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Sudden Wetland Dieback in Delaware’s Inland Bays

Sudden Wetland Dieback in Delaware’s Inland Bays. Chris Bason, Delaware Center for the Inland Bays Amy Jacobs, Delaware Dept. of Nat. Rsrcs. & Env. Cntrl. Piney Neck Sudden Wetland Dieback – A Brown Marsh. B. A. C. D. September 22, 2006 Aerial Survey Path.

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Sudden Wetland Dieback in Delaware’s Inland Bays

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  1. Sudden Wetland Dieback in Delaware’s Inland Bays Chris Bason, Delaware Center for the Inland Bays Amy Jacobs, Delaware Dept. of Nat. Rsrcs. & Env. Cntrl.

  2. Piney Neck Sudden Wetland Dieback – A Brown Marsh

  3. B A C D

  4. September 22, 2006 Aerial Survey Path GPS Photo-Link Software Assigns Lat and Long to image file

  5. Sudden Dieback Survey Results • Present in all 3 Bays • Varies greatly in intensity • Maybe present at low levels in the majority of marshes • Severe in a few different marshes • Natural autumn senescence partly obscuring definition • Upland and in-site disturbance not apparently influential of presence

  6. Green Marsh – Rehoboth Bay Back Barrier

  7. Piney Neck – I. R. Bay

  8. White’s Creek Area Marsh Dieback Comparison – Indian River Bay September 2002 September 2006

  9. Angola Neck – Rehoboth Bay

  10. Back Barrier Marsh South of Indian River Inlet

  11. Burton’s Island

  12. Cotton Patch Hills Marsh, IRB DELDOT Mitigation Site

  13. Indian River Marsh – No Ditching

  14. Severe Brown Brown/Green Green Insufficient Data Should be brown/green Dieback Distribution

  15. Frequency of Dieback by Tidal Wetland Polygon • Oblique photos did not allow area calculation • 929 wetland polygons total • 205 sufficiently observed (22%) • Frequency by dieback intensity

  16. 2006 Monitoring -- Initial Results • 4 sites, sampled vegetation & soils • No nematodes in roots • Some fungal leaf spots, nothing pathogenic, No Fusarium • Heavy metal concentrations not indicative of toxicity • Summer sampling showed normal salinity and pH.

  17. Widespread, sudden vegetation death Mostly Spartina alterniflora (low marsh) 1st noted ’68 in Louisiana Recent occurrences unprecedented Rate of recovery variable 2006 Source: Ron Rosa CT DEP Sudden Wetland Dieback on Atlantic and Gulf Coasts

  18. PRIME HOOK NWR, DE – 2006 Photo Credit: Marnie Pepper, University of Delaware

  19. 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Louisiana - Drought Georgia, South Carolina - Drought Maine - Drought Rain Event Delaware - Drought Dieback event - Drought Drought Precedes Dieback Source: Melanie Tymes, DE Dept. Nat. Rsrcs. Env. Cntrl.

  20. Southern Delaware Drought – Palmer Drought Severity Index • Mild drought AUG – SEP 05 • Mild drought JAN – MAR 06 • Moderate drought APR – JUN 06 • Wettest June on record 06 • Second driest August on record in 06

  21. Likely Causes from the Literature • Drought triggered phenomenon • Biotic agents probably secondary • Fusarium fungus • Periwinkle snails • Abiotic agents probably primary • McKee et al. 2004 have most compelling evidence for droughtsoil water deficitoxidationdecreased phincreased toxic metal concs. • However, Inland Bays & Cape Cod low marsh flood twice daily. • This is testable.

  22. Why Dieback is Important • Potential for rapid conversion of many acres of marsh to mudflat. • Saltmarsh has very high value. • Short term (30 yr) accretion rates 0.26 cm/yr < RSLR of 0.32 cm/yr (Wendy Carey 1996) • Rate of RSLR predicted to increase. • Marshes can’t migrate over houses. • Occurs with other stressors.

  23. Acknowledgments • Bob Mulrooney & Nancy Gregory, UDCE • Bill Moyer, Duffield Assc. • EJ Chalabala, CIB • Andy Howard & Melanie Tymes - DNREC Website: http://www.inlandbays.org/cib_pm/projects.php

  24. Maryland Coastal Bays, Isle of Wight Bay Restoration Site Ocean City, MD Photo Credit: Roman Jesien, Maryland Coastal Bays Program

  25. Die Back in Other Regions Virginia Long Term Ecological Research Resevere -- Delmarva

  26. Louisiana

  27. Cape Cod, Massachusetts 2002 2004

  28. What’s Next?

  29. The Occurrence of Dieback and the State’s Wetland Monitoring Program have raised important and timely questions for the marshes of our Estuaries.

  30. Long range migrant Winter’s in coastal mid-Atlantic & SE Forages in AG fields and marshes Greater Snow Goose

  31. 2002 2006 Greater Snow Goose Population From Menu et al. J. App. Ecol. 2002 and Environment Canada

  32. Snow Geese Overgrazing: Assawoman Wildlife Area – Little Assawoman Bay September 2006

  33. Areas of Likely Snow Geese Damage Tidal Wetlands Damage 1745 ac 745 ac For LAB

  34. Locations Experiencing Well Documented Rapid Salt Marsh Loss • Jamaica Bay, New York (Hartig et al., Wetlands 2002) • Blackwater National Wildlife Refuge, MD • Louisiana Gulf Coast • Venice Lagoon, Italy (Day et al., J.Coastl.Rsrch. 1998) • Elkhorn Slough, CA (Van Dyke & Wasson, Estuaries 2005)

  35. Marsh Collapse?

  36. Outcomes of the October 19th Meeting on Dieback in Delaware • Summarize dieback literature • Summarize climate, sea-level, and tidal prism data • Document change in grass cover in plots in 2007, add plots • Develop state-wide reporting protocol • Collect remote sensing data • Contact other researchers, managers involved in wetland loss, dieback • Next Meeting: Dec 4th, St. Jones Reserve

  37. Small Watercraft

  38. Gordon’s Pond Cape Henlopen SP Marshes near Lewes-Rehoboth Canal

  39. Questions • What are the rates of saltmarsh gain/loss? • What are the most important factors contributing to gain/loss? • Will saltmarshes keep pace with accelerated rates of sea-level rise in the future? • What management strategies are feasible given rapid loss?

  40. Recommendations to the STAC • Advise the Board on the nature of Sudden Dieback and recommend that they request that DNREC consider seeking additional funding to study the issue in the short term (1 – 2 years). • The STAC should consider the sustainability of the Inland Bays’ salt marshes under a changing climate and hydrologic regime and discuss potential for research.

  41. Possible Causes • Fungal Pathogens • Herbivore Fronts • Trophic Changes (decreased predator populations) • Eutrophication • Toxicity • Hydrologic Alteration • Changes in tidal cycles, amplitudes • Alteration through intense ditching • Climate Change • Increased variability in precipitation (deluge & drought) • Change in rate of sea level rise

  42. Assawoman Wildlife Area Geese Damage 2002

  43. Mean Sea Level Rise Current: 3.16 millimeters/year (1.04 feet/century) 1250-2000: 0.9 mm/year (Nikitina et al. 2000) http://www.tidesandcurrents.noaa.gov/sltrends/sltrends.html

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