The Occurrence and Characteristics of Microplastics in Seawater Surface and Sea Cucumber (Holothuria atra and Holothuria edulis) at Similan and Surin Islands (Andaman Sea), Thailand

Microplastics are considered to be one of the major threats that have significant effects on marine ecosystems and marine organisms. These tiny plastic particles can also absorb and carry toxic substances to marine life, potentially affecting human health through food chains. This study investigates microplastics in surface seawater and in two species of sea cucumber, Holothuria atra at Similan Island and Holothuria edulis at Surin Island. Color, shape, and components of microplastics were identified to evaluate sources of the microplastics found in the area. The results found that the average abundance of microplastics in seawater at Similan and Surin Islands is 1.93 ± 1.42 and 1.11 ± 0.75 pieces/m3, respectively. Black fiber is a dominant microplastic found in seawater and both species of sea cucumber. Fourier-Transform Infrared spectroscopy (FTIR) indicated that polyethylene terephthalate (PET) and polyester are the major components of microplastics in surface seawater, while cotton blends and other mixed components are the major components in sea cucumbers. These findings imply that microplastics found in surface seawater could potentially degrade from fishing and aquaculture equipment, maritime transport, and materials from plastic containers. Microplastics in sea cucumbers, on the other hand, are probably originating from domestic sewage discharge, especially textile washing and fishing equipment.