impacts of an oil spill. However, many organisms survive an oil spill and, if carefully protected, they will recover their populations and help treat the remaining oil.
The best historical example of cleanup "over kill" is the 1969 TORREY CANYON Spill in England : a lot of marine life that survived the oiling was killed by the kerosene-based solvents used to clean the rocky shorelines. Yes, the shoreline was clean (the removal was effective), but a lot of damage was done to surviving marine life (Hawkins and Southward 1992). A more recent example is the 1989 EXXON VALDEZ oil spill. On rocky shorelines, a large amount of inter-tidal marine life survived oiling but was killed by high-pressure hot-water washing (Lees et al. 1996). The washing was effective in removing oil from the rock surface but, compared to untreated shorelines, it also delayed recovery of marine life. Use of a chemical shoreline cleaner reduced the need for heavy washing, but it was not approved (Lees et al. 1996).
On cobble and sandy shorelines, hydraulic washing removed not only oil but also the fine-grained silt and mud that is required for successful growth of clams. Indeed, during washing it was possible to see many sediment plumes entering the clear water offshore (Mearns 1996). In addition, long-term monitoring studies at both spills confirm that heavy cleanup activity delayed recovery of shoreline marine life. In the case of the EXXON VALDEZ, which we have studied in great detail, heavy washing delayed the onset of recovery of seaweed by a least one year (Figure 2, Houghton et al. 1997 and Mearns 1996). Today, 8-years later, marine life thrives at both oiled and treated shorelines but the marine communities are still notfully recovered in terms of their structure and species composition (Houghton et al.1997).
2.3 Marine Life Protection: A Global of Shoreline Cleanup
As a result of this new understanding it is now generally agreed that the goal of shoreline cleanup is NOT to "get all the oil out" off the shoreline but rather to remove enough of the oil so that nature can complete the job. Too much cleanup (too many people, too many chemicals, too much washing) can add injury to marine life that has otherwise survived the spill itself, In short, too much cleanup can delay recovery.
3.0 Overview of Shoreline Cleanup Alternatives
Alternatives for shoreline cleanup include no response, physical treatment and removal, chemical treatment and biological treatment (bioremediation). Physical methods include manual treatment (pick up, raking, manual absorbents), mechanical treatment (tilling, scraping, berm relocation), flooding and hydraulic washing (cold or hot water, low or high pressure with skimming), burning (mainly in marshes), sand blasting and others. Chemical treatment includes use of surfactants or other chemicals to aid in physical removal or biodegradation. Biological treatment includes use of nutrients, tilling and / or oxygen to stimulate natural biodegradation or application of oil-degrading microbes. Each method works best within a certain "window of opportunity" and only on certain shoreline types and specific oils and fuels. Experience has lead NOAA and other agencies to use a "Shoreline Countermeasures Matrix" that guides the responder to the best methods for a specific situation and to deter inap-propriate applications (for example, Whitney 1994.)
3.1 Effectiveness of Shoreline Cleanup
"Effectiveness" describes how much oil is removed compared to how much was present or remains. No method is 100% effective. In some situations (sandy beaches, manmade structures in harbors) almost all the oil can be removed with manual, physical or chemical treatments with little or no impact on marine resources. However, on rocky and cobble shorelines (such as in the EXXON VALDEZ) and in marshes only a small fraction of the stranded oil can be removed without further damaging marine life. Overall, shoreline treatment removed 4 to 9% of the oil stranded on Alaska shorelines following the EXXON VALDEZ oil spill (Wolfe et al. 1994 ; Mearns1996) ; the rest was removed by winter storms and natural biodegradation (Michel et al. 1991 ). A small amount remains trapped inside several shoreline segments today. Elsewhere, such as in marshes, burning may be highly effective (Mendelssohn et al. 1995).
3.2 Effects and Limits of Shoreline Cleanup
It is important to repeat that lot of shoreline plants and animals survive light and moderate oiling. Anything that can be done to maintain their survival will speed the ecosystem recovery process. However, if surviving marine life is killed or removed along with the oil, ecosystem recovery will take longer. We are slowly learning what
