Update on Phosphorus and Cladophora in the Lake … Quality/Bootsma...1 Update on Phosphorus and...
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Transcript of Update on Phosphorus and Cladophora in the Lake … Quality/Bootsma...1 Update on Phosphorus and...
1
Update on Phosphorus and Cladophora in the Lake Michigan
Nearshore Zone
Harvey Bootsma
0
5
10
15
20
25
30
1980-84 1985-89 1990-94 1995-99 2000-05
[P] (μ
g L-1
)
Total Dissolved PTotal P
14.5
9.5
19.4
7.8
11.7
6.9
12.6
8.2
11.912.5
Nearshore TP and TDP Concentrations Since 1980,
Near Milwaukee Harbor
2
Spring Total P(mean of all pelagic stations)
0
1
2
3
4
5
6
719
8319
8419
8519
8619
8719
8819
8919
9019
9119
9219
9319
9419
9519
9619
9719
9819
9920
0020
0120
0220
0320
0420
05
Tota
l P ( μ
g/L) Michigan
Huron
GLWQA Target for Lake Michigan: 7 μg/L
0
0.05
0.1
0.15
0.2
0.25
0.3
1 /1 /8 2 1 /1 /8 3 1 /1 /8 4 1 2 /3 1 /8 4 1 /1 /8 6 1 /1 /8 7 1 /1 /8 8 1 2 /3 1 /8 8 1 /1 /9 0 1 /1 /9 1 1 /1 /9 2 1 2 /3 1 /9 2 1 /1 /9 4 1 /1 /9 5 1 /1 /9 6 1 2 /3 1 /9 6 1 /1 /9 8 1 /1 /9 9 1 /1 /0 0 1 2 /3 1 /0 0 1 /1 /0 2
mg/
L
SRP
TP
82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01
20-Year Phosphorus Trend at River Junction
Data Source: MMSD
3
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
1980 1985 1990 1995 2000 2005
Dis
solv
ed P
: To
tal P
Rat
io
In Milwaukee River, dissolved P is becoming a larger fraction of TP
0
1
2
3
4
5
1970 1975 1980 1985 1991 1994 1995
Ave
rage
[P] (
ppm
)So
il P
Stor
age
Cha
nge
(kg
ha-1
)
P in Wisconsin Cropland
Bundy and Sturgul 2001
0102030405060
1968-73
1974-77
1978-81
1982-85
1986-90
1991-94
1995-99
4
SRP (μg L-1)
Milwaukee River Transect, April 2005
0 20 40 60 80
1
2
3
4
5
6
7
8
9
10
infotrek.er.usgs.gov/.../ milwaukeemap.gif
0
50
100
150
200
250
J F M A M J J A S O N D
0
50
100
150
200
250
J F M A M J J A S O N D
0
50
100
150
200
250
J F M A M J J A S O N D
J F M A M J J A S O N D
J F M A M J J A S O N D
1982-87Mean = 102
1988-95Mean = 72
1996-2001Mean = 120
Tota
l P (μ
g L-
1 )
Milwaukee River TP Concentrations have increased in late spring.
5
0
5
10
15
20
25
30
35
40
J F M A M J J A S O N D
0
5
10
15
20
25
30
35
J F M A M J J A S O N D
0
5
10
15
20
25
30
35
J F M A M J J A S O N D
m3
s-1
1982-87Avg. = 18.4
Milwaukee River Discharge
1996-2001Avg. = 14.3
1988-95Avg. = 13.1
0
5
10
15
20
25
1981 1986 1991 1996 2001
Annual Means
Data source: USGS
6
10 km
Milw
aukee R.
Kinnickinnic R.
Menomonee R.
10 km
Milwaukee regionNearshore Phosphorus loads,
May – July 2006
Cladophora
zone
River load:120 mg P m-2
Mussel Excretion:506 mg P m-2
7
The Lake Michigan The Lake Michigan Phosphorus CyclePhosphorus Cycle
P Load
OutflowPhytoplankton
Fish
Zooplankton
Burial
DPDP
Nearshore Loop Offshore
Loop
Musselinvasion
Mussels have made nearshore water clear
Source: MMSD
9
0
1
2
3
4
5
6
7
8
9
10TD
P (m
g/L)
May June July Aug. Sep. Oct.
20062007
2008
Near-Bottom Total Dissolved Phosphorus
Atwater, Lake Michigan
TDP
(μg/
L)
0
5
10
15
20
25
Tem
pera
ture
(o C)
Apr May Jun Jul Aug Sep Oct Nov
2006
2008
Water Temperature at 9 m
10
4
5
6
7
8
9
10
11
12
13
14
1970 1975 1980 1985 1990 1995 2000 2005
June
- A
ugus
t Mea
n T
(o C)
Lake Michigan Nearshore
Summer Temperature TrendOptimum for Cladophora growth
no Cladophora growth
TEMPERATURE
PHOSPHORUS
CladophoraQuagga Mussel
11
00.0020.0040.0060.008
0.010.0120.0140.0160.018
0.02
0 5 10 15 20 25 30
Food Concentration (mg P ml-1)
μgP
mgD
W-1
hr-1
Lab Experiments:
Phosphorus Excretion by Quagga Mussels
10oC
15oC
22oC
0
50
100
150
200
250
300
350
400
0 5 10 15 20 25 30 35Temperature (oC)
Bio
mas
s (g
DW
m-2
)
00.020.040.060.080.10.120.140.160.180.2
Gro
wth
Rat
e (d
ay-1
)
B
μ no mussels
mussels
12
LIGHT ?
-0.1
-0.05
0
0.05
0.1
0.15
0.2
Clean Mussels Dirty Mussels Mussels + Cladophora
P Flux Between Mussels and Cladophora
μg P
mus
sel-1
hr-1
15
above mussels
mussel bed
K = 0.1 cm2 s-1
K = 0.01 cm2 s-1
0
0.2
0.4
0.6
0.8
1
1.2
-1000 1000 3000 5000 7000
O2 uptake rate (mg m-2 d-1)
Dep
th o
f ano
xic
zone
in m
usse
l bed
Effect of benthic respiration on thickness of anoxic layer
17
77.5
88.5
99.510
0 50 100
Time (minutes)
DO
(% S
at.)
Benthic O2 uptake by mussels
5,258 mg O2 m-2 d-1
0
0.2
0.4
0.6
0.8
1
1.2
-1000 1000 3000 5000 7000
O2 uptake rate (mg m-2 d-1)
Dep
th o
f ano
xic
zone
in m
usse
l bed
(cm
)
Effect of benthic respiration on thickness of anoxic layer
18
above mussels
mussel bed
K = 0.1 cm2 s-1
K = 0.01 cm2 s-1
Underwater Particle Image Velocimetry
(PIV) System
20
0
10
20
30
40
50
60
0 10 20 30 40 50
[SRP] (nmol l-1)
Hei
ght (
mm
)
Vertical Soluble Reactive Phosphorus ProfileOver Mussel Bed
dzdcDF =
The Cladophora Solution