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

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

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

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

Dissolved Oxygen Uptake influenced by condition of gillsUptake influenced by condition of gills – –

Oxygen Requirements Dependent on temperatureDependent on temperature Dependent on demands of organismDependent on demands of organism – – – –

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

Ammonia AmmoniaAmmonia – Two formsTwo forms – Chronic exposure (un-ionized form)Chronic exposure (un-ionized form)

Nitrite Nitrite (NO 2 - )Nitrite (NO 2 - ) – Nitrite levels greater than 0.5 to 0.6 mg/L or 10 times higher than the toxic threshold for un­ionized ammonia is toxic to fishNitrite levels greater than 0.5 to 0.6 mg/L or 10 times higher than the toxic threshold for un­ionized ammonia is toxic to fish Decreasing pHDecreasing pH –

Nitrite Brown blood disease (Methemoglobinemia)Brown blood disease (Methemoglobinemia) – –Blood appears dark in color TreatmentTreatment – –Recommend 10:1 ratio Hypertrophy and hyperplasia in the gill lamellaeHypertrophy and hyperplasia in the gill lamellae Lesions/hemorrhaging in thymusLesions/hemorrhaging in thymus

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

Nitrification 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

Relationships

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

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

Alkalinity Alkalinity is the capacity of water to buffer against wide pH swingsAlkalinity is the capacity of water to buffer against wide pH swings 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 -

Hardness Hardness is the measure of divalent cationsHardness is the measure of divalent cations – – –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 –

Hydrogen Sulfide SourceSource –Well water –Ponds –Under net-pens Extremely toxic to fishExtremely toxic to fish RemovalRemoval – –

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

Suspended Solids Potential problemsPotential problems – – – Reduce oxygen transportReduce oxygen transport ppm TSS reasonable for salmonids ppm TSS reasonable for salmonids

Chlorine DisinfectantDisinfectant – – Safe levelsSafe levels –less than 0.03 mg/L RemovalRemoval – – –Sunlight Chlorine reacts with water to form strong acidChlorine reacts with water to form strong acid

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 rapidlyResidual chlorine (free plus chloramine) ppm kills fish rapidly chlorine and nitrogenous organics = chloramines that are very toxicchlorine and nitrogenous organics = chloramines that are very toxic

Temperature EffectsEffects – – – – Fish CategoriesFish Categories –warmwater –coolwater –coldwater

Heavy Metal Contaminants Water quality is importantWater quality is important Heavy metals - Cd, Cu, Zn, Hg, must be all <.1 mg/L.Heavy metals - Cd, Cu, Zn, Hg, must be all <.1 mg/L. In aquaculture watch out for plumbing systems (copper, zinc alloys)In aquaculture watch out for plumbing systems (copper, zinc alloys) – Soft water makes a difference in toxicity of metalsSoft water makes a difference in toxicity of metals –

Dissolved Gasses Problem gassesProblem gasses – maintain less than 110%maintain less than 110% Problem sourcesProblem sources – –leaky pipes – leaky pipe Popeye/exophthalmia dorsal view

Characteristics of gas bubble disease Bubbles under skinBubbles under skin finsfins tailtail mouthmouth gas emboli in vascular system = deathgas emboli in vascular system = death similar to bends or decompression sicknesssimilar to bends or decompression sickness

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%? Effects on salmonidsEffects on salmonids –103 – 104% = yolk sac and fingerlings – % = older fingerlings and yearlings –118 % = adults

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

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% saturationLate 1970s fish were deeper than 1.5 m in 110% saturation Fish were using shallower water in normal saturationFish were using shallower water in normal saturation Fish ladders require fish to come to surface or near surfaceFish ladders require fish to come to surface or near surface

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?