Time scales of change in the San Francisco Bay benthos

Nichols, Frederic H.; Thompson, Janet K.

doi:10.1007/978-94-009-5528-8_8

Cited by 44 publications

(35 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These would accelerate the same types of trends in the bulk sediment as observed in the <lOO-pm fraction. Furthermore, bulk sediment collected by Nichols & Thompson (1985) in 1980-81 for southern South Bay was coarsest in late summer just as observed for the <lOO-pm fraction throughout the six years of our study at station 7.…”

Section: Discussionsupporting

confidence: 77%

Temporal fluctuations in grain size, organic materials and iron concentrations in intertidal surface sediment of San Francisco Bay

Thomson-Becker

Luoma

1985

Hydrobiologia

View full text Add to dashboard Cite

The physical and chemical characteristics of the oxidized surface sediment in an estuary fluctuate temporally in response to physical forces and apparently-fluctuating inputs. These characteristics, which include grain size and concentrations of organic materials and iron, will influence both trace-metal geochemistry and bioavailability. Temporal trends in the abundance of fine particles, total organic carbon content (TOC), absorbance of extractable organic material (EOM), and concentration of extractable iron in the sediment of San Francisco Bay were assessed using data sets containing approximately monthly samples for periods of two to seven years. Changes in wind velocity and runoff result in monthly changes in the abundance of fine particles in the intertidal zone. Fine-grained particles are most abundant in the late fall/ early winter when runoff is elevated and wind velocities are low; particles are coarser in the summer when runoff is low and wind velocities are consistently high. Throughout the bay, TOC is linearly related to fine particle abundance (r = 0.61). Temporal variability occurs in this relationship, as particles are poor in TOC relative to percent of fine particles in the early rainy season. Iron-poor particles also appear to enter the estuary during high runoff periods; while iron is enriched on particle surfaces in the summer. Concentrations of extractable iron and absorbance of EOM vary strongly from year to year. Highest absorbances of EOM occurred in the first year following the drought in 1976-77, and in 1982 and 1983 when river discharge was unusually high. Extractable-iron concentrations were also highest in 1976-77, but were very low in 1982 and 1983. Hydrobiologia 129, 91-107 (1985). 0 Dr W. Junk Publishers, Dordrecht. Printed in the Netherlands.

show abstract

Section: Discussionsupporting

confidence: 77%

Temporal fluctuations in grain size, organic materials and iron concentrations in intertidal surface sediment of San Francisco Bay

Thomson-Becker

Luoma

1985

Hydrobiologia

View full text Add to dashboard Cite

show abstract

“…Generally, this variation was large in comparison to the overall change observed during the experiment . Spatial and temporal variation can be influenced by stochastic storms (Nichols & Thompson, 1985), sediment stability (Madsen et al ., 1993), patchiness in meiofaunal grazing (Davis & Lee, 1983 ;Pinkney & Sandulli, 1990), patchiness in nutrient concentration (Hopner & Wonneburger, 1985), and light penetration through different sediment types (Kuhl et al ., 1994) . Sediment stability more likely affected chlorophyll a concentrations in the field where waves resuspended the upper centimeters of sediment .…”

Section: Discussionmentioning

confidence: 99%

Benthic microalgae: comparisons of chlorophyll a in mesocosms and field sites

1996

View full text Add to dashboard Cite

A mesocosm facility is being developed by the CSIRO Division of Fisheries to study the movement, fate and impact of pollutants in coastal marine environments . Initially, we are studying coastal habitats in S .W Australia that are subject to wave action . A 12 week experiment assessed changes in biotic and abiotic components of sediment brought from the field into mesocosms . In these sediments, benthic microalgae are the major primary producers .Microalgal standing stocks were measured as the concentration of chlorophyll a and phaeopigments in the top 2 cm of sediment, and these measures were compared among mesocosms and field sites . Significant increases in chlorophyll a and phaeopigments, increased numbers of species and a shift from episammic to periphytic diatoms were observed, possibly caused by decreased water motion in mesocosms or other containment effects . Results from statistical power analyses suggested that our sampling was sufficiently well replicated and successfully incorporated variation at small spatial and temporal scales . Sampling effort used in this experiment should form the basis for future work with benthic microalgae .

show abstract

“…The properties and modulating processes of suspended particulate matter -undifferentiated material from the rivers, ocean, sewage effluents, resuspended from the bottom, and produced in situ by biological processes -have been extensively discussed elsewhere (e.g. Conomos & Peterson, 1977;Conomos et al, 1979;Cloern et al, 1985;Nichols & Thompson, 1985). The gross distributions of suspended particulates show distinct differences between the northern reach and South Bay (Figs.…”

Section: Time Of Daymentioning

confidence: 98%

“…The deepest sec-tidal currents. The sediments of the shallows comtions of channel, such as at Golden Gate (110 m) prise silty clay, clayey silt and sand-silt-clay (Sheand Carquinez Strait (27 m), are topographic con-pard classification; Shepard, 1954), while sand and silty sand cover the deeper areas of Central Bay and the northern reach (Nichols & Thompson, 1985). Gravelly sands are found at Golden Gate, and grade seaward to a well sorted sand that covers most of the inner continental shelf region of the Gulf of the Farallones (Fig.…”

Section: The Settingmentioning

confidence: 99%

“…Thus, the prevailing winds can generate basin-wide circulation that is superimposed upon tidal circulation. Wind generated waves resuspend sediment (Krone, 1979;Nichols & Thompson, 1985), oxygenate the water (Peterson, 1979 Hammond, 1983, and by mixing water masses in this shallow environment, disperse dissolved and particulate matter, including organisms, throughout the bay. Evaporation (120 cm yrr) is effective in raising salinities over the bay's shallows, particularly in summer (16-18 cm mom', Fig.…”

Section: Climate and Weather Windmentioning

confidence: 99%

See 1 more Smart Citation

Environmental setting of San Francisco Bay

1985

View full text Add to dashboard Cite

San Francisco Bay, the largest bay on the California coast, is a broad, shallow, turbid estuary comprising two geographically and hydrologically distinct subestuaries: the northern reach lying between the connection to the Pacific Ocean at the Golden Gate and the confluence of the Sacramento-San Joaquin River system, and the southern reach (herein called South Bay) between the Golden Gate and the southern terminus of the bay. The northern reach is a partially mixed estuary dominated by seasonally varying river inflow, and the South Bay is a tidally oscillating lagoon-type estuary. Freshwater inflows, highest during winter, generate strong estuarine circulation and largely determine water residence times. They also bring large volumes of dissolved and particulate materials to the estuary. Tidal currents, generated by mixed semidiurnal and diurnal tides, mix the water column and, together with river inflow and basin geometry, determine circulation patterns. Winds, which are strongest during summer and during winter storms, exert stress on the bay's water surface, thereby creating large waves that resuspend sediment from the shallow bay bottom and, together with the tidal currents, contribute markedly to the transport of water masses throughout the shallow estuary.

show abstract

Time scales of change in the San Francisco Bay benthos

Cited by 44 publications

References 35 publications

Temporal fluctuations in grain size, organic materials and iron concentrations in intertidal surface sediment of San Francisco Bay

Temporal fluctuations in grain size, organic materials and iron concentrations in intertidal surface sediment of San Francisco Bay

Benthic microalgae: comparisons of chlorophyll a in mesocosms and field sites

Environmental setting of San Francisco Bay

Contact Info

Product

Resources

About