Zooplankton Ecology and Predation in Lakes

1
Zooplankton Ecology and Predation in Lakes

• AWER 4500
• 28 March 2007

2
Zooplankton Net
Plankton Trap
3
Energy and Material Transfer in the Limnetic
Zone of Lakes
Hypolimnion or Littoral Sediments
Nutrients
4
(No Transcript)
5
Zooplankton ecology grazing
Grazing by Zooplankton

Depth (m) Grazing ( / day)
6
Grazing by different taxa is size-specific
7
Energy and Material Transfer in the Limnetic
Zone of Lakes
Excretion
Hypolimnion or Littoral Sediments
Nutrients
8
Zooplankton Ecology Nutrient recycling
9
(No Transcript)
10
Zooplankton Ecology Predation On other
Zooplankton
CopepodsThe cheetahs of the pelagic
Prey
Bosmina-Prey
Predator
Prey
11
Effect of invertebrate size on susceptibility to
invertebrate predation. Feeding rate
coefficients of the copepod Heterocope, on
different sizes of Daphnia pulex. OBrien
Kettle. Ecology 60
Feeding Rate
Coefficient (k)
0.01
0.05 0.1
o.5
1.0 1.5 2.0
2.5 Prey Size (mm)
12
Cyclomorphosis
13
Daphnia
14
Vertebrate predation on zooplankton
15
No Alosa (limited fish predation)
Mode 0.8 mm
Frequency ()
Length mm
16
1942 No Alosa
Size-selective predation by fish structured
zooplankton community. First demonstration of
importance of predators changing community
composition of the prey. Top-down Control
1964 Alosa Pomolobus aestivalis
17
Size-selective predation on Daphnia by different
fishes in Flaming Gorge Res. in relation to size
of the Daphnia in the water column. Schnidervin
R.
Water Column Mean 1.0 mm
Rainbow Trout Mean 1.7 mm
Utah Chub Mean 1.6 mm
Kokanee Salmon Mean 1.5 mm
White Sucker Mean 1.3 mm
18
The Plankton Squeeze

• The open pelagic zone is dangerous,
• with limited refuge

Visual Vertebrate Predators
Zooplankton Prey Size
Tactile Invertebrate Predators
19
A Cold, Dark Refuge Diel Vertical Migration of
Zooplankton
?-------Night------?
?---------Day -----------?
Depth (m)
20
Experiments in Plankton TowersMax Planck
Institut fur Limnologie
21
How Do Fish Influence Diel Vertical Migration
(DVM) Of Daphnia? Hypothesis by odor
Depth
(meters)
Temp.
22
Fish odors cause Diel Vertical Migration into
Metalimnion
Depth
(meters)
23
No Fish Scent (controls)
DVM influences feeding and growth rate of
zooplankton
Growth Rate (per day)
Fish Scent
The Organ
F
-F
Warm Cold
Mean Depth (cm)
No Fish Scent (controls)
Growth Rate (per day)
Fish Scent
Dawidowicz Loose 1992 Limnol. Oceanogr. 371509
Mean Temperature (C)