investigated the effectiveness of three unique natural carrier materials (mussel shells, coir peat and mussel shell/agar complex) which allowed nutrients, hydrocarbonoclastic organisms and oil to be in contact, facilitating remediation. TPH analysis after 30 d showed that mussel shells exhibited the greatest capacity to degrade oil with a 55% reduction (123.3 mg l-1 from 276 mg l-1) followed by mussel shell/agar complex (49%) and coir peat (36%). Both the mussel shells and mussel shell/agar complex carriers were significantly different to the control (P = 0.008 and P = 0.002, respectively). DGGE based cluster analysis of the seawater microbial community showed groupings based on time rather than carriers. This study demonstrated that inexpensive, accessible waste materials used as carriers of hydrocarbonoclastic bacteria led to significant degradation of hydrocarbon contaminants in seawater.