Secchi Disk

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Secchi disk

[′sek·ē ‚disk]
An opaque white disk used to measure the transparency or clarity of seawater by lowering the disk into the water horizontally and noting the greatest depth at which it can be visually detected.

Secchi Disk


an instrument for measuring water transparency in a body of water. A white disk 30 cm in diameter, it is held horizontally and lowered into the water on a rope until it is no longer visible. The depth, in meters, at which it ceases to be visible is taken as a measure of the water transparency. The disk is named after A. Secchi, who measured the transparency of sea water by this method in 1865.

References in periodicals archive ?
Mean Secchi disk (n = 179) was 3.2 [+ or -] 2.2 m and ranged from 0.3 m in January 2009 to 8.1 m in April 2015 (Table 2).
A lake can vary in water transparency, so it is important to take numerous Secchi disk readings throughout the day.
Along with numbers of black sea bass at each site, abiotic factors were recorded, including water temperature (degrees Celsius), dissolved oxygen (milligrams per liter), salinity, Secchi disk depth (centimeters), and water depth (meters).
(12) In addition to the customary locational and structural variables, they use Secchi disk readings as an objective measure of water clarity.
Zooplankton samples were collected every month at five selected stations in the lake with three replicates, and the water temperature, dissolved oxygen, pH, Secchi disk depth, electrical conductivity, and depth were measured at the stations.
In present work, the infestation rate decreases with increase in turbidity, and water clarity measured with Secchi disk showed positive relation to isopod infestation.