Status of the Lake Michigan
lower trophic food web
Steven Pothoven
Great Lakes Environmental Research Laboratory
Henry Vanderploeg, Nathan Hawley (GLERL)
Gary Fahnenstiel (MTU)
Thomas Nalepa (UM)
Activities
temperature profiles, nutrients, chlorophyll,
zooplankton, Mysis, fish diets, fish condition
March-December (as conditions permit)
approx. monthly (or 2x/month)
• Grand Haven 100 m/Muskegon 110 m
1983-2003, 2007-2013
• Muskegon 45 m
1997-2003, 2007-2013
• Muskegon 15 m
1998-2003, 2007-2013
• Other misc. sites
Offshore (110 m site) water temperatures
10-m below surface
20
18
2010-2011
Temperature (C)
16
14
12
10
8
2012-2013
2011-2012
6
4
2
0
250
300
350
Day of Year
400
450
500
20,000
Number/m2
Quagga mussel density
15,000
2009
10,000
2012
2013 (incomplete)
5,000
0
25m
70
Percent
60
45m
100m
2013 Percentage of mussels < 5 mm
50
40
30
20
10
0
25m
45m
Site depth
100m
Veliger biomass (153 µm)
2.5
2.0
15-m
Veliger biomass (mg/m3)
1.5
1.0
0.5
0.0
1998 1999 2000 2001 2002 2003 2007 2008 2009 2010 2011 2012 2013
0.20
110-m
0.15
0.10
0.05
0.00
1998 1999 2000 2001 2002 2003 2007 2008 2009 2010 2011 2012 2013
40
Nearshore (15 m) Muskegon
Total phosphorus
TP (mg/m3)
35
30
April 2013
25
20
15
10
5
0
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2008
2010
2012
2014
chl a (mg/m3)
10
8
Nearshore (15 m) Muskegon
Chlorophyll
6
4
2
0
1994
1996
1998
2000
2002
2004
2006
TP (mg/m3)
180
160
140
120
100
80
60
40
20
0
Nearshore total phosphorus
(April-May)
chl a (mg/m3)
25
Nearshore chlorophyll
(April-May)
20
15
10
5
0
1972
1996
2013
Grand Haven
1972
1996
Muskegon
2013
Offshore (110 m) spring TP and chlorophyll
(March-May)
TP (mg/m3)
9
8
7
6
5
4
3
2
1
0
chl a (mg/m3)
4
3
2
1
0
Total phosphorus
Chlorophyll a
Offshore (110 m) spring secchi depth
(March-May)
25
Depth (m)
20
15
10
5
0
Offshore (110 m) June-July chlorophyll
(upper 10 m)
chl a (mg/m3)
3
2
1
0
Offshore Deep Chlorophyll layer
(June-July)
90
chl a (mg/m3)
Deep chlorophyll layer
0
50
40
30
20
10
2
3
4
5
20
Depth (m)
chl a (mg/m2)
70
60
1
0
80
40
60
80
100
0
120
2012
2013
2013 phytoplankton composition
(Fluoroprobe)
100%
80%
Cryptophyta
60%
Diatoms
40%
Bluegreen
Green Algae
20%
0%
M15
April
M15
June
M15
Sept
M15
Nov
M45
April
M45
June
M45
Sept
M45
Nov
M110
April
M110
June
M110
Sept
M110
Nov
MDS zooplankton community assemblage 2007-2012
Mean zooplankton abundance 2007-2012
Muskegon
Biomass (mg/m3)
25
20
Other
Daphnia galeata
15
Bosmina
10
Limnocalanus
Diaptomid
5
cyclopoid
0
M15
M45
M110
Nearshore (15-m) mean annual zooplankton abundance
Biomass (mg/m3)
35
30
other
25
Limnocalanus
20
Daphnia
15
Bosmina
10
calanoid
cyclopoid
5
0
1998 1999 2000 2001 2002 2003
2007 2008 2009 2010 2011 2012 2013
1975-1977 southern basin 10-20 m
Average zooplankton biomass = 42 mg/m3
(Hawkins and Evans 1979)
Biomass (mg/m3)
Offshore (110-m) mean annual zooplankton abundance
50
45
40
35
30
25
20
15
10
5
0
other
Limnocalanus
Daphnia
Bosmina
calanoid
cyclopoid
Offshore (110-m) mean seasonal Bythotrephes abundance
Biomass (mg/m2)
180
160
140
120
100
80
60
40
20
0
MDS offshore zooplankton community assemblage 2007-2012
2007 - 2008 differed from 2010 - 2012
2010-2012
Daphnia galeata mendotae and Cyclops spp. increased
Limnocalanus and Bythotrephes decreased
Mysis – mean annual abundance
350
Offshore 110 m
300
250
200
Abundance (#/m2)
150
100
50
0
1995 1996 1998 1999 2000
350
2007 2008 2009 2010 2011 2012 2013
Mid-depth 45 m
300
250
200
150
100
50
0
1995 1996 1998 1999 2000
2007 2008 2009 2010 2011 2012 2013