INFLUENCE OF HYPOXIA ON THE ECOLOGY OF ZOOPLANKTIVOROUS AND BENTHIVOROUS FISHES IN LAKE ERIE’S...
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INFLUENCE OF HYPOXIA ON THE ECOLOGY OF ZOOPLANKTIVOROUS AND BENTHIVOROUS FISHES IN LAKE ERIE’S CENTRAL BASIN. T.O. Höök 1,2,* , S.A. Ludsin 2 , S.A. Pothoven 3 , J.J. Roberts 1,2 , T.F. Nalepa 2 , H.A. Vanderploeg 2 , S.A. Ruberg 2 , and S.B. Brandt 2 . 1Cooperative Institute for Limnology and Ecosystems Research, University of Michigan, Ann Arbor, MI. 2National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, Ann Arbor, MI. 3National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, Muskegon, MI. *([email protected])
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Transcript of INFLUENCE OF HYPOXIA ON THE ECOLOGY OF ZOOPLANKTIVOROUS AND BENTHIVOROUS FISHES IN LAKE ERIE’S...
INFLUENCE OF HYPOXIA ON THE ECOLOGY OF ZOOPLANKTIVOROUS AND BENTHIVOROUS FISHES IN LAKE ERIE’S CENTRAL BASIN.
T.O. Höök1,2,*, S.A. Ludsin2, S.A. Pothoven3, J.J. Roberts1,2 , T.F. Nalepa2, H.A. Vanderploeg2, S.A. Ruberg2, and S.B. Brandt2. 1Cooperative Institute for Limnology and Ecosystems Research, University of Michigan, Ann Arbor, MI. 2National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, Ann Arbor, MI. 3National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, Muskegon, MI. *([email protected])
Hypoxia in Lake Erie:
Warm epilimnionWarm epilimnion
WestWest
CentralCentral EastEast
CoolCool
Low oxygen
Low oxygen
Source: Murray Charlton, NWRISource: Murray Charlton, NWRI
Cool hypolimnionCool hypolimnion(becomes hypoxic)(becomes hypoxic)
Natural phenomenon-Modified by various factors(e.g., nutrients, climate, water levels)
$Yellow perch Rainbow smelt
Walleye
ZooplanktonBenthic invertebrates
CommercialFisheries
RecreationalFisheries
$
$$
Effects of Hypoxia on Yellow Perch and Rainbow Smelt
Most abundant species in L. Erie’s central basin.
Yellow perch Rainbow smelt
ZooplanktonBenthic invertebrates
Diel vertical migrations
Omnivory
Hypoxia may alter:-Distributions-Diets-Growth/Condition
thermocline
Day
thermocline
Night
Effects of Hypoxia on Yellow Perch and Rainbow Smelt
-Zooplankton net and pump sampling
-Ponar grabs (benthos)
-Midwater and bottom trawling
• Zooplankton• Temperature• Dissolved oxygen• Light levels• Chlorophyll a
FishBiomass
24-hr paired-vessel sampling
0
2
4
6
8
10
12
BH
D
0
2
4
6
8
10
12
BAH
0
5
10
15
20
25
0 5 10 15 20
temperature (C)
DO (mg/l O2)D
ep
th (
m)
Site B
0
2
4
6
8
10
12
A
F
BC D
June
August
September
October
0 2 4 6 8 10 12
0 4 8 12 (mg/l)
5km diel station
0
5
10
15
20
25
0 5 10 15 20 25
temperature (C)
DO (mg/l O2)
Dep
th (
m)
Site B
September
2005
Effects of Hypoxia in Lake Erie.
– Distributions of perch and smelt.
– Diets of perch and smelt.
– Condition/Growth of perch and smelt.
All data from Station B
Strength of evidence
high
low
Night Day
Zooplankton (mg /l)
0.0 0.5 1.0 1.5 2.0 2.5
Fish biomass (dB)
-100 -80 -60 -40
Zooplankton (mg /l)
0.0 0.5 1.0 1.5 2.0 2.5
Fish biomass (dB)
-100 -80 -60 -40
October
20
10
0
Temperature (oC)
5 10 15 20 25 30
September
De
pth
(m)
20
10
0
August
Oxygen (mg/l)
0 3 6 9 12 15
20
10
0
Dep
th (
m)
High
High
Night Day
Vertical Distributions of Yellow Perch and Rainbow Smelt
Night Day
Zooplankton (mg /l)
0.0 0.5 1.0 1.5 2.0 2.5
Fish biomass (dB)
-100 -80 -60 -40
Zooplankton (mg /l)
0.0 0.5 1.0 1.5 2.0 2.5
Fish biomass (dB)
-100 -80 -60 -40
October
20
10
0
Temperature (oC)
5 10 15 20 25 30
September
De
pth
(m)
20
10
0
August
Oxygen (mg/l)
0 3 6 9 12 15
20
10
0
High
High
LowLowHypoxic
Dep
th (
m)
Night Day
Vertical Distributions of Yellow Perch and Rainbow Smelt
Night Day
Zooplankton (mg /l)
0.0 0.5 1.0 1.5 2.0 2.5
Fish biomass (dB)
-100 -80 -60 -40
Zooplankton (mg /l)
0.0 0.5 1.0 1.5 2.0 2.5
Fish biomass (dB)
-100 -80 -60 -40
October
20
10
0
Temperature (oC)
5 10 15 20 25 30
September
De
pth
(m)
20
10
0
August
Oxygen (mg/l)
0 3 6 9 12 15
20
10
0
High
High
High
High
LowLowHypoxic
Night Day
Vertical Distributions of Yellow Perch and Rainbow Smelt
0
2
4
6
Day Night Day Night Day Night Day Night
Bottom Trawl Midwater Trawl
0
2
4
6
Day Night Day Night Day Night Day Night
June Aug Sep(hypoxia)
Octln(c
pue+
1)
Yellow perch
Rainbow smelt
Vertical Distributions of Yellow Perch and Rainbow Smelt
0%
50%
100%
Day Night Day Night Day Night Day Night
June Aug Sep(hypoxia)
Oct
Die
t (%
of d
iet i
tem
s)
Yellow perch
Rainbow smelt
Diets of Yellow Perch and Rainbow Smelt
0%
50%
100%
Day Night Day Night Day Night Day Night
Zooplankton
BenthicInvertebrates
ChironomidPupae
0
0.01
0.02
0.03
June Aug Sep(hypoxia)
Oct
Dry
wei
ght o
f sto
mac
h co
nten
ts (
g g-1
)
Yellow perch
Rainbow smelt
Diets of Yellow Perch and Rainbow Smelt
0
0.01
0.02
0.03 a
b
c c
a aa a
0%
10%
20%
30%
June Aug Sep(hypoxia)
Oct
% D
ry/W
et w
eigh
t
Yellow perch
Rainbow smelt
Cumulative effects on condition and growth
a b b b
0%
10%
20%
30%
a b c d
Traditional measures of growth and condition.-Integrate feeding history and energetic utilization over the whole life-time of an organism.
RNA:DNA Ratios-DNA concentrations within cells remain fairly constant.-RNA concentrations increase as protein synthesis increases.-A recently well-fed, growing individual should have a high RNA:DNA ratio compared to a starving individual.
Quantifying Growth and Condition
0
1
2
3
0
1
2
3
4
5
June Aug Sep(hypoxia)
Oct
RN
A:D
NA
(liv
er)
Yellow perch
Rainbow smelt
aab
b nodata
Instantaneous effects on growth
aa a no
data
0
2
4
6
0
4
8
12
June Aug Sep(hypoxia)
Oct
RN
A:D
NA
(m
uscl
e)
Yellow perch
Rainbow smelt
a a a
nodata
Instantaneous effects on growth
a a bnodata
Effects of Hypoxia in Lake Erie.
– Distributions of perch and smelt.– Lower overall catches during hypoxia.– Avoid bottom waters during hypoxia.
– Diets of perch and smelt.– ↑Zooplankton; ↓Benthic invertebrates– Ration may be affected– Seasonal patterns may mask hypoxia effects
– Condition/Growth of perch and smelt.– Potential cumulative and instantaneous growth effects– Seasonal patterns may mask hypoxia effects
Str
engt
h of
evi
denc
e hig
hlo
w
META31%
EPI20%
HYPO49%
0 0.5 1 1.5 2 2.5
AugustSeptember
June
Daphnia mendotae (preliminary data)
Preliminary RNA:DNA patterns for Daphnia mendotae collected (via whole water column tows) in central Lake Erie during 2005.
RN
A:D
NA
Length (mm)META70%
EPI24%
HYPO6%
August
September
Daytime
Zoopl. vulnerability and individual growth may increase.
Does hypoxia affect production of L. Erie fishes??
Next Steps
– 2007 Field sampling.– Focus on spatial patterns.
– Experimental evaluations of yellow perch and walleye growth.
– Modeling analyses (EcoFore Project).– Statistical analyses, GRP, IBM, CASM,
EcoPath/EcoSim
Ecological Consequences of Hypoxia in Lake Erie:
International Field Year in Lake Erie (2005)www.glerl.noaa.gov/ifyleNOAA-GLERL led effort to understand the causes and ecological consequences of seasonal hypoxia in Lake Erie.
Microbes
Zooplankton
Phytoplankton
Nutrients
Benthic invertebrates
Invertivorous Fish
Piscivorous Fish
PhysicalProcesses
