Marine debris on beaches of the Greater Sydney Region

Marine debris directly threatens and indirectly impacts upon marine wildlife and humans throughout the world. Proper management requires information on debris abundance, distribution and sources for specific regions. This data was previously unavailable for the Greater Sydney Region, Australia. Thus, a marine debris survey was conducted on six selected beaches from the Greater Sydney Region. Two beaches from each of three areas with differing degrees of urbanisation were sampled once a month for five months. Sampling was conducted from within a series of transects, zones and strata to obtain information on the abundance, distribution, composition and sources of debris. On average sampled beaches had 33.3 items per 250m² transect equating to 2,664 items per kilometre of beach with a 20m wide cross-shore sub-aerial zone. The vast majority (89.8%) of debris found was plastic, particularly hard plastic (52.3%) predominantly originating from stormwater or beachgoers. The beaches with the highest debris density were those within the least urbanised area, possibly due to the relatively small distance (<50km) between sample areas and the ability of debris to disperse quickly from its source and travel long distances. Significant differences in debris abundance were found between sample areas, beaches, beach strata and over time. The abundance of marine debris within the Greater Sydney Region was comparable to some of the most polluted beaches around the world, and is thus a problem that requires immediate attention.