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Water Quality and Disease

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

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Water Quality and Disease

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  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. Daily or weekly tests Semi-annually or annually Water Quality

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

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

  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. Types dissolved gas ammonia ionized un-ionized nitrite nitrate Nitrogen Compounds

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

  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 >1 ppm treat immediately!

  13. Ammonia Toxicity

  14. 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. Nitrite

  15. 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 10:1 ratio Hypertrophy and hyperplasia in the gill lamellae Lesions/hemorrhaging in thymus Nitrite

  16. Nitrite (NO3-) Toxicity

  17. 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. Nitrate

  18. Nitrate Toxicity

  19. 1½ O2 1½ O2 NH3 NO2- NO3- nitrosomonas nitrobacter Nitrification: Good or bad? • Requires 3 moles oxygen to convert one mole of ammonia to nitrate • Nitrification is an acidifying reaction

  20. Relationships

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

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

  23. Alkalinity is the capacity of water to buffer against wide pH changes. Acceptable range 20-300 mg/L Alkalinity Bicarbonate: CO2 + H2O  H+ + HCO3- Carbonate: HCO3- H+ + CO3- Effects of calcite lime: CaCO3 + CO2 + H2O  Ca+2 + 2HCO3- *Dolomite CaMg(CO3)2 yields 4HCO3-

  24. 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 > 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 Hardness

  25. 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!) Hydrogen Sulfide (p. 225-226, Noga)

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

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

  28. 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 Chlorine

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

  31. Heavy Metal Contaminants • Heavy metals - Cd, Cu, Zn, Hg, must be all < .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. Problem gasses Oxgen? maintain less than 110% Problem sources Wells Leaky pipes Solved by using degassing columns dorsal view Popeye/exophthalmia leaky pipe Dissolved Gasses

  33. Characteristics of gas bubble disease • Bubbles under skin (crackles…just like diving) • and other soft tissues…fins, 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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