Asian Clam populations in Emerald Bay: Ecological results and future - - PowerPoint PPT Presentation

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Asian Clam populations in Emerald Bay: Ecological results and future - - PowerPoint PPT Presentation

Nov 14, 2022 419 likes •638 views

Asian Clam populations in Emerald Bay: Ecological results and future investigations Allison E. Gamble, Sudeep Chandra, Alexander L. Forrest, Marion E. Wittmann, John E. Reuter, S. Geoffrey Schladow Brant Allen Asian clam discovery in Emerald

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SLIDE 1

Asian Clam populations in Emerald Bay: Ecological results and future investigations

Allison E. Gamble, Sudeep Chandra, Alexander L. Forrest, Marion E. Wittmann, John E. Reuter, S. Geoffrey Schladow

Brant Allen

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SLIDE 2

Asian clam discovery in Emerald Bay

  • Discovered in 2008
  • Potential problem because of

aesthetics, nutrient excretion, further spread in to the bay

Jaxshells.org

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SLIDE 3

Emerald Bay

Lake Tahoe

Sill

Jim Markle

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SLIDE 4

Comparison: 2011 vs. 2009

  • 3.5 acres

(yellow) in 2009

  • 5.5 acres

(red) in 2011

  • Low

density (1- 100 clams/m2)

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SLIDE 5

Asian clam control: Pilot study

Emerald Bay

Lake Tahoe

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SLIDE 6

May 2011-May 2012: Two 10x100 foot bottom barriers

Pilot study: Methods

Brant Allen

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SLIDE 7
  • Dissolved oxygen
  • Clam mortality,

reproduction

  • Currents, velocities,

temperature

  • Sediment porosity,

permeability

  • Effect of biological

supplementation of the barriers

Pilot study: Data collected

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SLIDE 8
  • Dissolved oxygen
  • Clam mortality,

reproduction

  • Currents, velocities,

temperature

  • Sediment porosity,

permeability

  • Effect of biological

supplementation of the barriers

Pilot study: Data collected

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SLIDE 9

Dissolved oxygen

Brant Allen

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SLIDE 10

Marla Bay DO

Dissolved oxygen (mg/L)

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SLIDE 11

Emerald Bay DO

60 40 20 120 100 80 May 2011 October 2011 January 2012 May 2012 Dissolved oxygen (% saturation)

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SLIDE 12

Emerald Bay DO

60 40 20 120 100 80 May 2011 October 2011 January 2011 May 2011 Dissolved oxygen (% saturation)

Above mats Below mats

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SLIDE 13

Monitoring of Barriers for Clam Dynamics

  • Ponar, 1 m2 quadrats
  • Analysis at UNR (Chandra lab)

UCD TERC

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SLIDE 14

Monitoring of Existing Bottom Barriers for Clam Dynamics: Final Results

  • Control: 14% mortality
  • Barriers: average 80% mortality

– Barrier 1: 88% mortality, Barrier 2: 71% mortality

  • No significant difference

between egg numbers

  • f live clams in barriers
  • vs. controls

Brant Allen Brant Allen

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SLIDE 15

Effect of biological supplementation of bottom barriers

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SLIDE 16

BOD barriers

  • Rubber + Jute
  • Rubber + Jute & Straw
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SLIDE 17

Deployment:

  • Late March-May 2012
  • in line with larger clam mats
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SLIDE 18

BOD barriers: Jute Results

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SLIDE 19

BOD barriers: Jute + Straw Results

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SLIDE 20

Future Directions

  • Continue: Interpretation of pilot study results
  • Continue: Research on causes of patterns in DO

fluctuations, biological mechanisms causing clam mortality under the large barriers

  • BOD barriers: larger scale, materials

All leading to larger scale management efforts

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SLIDE 21

Acknowledgements

  • Katie Webb, Brant Allen, Annie Caires, Tim Caldwell,

Christine Ngai

  • UC Davis and UNR staff
  • Asian Clam Working Group
  • Lahontan RWQCB, TRPA, TRCD
  • US Forest Service, US Fish and Wildlife Service, CA

State Parks

  • CA State Lands Commission, Army Corps of

Engineers, NV Division of State Lands