Ponds, ponds, ponds...

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Ponds, ponds, ponds...

• Lecture 5
• Dr. Craig S. Kasper
• FAS 1012C Introduction to Aquaculture

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Acknowledgement

• Appreciation and sincere thanks are given to Dr.
  Joe Fox (TAMUCC) who kindly donated material for
  this presentation!!
• Please visit his website!
• (http//www.sci.tamucc.edu/pals/maric/Index/WEBPAG
  E/mari1.htm)

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Introduction

• Ponds were used as one of the first forms of
  aquaculture.
• Dates back to ancient China.
• Already had the water...just add fish, feed, and
  presto!
• Pond production has come along way since then!

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POND DESIGN CRITERIA (Ideal)

• Screened inflow gates at shallow end of pond
• Screened harvest gates at deep end
• Slope to harvest basin (0.5-1.0)
• Water depth 1.25 ? 2.00 M
• Feeding tray piers
• Rounded or square corners, steps or ramps for
  entry
• Primary dikes (levees) wide enough to accommodate
  vehicles

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GENERAL DESIGN, INTENSIVE POND
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Pond LeveeworkCONSTRUCTION CRITERIA

• Levees are typically constructed by D6-
  (Catepillar) sized bulldozers
• Construction is first undertaken on ponds nearest
  the sedimentation basins and pump station
• Bulldozers push earth up to create general form
  of the levee walls
• Follow stakes set along the length of the pond
• Smaller dozers used to put on finishing touches

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Pond LeveeworkDESIGN CRITERIA

• Heights determined by pond bottom elevation,
  tidal amplitude
• Perimeter levee often required for protection in
  flood areas
• Levees trapezoidal with slopes 12 for high clay,
  13-4 low clay
• Levee crown width varies with use
• Width of crown 5 m (driving), 3m (walking)
• Crown is sloped to reduce puddles on levee top
• Once formed, levees are sprigged with grass to
  reduce erosion

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Pond LeveeworkCONSTRUCTION CRITERIA

• Erosion is the main problem in maintaining levee
  slopes
• Source both rainfall and wave action
• Solution plants and vegetation (local grasses
  or Salicornia sp.) as soon as possible
• Pond sides receiving wind could be reinforced
  with rocks (contracted service)
• Tops of levees definitely need layer of rocks,
  especially if high clay content

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Typical Cross-section of Pond Levee
WIDTH4 TO 5 M
CANALSIDE
PONDSIDE
2.0M
2.0M
1.5M
4.0
3.0
CUT-OFFTRENCH
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Preventing Leaks

• Minimize amount of loss due to seepage- Proper
  compaction- Core trenching- Vertical plastic
  membranes- Vegetative coverage
• Remove burrowing animals (turtles, muskrat)
• (.243 Winchester works great!)
• Optimal clay content
• Construction during dry season

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Pond BottomCONSTRUCTION CRITERIA

• If detailed pond bottom slopes are required,
  usually accomplished by scrapers
• Small 4-6 m3 earthmovers towed by 4X4 tractors,
  laser-guided
• Bottom slope from upper end to lower end of pond
  usually 1m250-500m or 0.4-0.2 for large ponds
• In simple ponds, follows natural slope to estuary
• Must insure at least 20 cm height of harvest gate
  above high tide elevation (varies considerably by
  site)

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POND BOTTOM DESIGNS
crown
canal
canal
canal
canal
plateau
plateau
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POND BOTTOM ELEVATION

• Primary design criterion
• Based upon tidal amplitude (or drainage)
• Above the freshwater table
• Above mean high tide
• Determines canal/levee height
• Pond should be drainable at all times

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Pond Bottom vs. Tide
WHERE SHOULD YOU BE????
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WATER CONTROL STRUCTURESINFLOW GATES

• Used for control of pond water exchange
• Concrete structures with screen/bag filters on
  both
• sides of Levee
• Dual primary screens for pre-filtration (1/4" to
• 1/2)
• Secondary filtration screen bag eliminates
  potential
• predators (250-500 µM)
• Flashboards for controlling flow rate of water
• entering pond
• Multiple gates in larger ponds

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LeveeCROWN
LeveeSLOPE
LeveeSLOPE
CONCRETEAPRON
CORRUGATEDPLASTICTUBES
WINGWALL
FLASHBOARDS
BAGFILTER
PRIMARYFILTER
PLAN VIEW OF TYPICAL INFLOW GATE
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CROSS SECTION OF TYPICAL INFLOW GATE
CANALSIDE
ATTACHMENTSLOT
TOP OF Levee
PONDSIDE
CULVERTPIPE
BAGFILTER
PRIMARYFILTER
FLASHBOARDS
FILTER SLOT
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WATER CONTROL STRUCTURESHARVEST GATE

• Concrete w/harvest basin in pond
• Number/size of gates depends on speed
• of harvest required
• Screen to retain shrimp, mesh according to size
• Use of flashboards
• Canal side often modified
• for harvest pump

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LeveeSLOPE
LeveeCROWN
LeveeSLOPE
DRAINAGECANAL
HARVESTBASIN
PUMP BOX
CULVERT TUBES
NET SLOT
FILTERSCREEN
FLASHBOARD
WINGWALL
PLAN VIEW OF HARVEST GATE
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Harvest Gate inflow
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Harvest Gate outflow
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Harvest Gates outflow
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Harvest Gates multiple
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Gate Construction
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POND AERATION/OXYGENATION

• level determined by oxygen demand
• pumping vs. artificial aeration
• used for oxygenation and solids mobilization
• efficiency of devices varies
• paddlewheels 2.13 kg O2/kwh
• propeller/aspirator 1.58
• diffusors 0.97

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Typical Aerators
paddlewheel
air injector
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Multiple Aeration Units
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Estimating Oxygen Requirement

• During paddlewheel aeration and high density
  culture O2 requirement usually estimated on the
  basis of feed application to pond
• 1 kg of feed 0.2 kg O2 consumed via respiration
• 300 kg feed 60 kg O2 consumed/day
• Caveat Some O2 consumed by shrimp/fish, but
  more by primary productivity

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Estimating Paddlewheel Requirements
Biomass density (kg/ha) Hp (flow-through) Hp (limited water exchange)
lt 1,000 None None
1,000 2,000 2-4 4-8
2,000 4,000 4-8 8-16
4,000 8,000 8-10 16-20
Above 8,000 Above 10 Above 20
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Additional Paddlewheel Guidelines

• Use high quality switch boxes and adequate guage
  wire
• Orient paddlewheels to reduce dead spots in
  ponds (locate in corners) dont change
  orientation during a run
• More paddlewheels (e.g., 1.0 hp units)
• fewer dead spots but more (units parts)
• Stainless steel less corrosion!
• Pay attention to electrical demand and quality of
  electricity (less motor repair)

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ELECTRICAL SUPPLY

• More tecnology more demand!
• Semi-intensive ponds need electricity for ice
  production, living accomodations, perimeter
  lighting, laboratory, fry acclimation facility
• Usually provided by diesel generators (more
  dependable and, therefore, cheaper in the long
  run)
• Intensive and super-intensive operations have
  large energy demand (aeration is about 90 of
  demand)

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Electrical Distribution

• Distribution via high tension line with 20-50 kVA
  step-down transformers situated throughout the
  farm
• Demand could be as high as 50 kVA per ha
• 300 ha intensive farm could have 3,000 one hp
  paddlewheels 2.5 megawatt demand
• Electrical distribution system could cost well
  over 1 million

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ARTIFICIAL SUBSTRATES(POND LINERS)

• Used in areas where soil quality is poor
  (percolation/toxicity)
• Also used to reduce effluent solids via erosion
  of pond bottom and drainage canal
• Cost now 0.25/m2
• Long-term viability and uv resistance
• Use at least 30 mil thickness
• Dont install yourself!!
• (unless very good at it!)

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Soil-Cement Liners

• Made from 16-8 mixture of cement and sand
• Pond raked down to 3
• Cement added to achieve ratio
• Watered and smoothed via 3,000 lb roller
  compactor
• Rate 1ha/wk

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Stocking Densities

• Species dependent
• -catfish (3500-5000 fish/acre w/aeration)
• -tilapia... similar
• -prawn-start with 16,000/acre if substraight
  present
• -flounder-not density, but bottom coverage,
  usually tolerate 200 bottom coverage if adequate
  water flow.