Water Quality of San Francisco Bay Chlorophyll Time Series 1977-1997

By Water Resources Mission Area

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Each year there is a period of rapid growth of the phytoplankton population during spring, when chlorophyll concentration increases from about 1-2 milligrams per cubic meter to about 20 or 30 milligrams per cubic meter. This period of explosive population growth is called the spring bloom, which usually occurs in March or April.
The spring blooms are different each year. For example, the 1981 spring bloom was small, with peak chlorophyll concentrations of only 13 milligrams per cubic meter.
The spring blooms in 1983 and 1986 were very large, with chlorophyll concentrations reaching about 60 milligrams per cubic meter. These were both years of heavy precipitation and high river flow, so there is a connection between climate variability and phytoplankton population variability.

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