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

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

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  1. 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

  2. 1 m

  3. 0.2 m 1 m

  4. West Fork Gila River Middle Fork Gila West Fork Gila Focal reach Fish “refuge” sites

  5. A1 A4 A3 A2 Fish movement and habitat use • 23mm 134.2 kHz PIT tags, detection range 0.3-0.8 m, >500 tagged fish (180-500mm SL) in 2 km reach in 2008, 2009 • 8multiplexed stationary antennas (8.5-13 m wide, 2.3 scans/sec) • Weekly scans of refuge habitats over 4 km reach with portable antenna

  6. Fish movement and habitat use Full reach (2 km) Frequency transect (inset) #3 Diel sampling site

  7. Hourly fish activity Day Night Day

  8. Typical fish activity

  9. <20 cm visibility flood Typical fish activity

  10. Suckers as ecosystem engineers Transient effects

  11. 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)

  12. 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 6/29 06:30 6/29 09:30 6/28 09:30 6/28 12:30 6/28 15:30 6/28 18:30 6/28 20:30 6/28 22:30 6/29 01:30 6/29 04:30

  13. Suckers as ecosystem engineers Long lived effects

  14. 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

  15. flow Distribution of depressions 6/23/09

  16. 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

  17. #1 Frequency transects #3 0 4 6 Stationary antenna reach Quadrat scores #6 #9 Sites >10 suckers Reach length: 2 km #10

  18. Frequency transects Date Quadrat location Relative disturbance

  19. Quadrat location Quadrat location Quadrat location Flood

  20. From diel to seasonal, baseflow to flood event UNDERSTANDING MOVEMENT PATTERNS

  21. Added 6/25

  22. “Fine scale” movements 2009 data only shown, but including fish from both years

  23. 05/24/2009 06/21/2009 07/19/2009 05/24/2009 06/21/2009 07/19/2009 05/24/2009 06/21/2009 07/19/2009 date date date 05/24/2009 06/21/2009 07/19/2009 05/24/2009 06/21/2009 07/19/2009 05/24/2009 06/21/2009 07/19/2009 date date date “Large scale” movements of individual fish -3000 -3000 -3500 -3500 -4000 -4000 -4500 -4500 -5000 -5000 Location Location -5500 -5500 -6000 -6000 -6500 -6500 -7000 -7000 2009 data only shown, but including fish from both years