urban runoff, in areas where oil has been incorporated in sediments and is then released back to the water column, and in production fields. Chronic sources of hydrocarbon pollution remain a concern, and their effects on populations and ecosystems need further assessment. Federal agencies, especially the USGS, EPA, and NOAA should work with state and local authorities and industry to implement a comprehensive laboratory and field based investigation of the impact of chronic releases of petroleum hydrocarbons.
Biogenically-structured habitats, such as salt marshes and mangrove forests, are subject to destruction or alteration by acute oiling events. Because the structure of these habitats depends upon living organisms, when these are killed, the structure of the habitat, and sometimes the substrate on which it grows, is lost. Depending upon the severity of oiling and particularly if oil is incorporated in the sediments or structure of the habitat, recovery of the habitat and the organisms dependent on it may be exceptionally slow. In areas of sensitive environments or at-risk organisms, federal, state, and local entities responsible for contingency plans should develop mechanisms for higher level of prevention, such as avoidance, improved vessel tracking systems, escort tugs, and technology for tanker safety.
Although there is now good evidence for the toxic effects of oil pollution on individual organisms and on the species composition of communities, there is little information on the effects of either acute or chronic oil pollution on populations or on the function of communities or ecosystems. The lack of understanding of population-level effects lies partly in the fact that the structure of populations of most marine organisms is poorly known because of the open nature of communities and the flow of recruits between regions. Also, in some populations, (e.g., bony fish), the relationships between numbers of juveniles produced and recruitment to the spawning adult population are unknown. The U.S. Departments of Interior and Commerce should identify an agency, or combination of agencies, to develop priorities for continued research on:
the structure of populations of marine organisms and the spatial extent of the regions from which recruitment occurs,
the potential for cascades of effects when local populations of organisms that are key in structuring a community are removed by oiling, and
the basic population biology of marine organisms may lead to breakthroughs in understanding the relationship between sublethal effects, individual mortality, and population consequences.
There is a tremendous need for timely dissemination of information across state, federal, and international boundaries about the environmental effects of oil in the sea. Although the United States has experience that might benefit the international community, the United States might benefit greatly from lessons learned in other countries with offshore oil production, heavy transportation usage, and diffuse inputs of petroleum from land- and air-based sources. Therefore, the federal agencies identified above, in collaboration with similar international institutions, should develop mechanisms to facilitate the transfer of information and experience.