Quantifying effects of oil on coastal dune vegetation. Thomas Miller and Elise Gornish Biological Science, Florida State University

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1 Quantifying effects of oil on coastal dune vegetation Thomas Miller and Elise Gornish Biological Science, Florida State University

2 Natural History of Barrier Islands in the Northern Gulf Make up ~70% of the coast from Louisiana to the Florida Keys (and 15% of coasts worldwide) Storms (esp. surge) enhance erosion, especially of backshore areas, while regular winds and tides build islands on the front and tips Habitat for endangered species (e.g. birds and turtles) Protect inland waters and shores from storms, especially nursery areas such as sea grass beds and salt marshes Important for coastal towns and recreational areas

3 Natural History of Barrier Islands in the Northern Gulf Typically, they have highly dynamic foredunes, a flat interdune flooded following blowouts, and a more stable and older backdune area foredune Bay backdune interdune ocean There is a dynamic feedback between the plants and the geomorphology. The plants in each habitat (e.g. fore-, inter-, and backdune) stabilize the habitat, which promotes their own persistence.

4 There is virtually no literature on the effects of oil spills on the vegetation of coastal beaches and dunes. This may be due to: -- assuming that oil spill effects do not extend further in than beaches -- dune vegetation being more resistant to oil than species in other ecosystems -- a lack of investigation. These are very noisy systems, where the signal to noise ratio may be low, making investigations difficult.

5 Oil and Barrier Islands in the Northern Gulf foredune Bay backdune interdune ocean Long-term effects of oil -- Little oil will make it to back dunes, except in slacks -- Interdune will tend to hold oil -- Foredunes receive greater washover and less effect of oil -- patterns of deposition are expected to depend on storms

6 St. George Island Project -- using long term data St. George Island Map from New York Times

7 Census vegetation on m 2 plots each year since 1999.

8 Changes in Species Abundances through Time foredune interdune backdune

9 Documenting Effects of the Deepwater Horizon Oil Spill Two possible ways to deal with quantifying the effects of oil (or other disturbances) in ecosystems with high inherent variability. -- Use long-term data to be able to statistically separate signal from the noise. The amount of data required depends on the signal to noise ratio and could be quite high for coastal and coastal marine systems. -- Reduce the noise by quantifying the causes of the natural variation. We are trying to use a combination of both.

10 Use Ordination to find patterns foredune interdune backdune

11 Species abundances are correlated with dune height, soil moisture and soil % organic. These all co-vary.

12 BACKDUNE INTERDUNE FOREDUNE

13 We can use these long-term data to separate the effects of different factors in creating noise, both for species and community patterns. In particular, we can statistically define the effects of: -- dune habitat zone (foredune, interedune, backdune) -- successional time -- severe climatic events (e.g., hurricanes)

14 Sites from the Northern Gulf of Mexico Santa Rosa Island Trinity Island Horn Island Crooked Island St. George Island Anclote Key Cayo Costa Island Map from New York Times

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16 East Crooked Island, FL

17 Trinity Island, LA

18 Current Detectable Oil Across the Northern Gulf (TRPH)

19 Vegetation Patterns Across the Northern Gulf

20 Vegetation Patterns Across the Northern Gulf

21 Vegetation Patterns Across the Northern Gulf

22 Documenting Effects of the Deepwater Horizon Oil Spill Ultimate goals -- Create long-term data base for vegetation and environmental changes from seven sites in the Northern Gulf. -- Use St. George data to partition out the normal sources of variance, including: Habitat differences among dune zones Normal dune plant succession Effects of storm and recovery from storms Possible effects of anthropogenic disturbances such as oil.

23 Thanks to: -- staff of a variety of parks and reserves -- National Hurricane Service -- U.S. Fish and Wildlife Service -- National Oceanic and Atmospheric Administration National Estuarine Graduate Fellowship (Gornish) -- Northern Gulf Institute -- National Science Foundation -- many volunteer students, faculty and postdocs from Florida State University

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25 Coastal Dune Vegetation Survey (T. E. Miller, Biology, FSU Vegetation was censused from barrier islands at seven sites across the NGM, along with measures of edaphic factors including elevation, nutrients, and oil (TRPH). Sites cover a gradient of oil exposure from Deepwater Horizon. Prior long-term data from St. George Island in Florida allows us to calibrate data from other sites to account for recent climatic effects (hurricanes). Map from New York Times Short-term value includes documenting the patterns of background oil among habitats within sites and among sites, as well as quantifying current vegetation patterns in fore-, inter-, and backdune coastal zones. Long-term value is to provide baseline data to quantify chronic effects of oil. Information on species-specific responses to disturbances such as oil spills and hurricanes can inform managers on how to restore damaged areas.

26 backdune interdune foredune Hurricane George Hurricane Ivan Hurricane Dennis

27 Documenting Effects of the Deepwater Horizon Oil Spill Quantifying effects of natural and anthropogenic disasters can be very difficult, as discussed by a recent National Academy Report (2003). Natural variation in species and communities can easily mask the effects of disasters. Long-term data are almost always required the amount of prior data depends on the natural noisiness of the system.