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1.
Monitoring of the ocean environment in southern California, USA, has been conducted by a diverse array of public and private organizations with different motivations, working on a variety of spatial and temporal scales. To create a basis from which to integrate information from these diverse programs, we conducted an inventory of ocean monitoring activities in the Southern California Bight to address the following questions: (1) How much money is being expended annually on marine monitoring programs? (2) Which organizations are conducting the most monitoring? (3) How are resources allocated among the different types of monitoring programs? This inventory focused on programs existing, or those expected to be in existence, for at least 10 years and that were active at any time between 1994 and 1997. For each program identified for inclusion in this study, information was collected on the number of sites, sampling intensity, parameters measured, and methods used. Levels of effort were translated into cost estimates based upon a market survey of local consulting firms. One hundred fourteen marine monitoring programs, conducted by 65 organizations and costing US $31 million annually, were identified. Most of the effort (81 programs, 65% of samples, 70% of costs) was expended by ocean dischargers as part of their compliance with National Pollutant Discharge Elimination System (NPDES) permit requirements. Federal programs (11 programs, 25% of samples, 10% of total expenditures) expended more than state or local government programs. More than one quarter of monitoring expenditures were conducted to measure concentrations and mass of effluent inputs to the ocean. The largest effort expended on receiving water monitoring was for measuring bacteria, followed by sediments, fish/shellfish, water quality, and intertidal habitats. The large level of expenditures by individual agencies has presented opportunities for integrating small, site-specific ocean monitoring programs into regional- and national-scale monitoring and assessment programs.  相似文献   
2.
Feeding patterns during four 24-h periods, sampled at 3-h intervals, were investigated for the mummichog Fundulus heteroclitus, in a Delaware, USA tidal marsh. Two factors potentially influencing feeding patterns, time of day and tide height, were examined. On 2 of the sampling periods a low tide occurred in the morning, while on the other 2 sampling periods a high tide occurred in the morning. Results are reported as g-dry wt. of food per g-dry wt. of fish. F. heteroclitus is primarily a daytime feeder that most actively feeds at high tide, regardless of whether or not the high tide inundates marsh surface areas. When tide height was sufficient to inundate the marsh surface, fish invaded these areas and consumed prey characteristic of the marsh surface. F. heteroclitus is an important link in energy transfers between the marsh surface and subtidal systems, enhancing its own energy supplies by consuming marsh surface prey whenever available.  相似文献   
3.
A three-dimensional, baroclinic numerical circulation model is applied to the combined Rookery Bay and Naples Bay estuary complex. We focus on two aspects of the model simulations: the tidal circulation, for which we have observations of sea level and currents at several stations spanning Rookery Bay, and the salinity variations, for which we have observations at one station. After establishing model veracity through quantitative comparisons with observations, we use the model to address salinity changes that could arise due to regulatory fresh water flow rate modifications. Two different sets of experiments are performed. The first considers the salinity changes in Rookery Bay by increasing the fresh water flow rates into Henderson Creek through the addition of either 1.4 m3/s or 2.8 m3/s to the ambient flow rates. The second considers the salinity changes in Naples Bay by decreasing the fresh water flow rates through the subtraction of 9.9 m3/s from the Golden Gate Canals’ ambient flow rates. All of these scenarios result in significant, quantifiable salinity changes within the Rookery Bay and Naples Bay estuary complexes, demonstrating the environmental management utility of using high resolution, three-dimensional, numerical circulation models, as applied herein, for assessing the water properties of complex, multi-connected estuarine systems.  相似文献   
4.
Monitoring of the ocean environment in southern California, USA, has been conducted by a diverse array of public and private organizations with different motivations, working on a variety of spatial and temporal scales. To create a basis from which to integrate information from these diverse programs, we conducted an inventory of ocean monitoring activities in the Southern California Bight to address the following questions: (1) How much money is being expended annually on marine monitoring programs? (2) Which organizations are conducting the most monitoring? (3) How are resources allocated among the different types of monitoring programs? This inventory focused on programs existing, or those expected to be in existence, for at least 10 years and that were active at any time between 1994 and 1997. For each program identified for inclusion in this study, information was collected on the number of sites, sampling intensity, parameters measured, and methods used. Levels of effort were translated into cost estimates based upon a market survey of local consulting firms. One hundred fourteen marine monitoring programs, conducted by 65 organizations and costing US $31 million annually, were identified. Most of the effort (81 programs, 65% of samples, 70% of costs) was expended by ocean dischargers as part of their compliance with National Pollutant Discharge Elimination System (NPDES) permit requirements. Federal programs (11 programs, 25% of samples, 10% of total expenditures) expended more than state or local government programs. More than one quarter of monitoring expenditures were conducted to measure concentrations and mass of effluent inputs to the ocean. The largest effort expended on receiving water monitoring was for measuring bacteria, followed by sediments, fish/shellfish, water quality, and intertidal habitats. The large level of expenditures by individual agencies has presented opportunities for integrating small, site-specific ocean monitoring programs into regional- and national-scale monitoring and assessment programs.  相似文献   
5.
Aluminum is often used as a conservative tracer toseparate natural from anthropogenic components ofmetal contamination in marine sediments, butidentifying uncontaminated sites to develop baselinemetal:aluminum relationships can be problematic inpopulated areas. Here we present a new method foridentifying baseline relationships in high populationdensity areas. The method involves comparing theresidual from the metal:aluminum regression with anindependent estimate of laboratory measurement error,based on the premise that mean square error from theregression must equal laboratory measurement error forany data set that is free of anthropogenicallyenriched sites. The method is applied to data setsfrom the mid-Atlantic and Gulf coasts of the UnitedStates to test consistency in baseline relationshipsbetween these two coasts of geologically differentorigin. Differences in metal:aluminum relationshipsbetween coasts were found to be small and limited tothe least abundant trace metals.  相似文献   
6.
The spatial and temporal distribution of macrobenthic assemblages in the San Francisco Estuary and Sacramento–San Joaquin River Delta were identified using hierarchical cluster analysis of 501 samples collected between 1994 and 2008. Five benthic assemblages were identified that were distributed primarily along the salinity gradient: (1) a polyhaline assemblage that inhabits the Central Bay, (2) a mesohaline assemblage that inhabits South Bay and San Pablo Bay, (3) a low-diversity oligohaline assemblage primarily in Suisun Bay, (4) a low-diversity sand assemblage that occurs at various locations throughout the Estuary, and (5) a tidal freshwater assemblage in the Delta. Most sites were classified within the same assemblage in different seasons and years, but a few sites switched assemblage designations in response to seasonal changes in salinity from freshwater inflows.  相似文献   
7.
The US Environmental Protection Agency's Office of Research and Development has initiated the Environmental Monitoring and Assessment Program (EMAP) to monitor status and trends in the condition of the nation's near coastal waters, forests, wetlands, agro-ecosystems, surface waters, deserts and rangelands. the programme is also intended to evaluate the effectiveness of Agency policies at protecting ecological resources occurring in these systems. Monitoring data collected for all ecosystems will be integrated for regional and national status and trends assessments. the near coastal component of EMAP consists of estuaries, coastal waters, and the Great Lakes. Near coastal ecosystems have been regionalized and classified, and an integrated sampling strategy has been developed. EPA and NOAA have agreed to coordinate and, to the extent possible, integrate the near coastal component of EMAP with the NOAA National Status and Trends Program. A demonstration project was conducted in estuaries of the mid-Atlantic region (Chesapeake Bay to Cape Cod) in the summer of 1990. in 1991, monitoring continued in mid-Atlantic estuaries and was initiated in estuaries of a portion of the Gulf of Mexico. Preliminary results indicate: there are no insurmountable logistical problems with sampling on a regional scale; several of the selected indicators are practical and sensitive on the regional scale; and an efficient effort in future years will provide valuable information on condition of estuarine resources at regional scales.  相似文献   
8.
Harvest objectives for wild ungulates have traditionally been based on population models that do not consider ecosystem effects of ungulate herbivory, nor interactions between native and domestic ungulate species. There is a need for ecosystem models to allow wildlife managers to evaluate potential ecosystem effects of management scenarios. The utility of the SAVANNA simulation model for estimating elk population objectives within an ecosystem context was demonstrated for North Park, Colorado, USA. Effects of different elk population levels were evaluated for range condition, elk and cattle forage, elk and cattle condition, forage and condition of mule deer and moose, plant production, and plant community composition. Analyses were based on 30-year simulation runs using variable, historical weather. Another set of analyses utilized stochastic weather patterns. For management scenarios using the historical climate pattern, increasing elk populations caused biomass reductions of palatable plant species, particularly on areas of high winter density, where mean leaf biomass of palatable shrubs declined from 26.97 g/m2 at 0 elk to 20.82 g/m2 at 4000 elk (3.73 elk/km2), a 23% decline. At population levels of 5000 elk (4.68 elk/km2) or greater, elk body condition declined sharply following a severe winter. The availability of palatable browse on critical winter range was likely the limiting factor. However, when random climate patterns were simulated for the same scenarios, the threshold level for density-dependent effects varied with climate, ranging from 2000 to 10,000 elk. We suggest that elk population levels from 4000 to 5000 animals represent a conservative population objective for the North Park elk herd. Also, increasing elk population levels appears to intensify intraspecific competition among elk, far more than interspecific competition with cattle. Resolution of elk-cattle conflicts is likely to be facilitated by managing elk distribution, rather than overall elk population levels.  相似文献   
9.
An inventory was conducted to assess the number, type, spatial distribution, and costs of microbiological monitoring programs in southern California marine waters from Point Conception to the US/Mexico International Border. The location of each sampling site was determined using global positioning system (GPS), and estimates of geographic coverage were determined using geographic information system (GIS) techniques. Twenty-one programs conducted 87,007 tests annually at 576 sites in the study area. The largest number of sites was sampled in Orange County, whereas the largest number of analyses was performed in Los Angeles County because monitoring programs in this area focused on daily monitoring. Fifteen of the 21 programs were managed by National Pollutant Discharge Elimination System (NPDES) permitted sewage effluent dischargers who sampled both offshore and shoreline waters and typically tested for three indicator bacteria (total coliform, fecal coliform, and enterococcus). Their combined efforts comprised 82% of all of the microbiological indicator analyses conducted on an annual basis. Five of the remaining monitoring organizations were public health agencies, which typically focus their efforts on testing only total coliforms. Laboratory methodology also varied considerably, with NPDES permittees predominantly utilizing membrane filtration while public health agencies generally used multiple tube fermentation or premanufactured test kits. Nearly three quarters of all the effort expended in southern California occurred along the shoreline as opposed to offshore locations. Two thirds of this shoreline effort was focused on high-use sandy beaches and in proximity to perennial freshwater outlets (storm drains and creeks). Most sampling occurred at a set of fixed sites that were revisited frequently, but only represented about 7% of the total shoreline. We estimated that roughly $3 million is spent annually on monitoring bathing water quality in southern California, exceeding that spent in any other part of the country.  相似文献   
10.
Three methods (membrane filtration, multiple tube fermentation, and chromogenic substrate technology kits manufactured by IDEXX Laboratories, Inc.) are routinely used to measure indicator bacteria for beach water quality. To assess comparability of these methods, quantify within-laboratory variability for each method, and place that variability into context of variability among laboratories using the same method, 22 southern California laboratories participated in a series of intercalibration exercises. Each laboratory processed three to five replicates from thirteen samples, with total coliforms, fecal coliforms or enterococci measured depending on the sample. Results were generally comparable among methods, though membrane filtration appeared to underestimate the other two methods for fecal coliforms, possibly due to clumping. Variability was greatest for the multiple tube fermentation method. For all three methods, within laboratory variability was greater than among laboratories variability.  相似文献   
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