Where

1
Wheres The Peak? Observations of Tidal Marsh
Diversity Along The Patuxent and Nanticoke Rivers

• By
• Peter Sharpe and Andrew H. Baldwin
• The University of Maryland
• Department of Environmental Science and
  Technology
• May-August 2006

2
Research Objectives

• Describe plant species richness across a salinity
  gradient (fresh-brackish) in tidal marshes of two
  Chesapeake Bay Tributaries

3
Patuxent River
Washington D.C.
4
Patuxent River Watershed Features

• Watershed Size 2,356 km2
• Gradient Length 47 km
• Mean Tidal Range at Jug Bay 0.73 m
• Land Use
• 30 Agricultural
• 40 Forest
• 20 Urban
• 10 Other Land Uses

Number of Survey Plots - 13
5
Patuxent River
Washington D.C.
Nanticoke River
6
Nanticoke River Watershed Features

• Watershed Size 2,136 km2
• Gradient Length 56 km
• Mean Tidal Range at Sharptown, MD 0.76 m
• Land Use
• 48 Agricultural
• 41 Forest
• 2 Urban
• 8 Other Land Uses

Number of Survey Plots - 16
7
Patuxent and Nanticoke River Study Sites
Patuxent River Gradient 47 km
Nanticoke River Gradient 56 km
Seaford, DE
Jug Bay
Bivalve Harbor
Benedict
8
Methods

• Vegetation surveyed using nested plot design
  consisting of a series of 10x10 m modules (Peet
  et al. 1998)

20 m
50 m
GPS Reading
Piezometer Location
SCT Reading
9
Typical Sampling Location
Surveyed Area
10 m
10
Nanticoke River Species Richness Results
(May-August) Residual Depth
1000 m2 Survey Area
11
Patuxent River Species Richness Results
(May-August) Residuals
1000 m2 Survey Area
12
Conclusions

• Nanticoke River data show no immediate reduction
  in richness, actually an increase along the
  Nanticoke up to mean soil salinity of 3-4 ppt
  (peak observed at 0.8 ppt soil salinity)

• Patuxent River data show slight peak in June
  within limits of salt intrusion followed by
  maintenance of species richness along gradient up
  to 3 ppt

• Periodic salt water stress could promote
  coexistence of freshwater and brackish species

• Other potential factors soil nutrient
  concentrations, marsh hydroperiods, toxicants,
  invasive species

13
Acknowledgements
Project funding provided by the Maryland/D.C.
Chapter of The Nature Conservancy through a
Biodiversity Conservation Research Fund Grant
Special thanks to Dr. Andrew Baldwin, Dr. David
Tilley, Daniel Marcin, Robbie Vocke, Krissy
Rusello, Douglas Rau, and Katherine Sharpe