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

Research Objectives 1.Describe plant species richness across a salinity gradient (fresh-brackish) in tidal marshes of two Chesapeake Bay Tributaries Richness Salinity Richness Fresh Brackish Transitional

Washington D.C. Patuxent River

Patuxent River Watershed Features Watershed Size – 2,356 km 2 Gradient Length – 47 km Mean Tidal Range at Jug Bay – 0.73 m Land Use: 1.30% Agricultural 2.40% Forest 3.20% Urban 4.10% Other Land Uses Number of Survey Plots - 13

Washington D.C. Patuxent River Nanticoke River

Nanticoke River Watershed Features Watershed Size – 2,136 km 2 Gradient Length – 56 km Mean Tidal Range at Sharptown, MD – 0.76 m Land Use: 1.48% Agricultural 2.41% Forest 3.2% Urban 4.8% Other Land Uses Number of Survey Plots - 16

Patuxent and Nanticoke River Study Sites Patuxent River Gradient – 47 kmNanticoke River Gradient – 56 km Bivalve Harbor Seaford, DE Benedict Jug Bay

Methods Vegetation surveyed using nested plot design consisting of a series of 10x10 m modules (Peet et al. 1998) Piezometer Location GPS Reading SCT Reading 50 m 20 m Nest (Depth)DimensionsArea Depth 510 cm x 10 cm0.01 m2 Depth 432 cm x 32 cm0.1 m2 Depth 31m x 1m1 m2 Depth 23.16m x 3.16m10 m2 Depth 110m x 10m100 m2 Residuals20 m x 50m1,000 m2

Typical Sampling Location High Marsh Levee Low Marsh Surveyed Area 10 m

Nanticoke River Species Richness Results (May-August) Residual Depth 1000 m 2 Survey Area

Patuxent River Species Richness Results (May-August) Residuals 1000 m 2 Survey Area

Conclusions 1.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) 3.Periodic salt water stress could promote coexistence of freshwater and brackish species 4.Other potential factors: soil nutrient concentrations, marsh hydroperiods, toxicants, invasive species 2.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

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