Patterns of Eutrophication in Lake Matoaka
Transcript of Patterns of Eutrophication in Lake Matoaka
Patterns of Eutrophication in Patterns of Eutrophication in Patterns of Eutrophication in Patterns of Eutrophication in Lake MatoakaLake MatoakaLake MatoakaLake MatoakaWilliamsburg, VAWilliamsburg, VAWilliamsburg, VAWilliamsburg, VA
Lindsay Schwarting, Clarkson University
Dr. Randolph Chambers, College of William & Mary
REU Summer 2007
*Thanks to Mindy Forsyth for being my photographer*
IntroductionIntroductionIntroductionIntroduction
• Eutrophic watersheds– High organic productivity
– ‘Well-fed’ in phosphorus and nitrates
– Murky water depleted in oxygen
• Chlorophyll• Chlorophyll– Energy fixation in photosynthesis
– Assessment of algal biomass in lakes/ponds
– Accurate measure of photosynthetic activity
– Depends on availability of nutrients
ObjectivesObjectivesObjectivesObjectives• Develop a technique for measuring algal chlorophyll Develop a technique for measuring algal chlorophyll Develop a technique for measuring algal chlorophyll Develop a technique for measuring algal chlorophyll concentration in Lake Matoakaconcentration in Lake Matoakaconcentration in Lake Matoakaconcentration in Lake Matoaka
• Establish any patterns of anoxic zonesEstablish any patterns of anoxic zonesEstablish any patterns of anoxic zonesEstablish any patterns of anoxic zones
• Determine whether or not there are spatial/temporal/depth Determine whether or not there are spatial/temporal/depth Determine whether or not there are spatial/temporal/depth Determine whether or not there are spatial/temporal/depth gradients of chlorophyll within the lakegradients of chlorophyll within the lakegradients of chlorophyll within the lakegradients of chlorophyll within the lake– Hypothesis: Eastern side of the lake would have greater amounts of algae (and – Hypothesis: Eastern side of the lake would have greater amounts of algae (and therefore chlorophyll) due to the higher amounts of development-associated runoff
Materials & MethodsMaterials & MethodsMaterials & MethodsMaterials & Methods
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College CreekCollege CreekCollege CreekCollege Creek
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StrawberryStrawberryStrawberryStrawberry
PogoniaPogoniaPogoniaPogonia
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Lake MatoakaLake MatoakaLake MatoakaLake Matoaka
Materials & MethodsMaterials & MethodsMaterials & MethodsMaterials & Methods
• Field measurements– Temperature
– DO2
– Conductivity
• Filtration
• Spectrophotometric methods• Spectrophotometric methods
depth (m)
depth (m)
depth (m)
depth (m)
-1
0
1
2
Results:Results:Results:Results:Depth Patterns
average temperature (C)average temperature (C)average temperature (C)average temperature (C)
0 5 10 15 20 25 30 35
depth (m)
depth (m)
depth (m)
depth (m)
2
3
4
•no significant thermocline
•even mixing of water
Results:Results:Results:Results:Depth Patterns
depth (m)
depth (m)
depth (m)
depth (m)
-1
0
1
2
depth (m)
depth (m)
depth (m)
depth (m)
-1
0
1
2
[chlorophyll] ([chlorophyll] ([chlorophyll] ([chlorophyll] (µµµµg/L)g/L)g/L)g/L)
0 20 40 60 80 100
depth (m)
depth (m)
depth (m)
depth (m)
2
3
4
DODODODO2222 (mg/L) (mg/L) (mg/L) (mg/L)
0 2 4 6 8 10 12depth (m)
depth (m)
depth (m)
depth (m)
2
3
4
•decomposition > photosynthesis
Results:Results:Results:Results:Temporal Patterns
[Chlorophyll] (
[Chlorophyll] (
[Chlorophyll] (
[Chlorophyll] ( µµ µµg/L)
g/L)
g/L)
g/L)
20
30
40
50
60
temperature (C)
temperature (C)
temperature (C)
temperature (C)
10
15
20
25
30
35
datedatedatedate
6/11
/07
6/18
/07
6/25
/07
7/2/07
7/9/07
7/16
/07
[Chlorophyll] (
[Chlorophyll] (
[Chlorophyll] (
[Chlorophyll] (
0
10
datedatedatedate
6/11
/07
6/18
/07
6/25
/07
7/2/07
7/9/07
7/16
/07
0
5
•seasonal variation due to nutrient limitation
Results:Results:Results:Results:Spatial Patterns
[chlorophyll] (
[chlorophyll] (
[chlorophyll] (
[chlorophyll] ( µµ µµg/L)
g/L)
g/L)
g/L)
20
40
60
80
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locationlocationlocationlocation
0 1 2 3 4 5 6 7 8 9 10 11 12 13
0
College Creek 0.030 m3/s
Crim Dell 0.012 m3/s
Strawberry 0.008 m3/s
Pogonia 0.006 m3/s
Berkeley 0.005 m3/s
Table 1. Runoff into Lake Matoaka!(
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BerkeleyBerkeleyBerkeleyBerkeley
StrawberryStrawberryStrawberryStrawberry
PogoniaPogoniaPogoniaPogonia
Crim DellCrim DellCrim DellCrim Dell
99998888
7777
6666
55554444
12121212
11111111
10101010
Lake MatoakaLake MatoakaLake MatoakaLake Matoaka
Results:Results:Results:Results:Spatial Patterns
conductivity (
conductivity (
conductivity (
conductivity (
µµ µµS)S) S)S)
100
200
300
400
500
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locationlocationlocationlocation
0 1 2 3 4 5 6 7 8 9 10 11 12 13
conductivity (
conductivity (
conductivity (
conductivity (
0
100
•correlation between conductivity and runoff volume
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BerkeleyBerkeleyBerkeleyBerkeley
StrawberryStrawberryStrawberryStrawberry
PogoniaPogoniaPogoniaPogonia
Crim DellCrim DellCrim DellCrim Dell
99998888
7777
6666
55554444
12121212
11111111
10101010
Lake MatoakaLake MatoakaLake MatoakaLake Matoaka
ResultsResultsResultsResults
temperature (C)
temperature (C)
temperature (C)
temperature (C)
22
24
26
28
30
32
34
temperature (C)
temperature (C)
temperature (C)
temperature (C)
22
24
26
28
30
32
34r2 = .35 r2 = .37
[chlorophyll] ([chlorophyll] ([chlorophyll] ([chlorophyll] (µµµµg/L)g/L)g/L)g/L)
0 20 40 60 80 100 120
20
DODODODO2222 (mg/L) (mg/L) (mg/L) (mg/L)
0 2 4 6 8 10 12 14 16
20
•high chlorophyll and low DO2
at cold temperatures
•decomposition is occurring faster than photosynthesis
•warmer water near the surface receives more oxygen from atmosphere
•colder water at bottom has more respiration and decomposition
ConclusionsConclusionsConclusionsConclusions
•Chlorophyll concentration and conductivity correlates directly w. runoff volume
•Lake Matoaka as a large-scale BMP?
EutrophicEutrophicEutrophicEutrophic
Chlorophyll (Chlorophyll (Chlorophyll (Chlorophyll (µµµµg/L)g/L)g/L)g/L) >15
Phosphorus (Phosphorus (Phosphorus (Phosphorus (µµµµg/L)g/L)g/L)g/L) >15
Table 2. Lake Matoaka as a eutrophic system
Phosphorus (Phosphorus (Phosphorus (Phosphorus (µµµµg/L)g/L)g/L)g/L) >15
Depth (m) and Depth (m) and Depth (m) and Depth (m) and sedimentsedimentsedimentsediment
<10, organic bottom high in N
Source. Berner, E. Global Environment. p 251.
ReferencesReferencesReferencesReferences
1. Berner, E. Global Environment: Water, Air, and Geochemical Cycles. Prentice Hall. NJ. pp 247-260. 1996.
2. Lorenzen, C. 1967. Determination of Chlorophyll and Pheo-Pigments: Spectrophotometric Equations. Limnology and Oceanography 12: 343-346.
3. Lorenzen, C. 1970. Surface Chlorophyll as an Index of the Depth, Chlorophyll Content, and Primary Productivity of the Euphotic Layer. Limnology and Oceanography 15: 479-480.Limnology and Oceanography 15: 479-480.
4. Nelson, D. 1960. Improved Chlorophyll Extraction Method. Science 132: 351.
5. Oviatt, C. et al. 1986. Patterns of productivity during eutrophication. Marine Ecology 28: 69-80.
6. Wetzel, R. Limnology 2nd Ed. Saunders College Publishing. PA. 1983.
7. Yentsch, C. 1957. Short-Term Variations in Phytoplankton Chlorophyll and Their Significance. Limnology and Oceanography 2: 140-142.