Oil and gas resource assessment areas, U. S. Geological Survey, Geologic Division, 1980; Lower 48 states, regions 2 through 11, and 2A, 6A, and 11A
No abstract available.
Open-File Report↗
SEARCH · USGS Science
Results for “Regional Assessment Report”
Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Pesticides in U.S. streams and groundwater
A 10-year study by the U.S. Geological Survey’s (USGS’s) National Water-Quality Assessment (NAWQA) Program provides a national-scale view of pesticide occurrence in streams and groundwater. The 1992-2001 study builds upon a preliminary analysis from NAWQA’s first phase of studies during 1992-1996 (1, 2). Pesticide data available from various studies prior to 1992 did not allow national assessment because of limited and variable geographic coverage (usually focusing on individual states or regions), sparse and inconsistent inclusion of pesticides in use, and variable sampling designs (3-5). The expanded geographic coverage and improved data following 10 years of study (Figure 1) confirm and reinforce previously reported findings and enable more detailed analyses of each topic. This article summarizes selected findings from a comprehensive report (6), with a focus on the nature of pesticide occurrence and potential significance to human health and stream ecosystems. Information on study design and methods as well as additional analysis of geographic patterns and trends in relation to use and management practices are available in the full report (6).
Environmental Science & Technology↗
Genetic composition and connectivity of the Antillean manatee (Trichechus manatus manatus) in Panama
Genetic diversity and haplotype composition of the West Indian manatee (Trichechus manatus) population from the San San Pond Sak wetland in Bocas del Toro, Panama was studied using a segment of mitochondrial DNA (D’loop). No genetic information has been published to date for Panamanian populations. Due to the secretive behavior and small population size of the species in the area, DNA extraction was conducted from opportunistically collected fecal (N=20), carcass tissue (N=4) and bone (N=4) samples. However, after DNA processing only 10 samples provided good quality DNA for sequencing (3 fecal, 4 tissue and 3 bone samples). We found three haplotypes in total; two of these haplotypes are reported for the first time, J02 (N=3) and J03 (N=4), and one J01 was previously published (N=3). Genetic diversity showed similar values to previous studies conducted in other Caribbean regions with moderate values of nucleotide diversity (π= 0.00152) and haplotipic diversity (Hd= 0.57). Connectivity assessment was based on sequence similarity, genetic distance and genetic differentiation between San San population and other manatee populations previously studied. The J01 haplotype found in the Panamanian population is shared with populations in the Caribbean mainland and the Gulf of Mexico showing a reduced differentiation corroborated with Fst value between HSSPS and this region of 0.0094. In contrast, comparisons between our sequences and populations in the Eastern Caribbean (South American populations) and North Western Caribbean showed fewer similarities (Fst =0.049 and 0.058, respectively). These results corroborate previous phylogeographic patterns already established for manatee populations and situate Panamanian populations into the Belize and Mexico cluster. In addition, these findings will be a baseline for future studies and comparisons with manatees in other areas of Panama and Central America. These results should be considered to inform management decisions regarding conservation of genetic diversity, future controlled introductions, connectivity and effective population size of the West Indian manatee along the Central American corridor.
Bocas del Toro↗
National assessment of shoreline change: A GIS compilation of vector shorelines and associated shoreline change data for the sandy shorelines of Kauai, Oahu, and Maui, Hawaii
Sandy ocean beaches are a popular recreational destination, and often are surrounded by communities that consist of valuable real estate. Development is increasing despite the fact that coastal infrastructure may be repeatedly subjected to flooding and erosion. As a result, the demand for accurate information regarding past and present shoreline changes is increasing. Working with researchers from the University of Hawaii, investigators with the U.S. Geological Survey's National Assessment of Shoreline Change Project have compiled a comprehensive database of digital vector shorelines and shoreline-change rates for the islands of Kauai, Oahu, and Maui, Hawaii. No widely accepted standard for analyzing shoreline change currently exists. Current measurement and rate-calculation methods vary from study to study, precluding the combination of study results into statewide or regional assessments. The impetus behind the National Assessment was to develop a standardized method for measuring changes in shoreline position that is consistent from coast to coast. The goal was to facilitate the process of periodically and systematically updating the measurements in an internally consistent manner. A detailed report on shoreline change for Kauai, Maui, and Oahu that contains a discussion of the data presented here is available and cited in the Geospatial Data section of this report.
Hawai'i↗
The National assessment of shoreline change—A GIS compilation of vector shorelines and associated shoreline change data for the Pacific Northwest coast
Sandy ocean beaches are a popular recreational destination and are often surrounded by communities that consist of valuable real estate. Development along sandy coastal areas is increasing despite the fact that coastal infrastructure may be repeatedly subjected to flooding and erosion. As a result, the demand for accurate information regarding past and present shoreline changes is increasing. Investigators with the U.S. Geological Survey's National Assessment of Shoreline Change Project have compiled a comprehensive database of digital vector shorelines and rates of shoreline change for the Pacific Northwest coast including the states of Washington and Oregon. No widely accepted standard for analyzing shoreline change currently exists. Current measurement and methods for calculating rates of change vary from study to study, precluding the combination of study results into statewide or regional assessments. The impetus behind the national assessment was to develop a standardized method that is consistent from coast to coast for measuring changes in shoreline position. The goal was to facilitate the process of periodically and systematically updating the measurements in an internally consistent manner. A detailed report on shoreline change for the Pacific Northwest coast that contains a discussion of the data presented here is available and cited in the Geospatial Data section of this report.
Oregon, Washington↗
Mineral deposit density; an update
A robust method to estimate the number of undiscovered deposits is a form of mineral deposit model wherein numbers of deposits per unit area from well-explored regions are counted and the resulting frequency distribution is used either directly for an estimate or indirectly as a guideline in some other method. The 27 mineral deposit density estimates reported here for 13 different deposit types represent a start at compiling the estimates necessary to guide assessments.
Professional Paper↗
Effects of regulation on L-moments of annual peak streamflow in Texas
Several techniques exist to estimate annual peak-streamflow frequency for streamflows that have recurrence intervals ranging from 2 to 500 years for natural (unregulated) drainage basins in Texas. Unfortunately, such techniques have limited applicability in regulated basins. There are numerous regulated basins throughout Texas, which has more than 7,000 dams that are identified by Texas Natural Resource Conservation Commission permits. The effects on annual peak streamflow from reservoirs created by these dams range from negligible to the complete suppression of the flood hydrograph; also, reservoirs can artificially create flood-like hydrographs. The large number of reservoirs and their widespread distribution in Texas necessitate an assessment of flood characteristics in regulated basins. Therefore, the U.S. Geological Survey, in cooperation with the Texas Department of Transportation, conducted a study of the effects of regulation on L-moments of annual peak streamflow in Texas. For this report, the State was divided into three regions. Four regression equations to estimate the L-moments of natural annual peak-streamflow data for ungaged sites were derived for each region from data for 367 streamflow-gaging stations in natural basins. The explanatory variables in the equations are contributing drainage area, basin shape factor, and stream slope. The effects of regulation on the L-moments of annual peak-streamflow data were determined by analysis of maximum and normal storage-capacity data from reservoirs for 96 streamflow-gaging stations in variously regulated basins. The results indicate that as potential flood storage (defined by the difference between total maximum and normal capacity) in a basin increases, the mean annual peak streamflow decreases nonlinearly. Evidence strongly indicates (despite contrary expectation) that the higher L-moments (coefficient of L-variation, L-skew, and L-kurtosis) are unaffected by regulation.
Texas↗
Management implications of brood division in Golden-winged Warblers
Brood division in the postfledging period is a common avian behavior that is not well understood. Brood division has been reported in Golden-winged Warblers ( Vermivora chrysoptera) , but it is not known how common this behavior is, whether males and females exhibit different strategies related to parental care and habitat use, or how brood division might influence management strategies. We radiomarked fledglings and monitored divided broods of Golden-winged Warblers from fledging until independence from parental care at three sites in the western Great Lakes region from 2010 to 2012 to assess differences in strategies between male and female parents and to consider possible management implications. Male - and female-reared sub-broods exhibited different space use during the dependent post-fledging period despite similar fledgling survivial, cover-type use, and microhabitat use. By independence, female-reared sub-broods traveled over twice as far from the nest (mean = 461 ± 81) SE m) as male-reared sub-broods (164 ± 41 m). Additionally, female-reared sub-broods traveled over three times as far from the natal patch edge (35 ± 72 m) as male-reared sub-broods (108 ± 36 m). Without accounting for differential space use by male- and female-reared sub-broods, we would have reported broods traveling 292 (± 46 m) from the nest and 214 (± 40m) from the natal patch edge - distances that do not reflect how far females move sub-broods. Parental strategies differ between sexes with regard to movement patterns, and we recommend incorporating the differences in space use between sexes in future management plans for Golden-winged Warblers and other species that employ brood division. Specifically, management actions might be most effective when they are applied at spatial scales large enough to incorporate the habitat requirements of both sexes throughout the entire reproductive season.
Studies in Avian Biology↗
Development and application of a coastal change likelihood assessment for the northeast region, Maine to Virginia
Coastal resources are increasingly affected by erosion, extreme weather events, sea level rise, tidal flooding, and other potential hazards related to climate change. These hazards have varying effects on coastal landscapes because of the compounding of geologic, oceanographic, ecologic, and socioeconomic factors that exist at a given location. An assessment framework is introduced in this report that synthesizes existing datasets that cover the variability of the landscape, and hazards that may act on the landscape, to evaluate the likelihood of coastal change along the U.S. coastline on a decadal scale. The pilot study that aided in the development of the framework was run in the northeastern United States (from Maine to Virginia) and consists of datasets derived from a variety of Federal, State, and local sources. First, a decision-tree-based dataset was built that describes the resistance or integrity of the coastal landscape (called the fabric dataset for the purposes of this report) and includes land cover, elevation, slope, long-term (more than 50 years) shoreline change, dune height, and marsh stability data. A second database was generated from coastal hazards, which are divided into event hazards (for example, flooding, wave power, and probability of storm overwash) and persistent or perpetual hazards (for example, relative sea level rise rate, short-term [about 30-year] shoreline erosion rate, and storm recurrence interval). The fabric dataset was then merged with the coastal hazards databases, and a model training dataset made up of hundreds of polygons was generated from these combined data to support machine learning. The pilot study resulted in location-specific, 10-meter-resolution data classified into five raster datasets that include intrinsic characteristics of the coast used to determine the resistance of the landscape to change, the persistent and event hazards that act on the coast, the machine learning output (coastal change likelihood) based on the cumulative effects of the fabric and hazards datasets, and an estimate of the hazard type (event or persistent) that is the most likely to influence coastal change. Final outcomes are intended to be used as a first-order planning tool to determine which areas of the coast are more likely to change in response to future potential coastal hazards and to examine elements and drivers that make change in a location more likely.
Connecticut, Delaware, Maine, Maryland, Massachuse↗
Water availability and use pilot: Methods development for a regional assessment of groundwater availability, southwest alluvial basins, Arizona
Executive Summary: Arizona is located in an arid to semiarid region in the southwestern United States and is one of the fastest growing States in the country. Population in Arizona surpassed 6.5 million people in 2008, an increase of 140 percent since 1980, when the last regional U.S. Geological Survey (USGS) groundwater study was done as part of the Regional Aquifer System Analysis (RASA) program. The alluvial basins of Arizona are part of the Basin and Range Physiographic Province and cover more than 73,000 mi 2 , 65 percent of the State's total land area. More than 85 percent of the State's population resides within this area, accounting for more than 95 percent of the State's groundwater use. Groundwater supplies in the area are expected to undergo further stress as an increasing population vies with the State's important agricultural sector for access to these limited resources. To provide updated information to stakeholders addressing issues surrounding limited groundwater supplies and projected increases in groundwater use, the USGS Groundwater Resources Program instituted the Southwest Alluvial Basins Groundwater Availability and Use Pilot Program to evaluate the availability of groundwater resources in the alluvial basins of Arizona. The principal products of this evaluation of groundwater resources are updated groundwater budget information for the study area and a proof-of-concept groundwater-flow model incorporating several interconnected groundwater basins. This effort builds on previous research on the assessment and mapping of groundwater conditions in the alluvial basins of Arizona, also supported by the USGS Groundwater Resources Program. Regional Groundwater Budget: The Southwest Alluvial Basins-Regional Aquifer System Analysis (SWAB-RASA) study produced semiquantitative groundwater budgets for each of the alluvial basins in the SWAB-RASA study area. The pilot program documented in this report developed new quantitative estimates of groundwater budget components using recent (2000-2007) data and methods of data analysis. Estimates of inflow components, including mountain-front recharge, incidental recharge from irrigation of agriculture, managed recharge from recharge facilities, interbasin underflow from upgradient basins, and streamflow losses, are quantified for recent time periods. Mountain-front recharge is the greatest inflow component to the groundwater system and was estimated using two methods: a basin characteristic model and new precipitation information used in a previously developed regression equation. Annual mountain-front recharge for the study area for 1940-2007 estimated by the two methods is 730,000 acre-ft for the basin characteristic model and 643,000 acre-ft for the regression equation, representing 1.5 percent and 1.3 percent of precipitation, respectively. Outflow components, including groundwater withdrawals, evapotranspiration, and interbasin flow to downgradient basins, are also presented for recent time periods. Groundwater withdrawals accounted for the largest share of the water budget, with nearly 2.4 million acre-ft per year withdrawn from the study area in recent years. Evapotranspiration from groundwater was estimated at nearly 1.3 million acre-ft per year for the study area using a newly developed method incorporating vegetation indices from satellite images and land cover information. For water-budget components with temporal variation that could be assessed from available data, estimates for intervening time periods since before development were also developed. An estimate of aquifer storage change, representing both gains to and losses from the groundwater system since before development, was derived for the most developed basins in the study area using available estimates of groundwater-level changes and storage coefficients. An overall storage loss of 74.5 million acre-ft was estimated for these basins within the study area. Demonstration
Arizona↗
2002 assessment of undiscovered oil and gas resources of the Jurassic-Cretaceous Cotton Valley Group, Jurassic Smackover Interior Salt Basins Total Petroleum System, in the Louisiana-Mississippi Salt Basins Province of the northern Gulf Coast Region
Explore the source record for details and available documents.
Fact Sheet↗
South Florida Ecosystem Program of the U.S. Geological Survey
Introduction The South Florida Ecosystem Program is one of several study areas within the USGS Ecosystem Program. The Ecosystem Program was established to enable the USGS to enhance its scientific assistance to resource managers who require an improved scientific information base to resolve or prevent complex resource conflicts or environmental problems in specific ecosystem sites. Through 3-5-year efforts in each ecosystem site, USGS intensifies its provision of scientific information tailored to the specific management needs of that ecosystem. The information is designed to have a direct, significant, and immediate impact on management and policy decisions. It addresses regional or subregional issues that involve environmental resources such as water, minerals, and land. The sites may have as their focus such issues as water quality or water supply, environmental effects of mineral or energy use or extraction, effects of alterations in land use or land cover. Initially, the Ecosystem Program focussed on two ecosystems: San Francisco Bay and south Florida. Chesapeake Bay was added in FY 1996. Activities in each site last from three to five years, and additional ecosystem sites will be added as funding becomes available. The program is multidisciplinary and brings together scientists from appropriate disciplines to apply their diverse expertise to common problems. Disciplines in the present suite of ecosystems include land characterization, surface modeling, geospatial database management, ground- and surface-water hydrology, geophysics, ecology, geochemistry, paleontology, hydrologic modeling, and contaminant, sediment, and nutrient dynamics. The South Florida Ecosystem Program is an intergovernmental effort to reestablish and maintain the ecosystem of south Florida. One element of the restoration effort is the development of a firm scientific basis for resource decisionmaking. The U.S. Geological Survey (USGS) is one of the agencies that provides scientific information as part of the USGS South Florida Ecosystem Program. The Program, which was begun in fiscal year 1995, provides multidisciplinary hydrologic, cartographic, and geologic data that relates to the mainland of south Florida, the Florida Bay, and the Florida Keys and Reef ecosystems. The Program complements ongoing USGS work, such as the National Water-Quality Assessment Program , the Federal-State Cooperative Program, Marine and Coastal Geology Program and Regional Geology Program , and topographic mapping and digital cartography .
Florida↗
Quality of groundwater used for domestic supply in the northern San Joaquin Valley, California
Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project (PBP) of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and provides increased public access to groundwater-quality information. Private domestic and small-system drinking-water wells in the Northern San Joaquin Valley (NSJV) were the target for this assessment. These wells tend to pump water from shallower parts of alluvial aquifers compared to deeper, long-screened public-supply wells in the region.
California↗
The role of mineral resource assessments in ecological stewardship
Bedrock geology and mineral resource assessments can provide important information for ecologically based stewardship of land and water. Combining information derived from mineral resource assessments and geoenvironmental mineral deposit models provides a means to rapidly screen a large region for potential for mineral concentrations, to assess the environmental risk associated with mineralized bedrock and with human disturbances of mineralized bedrock, and to establish priorities for further studies.
Open-File Report↗
2010-2015 Juvenile fish ecology in the Nisqually River Delta and Nisqually Reach Aquatic Reserve
The return of tidal inundation to over 750 acres of the U. S. Fish and Wildlife Service Billy Frank Jr. Nisqually National Wildlife Refuge (NNWR) in fall of 2009 was the crowning moment in the effort to protect and restore the Nisqually Delta. The Nisqually NWR project complemented three earlier restoration projects completed by the Nisqually Indian Tribe (Tribe) on tribal property to restore over 900 acres of the estuary, representing the largest estuary restoration project in the Pacific Northwest and one of the most significant advances to date towards the recovery of Puget Sound (USFWS 2005). In 2011 the Washington Department of Natural Resources (WADNR established the over 14000 acre Nisqually Reach Aquatic Reserve (Reserve), complementing the protection and restoration successes in the Nisqually Delta. The Reserve includes all state-owned aquatic lands around Anderson, Ketron and Eagle islands and part of McNeil Island (Figure 1, WDNR 2011). The Reserve also includes a diverse assemblage of nearshore and offshore habitats important to resident and migratory fish including federal endangered species act listed fish like Chinook salmon (Oncorynchus tshawytscha) and steelhead (O. mykiss). Studies in the Nisqually Estuary (Ellings and Hodgson 2007, David et al. 2014, Ellings et al. 2016) and South Puget Sound (Duffy 2003) have summarized fish use of the area. However, the fish ecology of the reserve had not been systematically surveyed. The Tribe, U.S. Geological Survey (USGS), NNWR, Nisqually River Foundation (NRF), and others are currently conducting a multi-year, interdisciplinary, hypothesis-based research and monitoring study investigating the impact of delta restoration on estuarine processes, habitat structures, and functions. Our interdisciplinary monitoring framework enables us to link key estuarine processes with habitat development and biological response at multiple scales across the restored footprint, reference marshes, and throughout the Nisqually Reach. Key research components include hydrology and sediment regime, channel and marsh topography and development, vegetation colonization, and invertebrate, bird, and fish abundance, habitat use, and foraging ecology. After the Reserve was established, the WDNR and the research partnership led by the Tribe expanded the existing delta fish ecology assessment to include sampling stations throughout the Reserve. The results of the Reserve fish ecology assessment provide a unique regional analysis of fish ecology from the Nisqually River to McNeil Island.
Salmon Recovery Program Technical Report↗
Circulating fat-soluble vitamin concentrations and nutrient composition of aquatic prey eaten by American oystercatchers ( Haematopus palliatus ) in the southeastern United States
The American oystercatcher ( Haematopus palliatus palliatus ) is currently listed as a species of high concern by the United States Shorebird Conservation Plan. Because nutritional status directly impacts overall health and reproduction of individuals and populations, adequate management of a wildlife population requires intimate knowledge of a species' diet and nutrient requirements. Fat-soluble vitamin concentrations in blood plasma obtained from American oystercatchers and proximate, vitamin, and mineral composition of various oystercatcher prey species were determined as baseline data to assess nutritional status and nutrient supply. Bird and prey species samples were collected from the Cape Romain region, South Carolina, USA, and the Altamaha River delta islands, Georgia, USA, where breeding populations appear relatively stable in recent years. Vitamin A levels in blood samples were higher than ranges reported as normal for domestic avian species, and vitamin D concentrations were lower than anticipated based on values observed in poultry. Vitamin E levels were within ranges previously reported for avian groups with broadly similar feeding niches such as herons, gulls, and terns (eg, aquatic/estuarine/marine). Prey species (oysters, mussels, clams, blood arks [ Anadara ovalis ], whelks [ Busycon carica ], false angel wings [ Petricola pholadiformis ]) were similar in water content to vertebrate prey, moderate to high in protein, and moderate to low in crude fat. Ash and macronutrient concentrations in prey species were high compared with requirements of carnivores or avian species. Prey items analyzed appear to meet nutritional requirements for oystercatchers, as estimated by extrapolation from domestic carnivores and poultry species; excesses, imbalances, and toxicities—particularly of minerals and fat-soluble vitamins—may warrant further investigation.
Georgia, South Carolina↗
U.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2016 annual report
This is the ninth annual report highlighting U.S. Geological Survey (USGS) science and decision-support activities conducted for the Wyoming Landscape Conservation Initiative (WLCI). The activities address specific management needs identified by WLCI partner agencies. In fiscal year (FY) 2016, there were 26 active USGS WLCI science-based projects. Of these 26 projects, one project was new for FY2016, and three were completed by the end of the fiscal year (though final products were still in preparation or review). USGS WLCI projects were grouped under five categories: (1) Baseline Synthesis, (2) Long-Term Monitoring, (3) Effectiveness Monitoring, (4) Mechanistic Studies of Wildlife, and (5) Data and Information Management. Each of these topic areas is designed to address WLCI management needs: identifying key drivers of change, identifying the condition and distribution of key wildlife species and habitats and of species’ habitat requirements, development of an integrated inventory and monitoring strategy, use of emerging technologies and development and testing of innovative methods for maximizing the efficiency and efficacy of monitoring efforts, evaluating the effectiveness of habitat treatment projects, evaluating the responses of wildlife to development, and developing a data clearinghouse and information management framework to support and provide access to results of most USGS WLCI projects. In FY2016, we assisted with updating the WLCI Conservation Action Plan and associated databases as part of the Comprehensive Assessment, and we also assisted with the Bureau of Land Management 2015 WLCI annual report. By the end of FY2016, we completed or had nearly completed assessments of WLCI energy and mineral resources and had submitted a manuscript on modeled effects of oil and gas development on wildlife to a peer-reviewed journal. We also initiated a study on the effects of wind energy on wildlife in the WLCI region. A USGS circular on WLCI long-term monitoring was in review at the end of the fiscal year, and seven projects monitoring water and vegetation (including changes in sagebrush cover and patterns of sagebrush mortality) continued through the year. USGS scientists continued many projects in FY2016 that evaluate the effectiveness of habitat conservation actions (including sagebrush, cheatgrass, and aspen habitat treatments) and provide tools in support of mechanistic studies of wildlife. In FY2016, USGS scientists, along with university and State partners, continued work on five focal wildlife species/communities (pygmy rabbits [ Brachylagus idahoensis ], greater sage grouse , mule deer, sagebrush songbirds, and native fish). In FY2016, the USGS Information Management Team presented information to WLCI scientists on how USGS tools and resources can be used to fulfill the requirements of new USGS policies regarding data release, data management, and data visualization.
Wyoming↗
San Francisco Bay/delta regional monitoring program plankton and water quality pilot study, 1993, in 1993 Annual Report, San Francisco Estuary Regional Monitoring Program for Trace Substances: San Francisco Estuary Institute
The pilot program described here is motivated by a fundamental principle of the Regional Monitoring Strategy, namely “...the development of data that will provide information on status and trends in the Estuary.” As pointed out in the Strategy, knowledge of status and trends serves two primary purposes: (1) to become aware of or anticipate deleterious conditions in the Estuary, and (2) to assess the effectiveness of management actions. This program addresses these two purposes by focusing on aquatic resources, one of the five key management issues identified by the Comprehensive Conservation and Management Plan and central to the Regional Monitoring Strategy. It also bears on at least two of the other management issues - pollutants and water use. A regional monitoring program must cover many types of resources, including pelagic and benthic channel habitat, shoal habitat, wetlands, river channels, sloughs, and small bays and harbors. This particular program centers on the pelagic channel habitat. However, because of the intimate connection between channel habitat and many or most of these other habitats, channel measurements reflect to some extent the status of and trends in other resource types as well. A primary aim of this program is to provide a high-resolution description of critical aspects of habitat quality, which can be used along with other information (1) to determine the suitability of habitat for aquatic resources; (2) to monitor responsiveness of the habitat to freshwater flow variability; and (3) to provide a context for understanding pollutant distributions. In a single transect, measurements are made throughout the water column at up to 37 stations to define physical (salinity, temperature, suspended particulate matter, and light penetration), chemical (dissolved oxygen) and biological (chlorophyll a ) characteristics that influence both chemical and biological reactions. A second aim of the program is to investigate planktonic indicators of ecosystem structure and function. Phytoplankton production is the major single source of energy for the San Francisco Bay food web. Our measurements of chlorophyll and light penetration can be used to provide an estimate of this production, and therefore the availability of food for organisms at higher trophic levels. Phytoplankton community composition at the species level, which can be a sensitive indicator of habitat change, is also a standard component of this program. Community composition data enable detection of species known to be responsible for harmful or nuisance algal blooms. In 1993, two other indicators were also evaluated, photosynthetic parameters and water column respiration . Photosynthetic parameters partially characterize the physiological state of the phytoplankton and may provide indirect evidence of nutrient deficiency or the effects of pollutants. Water column respiration serves as a simple integrated measure of organic matter metabolism by the plankton, including bacteria, phytoplankton, and microzooplankton. It therefore reflects the total supply of organic matter, whether from photosynthesis, tidal marsh efflux, point sources, or upstream in the Delta. These biological indicators therefore contain much information about the flow of energy into the food web.
California↗