Thomas Hess and Christopher J. Anderson School of Forestry and Wildlife Sciences Auburn University

1. Evaluating oil spill effects and restoration potential of Alabama salt marshes using experimental wetlands Alabama Water ResourceConference 5 September 2013 Thomas Hess and Christopher J. Anderson School of Forestry and Wildlife Sciences Auburn University

2. 2010 Deepwater Horizon Oil Spill • ~4.5 million barrels of oil spilled in May 2010 • Impacted coastal areas without a history of oil spills from petroleum production • Some exposure to Alabama salt marshes

3. 2011 Mesocosm Research Goals Research Goals: Determine how Juncusroemerianusmarshes responds to dose and weathered condition of oil

4. 2011 Mesocosm Methods • 32 wetland mesocosms were developed using Juncus sod and designed to mimic tides • 3 dose treatments • Low (6 L /m2) • Medium (12 L /m2) • High (24 L /m2) • 3 weathering treatments • None (full strength) • 3 days • 3 weeks • Oil was applied to wetland mesocosmsin July 2011

5. 2011 Mesocosm Methods

6. 2011 Mesocosm Results Sep 1 July 16 Aug 4

7. 2011 Mesocosm Results Stem survival (Dose) a a a a a b b b b bc c c Mean (±SE) percent no. of live stems compared to pre-oil count

8. 2011 Mesocosm Results Stem survival (Weathering) a a a b b b b b b b b b Mean (±SE) percent no. of live stems compared to pre-oil count

9. 2011 Mesocosm Results Photosynthetic rate a a a a b a b ab NS b Mean (±SE) percent photosynthesis rate compared to control

10. 2012 Microcosm Research Goals Research Goals: Determine how amenable salt grass (Distichlisspicata) would be for remediation of oiled marshes.

11. 2012 Microcosm Project • Continuation of the mesocosm study aimed at determining the restoration potential of salt grass (Distichlis spicata) on oiled marshes. • Potential bioremediation: • Improved degradation of subsurface oil through root aeration of soil. • Reducing coastal erosion by re-establishing a root matrix.

12. 2012 Microcosm Methods • 84 marsh plugs from the 2011 mesocosm experiment • Used 2011 dosage treatments: • Control • Low • Medium • High • Hoses and drip irrigation valves used to recreate tidal fluctuations

13. 2012 Microcosm Methods • Planted- September 4, 2012 • Half of the pots were fertilized- September 18, 2012 • Pulsed with 50 gallons of brackish water two to three times a week • Stem counts and heights were taken once every three weeks • Final plant heights and biomass measured- December 17, 2012 Fig. 6

14. Total Petroleum Hydrocarbons (TPH) • Average TPH concentration for microcosms based on analyses in June 2012 (n=24) and December 2012 (n=18)

15. 2012 Microcosm ResultsInfluence of oil on stem heights

16. 2012 Microcosm ResultsInfluence of oil on stem counts Non-Fertilized

17. 2012 Microcosm Results Aboveground plant biomass b b b NS a Non-Fertilized Fertilized

18. 2012 Microcosm Results Final plant biomass b ab ab NS a n=4 n=8 n=8 n=8 Non-Fertilized Fertilized

19. Summary 2011 Mesocosm Study • Oil had a negative effect on stem survival • High dose wetlands had the most rapid decline in survivorship • Weathering seemed to have little effect on Juncus • Oil exposure had a negative effect on plant photosynthetic rates • Four weeks after application

20. Summary 2012 Microcosm Study • Soil TPH was substantially lower than concentrations in the 2011 study • Combination of lower soil TPH, and fertilizer produced the most grass stems • Control microcosms tended to produce greater below ground biomass

21. Questions

22. 2011 Mesocosm Results CO2 uptake rate a a b b NS b a b b bc c c c Mean (±SE) CO2 uptake rate per mesocosm

23. 2012 Microcosm Results Final plant biomass

24. 2012 Microcosm Results Root to Shoot Ratio