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

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Presentation on theme: "Water Quality and Disease Dr. Craig Kasper Aquaculture Disease Processes FAS 2253C."— Presentation transcript:

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.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!Inadequate water quality causes more losses than any other problem! Factors that influence water quality/quantity:Factors that influence water quality/quantity: –Feed rates –Feed types –Flow rates –Tanks/containers (flow dynamics) –Temperature

3 Water Quality Daily or weekly testsDaily or weekly tests Semi-annually or annuallySemi-annually or annually

4 Daily or Weekly Dissolved oxygenDissolved oxygen Nitrogen compoundsNitrogen compounds –ammonia –nitrite –nitrates pHpH AlkalinityAlkalinity HardnessHardness Carbon DioxideCarbon Dioxide TemperatureTemperature Hydrogen sulfideHydrogen sulfide Total suspended solidsTotal suspended solids ChlorineChlorine

5 Dissolved Oxygen ImportanceImportance –highest cause of mortality SolubilitySolubility –variables Safe levelsSafe levels

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

7 Oxygen Requirements Dependent on temperatureDependent on temperature Dependent on demands of organismsDependent on demands of organisms baseline 0 2 measure – sessilenormal – feedingelevated – activeelevated – stressed?elevated – CO 2 elevateddepressed

8 Nitrogen Compounds TypesTypes –dissolved gas –ammonia ionizedionized un-ionizedun-ionized –nitrite –nitrate

9 Ammonia AmmoniaAmmonia – NH 3, NH 4 + Two formsTwo forms – unionized NH 3 – ionized (NH 4 + ) pH a concern when dealing with exposurepH a concern when dealing with exposure Chronic exposure (un-ionized form)Chronic exposure (un-ionized form)

10 Nitrogen Equillibria: NH 3 /NH 4 + ammonia (NH 3 ) is toxic to fish/inverts pH affects proportion of NH 3 /NH 4 + as pH increases, NH 3 increases calculation example TAN = 1.5 mg/L, 26 o C, pH = 8.6 answer: 0.30 mg NH 3 /L Affect of pH/temp on NH 3 /NH 4 + equillibria (next slide)

11 Affect of pH/temp on NH 3 /NH 4 + equillibria Nitrogen Equillibria: NH 3 /NH 4 + ammonia (NH 3 ) is toxic to fish/inverts pH affects proportion of NH 3 /NH 4 + as pH increases, NH 3 increases calculation example TAN = 1.5 mg/L, 26 o C, pH = 8.6 answer: 0.35 mg NH 3 /L

12 Ammonia Prob.: How do I fix it? Lower pH below 7.0 (why?)Lower pH below 7.0 (why?) % water change -Use chemical to neutralize ammonia (zeolite) -Discontinue or reduce feeding -NH 3 >1 ppm treat immediately!

13 Ammonia Toxicity

14 Nitrite Nitrite (NO 2 - )Nitrite (NO 2 - ) – Secondary product of nitrification Nitrite levels greater than 0.05 to 0.06 mg/L can be toxic!Nitrite levels greater than 0.05 to 0.06 mg/L can be toxic! 10 times stronger than the toxic threshold for un­ionized ammonia10 times stronger than the toxic threshold for un­ionized ammonia Decreasing pH increases the harmful effects.Decreasing pH increases the harmful effects.

15 Nitrite Brown blood disease (p. 67 in Noga)Brown blood disease (p. 67 in Noga) (Methemoglobinemia)-“new-tank” syndrome –Blood appears dark in color Due to excessive presence of methemoglobin TreatmentTreatment – Flushing with fresh water – Add nitrifying bacteria –Salt! Recommend 10:1 ratio Hypertrophy and hyperplasia in the gill lamellaeHypertrophy and hyperplasia in the gill lamellae Lesions/hemorrhaging in thymusLesions/hemorrhaging in thymus

16 Nitrite (NO 3 - ) Toxicity

17 Nitrate Nitrate (NO 3 - ) is the final breakdown product in the oxidation of ammoniaNitrate (NO 3 - ) is the final breakdown product in the oxidation of ammonia Not as toxic to aquatics Not as toxic to aquatics Similar symptoms to nitrite toxicity, but values must be much higher. Similar symptoms to nitrite toxicity, but values must be much higher.

18 Nitrate Toxicity

19 Nitrification: Good or bad? NO 3 - NH 3 1½ O 2 nitrosomonasnitrobacter NO 2 - Requires 3 moles oxygen to convert one mole of ammonia to nitrateRequires 3 moles oxygen to convert one mole of ammonia to nitrate Nitrification is an acidifying reactionNitrification is an acidifying reaction

20 Relationships

21 pH Measure of the hydrogen ion concentrationMeasure of the hydrogen ion concentration 1-14 scale1-14 scale –less than 7 acidic –greater than 7 basic Safe rangeSafe range –6.5-9

22 Carbon Dioxide (CO 2 ) SourcesSources –Surface –Wells carboniferous rockcarboniferous rock RemovalRemoval – degassing –buffers calcium carbonatecalcium carbonate sodium bicarbonatesodium bicarbonate CH 2 O (food) + O 2  CO 2 + H 2 O

23 Alkalinity Alkalinity is the capacity of water to buffer against wide pH changes.Alkalinity is the capacity of water to buffer against wide pH changes. Acceptable range mg/LAcceptable range mg/L CaCO 3 + CO 2 + H 2 O  Ca HCO 3 - Bicarbonate: CO 2 + H 2 O  H + + HCO 3 - Carbonate: HCO 3 -  H + + CO 3 - Effects of calcite lime: *Dolomite CaMg(CO 3 ) 2 yields 4HCO 3 -

24 Hardness Hardness is the measure of divalent cationsHardness 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 > 50 ppm Hardness is used as an indicator of alkalinity but hardness is not a measure of alkalinityHardness 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 , Noga) SourceSource –Well water –Ponds Anerobic conditions of benthos Anerobic conditions of benthos –Under net-pens Extremely toxic to fishExtremely toxic to fish RemovalRemoval –Aeration –Raise pH –Lower temp. –Add Potassium Permanganate (freshwater only!)

26 Total Solids TypesTypes –suspended –settleable SourcesSources –runoff –uneaten food –feces Safe levelsSafe levels –less than 1,000 mg/L RemovalRemoval –filtration –settling chambers

27 Suspended Solids Potential problemsPotential problems – Light? – Turbidity? – Gills? Reduce oxygen transportReduce oxygen transport ppm TSS reasonable for salmonids ppm TSS reasonable for salmonids

28 Chlorine DisinfectantDisinfectant – Cl 2 (Chlorine gas choramine-T) – HClO (hypochlorous ion) (bleach) Safe levelsSafe levels –less than 0.03 mg/L RemovalRemoval – 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 acidChlorine reacts with water to form strong acid

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

30 Temperature EffectsEffects –Alters metabolism –Effects pathogens –Changes gas solubility Fish CategoriesFish Categories –warmwater –coolwater –coldwater

31 Heavy Metal Contaminants Heavy metals - Cd, Cu, Zn, Hg, must be all <.1 mg/L.Heavy metals - Cd, Cu, Zn, Hg, must be all <.1 mg/L. Old plumbing systems are problematic (Cu 2+, Zn alloys)Old plumbing systems are problematic (Cu 2+, Zn alloys) Soft water makes a difference in toxicity of metals (increases uptake)Soft water makes a difference in toxicity of metals (increases uptake) Most can be removed by using activated carbon filters!Most can be removed by using activated carbon filters!

32 Dissolved Gasses Problem gassesProblem gasses – Oxgen? maintain less than 110%maintain less than 110% Problem sourcesProblem sources – Wells – Leaky pipes – Solved by using degassing columns columns leaky pipe Popeye/exophthalmia dorsal view

33 Characteristics of gas bubble disease Bubbles under skin (crackles…just like diving)Bubbles under skin (crackles…just like diving) –and other soft tissues…fins, tail, mouth Gas emboli in vascular system = deathGas emboli in vascular system = death Similar to bends or decompression sicknessSimilar to bends or decompression sickness

34 Spill vs. no spill management of Columbia River History - Excess water removed used to be a big problem.History - Excess water removed used to be a big problem. Rough guidelines for negative response Clean Water Act says 110% is standard what difference between 110 and 120%?Rough guidelines for negative response Clean Water Act says 110% is standard what difference between 110 and 120%? Lethal Leves for salmonidsLethal Leves for salmonids –103 – 104% = yolk sac and fingerlings – % = older fingerlings and yearlings –118 % = adults

35 Columbia River In 1960s in Columbia River,In 1960s in Columbia River, –Adults ExophthalmiaExophthalmia bubbles in skin and mouthbubbles in skin and mouth hemorrhaged eyes later cause blindness - impair spawninghemorrhaged eyes later cause blindness - impair spawning External symptoms disappear rapidly after deathExternal symptoms disappear rapidly after death Changed water use and flip lipsChanged water use and flip lips 1990s high spill head burns in salmon1990s high spill head burns in salmon

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

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


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