to a great extent water quality determines the success or failure of a fish farming operation water...
TRANSCRIPT
To a great extent water quality determines the success or failure of a fish farming operation
WATER IN AQUACULTURE SYSTEMS
Fish perform allbodily functions in water
• Eat
• Breathe
•
•
• Take in and lose salts
WATER IN AQUACULTURE SYSTEMS
Water Balance in Freshwater Fish
Salts
Large quantitiesof dilute urine
Ammonia
Water
Water Balance in Saltwater Fish
Small quantities ofconcentrated urine
Ammonia
Water
Drinkssea water
Water Resources
• Water quality
• Water quantity
• Water sources
Inadequate water quality causes more Inadequate water quality causes more losses than any other problem!losses than any other problem!
WATER IN AQUACULTURE SYSTEMS
Physical
Temperature
• •
Chemical (“No effect” limits)
Physical Characteristicsof Water
•
• “Universal solvent”
–
WATER IN AQUACULTURE SYSTEMS
Dissolved Oxygen
• Importance– highest cause of mortality
• Solubility– variables
•
•
•
• Safe levels– > 5mg/l
7
6
5
4
3
2
1
05 pm 10 pm 5 am
Measured values
Projected values
mg/l
Projected Dissolved Oxygen Levels for Ponds
Uniform dissolved O in pond2
Decomposingmaterials
Low dissolvedoxygen (cool)
High dissolvedoxygen (warm)
Low dissolved oxygen - possible fish kill
TurnoverTurnover
Relationships
Temperature (F) (pH) 7.0 8.09.0
50 0.19 1.8315.7
68 0.40 3.8228.4
86 0.80 7.4644.6
Percent Ammonia
Percent of Total Ammoniain the Un-Ionized Form at
Various Temperatures and pH
Nitrification
NONO33-- NHNH33
1½ O1½ O22
nitrosomonas nitrosomonas nitrobacter nitrobacter
1½ O1½ O22 NONO22
--
• Requires 3 moles oxygen to convert one mole of ammonia to nitrate
•
Dissolved Gasses
• Problem gasses– Nitrogen (primarily)
•
• Problem sources – Wells and Springs
–
– leaky pipeleaky pipe
Popeye/exophthalmiaPopeye/exophthalmia
dorsal viewdorsal view
WATER IN AQUACULTURE SYSTEMS
Water quantity parameters
• Requirements are based on temperature-dependent and size-dependent standard metabolic rates for fish
•
WATER IN AQUACULTURE SYSTEMS
Water quantity parameters Suggested replacement times Linear
• Noncirculating – • Circulating
Suggested water velocity rates
• Noncirculating – • Circulating -
WATER IN AQUACULTURE SYSTEMS
Water quantity parameters
Flow measuring techniques Flow meters
• •
Pond filling time – not very accurate
WATER IN AQUACULTURE SYSTEMS
Water quantity parameters Weir gauges
• Sharp-crested – if outfall consists of dam boards
• V-notch
• Trapezoidal• •
Pre-Use treatment
Sediment removal• Settling basin/pond –
• Filtration –
Gas stabilization (O2 and/or N2)• Slatted inflow boards• •
WATER IN AQUACULTURE SYSTEMS
Pre-Use treatmentSterilization
• Ultraviolet –• • Chlorination-de-chlorination – •
Temperature control
• Heating • Chilling
WATER IN AQUACULTURE SYSTEMS
Water utilization• Open water systems
• Flow-through -Water enters pond or series of ponds and exits with/without treatment
-
-
WATER IN AQUACULTURE SYSTEMS
Water Sources
•
•
• Rivers, lakes and streams
• Surface
•
•
Springs
• Advantages– – few or no predators– no pathogens
• Disadvantages–
Wells• Types
– –
• Advantages– no predators– no pathogens
• Disadvantages– – low O2
Rivers, Lakes and Streams
• Advantages– large volumes– inexpensive
• Disadvantages– – excessive nutrients
Surface
• Advantages– inexpensive
• Disadvantages– contaminates– – 5-7 acre watershed
per surface acre of water
Groundwater
• Advantages–
• Disadvantages– hard to drain
•
• removal of fish
Municipal• Advantages
– – no predators–
• Disadvantages– disinfectants
• • chloramines
–
Water Quantity
• Ponds
• Raceways
• Cages
• Recirculating aquaculture systems
Ponds• Minimum requirement
– 13 gal/min or 50L/min per acre
• Rational– – to replace evaporation–
Raceways• Minimum requirement
– 500 gal/min. or 1900L/min• Rational
– –
Recirculating Aquaculture Systems
• Minimum requirement– varies depending on size of
system–
• Rational– needed to backflush filtersduring harvesting–
–
0.8
0.6
0.4
0.2
0.02 6 10 14 18 22
8
6
4
2
0
Ammonia(mg/l)
Nitrites &Nitrates(mg/l)
NHNO
NO
23
3
Time in Days
Time Requiredfor Bio-Filter to Mature