In the summer and fall of 2002, Dr. Scott Warren at Connecticut College and Ron Rozsa of the Connecticut Department of Environmental Protection, noticed the sudden (within one year) disappearance of emergent vegetation at several south shore Cape Cod wetlands connected to Nantucket Sound. The vegetation loss could not be explained by any typical New England causes of vegetation loss such as ice, wrack or herbivory (e.g., geese or muskrat).

These observations were shared at the regional meetings of the New England Estuarine Research Society (NEERS) but no scientists or managers reported similar losses in the region. The vegetation losses were persistent in 2003 and additional dieback sites were discovered on the south shore of Cape Cod. In 2004, Rozsa discovered that similar vegetation losses had been reported in Georgia and South Carolina, apparently in association with a period of drought. The Georgia website provided a link to the Louisiana Brown (diebacks began in 1998). Apparently the first known dieback of this type was observed in panhandle Florida (1990).

In the summer of 2004, Joseph Dowhan, the Refuge Research Manager for the Northeast, queried all refuges about sudden wetland dieback. As a result of this communication, it was learned that the Cape Cod National Seashore had inexplicable diebacks in the Wellfleet area.

Rozsa discovered photographs a dock application on the Neck River in Madison, Connecticut, showing extensive dieback of low marsh vegetation. Photographs from a fall 2000 field trip to the Pleasant Point marsh in Branford revealed low marsh dieback. Dr. Roman Zajac reported sudden dieback of Spartina alterniflora at the nearby Banca Marsh in 1999. Losses at the Banca Marsh (a section of Pleasant Point) that lies on Long Island Sound in 1999. That year was not only a drought period but began with a mild winter. LIS experienced the warmest summer on record with record lobster mortality and an early dieback (by July) of Zostera was reported in the Niantic River.

Rozsa reported a suspected dieback area on the North Fork of eastern Long Island in the fall of 2003. A recent field trip there has confirmed dieback at Oyster Ponds. 2002, a drought year, is the likely year that dieback began.

In the winter of 2005, Dr. Susan Adamowicz at the Racheal Carson USFWS Refuge organized a New England workshop on the subject of New England wetland dieback. The workshop was held in April 2005 at the Parker River Wildife Refuge. It was recommended that a website and a List Server be created to share information about sudden wetland dieback. Many of the powerpoint presentations and recommendations from that workshop are available through the Parker River Refuge website.

At the spring meeting of NEERS, the Board approved a proposal for the Society to host a New England Sudden Wetland Dieback website and List Server.

SUDDEN WETLAND DIEBACK QUESTIONS

SWD is a previously undescribed event for New England marshes and here are just some of the questions that scientists and managers are asking:

  1. What is the distribution of SWD in New England?
  2. What is the areal range of dieback areas?
  3. What marsh habitats or plant species are affected?
  4. What is the fate of dieback areas - do they recover and do the dieback zones expand? There are two instances of dieback recoveries from the 1999 dieback. Georgia is witnessing recovery in some areas and Louisiana reports recovery and persistent diebacks.
  5. The common factor in all diebacks is drought but what is the actual mechanism(s) that causes plant mortality? Two preliminary hypothesis have emerged from the studies in Louisiana and Georgia. The first is soil acidity (acid sulphate soil formation?) and potential metal toxicity at low pH. The second is the report of Fusarium sp., a new to Spartina pathogen/fungus which is present and harmless on plants except under stress conditions such as elevated salinity in the range of 38 ppt. A preliminary assessment of plant material from Cape Cod suggests that Fusarium is present.
  6. Is this a one time event or will diebacks occur during future droughts? Louisiana is reporting new diebacks in 2005 coincident with a new drought event. The Audubon Marsh on Cape Cod appears to be experiencing a dieback in 2005.
  7. Will future diebacks be more or less extensive?
  8. Should resource managers make adjustments to wetland management programs to avoid creating conditions that could lead to promoting wetland dieback? An example is the 'restoration' of marsh ponds and the use of the excavated soil to plug tidal ditches to restore former marsh hydrology and habitat such as pannes.