Abundance and distribution of marine litter on the beaches of Okinawa Island, Japan.

Abstract

This study evaluated the distribution and abundance of marine litter on 30 beaches around Okinawa Island, Japan. Beach quality indices and multivariate statistical analyses were used to assess the quality of the beaches and their pollution patterns. A total of 11,626 items weighing 513.49kg with an average density of 0.13±0.10 items/m2 were collected. Litter was dominated by plastics (81.72%), broken glass (8.38%), and cigarette butts (7.44%), and 74.05% of total litter was from land-based sources. Single-use plastics (SUPs) were present in all surveyed beaches and made up 30.54% of the total litter. The clean coast index (CCI), plastic abundance index (PAI), and hazardous index (HI) were between 0.1 and 7.6, 0.1-4.0 and 0.01-1.42, respectively, indicating low to moderate levels of pollution of Okinawan beaches. This study should aid in the formation of strategies to deal with marine litter in Okinawa, other areas of Japan and the Asia-Pacific region.