Research Areas > Marine Debris > Beach Debris in 1998

Project: Beach Debris in 1998

Background and Objective

Beyond being an aesthetic issue, debris on beaches can threaten marine mammals, birds, and turtles through ingestion and entanglement. Many studies have enumerated the types and amount of marine debris on beaches, and a few studies have quantified subsurface nearshore debris. Most of the data on beach debris outside the United States has been collected through systematic, scientifically rigorous studies, while most of the information within the United States has been derived from volunteer beach cleaning efforts.

The goal of this project was to quantitatively assess the types and amount of debris on the California coast, with a secondary objective of describing how debris differs among shoreline types.

Status

This project was completed in 1998.

Methods

Beach debris was surveyed and collected at 43 sites from Seal Beach to San Clemente on the Orange County, California, coast between August 2 and September 18, 1998. Sites were selected using a stratified random sampling design that was stratified by shoreline type (rocky shoreline and sandy beach). Sample sites were selected randomly within the strata and a systematic component was overlaid to minimize clustering. This structure ensured systematic separation of the sample sites, as well as an unbiased estimate of beach debris.

Each sample site was delineated as an area 25 yards in length that extended from the water’s edge to the first pavement or rocky cliff. All trash at the site was collected by at least three people walking systematically along transects to ensure that all areas within the sample site were examined. All debris was bagged and transported to the laboratory for identification and quantification. In addition, a five-gallon bucket was used to sieve one bucket of sand at each site to quantify the small items that were undetectable by visual examination. In the laboratory, debris was sorted into the broad categories used by the Center for Marine Conservation during their Coastal Cleanup days (i.e., glass, metal, plastics, foamed plastics, rubber, paper, wood, and cloth). From each broad category, debris was further sorted into more specific subcategories (e.g., cups, plates, etc.), enumerated, and weighed. Within the specific categories, brand names were recorded, when possible, to establish brand trends.

Findings

Based upon the survey data results, it was estimated that more than 106 million items, weighing approximately 13 tons, occur on Orange County shorelines. The most abundantly found item on southern California beaches was pre-production plastic pellets, which are likely lost during transport from the raw materials producers to the processors who mold the pellets into plastic products. The pellets, collected primarily through sieving the surface layers of sand, come in a variety of shapes (ovoid, cylindrical, etc.) and are typically less than 5 mm in diameter.

The relative distribution of brand-name products in the debris we collected largely reflected the product’s relative market share. One exception to the high correlation between brand-related debris quantity and market share was in the fast-food container category. Industry leader McDonalds constituted less than 10% of the total debris measured, while Jack in the Box accounted for nearly three times that level. Perhaps the geographic distribution of fast-food restaurants in relation to Orange County beaches was responsible for the discrepancy.

Four major sources were identified as pathways in the transport of debris to the Orange County shoreline: (1) littering by beachgoers, (2) wind currents from upland sources, (3) runoff from land-based activities, and (4) overboard disposal from boating activities (including accidental spills). Each of these sources requires a different management action to effect a reduction in beach debris. Although our study was not designed to differentiate sources of debris, our data suggest that water-based sources (runoff and overboard disposal) were more important than direct littering or wind. One line of evidence for this is that plastic pellets were found in abundance on all shoreline areas and are unlikely to originate from littering or wind. A second line of evidence is the greater density of most debris items found on less-frequented rocky shoreline as compared to sandy beaches. While this pattern was true for most debris, an exception was the greater amount of paper products, such as food wrappers, found on sandy beaches, suggesting that they were left by beachgoers.

Partners

This project was conducted in collaboration with researchers from the Southern California Marine Institute (SCMI) and Divers Involved Voluntarily in Environmental Rehabilitation and Safety (DIVERS).