Coastal Watersheds: The Lateral Link to Estuaries Fred Holland & Denise Sanger

Coastal Watersheds:
The Lateral Link to Estuaries
Fred Holland & Denise Sanger
Estuarine Gradients
Upland Creek
Saltmarsh Creeks
Objectives of Talk
„
Provide the scientific underpinnings linking
watershed characteristics and estuarine
water quality (at the scale of tidal creeks).
„
Document that tidal creek ecosystems are
at great risk to land cover alterations.
„ Complex food webs
„ Refuge and nursery
habitat
„ Primary hydrologic
link to uplands
„ Preferred sites for
development
Land Use Change in
Horlbeck Creek
1994
1999
Reference
Developed
Myrtle Beach
Georgetown
Charleston
Beaufort
Measured Parameters
„ Watershed Characteristics
‹
Drainage basin area, land cover and
impervious cover
„ Physical/Chemical
‹
‹
‹
Water quality: salinity, temperature, DO, pH
Sediment characteristics & contamination
Fecal coliform bacteria
„ Macrobenthos & Nekton
‹
Population and community level properties
Wando
River
Forested Watershed
In
te
rs
ta
te
52
6
Suburban Watershed
James Island
High School
Industrial
Watershed
Urban Watershed
1999
1992
100
90
80
70
60
50
Urban Criteria
40
30
20
Forested
Suburban
SH
KP
DL
VR
SM
NM
YC
PC
MC
HB
CC
BL
RT
LC
LI
LH
FT
0
Suburban Criteria
DP
10
BF
Impervious Surface Coverage (%)
Impervious Cover
Urban/Industrial
Human Population Density
Population (People/Hectare)
35
r2 =0.52 p <0.0001
30
1999
1992
25
20
15
10
5
0
0
20
40
60
80
Percent Impervious Cover
100
Salinity
40
Summer
1994
35
Winter
2000
25
20
15
10
Suburban
DL
KP
SH
Forested
NM
SM
VR
BL
CC
HB
MC
PC
YC
DL
KP
SH
SubUrban/
urban Industrial
BF
DP
FT
LH
LC
LI
RT
Forested
NM
VR
0
BL
CC
MC
PC
SM
YC
5
BF
DP
FT
HB
LH
LC
LI
RT
Salinity (ppt)
30
Urban/
Industrial
160
Summer
1994
140
Winter
2000
120
100
80
60
40
28% Saturation
BL
CC
HB
MC
PC
YC
NM
SM
VR
DL
KP
SH
DL
KP
SH
SubUrban/
urban Industrial
BF
DP
FT
LH
LC
LI
RT
Forested
NM
VR
0
BL
CC
MC
PC
SM
YC
20
BF
DP
FT
HB
LH
LC
LI
RT
Dissolved Oxygen (% Saturation)
Dissolved Oxygen
Forested
Suburban
Urban/
Industrial
Chlorophyll a (mg/m2)
Pore Water Ammonia
and
Benthic Chlorophyll a
NH4+ (µmol/l)
120
80
40
0
Forested
Suburban
Urban/
Industrial
160
120
80
40
0
Forested
Suburban
Urban/
Industrial
Fecal Coliforms vs. Impervious Cover
6
Log of Fecal Coliform
5
4
3
2
r2 = 0.35
p = 0.0081
1
0
0
10
20
30
40
50
60
Impervious Cover (%)
70
80
90
Chemical Contamination
0
r2 =0.52 p <0.0001
-0.2
-0.4
Log ERMQ
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
94 Cal
95 Val
-1.8
00 Cal
-2
0
20
40
60
Percent Impervious Cover
80
100
Macrobenthic Indicators
Summer 1994
Winter 2000
Relative Abundance (%)
80 Stress-Sensitive Taxa
60
40
20
0
80 Stress-Indicative Taxa
60
40
20
0
Forested Sub- Urban/
urban Industrial
Forested Sub- Urban/
urban Industrial
Stress
-Tolerant Taxa
Stress-Tolerant
Stress-Tolerant Taxa (%)
120
94 Cal
r2 =0.16 p =0.0038
94 Val
95 Val
100
00 Cal
80
60
40
20
0
0
20
40
60
Percent Impervious Cover
80
100
80
60
40
20
0
12
10
8
6
4
2
0
For
Sub
Ind
Urb
Penaeid Shrimp
For
Sub
Ind
Abundance (#/m2)
Grass Shrimp
120
100
Urb
Abundance (#/m2)
Abundance (#/m2)
Abundance (#/m2)
Fish and Crustaceans
0.6
0.5
0.4
0.3
0.2
0.1
0
3.0
2.5
2.0
1.5
1.0
0.5
0
Spot
For
Sub
Ind
Urb
Mummichog
For
Sub Ind
Urb
Penaeoid Shrimp (Log abundance)
Penaeoid Shrimp
1.6
r2 =0.36 p =0.0023
94 Cal
1.4
94 Val
1.2
95 Val
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
0
20
40
60
Percent Impervious Cover
80
100
Conceptual Model of Linkages
Stressor
Human Population
Density
Exposure
Physical-Chemical
Environment
Response
Living
Resources
Altered Land Cover
Altered Hydrography
Altered Abundance
Increased Impervious
Surface
Change in Salinity
Few Sensitive Taxa
Increased Pollution
Loadings
Chemical Contaminants
Sediment Characteristics
Increased Bacterial Load
15%Impervious Surface
Altered Food Webs
Shellfish Bed Closures
30% Impervious Surface
Management Conclusions
„ Imperviousness is an important indicator of
watershed condition for the lateral gradient.
„ Development alters physical, chemical, and
biological properties of lateral tidal creeks.
„ Biological properties (e.g., benthic communities)
had value in assessing tidal creek condition.
„ Tidal creeks respond to changes in watershed
properties on times scales of years to decades.
RECOMMENDATIONS
„ Plan “green” developments:
‹
‹
‹
Limit alterations to freshwater inflow
z require vegetated buffers.
z build bridges not causeways.
z utilizing grassy swales.
Minimize amount of impervious cover.
Maximize open space and vegetation.
„ Develop guidance for “environmental friendly”
living.
‹ Scale of development
‹ Engineered vs non-structured controls
‹ Maintain septic systems/holding ponds
‹ Control pet feces
RECOMMENDATIONS
„ Develop incentives and guidance to
encourage land conservation and
stewardship.
‹
Land trusts, reserves, sanctuaries
„ Monitor tidal creeks to assess the
effectiveness of management
actions.
“Green”
Planning and
Infrastructure
Encourage Cluster
Development
“Green” Planning
and Infrastructure
Utilize Grassy Swales
Unacceptable Buffer
Acceptable Buffer