34 March 2012 Fig. 3. Weathered oil from the Deepwater Horizon oil spill washed ashore on Dauphin Island, Alabama in June 2010. pontoons on the floating cage were flooded to sink the cage to the bay bottom, away from any surface oil. The bottom cage system required no modification because it was positioned directly on the bay bottom. There was not a good option for the floating bag system other than removing floats to allow the bag to sink to the bay bottom. This option was rejected because of concern that oysters in bags would suffocate in the bottom mud and also be susceptible to predation by oyster drills, a snail known for their voracious appetite for oysters. Floating bags were maintained on the surface, knowing that oysters might be directly impacted by floating oil. In the event of oiling, these oysters would provide a comparison of impacts to oysters that were held submerged. Oil Spill Aftermath: Meeting the Challenge Obvious impacts to the demonstration oyster farm site appeared to be minimal. Only small patches of light oil sheen were seen in this area on two separate occasions. When oyster drill predation was apparent on oysters cultured in gear placed near the bottom and presence of oil in the area appeared to be minimal, oyster gear was returned to normal operating positions. No attempts were made to relocate oysters to other areas because of the high cost associated with relocating an entire farm site. The major cost associated with the oil spill at the farm site was the increase of labor involved in managing gear. Waters in the area of the demonstration farm were reopened to harvest and testing has not indicated the presence of polycyclic aromatic hydrocarbons or oil dispersant in oyster tissues. Subsequent testing by an independent laboratory indicated that concentrations of contaminants were near or below levels of detection and hundreds of times below established levels of concern. Major impacts of the spill for the AUSL program were associated with increased time required for personnel to manage water supply for the hatchery and manage gear for the broodstock system at the hatchery and the demonstration oyster farm site, and the added feeding cost in the hatchery for post-set juvenile oysters. A less obvious but important effect was the stress on personnel of not knowing when the DHOS would end and how severely the programmatic impacts would be. With constant monitoring of the oil spill, innovative solutions to oil-related problems, and many extra hours invested by personnel, AUSL was able to persevere and meet its obligations to research and production needs for the AUSL program as well as the needs of other institutions. Despite the challenges of the DHOS, great leaps forward were made in developing and supporting an aquaculture industry for oysters in Alabama. Notes 1Auburn University Shellfish Laboratory, 150 Agassiz St., Dauphin Island, Alabama 36528 rikarfs@auburn.edu 2Shellfish Diet 1800, Reed Mariculture, Campbell, California, USA 3Adjustable Long Line System, BST Oyster Supply, Cowell, South Australia 4OysterGro ™, Bouctouche Bay Industries Ltd., Bouctouche, New Brunswick, Canada 5Floating Bag, supplied by Chesapeake Bay Oyster Company, Wake, Virginia, USA 6LowPro cage, Chesapeake Bay Oyster Company, Wake, Virginia, USA
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