Saturday, January 2, 2010

Algal Blooms - definition - 40 ppb of Chlorophyll a

Indicator 2.3 - Lake Okeechobee Algal Blooms

What is the desired restoration condition?

The desired restoration condition for Lake Okeechobee algal blooms is to substantially reduce the frequency of blue-green algal blooms in the pelagic (open water) region of the lake. Algal blooms are defined as chlorophyll a concentrations in excess of 40 parts per billion (ppb), and the numeric goal is to reduce the occurrence of such concentrations to less than 5 percent of water samples collected in the pelagic zone (as a five-year running average). Chlorophyll a is the green pigment found in algal cells that allows them to carry out photosynthesis. It is a reliable measure of the biomass of algae in the water. A concentration of 40 ppb is used by the State of Florida and other states as an indicator of a bloom. When water has 40 ppb of chlorophyll a, it is visibly green. The scientific basis for the 5 percent goal is provided in Havens and Walker (2002).

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