WEEKI WACHEE SPRINGS
N O 3 - (m g /L )
1
0.8
0.6
0.4
0.2
0
1930
1950
1970
1990
YEAR
Data provided by the Southwest Florida Water Management District and UF
2010
Data from Hornsby et al. 2002, 2003, 2004 and 2005 (slide courtesy of M. Cohen)
Is increased nutrient delivery
compromising the ecological
integrity of Florida’s spring-fed
coastal rivers?
Study Rivers
Image credit: Google Earth®
Homosassa
River
Chassahowitzka
River
Chassahowitzka River – Nitrate
Mean NITRATE (µg N/L)
500
400
300
200
100
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Open Circles = 1998 to 2000, Closed Circles = 2003 to 2005 within TRANSECT
Nitrate concentration has increased by 20%
Nitrate loading in the headwater region has increased by 43%
Chassahowitzka River – Soluble Reactive Phosphorus
Mean S. R. PHOSPHORUS (µg P/L)
20
18
16
14
12
10
8
6
4
2
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Open Circles = 1998 to 2000, Closed Circles = 2003 to 2005 within TRANSECT
SRP concentration has increased by 19%
SRP loading in the headwater region has increased by 44%
Effect of Nutrient Addition on Periphyton - Chas s ahowitzka River
µ
ug Chl per cm
2
9
8
7
6
5
4
C
N
P
Treatm ent
Figure from Notestein et al. 2003
N+P
Chassahowitzka River – Submersed Aquatic Vegetation
Mean Total SAV Biomass (kg/m2)
5
4
3
2
1
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
Open Circles = 1998 to 2000, Closed Circles = 2003 to 2005 within TRANSECT
Total SAV biomass has decreased by 31%
Rooted vascular plants have declined by 20%
9.5
10.0
Mean Periphyton (mg chl/g wet wt host plant)
Chassahowitzka River – Periphyton
0.26
0.24
0.22
0.20
0.18
0.16
1998 - 2000
2003 - 2005
Time Period
Periphyton associated with macrophytes has increased by 30%
Homosassa River – Nitrate
Mean NITRATE (µg N/L)
500
400
300
200
100
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Open Circles = 1998 to 2000, Closed Circles = 2003 to 2005 within TRANSECT
Nitrate concentration has increased by 6%
Nitrate loading in the headwater region has increased by 56%
Homosassa River – Soluble Reactive Phosphorus
Mean S. R. PHOSPHORUS (µg P/L)
20
18
16
14
12
10
8
6
4
2
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Open Circles = 1998 to 2000, Closed Circles = 2003 to 2005 within TRANSECT
SRP concentration has increased by 15%
SRP loading in the headwater region has increased by 46%
Homosassa River – Submersed Aquatic Vegetation
Mean Total SAV Biomass (kg/m2)
5
4
3
2
1
0
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
Open Circles = 1998 to 2000, Closed Circles = 2003 to 2005 within TRANSECT
Total SAV biomass has decreased by 67%
Rooted vascular plants have declined by 80%
10.0
10.5
Mean Periphyton (mg chl/g wet wt host plant)
Homosassa River – Periphyton
0.18
0.16
0.14
0.12
0.10
0.08
1998 - 2000
2003 - 2005
Time Period
Periphyton associated with macrophytes has increased by 85%
HOMOSASSA
RIVER
CHASSAHOWITZKA
RIVER
Images created in ArcMap®
Fish biomass in the Chassahowitzka and Homosassa Rivers
- Seine Collections -
Estimated Fish Biomass
Biomass (g m -2 )
2500
2000
1500
1000
500
0
Chassahow itzka
River
M.V. Lauretta et al. – February 2008
Hom osassa
Fish biomass in the Chassahowitzka and Homosassa Rivers
- Electroshocking -
Biomass (g m -2 )
Estimated Fish Biomass
18
16
14
12
10
8
6
4
2
0
Chassahow itzka
Hom osassa
River
M.V. Lauretta et al. – February 2008
EUTROPHICATION
PROGRESSION SCHEME
INCREASED
NUTRIENT
DELIVERY
R
G
A
G
N
ZI
ENHANCED
MICROALGAL AND
MACROALGAL GROWTH
INCREASED SHADING AND
BENTHIC RESPIRATION
MACROPHYTE LOSS
Adapted from C.M.Duarte (1995)
Acknowledgments