2. What is it for?
The Hydrolab is the name of the
sonde we will be using.
It is a scientific instrument used to
measure biological and physical
properties in water.
It can be used “in the field”

3. Advantages
It can store data in memory and
communicate with computers.
Some sondes can be programmed
and left in water to gather data over
a period of time.

4. Questions
 Think of a place a scientist might want to
place a sonde and leave it for a week?
 What about a year?
 What is an advantage to having an
electronic monitor like the Hydrolab instead
of pH paper and a hand held thermometer?

5. Sonde Data
The Sonde here has measured several parameters
over time

6. This sonde measured DO over time
in several rivers

7. Hand held
Surveyor Hydrolab

8. pH
Dissolved Oxygen
Temperature
Chlorophyll a

9. pH
 pH is a measure of the acidic or basic (alkaline) nature
of a solution

10. pH – A scale from 0-14
 A pH range of 6.0 to 9.0 provides protection for the life of
freshwater fish.
 Min Max Effects
 3.8 10.0 Fish eggs could be hatched, but deformed
young
 5.0 9.0 Tolerable range for most fish
 4.1 9.5 Range tolerated by trout
 6.0 7.2 Optimum (best) range for fish eggs
 4.0 10.1 Limits for the most resistant fish species
 4.6 9.5 Limits for perch
 5.4 11.4 Fish avoid waters beyond these limits
 3.3 4.7 Mosquito larvae live within this range
 7.5 8.4 Best range for the growth of algae

11. Dissolved Oxygen
 Dissolved oxygen – the amount of oxygen dissolved
in water.
 This is dependent on the water temperature. Cold
water can hold more of any gas, in this case
oxygen, than warmer water.
 Oxygen gets into water by diffusion from the
surrounding air, by aeration (rapid movement),
and as a waste product of photosynthesis.

12. Dissolved Oxygen - DO
 We will measure the saturation level of the
oxygen, the DO - % saturation.
 Rivers that have a dissolved oxygen value of
90 percent or higher are considered healthy
 Rivers below 90 percent saturation may have
large amounts of oxygen-demanding
materials, like organic waste from sewage
systems, urban or agricultural run-off, and
some industrial waste.

13. Questions
 What does it mean to have a higher number on the pH
scale?
 Turn to your neighbor and explain dissolved oxygen to
them in one sentence.

14. Temperature
 Aquatic life needs specific
temperatures
 Temperature also is important because
it influences water chemistry
(remember how DO is effected by
temperature?)

15. Fish and Temperature
Species Lower Optimum Upper
Avoidance Avoidance
Bluegill 58° F 69° F 75° F
Trout, Brook 44° F 58° F 70° F
Trout, Brown 44° F 56-65° F 75° F
Carp 75° F 84° F 88° F
Bass, 60° F 80° F 60° F
Largemouth
Muskellunge 55° F 63° F 72° F
Pike, Northern 56 63° F 74° F

16. Chlorophyll a
 Chlorophyll is the green part of plants that helps them
change light to food.
 Measuring the concentration of chlorophyll a
provides an estimate of algal biomass
 This is important to know because it tells us about the
health of a stream or lake.

17. Chlorophyll a
 Too much algal growth, or too much of a certain type
of algae (such as blue-green algae), can cause
problems in the lake ecosystem.
 When there is a rapid growth of a certain type of algae
it is called an algal bloom
 As the algae die off they sink to the bottom of the lake
and decompose. Decomposition uses up oxygen that
organisms need to live.

18. Algal bloom in Lake Erie 2011

20. Questions
 How can stream temperature effect a fish?
 How do you think they Hydrolab can measure the
chlorophyll a of a stream or Lake?
 Chlorophyll a levels change because of land use. Why?

21. Land Use that
Increases Chlorophyll a
 Agricultural run-off
 Water from sewage treatment plants
 Storm water runoff from developed land
 Nitrogen from burning fossil fuels
 Lawn and garden fertilizers
 Faulty septic systems
 Dumping or burning leaves in or near a lake

23. Proper Use
 Hold the Hydrolab by the metal bale. Deploy with the
colored cord.
Bale

24. Keep the Surveyor and Computer
dry

25. Other Terms
 Calibration: To standardize or correct sensors after
determining, by measurement or comparison with
a standard, the correct value.
 Conductivity: A measure of the ability of water to
pass an electrical current. This parameter indicates
the amount of dissolved substances (salts) present
in the water.
 Turbidity: a measure of the extent to which the
intensity of light passing through water is reduced
by the suspended matter.