The influence of movement dynamics on ecosystem structure: Suckers as ecosystem engineers

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The influence of movement dynamics on ecosystem
structure Suckers as ecosystem engineers

• Michael T. Booth, Alex S. Flecker, Nelson G.
  Hairston, Jr.
• Dept. of Ecology and Evolutionary Biology,
  Cornell University

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1 m
3
1 m
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West Fork Gila River
Middle Fork Gila
West Fork Gila
Focal reach
Fish refuge sites
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Fish movement and habitat use

• 23mm 134.2 kHz PIT tags, detection range 0.3-0.8
  m, gt500 tagged fish (180-500mm SL) in 2 km reach
  in 2008, 2009
• 8 multiplexed stationary antennas (8.5-13 m wide,
  2.3 scans/sec)
• Weekly scans of refuge habitats over 4 km reach
  with portable antenna

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Fish movement and habitat use
Full reach (2 km)
Frequency transect
(inset)
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Diel sampling site
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Hourly fish activity
Day
Day
Night
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Typical fish activity
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Typical fish activity
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Transient effects

• Suckers as ecosystem engineers

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Downstream fluxes

• 5 diel sampling events at focal pool, 2 events
  included other pools
• Collected seston samples at 10 time points (2-3
  hr intervals)

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Diel seston concentrations
Seston dry mass (3 replicates per time point)
Fish activity within focal reach
0.025
0.020
0.015
Dry Mass (g/L)
0.010
0.005
0.000
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6/29 0130
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6/29 0930
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Long lived effects

• Suckers as ecosystem engineers

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Methods Feeding transects

• 2 transects per divotable habitat over 2 km
  reach (30 area, silt/sand/gravel)
• 2-4 quadrats per transect, measured width and
  depth of 4 representative divots per quadrat, 5
  dates

0.5 m
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Distribution of depressions
flow
6/23/09
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Frequency transects

• 5 transects (7-14 m, 8-11 quadrats)
• 0.25 m2 quadrats, 5 numbered and bi-colored
  washers
• Scored daily or AM/PM (gravel/sand, moved,
  flipped, divot), 20 pts possible

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Frequency transects
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0
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Stationary antenna reach
Quadrat scores
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Sites gt10 suckers
Reach length 2 km
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Frequency transects
Date
Quadrat location
Relative disturbance
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Quadrat location
Quadrat location
Quadrat location
Flood
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UNDERSTANDING MOVEMENT PATTERNS

• From diel to seasonal, baseflow to flood event

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Added 6/25
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Fine scale movements
2009 data only shown, but including fish from
both years
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Large scale movements of individual fish
2009 data only shown, but including fish from
both years