Update on Phosphorus and Cladophora in the Lake Michigan Nearshore - - PDF document

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Update on Phosphorus and Cladophora in the Lake Michigan Nearshore - - PDF document

Sep 25, 2023 29 likes •240 views

Update on Phosphorus and Cladophora in the Lake Michigan Nearshore Zone Harvey Bootsma Nearshore TP and TDP Concentrations Since 1980, Near Milwaukee Harbor 30 Total Dissolved P Total P 25 19.4 20 [P] ( g L -1 ) 14.5 15 12.5 12.6

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Update on Phosphorus and Cladophora in the Lake Michigan Nearshore Zone

Harvey Bootsma

5 10 15 20 25 30 1980-84 1985-89 1990-94 1995-99 2000-05 [P] (μ g L-1)

Total Dissolved P Total P

14.5 9.5 19.4 7.8 11.7 6.9 12.6 8.2 11.9 12.5

Nearshore TP and TDP Concentrations Since 1980, Near Milwaukee Harbor

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Spring Total P

(mean of all pelagic stations)

1 2 3 4 5 6 7 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Total P (μg/L)

Michigan Huron

GLWQA Target for Lake Michigan: 7 μg/L 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 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

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0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1980 1985 1990 1995 2000 2005 Dissolved P : Total P Ratio

In Milwaukee River, dissolved P is becoming a larger fraction of TP

1 2 3 4 5 1970 1975 1980 1985 1991 1994 1995

Average [P] (ppm) Soil P Storage Change (kg ha-1)

P in Wisconsin Cropland

Bundy and Sturgul 2001

10 20 30 40 50 60 1968- 73 1974- 77 1978- 81 1982- 85 1986- 90 1991- 94 1995- 99

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SRP (μg L-1) Milwaukee River Transect, April 2005

20 40 60 80

1 2 3 4 5 6 7 8 9 10

infotrek.er.usgs.gov/.../ milwaukeemap.gif

50 100 150 200 250

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

50 100 150 200 250

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

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

1982-87 Mean = 102 1988-95 Mean = 72 1996-2001 Mean = 120

Total P (μg L-1) Milwaukee River TP Concentrations have increased in late spring.

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5 10 15 20 25 30 35 40 J F M A M J J A S O N D 5 10 15 20 25 30 35 J F M A M J J A S O N D 5 10 15 20 25 30 35 J F M A M J J A S O N D

m3 s-1 1982-87

  • Avg. = 18.4

Milwaukee River Discharge 1996-2001

  • Avg. = 14.3

1988-95

  • Avg. = 13.1

5 10 15 20 25 1981 1986 1991 1996 2001

Annual Means

Data source: USGS

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10 km

Milwaukee R.

Kinnickinnic R.

Menomonee R.

10 km Milwaukee region Nearshore Phosphorus loads, May – July 2006

C l a d

  • p

h

  • r

a z

  • n

e

River load: 120 mg P m-2 Mussel Excretion: 506 mg P m-2

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The Lake Michigan The Lake Michigan Phosphorus Cycle Phosphorus Cycle

P Load Outflow

Phytoplankton Fish Zooplankton

Burial

DP DP

Nearshore Loop Offshore Loop

Mussel invasion Mussels have made nearshore water clear

Source: MMSD

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November 2007 November 2008

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1 2 3 4 5 6 7 8 9 10 TDP (mg/L)

May June July Aug. Sep. Oct. 2006 2007 2008 Near-Bottom Total Dissolved Phosphorus Atwater, Lake Michigan TDP (μg/L)

5 10 15 20 25 Temperature (

  • C)

Apr May Jun Jul Aug Sep Oct Nov 2006 2008 Water Temperature at 9 m

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4 5 6 7 8 9 10 11 12 13 14 1970 1975 1980 1985 1990 1995 2000 2005 June - August Mean T (oC)

Lake Michigan Nearshore Summer Temperature Trend

Optimum for Cladophora growth no Cladophora growth

TEMPERATURE

PHOSPHORUS Cladophora Quagga Mussel

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0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02 5 10 15 20 25 30 Food Concentration (mg P ml

  • 1)

μgP mgDW-1 hr-1

Lab Experiments: Phosphorus Excretion by Quagga Mussels

10oC 15oC 22oC 50 100 150 200 250 300 350 400 5 10 15 20 25 30 35 Temperature (oC) Biomass (gDW m-2) 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 Growth Rate (day-1) B μ no mussels mussels

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LIGHT ?

  • 0.1
  • 0.05

0.05 0.1 0.15 0.2 Clean Mussels Dirty Mussels Mussels + Cladophora

P Flux Between Mussels and Cladophora

μg P mussel-1 hr-1

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Current Needs

  • 3. What is the botulism mechanism?

Photo: Alice Van Zoeren

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4 minutes after dye injection

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above mussels mussel bed K = 0.1 cm2 s-1 K = 0.01 cm2 s-1

0.2 0.4 0.6 0.8 1 1.2

  • 1000

1000 3000 5000 7000 O2 uptake rate (mg m-2 d-1)

Depth of anoxic zone in mussel bed

Effect of benthic respiration on thickness of anoxic layer

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7 7.5 8 8.5 9 9.5 10 50 100 Time (minutes) DO (% Sat.) Benthic O2 uptake by mussels 5,258 mg O2 m-2 d-1

0.2 0.4 0.6 0.8 1 1.2

  • 1000

1000 3000 5000 7000 O2 uptake rate (mg m-2 d-1)

Depth of anoxic zone in mussel bed (cm)

Effect of benthic respiration on thickness of anoxic layer

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above mussels mussel bed K = 0.1 cm2 s-1 K = 0.01 cm2 s-1

Underwater Particle Image Velocimetry (PIV) System

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PIV Image Analysis Results

Qian and Bootsma, in press

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10 20 30 40 50 60 10 20 30 40 50

[SRP] (nmol l-1) Height (mm) Vertical Soluble Reactive Phosphorus Profile Over Mussel Bed

dz dc D F =

The Cladophora Solution

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Bruce Mozert / University of Florida Press