The role of ecosystem ecology in estuarine ecosystem managment

Mike Piehler

UNC-CH Institute of Marine Sciences UNC Coastal Studies Institute

“We can't solve problems by using the same kind of thinking we used when we created them.”

Albert Einstein

A.Partnerships -- Those people most affected by management decisions are involved throughout and shape key decisions.

B.Geographic Focus -- Activities are directed within specific geographic areas, typically the areas that drain to surface water bodies or that recharge or overlay ground waters or a combination of both.

C.Sound Management Techniques based on Strong Science and Data

i.assessment and characterization of the natural resources and the communities that depend upon them; ii.goal setting and identification of environmental objectives based on the condition or vulnerability of resources and the needs of the aquatic ecosystem and the people within the community; iii.identification of priority problems; iv.development of specific management options and action plans; v.implementation; and vi.evaluation of effectiveness and revision of plans, as needed.

Watershed Approach

Watershed conservation, restoration and rehabilitation

•Terrestrial•Land-water margin•Aquatic•Atmospheric

Sources

Transport

Transformation

Water management

• Minimize consumptive uses

• Remove obstructions• Maintain natural

connectivity between aquatic and terrestrial systems

• Consider flow management where tenable

Nutrient management

• Identify limiting nutrients• Identify sources of the

limiting nutrients in the watershed

• Identify a tenable and effective reduction target

• Manage point sources where possible

• Manage non-point sources as appropriate

Application of ecosystem ecology

• Are BMPs really the best?

• Can estuarine nutrient management exacerbate eutrophication?

• Is the application of ecological threshold theory of value to estuarine nutrient management?

A cap on nitrogen load and a 30% loading reduction have been mandated for the Neuse River Estuary (NRE) watershed

NeuseRiverEstuary

• Includes rules for wastewater, urban stormwater, agriculture and general nutrient management

• Utilization of agricultural Best Management Practices (BMPs) is among the alternatives for agricultural operations in the NRE to become compliant under the Neuse Rules

• Understanding the effectiveness of BMPs such as constructed wetlands is critical to guiding the process and eventually assessing the success of the nutrient reduction efforts

“The Neuse Rules”

Open Grounds Farm

• ~45,000 acre row crop farm• Crops include corn, soybeans,

wheat and cotton• Constructed wetland built in

1999 on 20 acre site• Significant proportions of the

runoff from OGF enters the South River and then the NRE

Monitoring and Analyses

NH4 NO3 PO4 DON0

100000

200000

300000

400000

500000

600000

700000

800000Load inLoad out

mo

les

32%

46%

34%

The bottom line…

Open Grounds Farm – 2001

•Dry much of the year

•Watershed of the wetland was planted in corn

•Fertilizer spill 4-4-01

~200-300 gallons

50% UAN

50% 11-37-0 (N-P-K)

J F M A M J J A S O N D-20

0

20

40

60

80

100

120

NH4 load inNH4 load out

J F M A M J J A S O N D-200

0200400600800

10001200140016001800

NO3 load inNO3 load out

J F M A M J J A S O N D-20

020406080

100120140

PO4 load inPO4 load out

kilo

gra

ms

Wetland Nutrient Loading

Jan

uar

y

Feb

ruar

y

Mar

ch

Ap

ril

May

Jun

e

July

Au

gu

st

Sep

tem

ber

Oct

ob

er

No

vem

ber

Dec

emb

er

0

100

200

300

400

500

600

700

Nitrate removedDenitrification

kg N

- N

O3

Nitrate removal and Denitrification - 2001

Jan

Feb

Mar

Ap

r

May

Jun

Jul

Au

g

Sep Oct

No

v

Dec

Jan

00.5

11.5

22.5

33.5

44.5

5

Nitrate

Jan

Feb

Mar

Ap

r

May

Jun

Jul

Au

g

Sep Oct

No

v

Dec

Jan

0

0.5

1

1.5

2

2.5

Ammonium

Jan

Feb

Mar

Ap

r

May

Jun

Jul

Au

g

Sep Oct

No

v

Dec

Jan

0

0.05

0.1

0.15

0.2

0.25

Phosphate

Bridge

mg

/l

Jan-01Feb-01

Mar-01Apr-01

May-01Jun-01

Jul-01Aug-01

Sep-01Oct-01

Nov-01Dec-01

0

50

100

150

200

250

160165180

Jan-01Feb-01

Mar-01Apr-01

May-01Jun-01

Jul-01Aug-01

Sep-01Oct-01

Nov-01Dec-01

050

100150200250300350400450500

Legend160165180

Jan-01Feb-01

Mar-01Apr-01

May-01Jun-01

Jul-01Aug-01

Sep-01Oct-01

Nov-01Dec-01

0102030405060708090

160165180

ug

l-1

nitrate

ammonium

phosphate

Neuse River Estuary

Jan-01

Feb-01Mar-01

Apr-01May-01

Jun-01Jul-01

Aug-01Sep-01

Oct-01Nov-01

Dec-01Jan-02

0

2

4

6

8

10

12

14

160165180

Bottom DO

mg

l-1

Jan-01Feb-01

Mar-01Apr-01

May-01Jun-01

Jul-01Aug-01

Sep-01Oct-01

Nov-01Dec-01

0

10

20

30

40

50

60

Legend160165180

Chlorophyll a

ug

l-1

Neuse River Estuary

Why worry about stimulating estuarinemicrobial N2 fixation?

•Many N2 fixing species are nuisance organisms, and their proliferation may decrease water quality

•Biological fixation of N2 may circumvent engineered N loading reductions

•Selection for N2 fixing organisms may cause trophic disruption by increasing abundances of less palatable or less nutritious phytoplankton

10 m

a.

f.d.c.

b.

e.

Anabaena aphanizomenoides (a)

Anabaenopsis sp. (b)

Cylindrospermopsis raciborskii (c,

d) Anabaena compacta (e, f)

Dilution Bioassay Setup

Control30%

Dilution

10L Neuse River

7L Neuse River Water 3L Major Ion Solution

30%Dilution

water

+P

Marker 15 N & Preduced

Nreduced

N:Preduced

July 1997

control 30% dilution 30%+P0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Anabaena aphanizomenoides

salinity NOx NH4 PO4 DIN:DIP

(ppt) (uM) (uM) (uM)

0.3 0.4 0.9 1.7 0.7

Control 30% Dilution 30% Dilution + P0

5

10

15

20

25

30

0

2

4

6

8

10

12

Ace

tyle

ne

Red

uct

ion

/ ch

loro

ph

yll a

(nm

ol C

2H

4 l-1

g

Ch

l a-1 h

-1)

Assim

ilation

Nu

mb

er(m

g C

mg

Ch

l a-1 h

-1)

Assimilation NumberAcetylene Reduction

July 1998

control 20% 20%+P 30% 30%+P 40% 40%+P 50% 50%+P0

1000

2000

3000

4000

5000

6000

7000

8000Anabaena aphanizomenoidesAnabaenopsis sp.Anabaena compacta

salinity NOx NH4 PO4 DIN:DIP

(ppt) (uM) (uM) (uM)

2.2 0.0 0.5 2.3 0.2

0

5

10

15

20

0

1

2

3

4

5

6

7

8

9

Ace

tyle

ne

Red

uct

ion

/ ch

loro

ph

yll a

(nm

ol C

2H

4 l-1

g

Ch

l a-1 h

-1)

Assim

ilation

Nu

mb

er(m

g C

mg

Ch

l a-1 h

-1)

Assimilation NumberAcetylene Reduction

August 1998

control 30% dilution 30%+P0

200

400

600

800

1000 Anabaena aphanizomenoides

salinity NOx NH4 PO4 DIN:DIP

(ppt) (uM) (uM) (uM)

4.4 0.1 0.8 2.7 0.3

Control 30% Dilution 30% Dilution + P0

5

10

15

20

25

30

0

1

2

3

4

5

6

Ace

tyle

ne

Red

uct

ion

/ ch

loro

ph

yll a

(nm

ol C

2H

4 l-1

g

Ch

l a-1 h

-1)

Assim

ilation

Nu

mb

er(m

g C

mg

Ch

l a-1 h

-1)

Assimilation NumberAcetylene Reduction

02468

1012141618

0100200300400500600700800

0

20

40

60

80

100

120

140

7-Ja

n-97

15-A

pr-9

7

22-J

ul-9

720

-Aug

-97

14-O

ct-9

7

22-D

ec-9

721

-Jan

-98

16-M

ar-9

8

20-M

ay-9

815

-Jun

-98

17-A

ug-9

8

2-N

ov-9

81-

Dec

-98

3-Fe

b-99

29-M

ar-9

926

-Apr

-99

1-Ju

l-99

24-A

ug-9

920

-Sep

-99

4-N

ov-9

9

7-Ja

n-97

21-J

an-9

8

1-D

ec-9

8

20-S

ep-9

9

0

20

40

60

80

100

120

Sal

inity

(ppt

)N

O3

- (u

g/l)

NH

4+

(ug/

l)P

O4

+ (u

g/l)

What is the potential importance of N2 fixation to the NRE N budget?

7x107 m2

1.25 x 10-5 mol N m-3 y-1120 d y-112 h d-12 m deep3.5X104 kg Nas much as 3% of riverine DINload to NRE

Evolving scientific basis for management

Ecological thresholds

•Ecosystem responses to forcing are often discontinuous and non-linear

•Threshold - A critical value of a pressure beyond which a state indicator shifts to a different regime

UltimateDriver

ProximalDriver

StatusIndicator

= f

Ecologicalgoods and services

e.g. nutrient concentrations and/or

flow regime

e.g. landuse

350N 350N

770W

770W

UpperNRE

Middle NRE

Lower NRE

SW PSSE PS

Neuse RiverEstuary

PamlicoSound

AtlanticOcean

NorthCarolina

350N 350N

770W

770W

UpperNRE

Middle NRE

Lower NRE

SW PSSE PS

Neuse RiverEstuary

PamlicoSound

AtlanticOcean

NorthCarolina

TP

0

2

4

6

8

10

12

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

Year

TP

(µ

M)

TP

0

10

20

30

40

50

60

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

Year

Chl

orop

hyll a

(µ

g L-1

)

Chl a350N 350N

770W

770W

UpperNRE

Middle NRE

Lower NRE

SW PSSE PS

Neuse RiverEstuary

PamlicoSound

AtlanticOcean

NorthCarolina

350N 350N

770W

770W

UpperNRE

Middle NRE

Lower NRE

SW PSSE PS

Neuse RiverEstuary

PamlicoSound

AtlanticOcean

NorthCarolina

nitrogen load

phytoplankton

estuarine ecosystem services

TMDL for nitrogen in the Neuse River Estuary

0123456789

101

97

81

97

91

98

01

98

1

19

82

19

83

19

84

19

85

19

86

19

87

19

88

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

Year

DIN

Lo

ad

(to

ns

N d

-1)

05

1015202530354045

19

78

19

79

19

80

19

81

19

82

19

83

19

84

19

85

19

86

19

87

19

88

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

Year

Ch

loro

ph

yll

a (

ug

l-1)

350N 350N

770W

770W

UpperNRE

Middle NRE

Lower NRE

SW PSSE PS

Neuse RiverEstuary

PamlicoSound

AtlanticOcean

NorthCarolina

350N 350N

770W

770W

UpperNRE

Middle NRE

Lower NRE

SW PSSE PS

Neuse RiverEstuary

PamlicoSound

AtlanticOcean

NorthCarolina

Riverine DIN and mid-estuary chlorophyll a