List 3 basic physical-chemical parameters
Temperature, DO, pH, salinity, alkalinity, water hardness, turbidity, Ammonia, nitrite, nitrate
Give 2 effects of low temperature on fish.
decreasing/stopping food intake. reducing the growth of juveniles and older fish. delaying/preventing maturation and spawning. slowing down the egg development.
Give 3 examples of trophic levels
Primary producers, primary consumers, secondary consumers
Inshore vs offshore
Inshore = near or toward the coast; Off shore = away from the coast
Current vs wave
Current = Continuous movement of water in one direction; Wave = surface movement of water
3 examples of environmental impacts by open water culture.
Wastes from cage cultures; Farm escapees and invasive; Genetic pollution and disease and parasite transfer; Drugs and chemicals Fish meal and fish oil Predators
2 effects of low temperature on fish
decreasing/stopping food intake. reducing the growth of juveniles and older fish. delaying/preventing maturation and spawning.
TWO effects of high temperature on fish.
Increase growth rate, food requirements and food conversion efficiency. Stimulating fish gonad maturation and spawning activity. Increase oxygen demand.
THREE factors that determine oxygen requirements by fish
Fish species; fish size; water temperature; activity; feeding & digestion; sexual maturation & spawning
Optimum range of DO for fish.
> 5 mg/L
Best pH range for fish
6.5 - 8.5
Daily changes of pH
Sunrise - lowest pH; Late afternoon - highest pH
Explain daily fluctuation of oxygen levels in the pond.
From sunrise to sunset: photosynthesis increases the DO level. At night: respiration reduces the DO content until sunrise.
2 signs of low DO in fish pond.
Not feeding well or stop feeding. Coming to the water surface in an effort to breath from the thin, better oxygenated surface film - this behaviour is
Effect of high pH?
Increases ammonia toxicity, which can damage gills and lead to fish mortality. Causes stress and reduced feeding efficiency.
Effect of low pH.
Reduces enzyme activity and metabolic processes in fish. Can cause gill irritation and mucus buildup, affecting oxygen uptake.
