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Water Quality and Disease

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Water quality and quantity is one of the most important factors ... Anerobic conditions of benthos. Under net-pens. Extremely toxic to fish. Removal. Aeration ... – PowerPoint PPT presentation

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Title: Water Quality and Disease


1
Water Quality and Disease
  • Dr. Craig Kasper
  • Aquaculture Disease Processes
  • FAS 2253C

2
Aquatic Environment
  • Water quality and quantity is one of the most
    important factors to maintain fish health.
  • Inadequate water quality causes more losses than
    any other problem!
  • Factors that influence water quality/quantity
  • Feed rates
  • Feed types
  • Flow rates
  • Tanks/containers (flow dynamics)
  • Temperature

3
Water Quality
  • Daily or weekly tests
  • Semi-annually or annually

4
Daily or Weekly
  • Dissolved oxygen
  • Nitrogen compounds
  • ammonia
  • nitrite
  • nitrates
  • pH
  • Alkalinity
  • Hardness
  • Carbon Dioxide
  • Temperature
  • Hydrogen sulfide
  • Total suspended solids
  • Chlorine

5
Dissolved Oxygen
  • Importance
  • highest cause of mortality
  • Solubility
  • variables
  • Safe levels

6
Dissolved Oxygen
  • Uptake influenced by condition of gills
  • healthy gills, uptake easy
  • damaged, oxygen uptake impaired

7
Oxygen Requirements
  • Dependent on temperature
  • Dependent on demands of organisms
  • baseline 02 measure
  • sessile normal
  • feeding elevated
  • active elevated
  • stressed? elevated
  • CO2 elevated depressed

8
Nitrogen Compounds
  • Types
  • dissolved gas
  • ammonia
  • ionized
  • un-ionized
  • nitrite
  • nitrate

9
Ammonia
  • Ammonia
  • NH3, NH4
  • Two forms
  • unionized NH3
  • ionized (NH4)
  • pH a concern when dealing with exposure
  • Chronic exposure (un-ionized form)

10
Nitrogen Equillibria NH3/NH4
  • ammonia (NH3) is toxic to fish/inverts
  • pH affects proportion of NH3/NH4
  • as pH increases, NH3 increases
  • calculation example TAN 1.5 mg/L, 26oC, pH
    8.6
  • answer 0.30 mg NH3/L

Affect of pH/temp on NH3/NH4 equillibria (next
slide)
11
Nitrogen Equillibria NH3/NH4
  • ammonia (NH3) is toxic to fish/inverts
  • pH affects proportion of NH3/NH4
  • as pH increases, NH3 increases
  • calculation example TAN 1.5 mg/L, 26oC, pH
    8.6
  • answer 0.35 mg NH3/L

Affect of pH/temp on NH3/NH4 equillibria
12
Ammonia Prob. How do I fix it?
  • Lower pH below 7.0 (why?)
  • -25 - 50 water change
  • -Use chemical to neutralize ammonia (zeolite)
  • -Discontinue or reduce feeding
  • -NH3 gt1 ppm treat immediately!

13
Ammonia Toxicity
14
Nitrite
  • Nitrite (NO2-)
  • Secondary product of nitrification
  • Nitrite levels greater than 0.05 to 0.06 mg/L
    can be toxic!
  • 10 times stronger than the toxic threshold for
    unionized ammonia
  • Decreasing pH increases the harmful effects.

15
Nitrite
  • Brown blood disease (p. 67 in Noga)
  • (Methemoglobinemia)-new-tank syndrome
  • Blood appears dark in color
  • Due to excessive presence of methemoglobin
  • Treatment
  • Flushing with fresh water
  • Add nitrifying bacteria
  • Salt! Recommend 101 ratio
  • Hypertrophy and hyperplasia in the gill lamellae
  • Lesions/hemorrhaging in thymus

16
Nitrite (NO3-) Toxicity
17
Nitrate
  • Nitrate (NO3-) is the final breakdown product in
    the oxidation of ammonia
  • Not as toxic to aquatics
  • Similar symptoms to nitrite toxicity, but values
    must be much higher.

18
Nitrate Toxicity
19
Nitrification Good or bad?
  • Requires 3 moles oxygen to convert one mole of
    ammonia to nitrate
  • Nitrification is an acidifying reaction

20
Relationships
21
pH
  • Measure of the hydrogen ion concentration
  • 1-14 scale
  • less than 7 acidic
  • greater than 7 basic
  • Safe range
  • 6.5-9

22
Carbon Dioxide (CO2)
CH2O (food) O2 ? CO2 H2O
  • Sources
  • Surface
  • Wells
  • carboniferous rock
  • Removal
  • degassing
  • buffers
  • calcium carbonate
  • sodium bicarbonate

23
Alkalinity
  • Alkalinity is the capacity of water to buffer
    against wide pH changes.
  • Acceptable range 20-300 mg/L

Bicarbonate CO2 H2O ? H HCO3-
Carbonate HCO3- ? H CO3-
Effects of calcite lime
CaCO3 CO2 H2O ? Ca2 2HCO3-
Dolomite CaMg(CO3)2 yields 4HCO3-
24
Hardness
  • Hardness is the measure of divalent cations
  • Ca 2, Mg 2, Mn 2
  • Calcium is used for bone and exoskeleton
    formation and absorbed across gills
  • Soft water molt problems, bone deformities
  • Suggest gt 50 ppm
  • Hardness is used as an indicator of alkalinity
    but hardness is not a measure of alkalinity
  • Magnesium or calcium sulfate increases hardness
    but has no affect on alkalinity

25
Hydrogen Sulfide (p. 225-226, Noga)
  • Source
  • Well water
  • Ponds
  • Anerobic conditions of benthos
  • Under net-pens
  • Extremely toxic to fish
  • Removal
  • Aeration
  • Raise pH
  • Lower temp.
  • Add Potassium Permanganate (freshwater only!)

26
Total Solids
  • Types
  • suspended
  • settleable
  • Sources
  • runoff
  • uneaten food
  • feces
  • Safe levels
  • less than 1,000 mg/L
  • Removal
  • filtration
  • settling chambers

27
Suspended Solids
  • Potential problems
  • Light?
  • Turbidity?
  • Gills?
  • Reduce oxygen transport
  • 80 - 100 ppm TSS reasonable for salmonids

28
Chlorine
  • Disinfectant
  • Cl2 (Chlorine gas choramine-T)
  • HClO (hypochlorous ion) (bleach)
  • Safe levels
  • less than 0.03 mg/L
  • Removal
  • Aeration
  • Chemical (Sodium Thiosulfate, 200 mg/L available
    chlorine is neutralized by 1.5 g sodium
    thiosulfate)
  • Sunlight
  • Chlorine reacts with water to form strong acid

29
Chlorine toxicity
  • Acid is more toxic than hypochlorite ion
  • Destroys epidermal surfaces gills
  • Toxicity depends on temp, DO, free chlorine
    present, presence other pollutants
  • Residual chlorine (free plus chloramine)0.2 -
    0.3 ppm kills fish rapidly (ornamentals 0.09
    ppm!!)
  • Chlorine and nitrogenous organics chloramines
    that are very toxic

30
Temperature
  • Effects
  • Alters metabolism
  • Effects pathogens
  • Changes gas solubility
  • Fish Categories
  • warmwater
  • coolwater
  • coldwater

31
Heavy Metal Contaminants
  • Heavy metals - Cd, Cu, Zn, Hg, must be all lt .1
    mg/L.
  • Old plumbing systems are problematic (Cu2, Zn
    alloys)
  • Soft water makes a difference in toxicity of
    metals (increases uptake)
  • Most can be removed by using activated carbon
    filters!

32
Dissolved Gasses
  • Problem gasses
  • Oxgen?
  • maintain less than 110
  • Problem sources
  • Wells
  • Leaky pipes
  • Solved by using degassing
  • columns

33
Characteristics of gas bubble disease
  • Bubbles under skin (cracklesjust like diving)
  • and other soft tissuesfins, tail, mouth
  • Gas emboli in vascular system death
  • Similar to bends or decompression sickness

34
Spill vs. no spill management of Columbia River
  • History - Excess water removed used to be a big
    problem.
  • Rough guidelines for negative responseClean
    Water Act says 110 is standardwhat difference
    between 110 and 120?
  • Lethal Leves for salmonids
  • 103 104 yolk sac and fingerlings
  • 105- 113 older fingerlings and yearlings
  • 118 adults

35
Columbia River
  • In 1960s in Columbia River,
  • Adults
  • Exophthalmia
  • bubbles in skin and mouth
  • hemorrhaged eyes later cause blindness - impair
    spawning
  • External symptoms disappear rapidly after death
  • Changed water use and flip lips
  • 1990s high spill head burns in salmon

36
Does Compensation Occur?
  • One meter depth about 10 reduction in gas
    saturation.
  • Late 1970s fish were deeper than 1.5 m in 110
    saturation.
  • Fish were using shallower water in normal
    saturation.
  • Fish ladders require fish to come to surface or
    near surface.

37
Questions/uncertainty
  • Behavioral Compensation? Does it occur?
  • Migration pathways for Adult salmon
  • Migration pathways for juvenile salmon
  • How good are flip lips?
  • Voluntary vs non-voluntary spill issues?
  • Immediate vs delayed mortality?
  • Predisposition to other invasions?
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