Temperature and DO
Temperature
A measure of heat
Dissolved Oxygen (DO)
The concentration of oxygen (gas) which is
dissolved in water.
Both are important individually and to one another
Why is Temperature Important?
Most aquatic organisms are
poikilothermic (“cold-blooded”), which
means they don’t internally regulate
their core body temperature.
The rate of many chemical reactions
increases at higher temperatures.
Oxygen solubility
Temperature - Units
Fahrenheit (°F), Celsius (°C), Kelvin (K)
Celsius (°C) used for most science (SI unit)
– a.k.a. centigrade, where “centi-” = hundredth
Water Freezes at 0°C = 32°F = 273.15 K
Water Boils at 100°C = 212°F = 373.15 K
0°C
100°C
32°F
212°F
Temperature - Units
Conversion Factors
(°F – 32)
°C =
1.8
°F = (°C x 1.8) + 32
Temperature – Q10 Rule
General rule which predicts:
Growth rates of cold-blooded aquatic
organisms and many biochemical
reaction rates will double for every
10°C (18°F) temperature increase
within their "preferred" range.
Temp – Biological Effects
Growth Rate
Optimum
Lethal
0
10
20
30
40
Temperature (Celsius)
50
Max weekly AVG
temp for spawning
35
Max temp for
embryo spawning
25
20
15
Max weekly AVG
for juvenile growth
10
Atlantic Salmon
Sockeye Salmon
Brook Trout
Rainbow Trout
Smallmouth Bass
Largemouth Bass
Bluegill
0
Common Carp
5
Channel Catfish
Temperature
30
Max temp for
survival of short
exposure
(juveniles)
Temperature Standards
Temperature
All waters
64°F (17.8°C)
Salmon spawning, egg
55°F (12.8°C)
incubation, and fry emergence
Bull Trout
50°F (10°C)
Columbia River (to RM 309)
68°F (20°C)
Willamette River (to RM 50)
68°F (20°C)
Rolling 7-day average of maximum daily temperatures
Temperature – Deep Cr (Clack)
22
21.3
20.9
21.0
20.9
20.9
20.5
20
19.4
18
16
7-day max AVG = 20.6°C
8/2
8/2
8/1
8/1
7/31
7/31
7/30
7/30
7/29
7/29
7/28
7/28
7/27
7/27
7/26
14
7/26
Temperature (*C)
20.2
Temperature – Causes
Loss of riparian shading
Warm water inputs
– Retention ponds
– Municipal or industrial wastewater
– Stormwater runoff
Groundwater inputs
Weather
– Air temperature, cloud cover, day length
Turbidity
Dissolved Oxygen
O2 gas dissolved in water
Atmosphere
Water
O2
CO2
21 %
0.035 %
0%
20 %
Required by nearly all aquatic life
DO – Solubility
Inverse, non-linear relationship to
temperature
Decreases with decreasing barometric
pressure
– Weather, elevation
High salinity reduces solubility
DO – Solubility
15.00
Dissolved Oxygen (mg/L)
14.00
13.00
12.00
11.00
10.00
9.00
8.00
7.00
6.00
5.00
0
5
10
15
20
Temperature (Degrees C)
25
30
DO – Units
Concentration:
mg/L = µg/mL = ppm (parts per million)
Percent Saturation:
Measured DO (mg/L)
DO % Sat. =
Solubility (mg/L)
DO – Sources
Photosynthesis
– Influenced by sunshine, temperature, water
velocity
Atmospheric Re-aeration
– Turbulent mixing
• Water velocity and depth
• Oxygen deficit
Inflow of oxygenated water
DO – Sinks
Respiration
– Greatest source of DO loss in summer
Biochemical Oxygen Demand (BOD)
– Decomposition of organic wastes
– Standard measure is 5-day BOD = BOD5
Nitrification (NBOD)
– NH3 + O2 = NO3
Dissolved Oxygen
DO – Diel Fluctuations
PM
AM
Time of Day
DO – Standards
Salmonid Spawning thru Fry Emergence
unless
or
Water Quality Standard
> 11 mg/L
Intergravel Standard
> 6 mg/L
Intergravel DO > 8 mg/L
> 9 mg/L
Natural conditions
> 95% sat.
Cold-water Aquatic Resources
Natural conditions
> 8 mg/L
> 90% sat.
Cool-water Aquatic Resources
> 6.5 mg/L
Warm-water Aquatic Resources
> 5.5 mg/L
DO and Temp Data Quality
Temperature
Dissolved
Oxygen
Accuracy
Precision
+ 0.5°C
+ 1.0°C
+ 0.3 mg/L
+ 0.5 mg/L
Measuring DO and Temp
Measure Immediately - In Field
Measure Both at Same Time
Recording Time is Crucial
Sample Collection
– Below surface ~ 4 inches (or ½ way to bottom
of shallow stream)
– Cap DO bottle underwater