1977 Reference Survey Trawl Invertebrates Biomass

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator:

Southern California Coastal Water Research Project (SCCWRP)

Publication_Date: 20000801

Publication_Time: 20000402

Title: 1977 Reference Survey Trawl Invertebrates Biomass

Edition: 1.0

Publication_Information:

Publication_Place: Costa Mesa, California

Publisher:

Southern California Coastal Water Research Project (SCCWRP)

Online_Linkage:

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Description:

Abstract:

All wastewater monitoring programs assess the environmental situation in the discharge area by comparing it to the situation where there is no discharge. Thus the selection of the reference or control stations is of critical importance in evaluating effects: Control stations must be as similar as possible to the area being studied except that they are not exposed to outfall materials. The Project has encountered the problem of selecting proper control sites in designing its surveys of southern California discharge areas. We considered using sites off the Channel Islands but rejected them because they are not oceanographically or biologically comparable to mainland sites. We also looked at data from the control sites used in the past by various dischargers and found that some of these were in areas influenced' by the outfalls being investigated and consequently gave invalid reference information. In some monitoring surveys, a single reference station and a single set of measurements have been used as the basis for determining the natural or background conditions for an outfall site. Yet careful analysis of many samples reveals that chemical and biological conditions vary with water depth and type of bottom material and can differ by as much as a factor of 10, even in areas not influenced by man. Plainly, no single control station or set of measurements is valid for reference purposes. Numerous benthic monitoring surveys, designed to assess the effects of existing or future discharges, have been taken on the southern California mainland shelf since 1956. While such surveys have provided much new information on the abundance and diversity of thousands of species of bottom organisms and fishes, and on the levels of pollutants in sediments around outfalls, few have provided a data base that would permit the identification of control sites, or areas where background conditions exist. An outstanding exception is the mainland shelf survey produced by the California State Water Resources Control Board and conducted some 20 years ago by the Allan Hancock Foundation, University of Southern California (California State Water Resources Control Board 1967; Jones 1969). That survey provided useful information on conditions at that time; however, we do not know if the results are representative today. Moreover, the previous survey did not provide data on sediment pollutant concentrations or trawl-caught fish and invertebrate populations--two types of information that are needed at present, particularly for rural areas of this coast. Accordingly, in 1977, the Coastal Water Research Project sponsored a new survey of the mainland shelf from Point Conception to the United States/Mexico border. The goal of the survey was to identify possible control areas for contrasting with existing municipal wastewater discharge sites and to define the apparent normal variations in the chemistry and biology of the fine sediment areas covering much of the mainland shelf.

Purpose:

We now believe we have identified 29 locations, the combined information from which can be used as control data for one depth--60 meters. We chose to limit this survey to the single depth because this is the depth of discharge of the largest municipal wastewater treatment plants along the coast -and because discharged materials tend to drift along depth contours. Details on the methods and results of the survey are given in the following sections.

Supplemental_Information:

Grabs, Trawls, and Water Quality casts were conducted at each of the stations to yield Benthic infauna, Sediment Chemistry, Trawl Fish, Macro Invertebrate, water column characterization at one meter increments from surface to bottom, and sediment grain size data. These data types can be aggregated using the StationID variable in each table. Between 28 April and 9 August 1977, 70 benthic grab samples and 53 trawl samples were taken at 71 stations between Point Conception and the U.S./Mexico border. The stations were located at intervals of approximately 10 km along the 360 km of coastline at depths of approximately 60 meters. In certain areas near the major municipal wastewater outfalls, stations were more closely spaced to delineate the expected outfall effects. Station locations are given in tblStations. Position on station was determined through the combined use of dead reckoning, sightings off headlands, radar fixes, and depth measurements from a recording fathometer. We have estimated that the inaccuracy of positioning do not exceed 100 meters. The vessels used during the survey are as follows: 1. M/V Marine Surveyor, Los Angeles City, John Keller, Skipper. 2. M/V Fury II, Orange County Department of Education, John Haas, Skipper~ 3. M/V Monitor II, San Diego City, Susan Hamilton, director of collecting efforts. 4. M/V Enchanter IV, Fred Munson, Owner/Operator. 5. R/V Sea-S-Dee, Los Angeles County Sanitation Districts, Rusty Shields, Skipper. 6. R/V Van Tuna, Occidental College, Elden McAllicher, Operator.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19770801

Ending_Date: 19770831

Currentness_Reference: ground condition

Status:

Progress: COMPLETE

Maintenance_and_Update_Frequency: None Planned

Spatial_Domain:

Description_of_Geographic_Extent: Southern California Bight

Bounding_Coordinates:

West_Bounding_Coordinate: -120.4458

East_Bounding_Coordinate: -117.265

North_Bounding_Coordinate: 34.44111

South_Bounding_Coordinate: 32.55833

Keywords:

Theme:

Theme_Keyword_Thesaurus: None

Theme_Keyword: Invertebrates

Access_Constraints: None

Use_Constraints: None

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Information Systems Manager

Contact_Address:

Address_Type: physical address

Address: 3535 Harbor Blvd., Suite 110

City: Costa Mesa

State_or_Province: California

Postal_Code: 92626

Country: USA

Contact_Voice_Telephone: 714.755.3200

Contact_Facsimile_Telephone: 714.438.1016

Contact_Electronic_Mail_Address: im_contact@sccwrp.org

Hours_of_Service: 8:00 a.m. to 4:00 p.m. Monday Through Friday

Contact_Instructions: email preferred

Data_Set_Credit: SCCWRP

Native_Data_Set_Environment: Microsoft Access Version 2000