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B.E. Cole

Publications and source records attributed to B.E. Cole.

16 recordsLinked to original sources
USGS2002

Annual primary production: Patterns and mechanisms of change in a nutrient-rich tidal ecosystem

Although nutrient supply often underlies long-term changes in aquatic primary production, other regulatory processes can be important. The Sacramento-San Joaquin River Delta, a complex of tidal waterways forming the landward portion of the San Francisco Estuary, has ample nutrient supplies, enabling us to examine alternate regulatory mechanisms over a 21-yr period. Delta-wide primary productivity was reconstructed from historical water quality data for 1975–1995. Annual primary production averaged 70 g C m −2 , but it varied by over a factor of five among years. At least four processes contributed to this variability: (1) invasion of the clam Potamocorbula amurensis led to a persistent decrease in phytoplankton biomass (chlorophyll a) after 1986; (2) a long-term decline in total suspended solids—probably at least partly because of upstream dam construction—increased water transparency and phytoplankton growth rate; (3) river inflow, reflecting climate variability, affected biomass through fluctuations in flushing and growth rates through fluctuations in total suspended solids; and (4) an additional pathway manifesting as a long-term decline in winter phytoplankton biomass has been identified, but its genesis is uncertain. Overall, the Delta lost 43% in annual primary production during the period. Given the evidence for food limitation of primary consumers, these findings provide a partial explanation for widespread Delta species declines over the past few decades. Turbid nutrient-rich systems such as the Delta may be inherently more variable than other tidal systems because certain compensatory processes are absent. Comparisons among systems, however, can be tenuous because conclusions about the magnitude and mechanisms of variability are dependent on length of data record.

California↗
USGS2000

Spatial and temporal variability of picocyanobacteria Synechococcus sp. in San Francisco Bay

We collected samples monthly, from April to August 1998, to measure the abundance of autotrophic picoplankton in San Francisco Bay. Samples taken along a 160-km transect showed that picocyanobacteria (Synechococcus sp.) was a persistent component of the San Francisco Bay phytoplankton in all the estuarine habitats, from freshwater to seawater and during all months of the spring-summer transition. Abundance ranged from 4.6 X 106 to 5.2 X 108 cells L-1, with peak abundance during the spring bloom (April and May) and during July with a persistent spatial pattern of smallest abundance near the coastal ocean and highest abundance in the landward domains of the estuary. The picocyanobacterial component (as estimated percentage of chlorophyll a concentration) was, on average, 15% of total phytoplankton biomass during the summer-autumn nonbloom periods and only 2% of chlorophyll biomass during the spring bloom. This result is consistent with the emerging concept of a gradient of increasing importance of picocyanobacteria along the gradient of decreasing nutrient concentrations from estuaries to the open ocean.

Limnology and Oceanography↗
USGS2000

Dynamics of nutrient cycling and related benthic nutrient and oxygen fluxes during a spring phytoplankton bloom in South San Francisco Bay (USA)

Benthic oxygen uptake and nutrient releases of N, P and Si were measured weekly at 2 sites in South San Francisco Bay around the 1996 spring bloom. Exchanges across the sediment-water interface were estimated from whole core incubations performed in the laboratory at in situ temperature and in dark. Fluxes changed significantly on a weekly time scale. Over a period of 15 wk the fluxes of dissolved inorganic N, P and Si ranged from -40 to +200, 0 to 13 and from 30 to 400 µmol m -2 h -1 respectively. Sediment oxygen demand increased from 10 before to 64 mg O 2 m -2 h -1 just after the bloom period. During the bloom, nutrient fluxes represented about 20, 16 and 9% of the Si, P and N requirements for primary production. Before and after the bloom period, Si fluxes contributed up to 30 and >100% of this requirement and P and N fluxes up to 15 and 50% respectively. Simple empirical models explain most of the spatial-temporal variability of benthic fluxes of Si, P and NH 4 (but not NO 3 ) from 3 predictor variables: sediment porosity, nutrient concentration in bottom waters and chlorophyll content of surficial sediments. These models show that algal blooms influence benthic-pelagic nutrient exchange through 2 processes: (1) depletion of nutrients from the water column (which enhances gradient-driven transports across the sediment-water interface) and (2) sedimentation of labile phytodetritus (which promotes remineralization in or on the surficial sediments). Rates and patterns of nutrient cycling were very different at the shallow and deep study sites, illustrating the challenge of extrapolating measurements of coupled algae-nutrient dynamics to whole ecosystems.

Marine Ecology Progress Series↗
USGS1999

Water-quality variability in San Francisco Bay: general patterns of change during 1997

The 1997 Annual Report is the fifth Annual Report from the Regional Monitoring Program for Trace Substances (RMP) and contains a comprehensive description of RMP results from the 1997 monitoring year. As in previous years, the report includes results from the Base Program (water, sediment, and bivalve monitoring) and results from Pilot and Special Studies completed in 1997, in addition to an update on the RMP Five-Year Review implementation. It also includes papers contributed by RMP investigators and other scientists. These articles address related monitoring activities, and help to provide additional insight into contaminant patterns and the impacts of those contaminants on the San Francisco Estuary. The 1997 monitoring year proved to be an unusual one, with record-setting precipitation in December and January followed by unusually dry weather in February and March. These weather patterns had a visible effect on RMP results, frequently creating sharp contrasts in results between the first two sampling cruises of the year, and higher than normal contaminant concentrations at many RMP sampling sites in February. These results, and results from the other aspects of the RMP, are summarized below.

California↗
USGS1997

Water quality variability in San Francisco Bay, Some gGeneral lessons from 1996 sampling: 1996 annual report, San Francisco estuary regional monitoring program for trace substances

This report describes the results from the 1996 Regional Monitoring Program for Trace Substances (RMP). It is the fourth Annual Report from the RMP which began in 1993 and attempts to synthesize the most obvious data patterns from the last four years. This report includes data from Base Program monitoring activities, as well as results of Pilot and Special Studies conducted or completed in 1996. Additionally, several articles contributed by RMP investigators and others, are included. These articles provide perspective and insight on important contaminant issues identified by the RMP. This summary addresses which kinds of pollutants measured by the RMP appear to be at levels that warrant concern, what kinds of trends may be discerned, and which stations have consistently shown elevated contaminant levels. The goals or general objectives of the RMP are: 1. To obtain high quality baseline data describing the concentrations of toxic and potentially toxic trace elements and organic contaminants in the water and sediment of the San Francisco Estuary. 2. To determine seasonal and annual trends in chemical and biological water quality in the San Francisco Estuary. 3. To continue to develop a data set that can be used to determine long-term trends in the concentrations of toxic and potentially toxic trace elements and organic contaminants in the water and sediments of the San Francisco Estuary. 4. To determine whether water quality and sediment quality in the Estuary at large are in compliance with objectives established by the Basin Plan (the regulatory planning document used by the Regional Water Quality Control Board). 5. To provide a database on water and sediment quality in the Estuary which is compatible with data being developed in other ongoing studies, including wasteload allocation studies and model development, sediment quality objectives development, in-bay studies of dredged material disposal, Interagency Ecological Program (IEP) water quality studies, primary productivity studies, local effects biomonitoring programs, and state and federal mussel watch programs.

California↗
USGS1996

Seasonal fluctuations of water quality in San Francisco Bay during the first three years of the regional monitoring program, 1993-1995

The 1995 Regional Monitoring Program (RMP) Annual Report includes monitoring results from the Base Program, Pilot and Special Studies, and summary and perspective articles contributed by RMP investigators and other scientists. The purpose of the RMP is to provide information on the status and trends of contamination in San Francisco Estuary water, sediment, and bivalve tissue, and to assess the potential for biological effects from exposure to those contaminants. The objectives, background, and rationale for the RMP are described in the Introduction (Chapter 1). The 1995 RMP Base Program was essentially the same as in 1994. Water monitoring was conducted in February, April, and August at 24 stations throughout the Estuary. Aquatic bioassays were conducted in February and August at 13 of those stations. Sediment monitoring was conducted in February and August at all 24 stations, and sediment bioassays were conducted at 12 of those stations. Bioaccumulation of contaminants by transplanted bivalves was monitored at 15 stations during two 90 day sampling periods: January to April and July to September. Pilot Studies on benthic fauna and tidal wetlands were conducted and Special Studies on trends in trace elements and development of sediment indicators were also included.

California↗
USGS1994

Studies of the San Francisco Bay, California, estuarine ecosystem: Pilot regional monitoring program results, 1993

Water samples were collected in the San Francisco Bay estuary during 22 cruises from January through December 1993. Conductivity, temperature, light attenuation, turbidity, oxygen, and in-vivo fluorescence were measured 1ongitudinally and vertically in the main channel of the estuary from south of the Dumbarton Bridge in the southern part of the bay to Rio Vista on the Sacramento River. Discrete water samples were analyzed for chlorophyll a, phaeopigments, suspended particulate matter, and dissolved oxygen. Water density was calculated from values for salinity, temperature, and pressure (depth), and is included in the data summaries. Photosynthetic parameters, water column respiration, and phytoplankton species abundance and cell volume were determined at selected stations every other month.

California↗
USGS1992

Measurement of filtration rates by infaunal bivalves in a recirculating flume

A flume system and protocol for measuring the filtration rate of infaunal bivalves is described. Assemblages of multi-sized clams, at natural densities and in normal filter-feeding positions, removed phytoplankton suspended in a unidirectional flow of water. The free-stream velocity and friction velocity of the flow, and bottom roughness height were similar to those in natural estuarine waters. Continuous variations in phytoplankton (Chroomonas salinay) cell density were used to measure the filtration rate of the suspension-feeding clam Potamocorbula amurensis for periods of 2 to 28 h. Filtration rates of P. amurensis varied from 100 to 580 liters (gd)-1 over a free-stream velocity range of 9 to 25 cm s-1. Phytoplankton loss rates were usually constant throughout the experiments. Our results suggest that suspension-feeding by infaunal bivalves is sensitive to flow velocity. ?? 1992 Springer-Verlag.

Marine Biology↗
USGS1987

An empirical model for estimating phytoplankton productivity in estuaries

e have previously shown that primary productivity in San Francisco Bay, USA, is highly correlated with phytoplankton biomass B (chlorophyll a concentration) and an index of light avallability in the photic zone, 2, I, (photic depth times surface irradiance). To test the generality of this relation, we compiled data from San Francisco Bay and 5 other USA estuarine systems (Neuse and South Rivers, Puget Sound, Delaware Bay and Hudson River Plume), and regressed daily produclvity J' P (mg C m-2 d-') against the composite parameter B Z, I,. Regressions for each estuary were significant and typically over 80 % of the varialon in P was correlated with variations in B Z,I,. Moreover, the pooled data (n = 211) from 4 estuaries where methodologies were comparable fell along one regression line (r2= 0.82), indicating that primary productivity can be estimated in a diversity of estuarine waters from simple measures of phytoplankton biomass and hght availability. This implies that physiological variabhty (e. g. responses to variations in nutrient availabhty, temperature, sahnity, photoperiod) is a secondary control on phytoplankton production in nutrient-rich estuaries, and that one empirical function can be used to estimate seasonal variations in productivity or to map productivity along estuarine gradients of phytoplankton biomass and turbidity.

Marine Ecology Progress Series↗
USGS1985

Temporal dynamics of estuarine phytoplankton: A case study of San Francisco Bay

Detailed surveys throughout San Francisco Bay over an annual cycle (1980) show that seasonal variations of phytoplankton biomass, community composition, and productivity can differ markedly among estuarine habitat types. For example, in the river-dominated northern reach (Suisun Bay) phytoplankton seasonality is characterized by a prolonged summer bloom of netplanktonic diatoms that results from the accumulation of suspended particulates at the convergence of nontidal currents (i.e. where residence time is long). Here turbidity is persistently high such that phytoplankton growth and productivity are severely limited by light availability, the phytoplankton population turns over slowly, and biological processes appear to be less important mechanisms of temporal change than physical processes associated with freshwater inflow and turbulent mixing. The South Bay, in contrast, is a lagoon-type estuary less directly coupled to the influence of river discharge. Residence time is long (months) in this estuary, turbidity is lower and estimated rates of population growth are high (up to 1-2 doublings d-1), but the rapid production of phytoplankton biomass is presumably balanced by grazing losses to benthic herbivores. Exceptions occur for brief intervals (days to weeks) during spring when the water column stratifies so that algae retained in the surface layer are uncoupled from benthic grazing, and phytoplankton blooms develop. The degree of stratification varies over the neap-spring tidal cycle, so the South Bay represents an estuary where (1) biological processes (growth, grazing) and a physical process (vertical mixing) interact to cause temporal variability of phytoplankton biomass, and (2) temporal variability is highly dynamic because of the short-term variability of tides. Other mechanisms of temporal variability in estuarine phytoplankton include: zooplankton grazing, exchanges of microalgae between the sediment and water column, and horizontal dispersion which transports phytoplankton from regions of high productivity (shallows) to regions of low productivity (deep channels). Multi-year records of phytoplankton biomass show that large deviations from the typical annual cycles observed in 1980 can occur, and that interannual variability is driven by variability of annual precipitation and river discharge. Here, too, the nature of this variability differs among estuary types. Blooms occur only in the northern reach when river discharge falls within a narrow range, and the summer biomass increase was absent during years of extreme drought (1977) or years of exceptionally high discharge (1982). In South Bay, however, there is a direct relationship between phytoplankton biomass and river discharge. As discharge increases so does the buoyancy input required for density stratification, and wet years are characterized by persistent and intense spring blooms. ?? 1985 Dr W. Junk Publishers.

Hydrobiologia↗
USGS1983

River discharge controls phytoplankton dynamics in the northern San Francisco Bay estuary

Phytoplankton dynamics in the upper reach of the northern San Francisco Bay estuary are usually characterized by low biomass dominated by microflagellates or freshwater diatoms in winter, and high biomass dominated by neritic diatoms in summer. During two successive years of very low river discharge (the drought of 1976-77), the summer diatom bloom was absent. This is consistent with the hypothesis that formation of the diatom population maximum is a consequence of the same physical mechanisms that create local maxima of suspended sediments in partially-mixed estuaries: density-selective retention of particles within an estuarine circulation cell. Because the estuary is turbid, calculated phytoplankton growth rates are small in the central deep channel but are relatively large in lateral shallow embayments where light limination is less severe. When river discharge falls within a critical range (100–350 m 3 s −1 ) that positions the suspended particulate maximum adjacent to the productive shallow bays, the population of neritic diatoms increases. However, during periods of high discharge (winter) or during periods of very low discharge (drought), the suspended particulate maximum is less well-defined and is uncoupled (positioned downstream or upstream) from the shallow bays of the upper estuary, and the population of neritic diatoms declines. Hence, the biomass and community composition of phytoplankton in this estuary are controlled by river discharge.

California↗
USGS1983

Autotrophic processes in meromictic Big Soda Lake, Nevada.

Daily rates of oxygenic photosynthesis (OP) by phytoplankton, anoxygenic photosynthesis (AP) by purple sulfur bacteria, and chemoautotrophic productivity (CP = dark CO2 assimilation) were measured once each season. Total daily productivity and the relative importance of each autotrophic process varied with seasonal changes in vertical mixing, light availability, and the biomass of phototrophs. Daily productivity was highest (2830 mg C.m-2) and was dominated by OP in winter when the mixolimnion was isothermal, the biomass of phytoplankton was high, and the biomass of purple sulfur bacteria was low. During the summer-fall period of thermal stratification, phytoplankton biomass decreased, a plate of purple sulfur bacteria formed below the oxycline, and daily rates of dark CO2 assimilation (CP = 390-680 mg C.m-2) exceeded phototrophic productivity (OP + AP = 200-370 mg C.m-2). Total annual productivity was approx 500 g C.m-2, of which 60% was produced by phytoplankton (mostly in winter), 30% by chemoautotrophs (nitrifying and sulfur-oxidizing bacteria), and only 10% by photosynthetic bacteria. -Authors

Limnology and Oceanography↗