Microplastic Pollution in Hong Kong and Its Effects on Energetics of Sandy Shore Bivalves

Description

Plastics are polymers that have been extensively used and revolutionized our lives in the last fewdecades. The largest contributors of plastics debris encountered in the marine environmentinclude beach litter and the fishing industry. Various kinds of marine life are threatened byplastic debris through entanglement, ingestion, suffocation and general debilitation. Thecontamination of the oceans by microplastics just started to receive attention at the turn of thecentury and now they are even found in remote islands and deep sea sediments. Most of themonitoring work on microplastics was conducted in Europe and America. Similar studies,however, are very limited in Asia and information in the Greater China is virtually unknown,including Hong Kong, not to mention that the Pearl River Delta where Hong Kong is situated isone of the largest industrial hubs in mainland China. Microplastics contamination in Hong Kongdid not receive any public concern until in late July 2012, over 150 tons of plastic pellets wereknocked from a ship into the ocean during a typhoon and more than 35 beaches werecontaminated. We conducted a preliminary survey of mesoplastics (500 μm - 2 mm) on twobeaches on Lantau Island, Hong Kong in 2013. The abundance of mesoplastics varied between116 and 2081 items m-2 with the most common forms being fibrous (66%) and fragments (14%).Ingestion of microplastics has been reported in various invertebrates. Predators can also ingestmicroplastics through consumption of prey. Various biological effects of plastic ingestion havebeen reported on vertebrates that include inhibition of feeding and digestion, hormone secretionand reproduction. Ingestion of microplastics in invertebrates such as mussels induced stronginflammatory responses. Deposit-feeding lugworms exposed to microplastics reduced energyreserves by up to 50%. Although microplastics are inert and considered as non-toxic, the largesurface area to volume ratio of microplastics enhances the adsorption of pollutants from thewater. Additives in the plastics are also toxic to marine organisms. Polybrominated diphenylethers (PBDEs) are widely used as flame retardants in plastics. They are considered to be toxicand associated with endocrine disruption, cancer and reproductive toxicity. Accumulation ofPBDEs through ingestion of microplastics was reported upon in lugworms on mudflats, fish andseabird. When microplastics are ingested by marine organisms, the pollutants may leach out andare absorbed and bioaccumulated.The proposed study will include the first territory-wide survey of microplastics on soft shoreswith different degrees of wave exposure and at different distances from the mouth of the PearlRiver. On each shore, microplastics in sediments at two shore heights and two sediment depthsand in associated invertebrates will be quantified. Concentration of PBDEs in micropalstics willbe determined using gas chromatography/mass spectrometry. Characterization of microplasticswill be conducted using Infrared and Raman spectroscopies and quantification using pyrolysisgas chromatography-mass spectroscopy (pyrolysis GC-MS) and IR spectroscopy. Energybalance will be studied in sandy shore clams in a laboratory experiment to understand how theconcentration and shape of microplastics affect the energetics in dominant filter feeders on sandyshores.The knowledge we gain from this research will provide a basis for developing guidelines forbetter management of the microplastic debris disposal and assessing the long term ecologicalimpacts of microplastics debris.