Abstract:
Microplastic (MPs) is a ubiquitous pollutant in both the waters and sediment of marine
environments. Its small size (< 5mm) has made it readily available for the marine
organisms to ingest during foraging and burrowing. Investigating the potential of MPs
intake by burrowing sandy shore (SS) bivalves could be considered as a crucial
experimental spectacle in screening of MPs in beach sediment. Further, it would assist
in comprehend the trophic transfer of MPs from beach sediments to molluscs and the
possibility of transferring MPs through the coastal food chains. A 100 m stretch of SS
was sampled for Donax cuneatus (n=9) which were trapped in washed away slender
wart weed, Gracillaria lemaneiformis on the SS by random quadrate sampling at
Nilaveli beach, Sri Lanka, followed by stored frozen for MPs detection. Bivalves were
defrosted; wet weight of the tissue samples was measured and alkaline tissue digestion
was performed (10% KOH) to extract MPs. The filtered tissue samples were oven dried
at 40˚ C overnight and exposed to microscopic observation under a stereoscopic
microscope. Tissue samples of the D. cuneatus had MPs and the majority were threads
(2.928±1.176 items/g, mean tissue wet weight = 3.077±1.176 g). The SS burrowing
bivalves were contaminated with MPs trapped among the sand particles which
eventually would act as a bridging biotic vector for MPs from beach sand to the higher
trophic levels in the coastal food chains. Thus, it is recommended to take measures to
avoid polluting the SS shore with single used MPs and to employ adequate beach
cleaning to remove macro plastics which eventually weathered to MPs with the time in
order to conserve the unseen lives in sandy shores.
