SUBMERGENCE OF NEW YORK'S SALT MARSHES

A CASE STUDY IN WESTERN LONG ISLAND SOUND, NY

Marshlands Conservancya wildlife sanctuary operated by Westchester County Dept. of Parks

Study conducted with support from Friends of Marshlands Inc.

Ellen Kracauer Hartig, Chris Pratt, Polly Endreny, Eymund Diegel (Mashlands Conservancy)

Vivien Gornitz, (Columbia University and NASA/GISS)

Submerged Wetland Sites, New York(source: F. Mushacke)

Marshlands Conservancy

Yellow Bar Hassock, Jamaica Bay, NY

Mechanisms of Erosion

- Coalescing tidal pools

- fragmenting of marsh

- die back of vegetation

Marshland Conservancy Location,

Rye, New York

(map source: Save The Sound)Residential Development

LOSS OF VEGETATED SALT MARSHESLONG ISLAND, NY Adapted in part from F. Mushacke, NYSDEC

Location 1974 Acres (Ha) 1994-2002 Acres (Ha) Per Year

Lost % Loss

NORTH SHORE – Long Island Sound

Marshlands Cons. 25 (10) 15 (6) - 1.5 %

Manhasset Bay 24 (10) 9.4 (4) - 2.4 %

Stony Brook Harb. 300 (121) 191 (77) - 1.5 %

SOUTH SHORE - Atlantic

Jamaica Bay 1974 (799) 1223 (495) - 1.5 %

Oyster Bay Area 1302 (526) 1018 (411) - 0.9 %

Shinnecock Bay-

Islands only 30 (12) 18 (7) - 1.9 %

Shinnecock Bay-

Shore only 437 (177) 450 (181) - 0.14 %

Based on aerial photography comparisons between 1974 and (varies) 1994, 1995, 1998, 1999, 2001, 2002.

Marshlands Conservancy, Rye, NY

A A A

B BB

CC C

DD

D

EEE

New Canal

Old Canal

Marshlands Conservancy, Rye N Changes from 1926 to 2002

1926 wetlands still existing in 20021926 wetlands now submerged by water in 2002

1926 open water that is collecting sediment and in some cases, revegetating

Marshlands Conservancy, Rye NY

Marshlands Conservancy, Rye NY

washed out wetland

Marshlands Conservancy, Rye NY

Overview of Site & Major Historical Issues

Marshlands Conservancy, Rye, NY

Marshland Loss 1926-2002

Total Marshlands in 1926: +/- 42 acres

Total Marshlands in 2002: +/- 24 acres

Total Marshlands lost over 75 years: +/- 18 acres

42% loss over 75 years

Upland

1926 marshlands still existing in 2002

1926 marshlands submerged by open water in 2002

1926 open water where fluctuating sedimentation gains have occurred

+/- 5.4 acres lost

+/- 7.3 acres lost

+/- 5.3 acres lost

Aerial photos revealed Aerial photos revealed accelerated marsh loss with accelerated marsh loss with recent losses of 3% per year.recent losses of 3% per year.

Land cover sampling showed Land cover sampling showed 50% low marsh conversion to 50% low marsh conversion to mudflats and original high marsh mudflats and original high marsh converted to low marsh.converted to low marsh.

Some Some S. S. alternifloraalterniflora gains found gains found on sand.on sand.

Ground observations indicate Ground observations indicate that mechanisms of marsh loss that mechanisms of marsh loss include: increased include: increased pondingponding, , slumping along marsh edges, slumping along marsh edges, and widening of tidal inletsand widening of tidal inlets

Land use analysis Land use analysis revealed human revealed human alterations that may have alterations that may have contributed to marsh contributed to marsh loss.loss.

Onsite salt marshes are Onsite salt marshes are unlikely to keep pace with unlikely to keep pace with accelerated rates of seaaccelerated rates of sea--level rise or urbanization level rise or urbanization impacts in the future. impacts in the future.

CONCLUSIONS