To evaluate the state of water quality in the San Francisco Bay a number of monitoring studies mostl

1
Daily Monitoring of Estuarine Water Quality
(Eutrophication and Phytoplankton Blooms) in San
Francisco Bay
Frances Wilkerson, Kevin Lew, Jim Fuller, Dick
Dugdale, Al. Marchi, Florian Koch Romberg Tiburon
Center, San Francisco State University, Tiburon,
CA 94920
Sampling Approaches
Preliminary Continuous Data
Introduction To evaluate the state of water
quality in the San Francisco Bay a number of
monitoring studies (mostly state or federally
organized) are in progress that use ship-based
measurements that are collected monthly. Few
studies measure the water quality on shorter time
scales or are real-time automated systems. For
the last two years we have been making almost
daily measurements of dissolved inorganic
nutrients (nitrate, ammonium, silicate and
phosphate), phytoplankton abundance (chlorophyll)
and size spectra with some of these parameters
being measured continuously using automated
sampling, in situ sensors and on-line
instrumentation. These data highlight the changes
( e.g. chlorophyll peaks) that may be missed by
monthly measurements.
Salinity and derived chlorophyll measured every 5
minutes using CTD and SCUFA (in vivo fluorescence)
Extracted chlorophyll measured daily using bucket
and in vitro fluorescence
Nitrate measured every 30 minutes using
Envirotech nutrient sensor
Nitrate measured daily using bucket and an
AutoAnalyzer
monthly data collected by ship
daily data collected by hand from fixed location
data collected continuously by sensors on pier
Study Site
Our water quality studies of the Central San
Francisco Bay have included samples collected a)
weekly to monthly using near surface samples
collected from the R/V Questuary or Twin-Vee
(data not shown here), b) 2-3 times a week using
a surface bucket deployed from the seawall/finger
pier at the Romberg Tiburon Center and c)
continuously using near-surface water pumped from
off RTC and from sensors deployed from the RTC
finger pier (preliminary data) at the SFBEAMS
site. Discrete water samples collected monthly
(data not shown here) or bi-daily are analyzed
for chlorophyll-a using in vitro fluorometry,
dissolved inorganic nutrients (nitrate, silicate,
phosphate and ammonium) using a Bran and Luebbe
Technicon II AutoAnalyzer, size spectra of
fluorescing cells using a CytoBuoy flow
cytometer, and biomass measurements of biogenic
silica and particulate carbon and nitrogen (data
not shown here). Continuous data collected
includes salinity, temperature and in vivo
fluorescence (used to obtain chlorophyll) using a
SeaBird CTD equipped with a Turner Designs
SCUFA-Self Contained Underwater Fluorescence
Apparatus (SCUFA) that analyzed pumped surface
data until recently when it was deployed from the
RTC finger pier. Preliminary continuous
measurements of nutrients were made using
Envirotech 4 channel nutrient sensors and size
spectra of fluorescing particles using the
CytoSens flow cytometer in continuous mode.
Phosphate measured every 30 minutes using
Envirotech nutrient sensor
Phosphate measured daily using bucket and an
AutoAnalyzer

• Conclusions
• Time series monitoring on the time scale of days
  is enables water quality (nutrients) and bloom
  dynamics to be observed in Central SFB
• The availability of on-line continuous monitoring
  systems for nutrients and chlorophyll will
  enhance this capability and are essential for
  management agencies.

RTC Romberg Tiburon Center finger pier (SF
Beams)
SF Beams
SF Beams is a monitoring station in Central San
Francisco Bay that measures water quality and
weather condition that are reported in as near
real-time as possible through the web site
http//sfbeams.sfsu.edu/ (see below) It is
maintained by scientists at the Romberg Tiburon
Center. It is expected that the continuous SCUFA,
nutrient data and flow cytometry data collected
by these authors will be available.
Daily Measurements of Chlorophyll and Nutrients
in 2005
spring bloom
Total number of red fluorescing cells
(phytoplankton) and cells gt 5 mm in diameter
measured every 30 minutes using Cytobuoy flow
cytometer
Daily data indicate that chlorophyll and ammonium
levels may be linked. Spring bloom accompanied by
lower than average ammonium concentrations ( lt 2
mM) but relatively high nitrate values (20 mM)
(far left plots). When there is high ammonium,
chlorophyll is low (e.g. January). Flow
cytometry counts of number of red fluorescing
cells (i.e. phytoplankton) parallels the
chlorophyll data (e.g. peak on 5/16/2005).
Preliminary data using automated sensors that
measure almost continuously show more variability
that daily collected samples. These sensors,
especially the nutrient sensors, are
technological newcomers to estuarine studies on
the west coast, and need careful calibration and
validation. However the potential ability for
these sensors to measure maxima (eutrophication?)
or minima (high nutrient drawdown?) on an hourly
basis is important. The flow cytometry data will
yield information on community structure (diatom
chains vs solitary dinoflagellate cells etc) with
further software development.
Acknowledgements USC Sea Grant and NOAACI-CORE
provided financial support for this study