Plastic debris causes extensive damage to the marine environment, largely due to its ability to resist degradation. Attachment on plastic surfaces is a key initiation process for their degradation. The tendency of environmental marine bacteria to adhere to poly(ethylene terephthalate) (PET) plastic surfaces as a model material was investigated. It was found that the overall number of heterotrophic bacteria in a sample of sea water taken from St. Kilda Beach, Melbourne, Australia, was significantly reduced after six months from 4.2-4.7×10³ cfu mL^-1 to below detectable levels on both full-strength and oligotrophic marine agar plates. The extinction of oligotrophs after six months was detected in all samples. In contrast, the overall bacterial number recovered on full strength marine agar from the sample flasks with PET did not dramatically reduce. Heterotrophic bacteria recovered on full-strength marine agar plates six months after the commencement of the experiment were found to have suitable metabolic activity to survive in sea water while attaching to the PET plastic surface followed by the commencement of biofilm formation.