Size%20distribution%20and%20sinking%20velocity%20of%20the%20feces%20and%20pseudofeces%20of%20the%20blue%20mussel,%20Mytilus%20edulis - PowerPoint PPT Presentation

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Size%20distribution%20and%20sinking%20velocity%20of%20the%20feces%20and%20pseudofeces%20of%20the%20blue%20mussel,%20Mytilus%20edulis

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... sinking velocity of the feces and pseudofeces of the blue mussel, Mytilus edulis ... Mussels in open tube for 12 hours. Remove animals and rotate tube ... – PowerPoint PPT presentation

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Title: Size%20distribution%20and%20sinking%20velocity%20of%20the%20feces%20and%20pseudofeces%20of%20the%20blue%20mussel,%20Mytilus%20edulis


1
Size distribution and sinking velocity of the
feces and pseudofeces of the blue mussel, Mytilus
edulis
  • Megan Cahill
  • Supervisor Dr. Jonathan Grant
  • Department of Oceanography, Dalhousie University

2
Outline
  • Background
  • Purpose
  • Materials and Methods
  • Results
  • Practical Applications

3
Background
  • Mytilus edulis as an aquaculture species
  • Filter feeder
  • Fate of material sorted, adsorbed, defecated
  • Anything not adsorbed is released
  • Falls through the water column

4
Materials and Methods
  • Modes of particle capture
  • Sediment traps
  • In situ observation
  • Collection
  • Degradation during storage

5
  • Transverse Niskin
  • Collective device
  • Transparent walls
  • Rectangular
  • Horizontal alignment during gathering
  • Vertical to induce sinking
  • Use in the field and the lab

6
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7
  • Laboratory work
  • Large tank
  • Flow through of unfiltered seawater
  • Mussels in open tube for 12 hours
  • Remove animals and rotate tube

8
  • Image collection
  • Digital camera
  • Series of pictures at known intervals
  • One image every two seconds
  • Inclusion of ruler in the picture for image
    calibration

9
  • Image analysis
  • SigmaScan Pro 5 software
  • Calibration of distance
  • Select particles based on pixel intensity
  • Automatically calculates area from calibration
  • Track through time to determine rate

10
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11
Results
  • Pilot data
  • area of smallest particle detected is
  • 0.036 mm2
  • mean area 0.2 mm2
  • mean sinking rate 2.17 mm sec-1
  • limited data set

12
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13
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14
  • Other components to sinking rate
  • Particle density
  • Feces versus pseudofeces
  • Viscosity of medium
  • Temperature and salinity measured by Aquatron
  • Particle shape

15
  • Difficulties
  • Particles are not necessarily discrete
  • Inclusion of organic matter
  • Diffuse
  • Trace function more subjective
  • Focus!

16
Still to Come
  • Field work
  • Pseudofeces?
  • Turbid conditions
  • Analyze results

17
Importance
  • Aquaculture systems
  • Large areas with many animals
  • Alter flow regimes and depletes seston
  • Significant pelagic-benthic flux

18
  • Pelagic-benthic flux
  • Nutrient loading
  • Nutrient source for benthic/demersal organisms
  • Implications for polyculture?

19
  • Modeling
  • Dynamic systems
  • Coastal zone management
  • Outside influences
  • Contaminant concentration

20
Acknowledgements
  • Thank you to Dr. Grant and
  • Marie Archambault
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