Wheres The Peak? Observations of Tidal Marsh Diversity Along The Patuxent and Nanticoke Rivers By...
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Transcript of Wheres The Peak? Observations of Tidal Marsh Diversity Along The Patuxent and Nanticoke Rivers By...
Where’s The Peak? Observations of Tidal Marsh
Diversity Along The Patuxent and Nanticoke Rivers
ByPeter Sharpe and Andrew H. Baldwin
The University of MarylandDepartment of Environmental Science and Technology
May-August 2006
Research Objectives1. Describe plant species richness across a
salinity gradient (fresh-brackish) in tidal marshes of two Chesapeake Bay Tributaries
Ric
hn
es
s
Salinity Salinity
Ric
hn
es
s
Fresh
Brackish
Transitional
Washington D.C.Patuxent River
Patuxent River Watershed Features
Watershed Size – 2,356 km2
Gradient Length – 47 kmMean Tidal Range at Jug Bay – 0.73 mLand Use:
1. 30% Agricultural 2. 40% Forest 3. 20% Urban4. 10% Other Land Uses
Number of Survey Plots - 13
Washington D.C.Patuxent River
Nanticoke River
Nanticoke River Watershed Features
Watershed Size – 2,136 km2
Gradient Length – 56 kmMean Tidal Range at Sharptown, MD – 0.76 mLand Use:
1. 48% Agricultural 2. 41% Forest 3. 2% Urban4. 8% Other Land Uses
Number of Survey Plots - 16
Patuxent and Nanticoke River Study Sites
Patuxent River Gradient – 47 km Nanticoke River Gradient – 56 km
Bivalve Harbor
Seaford, DE
Benedict
Jug Bay
MethodsVegetation surveyed using nested plot design consisting of
a series of 10x10 m modules (Peet et al. 1998)
10
2 3
7
4
6
54
2
3
2
892
43
2
1
Piezometer Location
GPS Reading
SCT Reading
50 m
20 m
Nest (Depth) Dimensions Area
Depth 5 10 cm x 10 cm 0.01 m2
Depth 4 32 cm x 32 cm 0.1 m2
Depth 3 1m x 1m 1 m2
Depth 2 3.16m x 3.16m 10 m2
Depth 1 10m x 10m 100 m2
Residuals 20 m x 50m 1,000 m2
Typical Sampling Location
High Marsh
Le
ve
e
Lo
w M
ars
h
Surveyed Area
10 m
Nanticoke River Species Richness Results (May-August) Residual Depth
1000 m2 Survey Area
Nanticoke River Residuals - May 2006
Distance Upstream (km)
0 10 20 30 40 50 60
Nu
mb
er
of
Sp
eci
es
0
5
10
15
20
25
30
35
40
Me
an
So
il S
alin
ity (
ppt)
0
1
2
3
4
5
6
7
8
9
10Nanticoke River Residuals - August 2006
Distance Upstream (km)
0 10 20 30 40 50 60N
um
be
r o
f S
pe
cie
s0
10
20
30
40
50
Me
an
So
il S
alin
ity (
pp
t)
0
1
2
3
4
5
6
7
8
Patuxent River Species Richness Results (May-August) Residuals
1000 m2 Survey Area
Patuxent River Residuals - June 2006
Distance Upstream (Km)
0 10 20 30 40 50
Num
ber o
f Spe
cies
5
10
15
20
25
30
35
Mea
n S
oil S
alin
ity (p
pt)01234567891011
Patuxent River Resdiuals - August 2006
Distance Upstream (Km)
0 10 20 30 40 50
Num
ber o
f Spe
cies
0
5
10
15
20
25
30
35
Mea
n S
oil S
alin
ity (p
pt)
0123456789101112
Conclusions1. 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