Though the results from monitoring bioremediation applications were not unequivocally positive, they provided some very important pieces of information about bioremediation and its performance at oil spills. Data collected at the Apex Barges, one of the 1990 Gulf of Mexico spills, clearly showed that, bioremediation could not be measured in minutes or even hours, but only over a period of days to weeks.
The difficulty in comparing oil concentrations in sediments between bioremediated and control sites was a confounding factor in measuring effectiveness at Exxon Valdez and at Prall’s Island in New York. Positive information gained about bioremediation was that background microbial degradation occurred at faster rates than many had expected, especially in the relatively cold temperatures of Alaska. This fact was encouraging for those who support an approach of minimal intervention after oil spills (allowing natural weathering to degrade the oil) as a viable option under certain circumstances. The noteworthy results from field monitoring of actual bioremediation applications confirmed the theoretical information base that had already been established by previous scientific studies.
Researchers had often documented that indigenous microbes usually out-compete foreign or introduced strains. The addition of nutrients in the form of fertilizer to indigenous microorganisms has proved to be effective in enhancing biodegradation and environmentally safe at the same time. It has also been observed, that microbes with the capacity to degrade oil are present in nearly all coastal environments, and that environmental parameters besides nutrients will affect actual degradation rates in the field. Thus field applications of nutrients are still to some degree influenced by temperature, water runoff, substrate, and other environmental parameters that are neither fully understood nor easily quantified.
However, there still remains a role for bioremediation in marine oil spill cleanup since experience has shown that no single technique will ever be appropriate for all incidents requiring response after oil spills. Finally, there are many advantages to be gained from a quick cleanup of an oil spill, some of which relate not to the marine ecosystem, but to other concerns. These include economic impacts from lost us of shorelines for recreation, legal liabilities and settlement of claims, and aestethic considerations. Besides, rapid oil disappearance made the Alaskan beaches safer for local wildlife and minimized the movement of undegraded oil from the beaches into the water column.
