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Laurence E. Schemel

Publications and source records attributed to Laurence E. Schemel.

27 records · Page 2Linked to original sources
USGS1989

Potamocorbula amurensis discovered in San Francisco Bay

The small Asian clam, Potamocorbula amurensis , is now a major component of benthic communities in most areas of northern San Francisco Bay and some areas of South Bay. Because of its wide tolerance of salinity and other environmental variables and its high abundance in many areas, benthic ecologists believe this recent invasion may represent a major and permanent change in the bay system.

California↗
USGS1988

Riverine C, N, Si and P transport to the coastal ocean: An overview

Terrestrial ecosystems cycle and recyle inorganic nutrients including a feedback to atmospheric dry deposition and precipitation (cf. Lewis et al., 1985). Each year, however, a small fraction per unit area of the atmosphere/plant/soil flux leaks from these land-based cycles via precipitation/runoff (Meybeck, 1982). These losses are, in general, unpreventable. Moreover, such nutrient “losses” have increased with increasing human population (Wollast, 1983); although to some extent this anthropogenic component can be controlled. Most rivers eventually flow into estuaries and the coastal ocean where their natural and anthropogenic nutrient loads continue to recycle, are lost to the atmosphere, or are buried in sediment. In one extreme, when riverine nutrient concentrations are exceedingly low, as in southwestern Canadian streams (Naiman and Sibert, 1978; Stockner and Shortreed, 1978, 1985), downstream plant biomass can be nutrient limited. In the other extreme, when these nutrient concentrations are very high such as in highly populated European river basins, downstream plant biomass can increase, perhaps intensifying natural anoxia cycles within the receiving estuarine/coastal ocean waters if these waters are stratified (Rosenberg, 1985).

Book chapter↗
USGS1988

Benthic macrofauna and ancillary data for San Francisco Bay, California, March to November 1987

Benthic macrofauna and ancillary data were collected during 1987 as part of the U.S. Geological Survey Regional Effects Monitoring Program in San Francisco Bay, California. Data were collected during five cruises at 2-month intervals from March through November. Benthic macrofauna for identification of species and sediment for size analysis were sampled at eight stations. Ancillary data, which consisted of salinity, temperature, dissolved-oxygen concentrations, and suspended sediment, were collected at 12 stations. Salinity and temperature were measured at three stations that coincided with continuous water quality monitors. Abundances and geographical distributions of a newly introduced species of clam were measured. (USGS)

Open-File Report↗
USGS1984

Response of northern San Francisco Bay to riverine inputs of dissolved inorganic carbon, silicon, nitrogen and phosphorus

Estuarine processes can be effective in modifying (filtering) distributions of dissolved inorganic forms of carbon (DIC), silicon (DIS), nitrogen (DIN), and phosphorus (DIP) in northern San Francisco Bay. During winter, high inflow from the Sacramento-San Joaquin river system supplied these nutrients to the estuary at rates that exceeded potential rates of estuarine supply and removal processes. During spring and summer, when inflow rates were lower, the estuary was an effective “filter” of the river inflow “signal” because rates of estuarine processes were high relative to river and other supply rates. At lower inflow rates, the river apparently influenced estuarine hydrodynamic features that controlled rates of phytoplankton nutrient removal. Largest biological removal effects were localized in San Pablo Bay during spring and Suisun Bay during summer, and they were generally more pronounced in shallow water areas of the bays. In San Pablo Bay, effects of biological removal appeared soon after river inflow decreased from high winter rates, but persisted for only a short time. During the following summer months, DIN and DIP distributions in San Pablo Bay indicated that estuarine sources contributed to higher concentrations of these nutrients.

California↗
USGS1979

Water and sediment measurements in San Francisco Bay, California

Water samples collected in San Francisco Bay, the Gulf of the Farallones, and the delta of the Sacramento and San Joaquin rivers were analyzed for salinity, temperature, partial pressure of carbon dioxide (pCO 2 ), chlorophyll a, alkalinity, particulate organic carbon (POC), and the stable carbon isotope ratio ( δ 13 C) of the POC and total CO 2 . Water sampling occurred between January 1976 and March 1977. Bottom sediments for total organic carbon isotopic analyses ( δ 13 C(TOC)) were collected during August 1973. Numerical values are tabulated, sampling locations are identified, and the analytical methods are briefly described.

California↗
USGS1979

A continuous water sampling and multi-parameter measurement system for estuaries

Salinity, temperature, light transmissivity, oxygen saturation, turbidity, pH, pCO2, and chlorophyll a fluorescence of a pumped water sample are continuously measured with a system designed primarily for estuarine studies. Near-surface water from a depth of 2 m is sampled continuously while the vessel is underway or water at depths to 100 m can be collected with an in situ pump, in which case the sampling depth and temperature are measured by an in situ probe. The system is comprised of commercially available instruments, equipment, and components, and of specialized items designed and fabricated by the authors. Data can be read from digital displays and analog strip-chart recorders. Tables and figures describing specialized items are included.

Open-File Report↗
USGS1979

Particulate organic carbon in San Francisco Bay, California, 1971-1977

The organic-carbon content of suspended particulate matter is determined by wet oxidation and analysis of the resulting CO 2 with an infrared analyzer. Modifications of methods and improved designs of apparatus are presented. Results of particulate organic carbon (POC) analyses from 1971 through 1977 show that concentrations in North San Francisco Bay (estuary) typically decrease from the delta of the Sacramento and San Joaquin rivers to Golden Gate (seaward). Median winter (November through February) concentrations decrease from 85 to 30 µ g-at./L seaward. During March through October, median concentrations are higher and ranges are wider. Concentrations frequently exceed 250 µ g-at./L in the upper estuary. POC concentrations in South San Francisco Bay are highest at the southern reach. POC is more abundant during March through October than during winter, but POC is not as abundant in South San Francisco Bay as it is in the estuary.

California↗