Biology 124 Biological Oceanography
Online Project

TOOLS OF THE OCEANOGRAPHER: Equipment: Measuring tools: Visibility

B.  Taking Measurements of the Marine Environment
1. Temperature
• Standard Thermometer
• Bucket Thermometer
• Reversing Thermometer (for Nansen Bottle)
• Bathythermograph (BT)
2. Salinity
• Hydrometer (quick test type for aquariums)
• Hydrometer Set
• Chemical Test Kit (Knudsen)
• Salinometer
3. Oxygen
• Chemical Test Kit (Winkler Titration)
• Dissolved Oxygen Probe
4. pH
• pH test strips
• Chemical Test Kit
• pH meter
5. Visibility & Color
• Secchi Disk (used by itself)
• Forel/Ule Scale (used with the Secchi disk)
6. Other
• There are chemical tests for numerous dissolved substances including Carbon Dioxide, Nitrogen, Phosphates, Ammonia, Lead, Copper and Manganese
7. Depth & Profile
• Sounder (lead line)
• Fathometer
•Surveying Equipment
8. Currents
• Current Meter
• Dye
• Drogues
• Drift Bottles
• Drift Cards

5. Visibility & Color  
Secchi Disk to top of page
secci disk
Measures: Visibility (vertical)
Operates: By hand on a line to the depth where it becomes invisible
Notes: May be hard for the viewer to be exact but a good approximation

Forel/Ule Scale to top of page
Forel/Ule Scale
Measures: Color of the water (in roman numerals associated with colors from brown to green to blue)
Operates: As a color comparator with the use of the secchi disk lowered to one meter for background so the color of the bottom won't interfere
Notes: Can be hard for the viewer to choose the exact color

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