Hein AMSS Talk

Sediment organization in the heterogeneous, coarse-grained beaches of western Prince William Sound: Long-term effects of post-spill beach washing Christopher Hein, Dennis Lees, Emily Carruthers, Duncan FitzGerald Alaska Marine Sciences Symposium 19 January 2012

Rocks ≠Living

Pictures of Lower Trophic Level Organisms Pictures of Rocks

This Talk

But, Geology is Important!: Sediment Organization River Bed Sediment Organization (photo credit: wikipedia “Stream Bed”)

Cobble Lag (natural “armoring”)

Desert Pavement, Eastern Desert, Egypt Fourth Cliff, Scituate, MA (photo: wunderground.com)

Sediment Organization in Nature

Modified from: Isla, 1993, Marine Geo.

Initial Conditions

Organized Beach

Modified from: Hayes and Michel, 1999, Mar. Poll. Bull.

Sediment Organization in Prince William Sound • Two-layer structure • Fines in lower layer reduce permeability • Outcome: oil quickly removed from upper layer; remains in lower layer for many years after spill Li & Boufadel, 2010, Nat. Geosci.

1 Year After Spill

8-10 Years After Spill Modified from: Hayes and Michel, 1999, Mar. Poll. Bull.

Sediment Organization in Prince William Sound Treatment and Remediation: HP/HW Wash: 1989-1990 Outcome: severe disturbance to beach & intertidal infaunal communities

High Pressure (HP): 950 – 1900 liters/min; 50-120 psi Hot Water (HW): 60o C

Sediment Organization in Prince William Sound Treatment and Remediation: HP/HW Wash: 1989-1990

before washing

recently washed

Observation: Reduced Clam Populations Organization Benefits: • Enhanced beach stability • Protect recruiting infauna from natural disturbance (waves, currents) • Semi-permanent burrow systems

(Lees et al., 2012, AMSS poster)

NOAA Shoreline Treatment Effects Study (1990-1996): negative effects on infaunal at treated sites Hard-Shell Clam Study (2002): long-lived clams >65% less abundant at treated sites (Lees and Driskell, 2008) Follow-Up Study (2010): dramatic decline in clams across sites (Lees et al., 2012, AMSS poster)

Field Methods Intertidal Surf / Subsurf Oiling (1989)

NOAA Study Sites

Knight Island

Explanation Heavy Imp. Mod. Imp. Light Imp. No Impact

Explanation Reference Sites (16) Treated Sites (22)

Field Methods 38 sites; 2 plots each; lower intertidal: • Morphological characteristics • Shallow trenching • Surficial clast measurements • Stereo photos 4 plots: “disturbed” Depth sampling and grain-size analysis (0-5 cm; 5-10 cm; 10-15 cm)

Laboratory Methods & Analyses

Plot KN106A-1

Laboratory Methods & Analyses

DEM Analysis • ~1 m2 plots • Sub-mm-scale resolution • Exported as x,y,z grids

• Detrend (beach slope) • Plot statistics; 5 mm depth slices

Results: DEM Elevations

c-dim

Results: DEM Slices

Elevation Inc. 25-mm Depth Slice

Results: DEM Slices

Elevation Inc. 50-mm Depth Slice

Results: DEM Slices

Elevation Inc. 75-mm Depth Slice

Results: DEM Slices

Elevation Inc. 100-mm Depth Slice

Results: DEM Slices S.E.

Time Increases

DEMs are ~1.4 cm (ave) higher at treated sites than reference sites (p < 0.02)

Conclusions: Disturbance of Sediment Organization in Prince William Sound Geology: Gradual return to “natural” condition; dependent upon: • Grain size (coarser sites – resistance to organization) • Exposure to high energy events Biology: HP/HW Wash disturbance of sediment organization reduced clam populations at treated sites (???)

Acknowledgements Funding: Exxon Valdez Oil Spill (EVOS) Trustees Council Field and Lab Assistance: • Marcio Albernaz (UNIVALI / Delft University of Technology) • Captain David Janka and crew of the R/V Auklet (Auklet Charter Services, Cordova, AK) • Terry Kennedy (Cordova Air) • Kathleen Lees, Jon & Kathleen Houghton • Dan Mills (DCM Technical Services, Toronto, ON)