What does turbidity mean?

As defined on NOAA’s National Ocean Service Education website, turbidity is “essentially a measurement of how cloudy or clear the water is, or, in other words, how easily light can be transmitted through it.”
To learn more about turbidity, visit the NOAA page about Turbidity.

This weekend Cassidy and Trevor joined me for a REEF survey while Jeannie watched our gear on the beach. Unfortunately, the water was pretty chilly and the visibility was under 10 feet. In Waikīkī, tides, currents, and wave or wind swell can re-suspend sediment, significantly decreasing the visibility and increasing the turbidity. Cassidy was able to capture a picture of two Bluefin Jacks and the turbid water:

While bad visibility makes for an unpleasant snorkel, the sediment can cause even more harm to the coral communities in Waikīkī. The following quote is from a 2010 paper published in the Journal of Coastal Research:

“The presence of suspended sediment may stress corals by reducing incident light levels (Rogers, 1990), and moreover, particles that settle on coral surfaces interfere with photosynthesis and hinder feeding (Bak, 1978).”

Essentially, suspended sediment can stress the health of coral colonies. In addition, the problem of suspended sediments may become worse with climate change. Andrea Ogston and Michael Field, the authors of the paper quoted above, predict that sea level rise will increase the amount of suspended sediment and shoreline erosion in areas with fringing reefs, such as the island of Molokai.

Ogston, A. S. and Field, M. E., 2010, Predictions of Turbidity Due to Enhanced Sediment Resuspension Resulting from Sea-Level Rise on a Fringing Coral Reef: Evidence from Molokai, Hawaii. Journal of Coastal Research, Vol. 26, No. 6, p 1027-1037.

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2 Responses to “What does turbidity mean?”

  1. On 11/22/10 & 11/24/10, I noticed decreased visibility (increased turbidity) at Hanauma Bay, inner reef. Today (11/24/10) was worse (< 10') than Monday.

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  1. It came in the water and caused disease | A closer look - March 21, 2012

    […] was confirmed the data recorded by the two drinking water plants were examined. It showed that the turbidity, describing the amount of particles in the water, was drastically increased. However it never […]

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