Nitrogen, Phosphorus and Chlorophyll 

Relationships in the Big Bend 

Numeric nutrient criteria meeting

23 February 2010


What do we measure?

• Temperature

• Salinity

• Dissolved Oxygen

• Light Attenuation (Kd)

• Secchi Depth

• Color

• Chlorophyll

• Total Nitrogen

• Total Phosphorus
Average Values (+ Std Err) by System 

Estuary Stations

0

100

200

300

400

500

600

700

TN (ug/L)

Mean Total Nitrogen (μg/L) by System
Average Values (+ Std Err) by System 

Estuary Stations

0

10

20

30

40

50

60

TP (ug/L)

Mean Total Phosphorus (μg/L) by System
Average Values (+ Std Err) by System 

Estuary Stations

0

2

4

6

8

10

12

CHL (ug/L)

Mean Chlorophyll-a (μg/L) by System
All Systems Estuary Stations

0

200

400

600

800

1000

1200

1400

1600

1800

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

All Systems Monthly Average Total Nitrogen (TN) 

1996 through 2008 Estuarine Stations 

Anclote

Aripeka

Chassahowitzka

Crystal

Homosassa

Hudson

Pithlachascotee

Weeki Wachee

Withlacoochee

Steinhatchee

Suwannee

Waccasassa

0

20

40

60

80

100

120

140

160

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

All Systems Monthly Average Total Phosphorus (TP) 

1996 through 2008 Estuarine Stations

Anclote

Aripeka

Chassahowitzka

Crystal

Homosassa

Hudson

Pithlachascotee

Weeki Wachee

Withlacoochee

Steinhatchee

Suwannee

Waccasassa

0

5

10

15

20

25

30

35

40

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

All Systems Average Chlorophyll-a (CHL-a)

1996 through 2008 Estuarine Stations 

Anclote

Aripeka

Chassahowitzka

Crystal

Homosassa

Hudson

Pithlachascotee

Weeki Wachee

Withlacoochee

Steinhatchee

Suwannee

Waccasassa
Steinhatchee Estuary

0

100

200

300

400

500

600

700

800

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

Steinhatchee Monthly Average Total Nitrogen (TN) 

1997 through 2008 Estuarine Stations

0

5

10

15

20

25

30

35

40

45

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

Steinhatchee Monthly Average Total Phosphorus (TP) 

1997 through 2008 Estuarine Stations

0

2

4

6

8

10

12

14

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

Steinhatchee Average Chlorophyll-a (CHL-a)

1997 through 2008 Estuarine Stations 
Suwannee Estuary

0

200

400

600

800

1000

1200

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

Suwannee Monthly Average Total Nitrogen (TN) 

1997 through 2008 Estuarine Stations

0

20

40

60

80

100

120

140

160

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

Suwannee Monthly Average Total Phosphorus (TP) 

1997 through 2008 Estuarine Stations

0

5

10

15

20

25

30

35

40

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

Suwannee Average Chlorophyll-a (CHL-a)

1997 through 2008 Estuarine Stations 
Waccasassa Estuary

0

200

400

600

800

1000

1200

1400

1600

1800

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

Waccasassa Monthly Average Total Nitrogen (TN) 

1997 through 2008 Estuarine Stations

0

20

40

60

80

100

120

140

160

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

Waccasassa Monthly Average Total Phosphorus (TP) 

1997 through 2008 Estuarine Stations

0

5

10

15

20

25

30

35

40

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

Waccasassa Average Chlorophyll-a (CHL-a)

1997 through 2008 Estuarine Stations 

Correlation coefficient = 0.46

p < 0.001

-1.0

0.0

1.0

2.0

2.0 2.5 3.0 3.5

log10[Chlorophyll (μg L-1)]

Log10[Total nitrogen (μgL-1)]

Figure 3. Relationship between log10-transformed monthly mean chlorophyll and total 

nitrogen concentrations from all estuarine systems (From Jacoby et al. 2009).
Correlation coefficient = 0.84

p < 0.001

-1.0

0.0

1.0

2.0

0.0 0.5 1.0 1.5 2.0 2.5

log10[Chlorophyll (μg L-1)]

Log10[Total phosphorus (μgL-1)]

Figure 2. Relationship between log10-transformed monthly mean chlorophyll and total 

phosphorus concentrations from all estuarine systems (From Jacoby et al. 2009).
Withlacoochee Estuary

0

200

400

600

800

1000

1200

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

Withlacoochee Monthly Average Total Nitrogen (TN) 

1996 through 2008 Estuarine Stations

0

20

40

60

80

100

120

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

Withlacoochee Monthly Average Total Phosphorus (TP) 

1996 through 2008 Estuarine Stations

0

5

10

15

20

25

30

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

Withlacoochee Average Chlorophyll-a (CHL-a)

1996 through 2008 Estuarine Stations 
Crystal Estuary

0

200

400

600

800

1000

1200

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

Crystal Monthly Average Total Nitrogen (TN) 

1996 through 2008 Estuarine Stations

0

10

20

30

40

50

60

70

80

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

Crystal Monthly Average Total Phosphorus (TP) 

1996 through 2008 Estuarine Stations

0

5

10

15

20

25

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

Crystal Average Chlorophyll-a (CHL-a)

1996 through 2008 Estuarine Stations 
Homosassa Estuary

0

200

400

600

800

1000

1200

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

Homosassa Monthly Average Total Nitrogen (TN) 

1996 through 2008 Estuarine Stations 

0

10

20

30

40

50

60

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

Homosassa Monthly Average Total Phosphorus (TP) 

1996 through 2008 Estuarine Stations

0

5

10

15

20

25

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

Homosassa Average Chlorophyll-a (CHL-a)

1996 through 2008 Estuarine Stations 
Chassahowitzka Estuary

0

200

400

600

800

1000

1200

1400

1600

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

Chassahowitzka Monthly Average Total Nitrogen (TN) 

1997 through 2008 Estuarine Stations 

0

5

10

15

20

25

30

35

40

45

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

Chassahowitzka Monthly Average Total Phosphorus (TP) 

1997 through 2008 Estuarine Stations

0

5

10

15

20

25

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

Chassahowitzka Average Chlorophyll-a (CHL-a)

1997 through 2008 Estuarine Stations 
Weeki Wachee Estuary

0

200

400

600

800

1000

1200

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TN (ug/L)

Weeki Wachee Monthly Average Total Nitrogen (TN) 

1997 through 2008 Estuarine Stations 

0

5

10

15

20

25

30

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

TP (ug/L)

Weeki Wachee Monthly Average Total Phosphorus (TP) 

1997 through 2008 Estuarine Stations

0

2

4

6

8

10

12

Mar-96 Aug-97 Dec-98 May-00 Sep-01 Jan-03 Jun-04 Oct-05 Mar-07 Jul-08

CHL-a (ug/L)

Weeki Wachee Average Chlorophyll-a (CHL-a)

1997 through 2008 Estuarine Stations 
Nitrogen Phosphorus Chlorophyll

= significant positive correlation = significant negative correlation

Temporal correlations with TN, TP and Chlorophyll

- Wet Months -
= significant positive correlation = significant negative correlation

Temporal correlations with TN, TP and Chlorophyll

- Transitional Months -

Nitrogen Phosphorus Chlorophyll
Nitrogen Phosphorus Chlorophyll

= significant positive correlation = significant negative correlation

Temporal correlations with TN, TP and Chlorophyll

- Dry Months -
Primary limiting nutrient by system

(Springs Coast 2000-2001)

.

Limiting Nutrient (Primary) 

System % N % P % CO % U

Weeki Wachee 0 79 6 15

Chassahowitzka 4 40 40 17

Homosassa 0 51 32 17

Crystal 29 29 29 13

Withlacoochee 50 27 15 8

P = phosphorus limited

N = nitrogen limited

CO =phosphorus and nitrogen limited

U = not nutrient limited

-1.0

-0.5

0.0

0.5

1.0

2.0 2.2 2.4 2.6 2.8 3.0 3.2

Log10[Total nitrogen (μg L-1)]

Log10[Chlorophyll (μg L-1)]

Correlation coefficient = 0.48

p < 0.001

Relationship between log10-transformed monthly mean chlorophyll and total 

nitrogen concentrations from all estuarine systems (From Jacoby et al. 2009).
-1.0

-0.5

0.0

0.5

1.0

0.5 1.0 1.5 2.0

Log10[Total phosphorus (μg L-1)]

Log10[Chlorophyll (μg L-1)]

Correlation coefficient = 0.72

p < 0.001

Relationship between log10-transformed monthly mean chlorophyll and total 

phosphorus concentrations from all estuarine systems (From Jacoby et al. 2009).
Aripeka Estuary

0

100

200

300

400

500

600

700

800

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

TN (ug/L)

Aripeka Monthly Average Total Nitrogen (TN) 

2000 through 2008 Estuarine Stations 

0

2

4

6

8

10

12

14

16

18

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

TP (ug/L)

Aripeka Monthly Average Total Phosphorus (TP) 

2000 through 2008 Estuarine Stations

0

1

2

3

4

5

6

7

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

CHL-a (ug/L)

Aripeka Average Chlorophyll-a (CHL-a)

2000 through 2008 Estuarine Stations 
Hudson Estuary

0

100

200

300

400

500

600

700

800

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

TN (ug/L)

Hudson Monthly Average Total Nitrogen (TN) 

2000 through 2008 Estuarine Stations 

0

5

10

15

20

25

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

TP (ug/L)

Hudson Monthly Average Total Phosphorus (TP) 

2000 through 2008 Estuarine Stations

0

1

2

3

4

5

6

7

8

9

10

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

CHL-a (ug/L)

Hudson Average Chlorophyll-a (CHL-a)

2000 through 2008 Estuarine Stations 
Pithlachascotee Estuary

0

100

200

300

400

500

600

700

800

900

1000

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

TN (ug/L)

Pithlachascotee Monthly Average Total Nitrogen (TN) 

2000 through 2008 Estuarine Stations 

0

5

10

15

20

25

30

35

40

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

TP (ug/L)

Pithlachascotee Monthly Average Total Phosphorus (TP) 

2000 through 2008 Estuarine Stations

0

2

4

6

8

10

12

14

16

18

20

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

CHL-a (ug/L)

Pithlachascotee Average Chlorophyll-a (CHL-a)

2000 through 2008 Estuarine Stations 
Anclote Estuary

0

100

200

300

400

500

600

700

800

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

TN (ug/L)

Anclote Monthly Average Total Nitrogen (TN) 

2000 through 2008 Estuarine Stations 

0

5

10

15

20

25

30

35

40

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

TP (ug/L)

Anclote Monthly Average Total Phosphorus (TP) 

2000 through 2008 Estuarine Stations

0

2

4

6

8

10

12

May-99 Oct-00 Feb-02 Jun-03 Nov-04 Mar-06 Aug-07 Dec-08

CHL-a (ug/L)

Anclote Average Chlorophyll-a (CHL-a)

2000 through 2008 Estuarine Stations 
= significant positive correlation = significant negative correlation

Temporal correlations with TN, TP and Chlorophyll

- Wet Months -

Nitrogen Phosphorus Chlorophyll
= significant positive correlation = significant negative correlation

Temporal correlations with TN, TP and Chlorophyll

- Transitional Months -

Nitrogen Phosphorus Chlorophyll
= significant positive correlation = significant negative correlation

Temporal correlations with TN, TP and Chlorophyll

- Dry Months -

Nitrogen Phosphorus Chlorophyll