Spatial and temporal patterns of river metabolism along the Cahaba River, AL

Spatial and temporal patterns of river metabolism along the Cahaba River, AL

Elise Chapman, Ryan Sponseller & Jennifer Edmonds

The University of AlabamaDepartment of Biological Sciences

Continuing pressure on water resources• Growing urbanization and agricultural demands on

our landscape occur due to population growth.• These demands often result in physical and chemical

changes to waterways.• Eutrophication• Loss of species diversity• Harmful Algal Blooms

Randy Haddock, Cahaba River Society

Stream mitigation of nutrient loading

Small Streams• Lower ratio of water volume to

sediment area (Alexander et al. 2000)

• Account for majority of stream length (Leopold et al. 1964)

Rivers• Longer transport distance and

water residence time (Wollhiem et al. 2006, Mulhollnad et al. 2008)

• Elevated nutrient concentrations

O2

Reaeration (k)

Ecosystem Respiration (ER)

Gross Primary Production (GPP)

Ecosystem metabolism

Estimating metabolic parametersBayesian Metabolism Model

Gulf Coastal Plain

Valley & Ridge

Fall Line

Mobile River Basin Valley & Ridge

Gulf Coastal

Plain

Fall Line

Modified from USGS map

Mobile River Basin Valley & Ridge

Gulf Coastal

Plain

Fall Line

Modified from USGS map

The Cahaba River

Research ObjectiveIdentify spatial and temporal patterns of ecosystem metabolism in a mid-sized river.

Hypothesis: GPP & ER will be highest along the Fall Line due to highly heterogeneous channel form.

Spatial patterns of GPP & ER

1 2 30123456789

10

Spring

GPPER

g O

2 m

-2 d

ay-1

1 2 30123456789

10

Fall

GPPER

g O

2 m

-2 d

ay-1

VR FL CP

VR FL CP

1 2 30

2

4

6

8

10

12

Summer

GPPER

g O

2 m

-2 d

ay-1

VR FL CP

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10

Winter

GPPER

g O

2 m

-2 d

ay-1

VR FL CP

Spatial patterns of GPP:ER

1 2 30.4

0.6

0.8

1

1.2

1.4

Winter

GPP

: ER

1 2 30.4

0.6

0.8

1

1.2

1.4

Fall

GPP

: ER

1 2 30.4

0.6

0.8

1

1.2

1.4

Summer

GPP

: ER

1 2 30.4

0.6

0.8

1

1.2

1.4

Spring

GPP

: ER

VR FL CP

VR FL CPVR FL CP

VR FL CP

ConclusionsBoth GPP and ER were higher in spring and summer compared to

fall and winter.In most cases ER exceeded GPP indicating net heterotrophy.

Hypothesis: GPP and ER will be highest along the Fall Line due to highly heterogeneous channel form.

No and Yes

1 2 30

2

4

6

8

10

12

Summer

GPPER

g O

2 m

-2 d

ay-1

VR FL CP1 2 3

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10

Winter

GPPER

g O

2 m

-2 d

ay-1

VR FL CP

Field Help

Acknowledgments

Questions?

Comparison to other rivers

Townsend et al. 2011

Example ecosystem metabolism parameter estimates from BaMM

Gross primary production (GPP, g O2 m-2 day-1), respiration (R, g O2 m-2 day-1), P/R, and gasexchange (k, day-1) estimated by BaMM in winter along the Cahaba River , AL.