遇见数据集

Old - Bight 03 Trawl Debris

收藏
ArcGIS Hub2026-04-20 更新2026-07-05 收录
官方服务:

资源简介:

The first objective, estimating the amount of area (i.e., number of acres) in the SCB that ecological conditions differ from reference conditions, is a departure from traditional approaches to environmental monitoring, which generally focus on estimating average condition. Estimating the areal extent of ecological change offers several advantages. First, it provides a more direct assessment of status. For instance, identifying that the average concentration of dissolved oxygen in the Bight is 6.7 ppm provides less useful information for environmental managers than does identifying what percentage of the area in the Bight fails to meet water quality standards. A second advantage of estimating areal extent concerns trend detection. If conditions in the Bight change over time such that some areas improve and others worsen, the average condition might not change. By estimating the areal extent of alteration, we will be better able to describe these changes. There are two sub objectives within the areal extent and magnitude objective. The first sub objective is to determine if the areal extent and magnitude vary among geographic regions. If we answer this question, then managers can determine if specific areas are in worse condition than others, such as areas near anthropogenic inputs versus those areas distant from inputs. Therefore, Bight 2003 will compare condition among 11 geographic areas of interest (Table II-1). These subpopulations of our study area were selected to represent a range of natural and potentially affected habitats, and include all of the habitats sampled in 1998. There are three new habitats to be sampled in Bight 2003. The first two are located offshore of previously sampled habitats; the upper continental slope (200-500m) and the lower slope and inner basin (500-1000m). The break in deep water strata is a reflection of an ecotone between upper slope and lower slope biological communities. The third habitat is inshore of previous sampled habitats and includes coastal lagoons. Comparison of the relative condition among strata not only provides information about the geographic distribution of impacts, it also allows comparison of relative risk from a variety of point and nonpoint source discharges. Comparison of conditions may be conducted by comparing the extent of area exceeding a threshold of concern or by comparison of mean condition. The second sub objective within the areal extent and magnitude objective is assessing the relationship between biological responses and contaminant exposure. Such associations provide the information necessary for risk assessment, and for developing efficient regional strategies for protecting the environment by identifying the predominant types of stress in the SCB ecosystem. Therefore, this sub objective will be accomplished by simultaneously collecting numerous measures of biological response, contaminant exposure and habitat condition (Table II-2) to better identify when exposure has reached a level of concern. Measuring multiple indicators also permits us to identify the most likely type of exposure leading to biological response. The second primary objective will create a mass balance of contaminants in the SCB. This objective recognizes that local monitoring programs only address a portion of what is discharged to the SCB and that contaminant inputs to the SCB are cumulative both among sources and over time. Ultimately, both environmental managers and the public want to know what fraction of the contaminants that are discharged remain in the SCB and what fraction leaves the SCB. Therefore, Bight 2003 will create an inventory of contaminants that reside in the SCB in sediment, water column, and biological compartments. The total mass of contaminants in these compartments will be compared to estimates of mass discharged from land based activities. Understanding how much mass is in the SCB will require some new measurements including measurements of not just sediment chemistry, but estimates of accumulation rates in sediments, as well as new measurements in the water column. The Southern California Bight (SCB; Figure I-1), an open embayment in the coast between Point Conception and Cape Colnett (south of Ensenada), Baja California, is an important and unique ecological resource. The SCB is a transitional area that is influenced by currents from cold, temperate ocean waters from the north and warm, tropical waters from the south. In addition, the SCB has a complex topography, with offshore islands, submarine canyons, ridges and basins, which provide a variety of habitats. The mixing of currents and the diverse habitats in the SCB allow for the coexistence of a broad spectrum of species, including more than 500 species of fish and several thousand species of invertebrates. The SCB is also a major migration route, with marine bird and mammal populations ranking among the most diverse in north temperate waters. The coastal zone of the SCB is a substantial economic resource. Los Angeles/Long Beach Harbor is the largest commercial port in the United States, and San Diego Harbor is home to one of the largest US Naval facilities in the country. More than 100 million people visit southern California beaches and coastal areas annually, bringing an estimated $9B into the economy. Recreational activities include diving, swimming, surfing, and boating, with about 40,000 pleasure boats docked in 13 coastal marinas within the region (NRC 1990). Recreational fishing brings in more than $500M per year. The SCB is one of the most densely populated coastal regions in the country, which creates stress upon its marine environment. Nearly 20 million people inhabit coastal Southern California, a number that is expected to increase another 20% by 2010 (NRC 1990). Population growth generally results in conversion of open land into non-permeable surfaces. More than 75% of southern Californian bays and estuaries have already been dredged and filled for conversion into harbors and marinas (Horn and Allen 1985). This hardening of the coast increases the rate of runoff and can impact water quality through addition of sediment, toxic chemicals, pathogens and nutrients to the ocean. Besides the impacts of land conversion, the SCB is already home to fifteen municipal wastewater treatment facilities, eight power generating stations, 10 industrial treatment facilities, and 18 oil platforms that discharge to the open coast. Each year, local, state, and federal agencies spend in excess of $31M to monitor the environmental quality of natural resources in the SCB (Schiff et al 2001). At least 75% of this monitoring is associated with National Pollutant Discharge Elimination System (NPDES) permits and is intended to assess compliance of waste discharge with the California Ocean Plan and the federal Clean Water Act, which set water quality standards for effluent and receiving waters. Some of this information has played a significant role in management decisions in the SCB. While these monitoring programs have provided important information, they were designed to evaluate impacts near individual discharges. Today, resource managers are being encouraged to develop management strategies for the entire SCB. To accomplish this task, they need regionally-based information to assess cumulative impacts of contaminant inputs and to evaluate relative risk among different types of stresses. It is difficult to use existing data to evaluate regional issues because the monitoring was designed to be site-specific and is limited to specific geographic areas. The monitoring provides substantial data for some areas, but there is little or no data for the areas in between. Beyond the spatial limitations, data from these programs are not easily merged to examine relative risk. The parameters measured often differ among programs. Even when the same parameters are measured, the methodologies used to collect the data often differ and interlaboratory quality assurance (QA) exercises to assess data comparability are rare. Previous Regional Monitoring Studies To begin addressing these concerns, there have been two previous regional monitoring efforts. The first regional monitoring survey in 1994, called the Southern California Bight Pilot Project (SCBPP), was a compilation of 12 agencies that cooperatively sampled 261 sites along the continental shelf between Point Conception and the United States/Mexico border. The second regional monitoring survey, called the Southern California Bight 1998 Regional Monitoring Project (Bight1 998), was comprised of 64 agencies that cooperatively sampled 416 sites between Point Conception and Punta Banda, Mexico. In both surveys, assessments were made of water quality, sediment contamination, the status of biological resources and species diversity, and the presence of marine debris in depths of 10 to 200m, with some special emphasis in areas of anthropogenic inputs such as large publicly owned treatment works (POTWs) or large river and creek mouths. However, Bight 1998 extended what was done in 1994 by adding additional habitats such as offshore islands and inshore areas like bays/harbors, as well as additional areas of anthropogenic inputs such as marinas, ports, and small POTWs. Moreover, a regional evaluation of shoreline water quality was added in 1998 that provided our first evaluation of the swimmability of southern California beaches during dry and wet weather. Benefits derived from both the SCBPP and Bight 1998 also included the development of new useful technical tools that could only be developed with regional data sets and participation by multiple organizations. For example, the project produced iron-normalization curves for the SCB, allowing distinction between natural and anthropogenic contributions of metals in sediments (Schiff and Weisberg 1998). A Benthic Response Index was developed that integrates complex benthic infaunal data into an easily interpreted form that describes the degree of perturbation at a site (Bergen et al. 1998). Newer, cheaper microbiological methods were tested and evaluated alongside traditional microbial measurement methods and now have been accepted by both the state health agencies for routine shoreline monitoring (ref). Bight 1998 also improved the comparability among the major laboratories in the SCB as a result of the quality assurance and quality control (QA/QC) laboratory intercalibration exercises for chemistry and microbiology. The project also produced a series of manuals containing standardized field, laboratory and data management activities that increased continuity of data and data reporting among participants, even after the regional monitoring surveys were completed. 2003 Survey The proposed Southern California Bight 2003 Regional Monitoring Project (Bight 2003) is a continuation of the successful cooperative regional-scale monitoring begun in southern California during the 1990's. Bight 2003 builds upon the previous successes and expands on the 1998 survey by including new participants, sampling more habitats, and measuring more parameters or using new methods. [Number] organizations, including international and volunteer organizations, have agreed to participate (Table I-1). The inclusion of multiple participants, many of them new to regional monitoring, provides several benefits. Cooperative interactions among many organizations with different perspectives and interests, including a combination of regulators and dischargers, ensures that an appropriate set of regional-scale questions will be addressed by the study. The additional resources brought by numerous participants also expands the number of habitats and indicators that will be sampled. Sampling for Bight 2003 will include all of the areas sampled in 1998, plus a new focus on nearshore habitats (coastal lagoons) and offshore habitats (inner continental slopes and basins). Several new technologies will be brought to bear in Bight 2003 including remote sensing from satellite, aerial, and land-based platforms, new microbial genetic and phenotypic source tracking techniques, and radiodating of sediments to determine age and accumulation of chemicals in sediments.

创建时间:
2022-04-19
二维码
社区交流群
二维码
科研交流群
商业服务