USGS Monitors the San Francisco Bay with Turner Designs Instrumentation

Parameters: Chlorophyll

For over three decades our project at the U.S. Geological Survey has researched phytoplankton and water quality dynamics in San Francisco Bay, and maintained what may be the longest continuous program of water quality monitoring in a United States estuary. We have been using Turner Designs fluorometers in the lab and on our research vessel Polaris since the early 70s. During our research cruises, surface water is continuously pumped through a 10-AU fluorometer enabling us to obtain high frequency spatial fluorescense measurements in San Francisco Bay. We calibrate these data with extracted chlorophyll samples and find consistently excellent regressions. The auto-ranging feature and wide dynamic range make this instrument especially easy to calibrate and use. In the laboratory, we use the TD-700 to determine chlorophyll a and pheopigment concentrations in acetone extracted samples. We have found this instrument to be quite easy to use and the sensitivity is much greater than that of the spectrophotometer we formerly used for these analyses. We have been testing the SCUFA® sensor at a moored station in San Francisco Bay and are very excited by the initial time series results, which reveal interesting temporal patterns of phytoplankton biomass. We found the copper anti-fouling system to be indispensable; as a result the unit only needs cleaning every 2 to 3 weeks. We are so pleased with the SCUFA's high frequency sampling, low price, and ease of use that we will be deploying a number of units as part of a new study we are conducting in the Sacramento-San Joaquin Delta. Overall we have found Turner Designs fluorometers to be consistently reliable, stable, and affordable and the support staff to be exceptionally helpful and accommodating.

Author: Dr. James Cloern & Tara Schraga Institution: United States Geological Survey, Menlo Park, California, USA