Microplastics in the Benthic Invertebrates from the Coastal Waters of Kochi, Southeastern Arabian Sea

Environ Geochem Health https://doi.org/10.1007/s10653-017-0062-z SHORT COMMUNICATION Microplastics in the benthic invertebrates from the coastal waters of Kochi, Southeastern Arabian Sea S. A. Naidu . V. Ranga Rao . K. Ramu Received: 26 September 2017 / Accepted: 22 December 2017 Ó Springer Science+Business Media B.V., part of Springer Nature 2018 Abstract This study examined microplastic parti- Introduction cles present in the benthic invertebrates Sternaspis scutata, Magelona cinta (deposit feeders) and Tellina The pollution of the marine environment by plastic sp. (suspension feeder) from the surface sediments of litter from the shallow coastal areas to the open oceans off-Kochi, southwest coast of India. The microplastic is a global problem and has been well documented particles and thread-like fibres detected in these (Thompson et al. 2004; Law and Thompson 2014; Ivar organisms were identified to be polystyrene by using do Sul and Costa 2014). Because of the growing DXR Raman microscope. Examination of the demand, usage pattern and production trends of microplastic particle in Sternaspis scutata by epiflu- plastics, the improper disposal of the plastic waste orescent microscopy showed fragmentation marks on will lead to an increase in plastics debris in the oceans the surface suggesting that the microplastic particle (Thompson et al. 2009; Eriksen et al. 2014). The input was degraded/weathered in nature. The study provides of microplastics to the oceans from the land can be preliminary evidence of the presence of microplastics attributed to the direct introduction with runoff from in benthic fauna from the coastal waters of India. densely populated or industrialized areas and the However, further studies are required to understand subsequent breakdown of plastic litter by physical the sources, distribution, fate and toxicity of the (wind, waves and currents), chemical (UV radiation) different types of microplastics in benthic inverte- and biological (microbial) degradation (Wright et al. brates in order to identify any potential threats to 2013; Ivar do Sul and Costa 2014). Ships and vessels, higher trophic level organisms. offshore oil and gas platforms and aquaculture instal- lations are some of the sea-based sources of plastic Keywords Microplastics Á Coastal water Á Arabian litter (UNEP 2005). In recent years, several studies Sea Á Polychaetes Á Polystyrene have revealed that microplastics are widespread and ubiquitous within the marine environment (Cole et al. 2011; Van Cauwenberghe et al. 2013; Ivar do Sul and Costa 2014). The most widely used synthetic plastics are low- and high-density polyethylene (PE), polypropylene S. A. Naidu Á V. Ranga Rao Á K. Ramu (&) (PP), polyvinyl chloride (PVC), polystyrene (PS) and Integrated Coastal and Marine Area Management-Project polyethylene terephthalate (PET) (Andrady and Neal Directorate, Ministry of Earth Sciences, NIOT Campus, Chennai, India 2009; Hidalgo-Ruz et al. 2012). Typically, the high- e-mail: [email protected] density polymer particles sink and accumulate in the 123 Environ Geochem Health sediment, while the low-density polymer particles container cargo vessels (Ramzi et al. 2017). Due to float at the sea surface. Since microplastics occur in the dense population, large riverine discharge, indus- sedimentary habitats and because of their small size, trial and maritime activities, the coastal waters of both benthic suspension and deposit feeders may Kochi are vulnerable to pollution by plastics. accidentally or selectively ingest sinking and sedimentary microplastics (Bolton and Havenhand 1998; Sampling methodology Thompson et al. 2004; Cole et al. 2011; Wright et al. 2013; Van Cauwenberghe et al. 2015). Studies suggest As part of the Ecosystem Modelling Project for the that the hydrophobic pollutants available in the southwest coastal waters of India, five transects with seawater adsorb onto plastic debris under ambient 25 locations orthogonal to the Kochi coast, southeast- environmental conditions (Thompson et al. 2009; Cole ern Arabian Sea are being monitored seasonally for the et al. 2011). Thus, the ingestion of microplastics by the benthic macrofauna to understand the linkages lower trophic level organisms has a potential for between benthic and pelagic environments. In Novem- bioaccumulation of pollutants (Teuten et al. 2009). A ber 2016, benthic macrofauna from two locations was number of studies have shown that microplastics can collected for the examination of microplastics as the be ingested by marine biota under laboratory condi- ingestion of microplastics is of concern and has been tions (von Moos et al. 2012; Van Cauwenberghe et al. recently observed in a wide range of taxa (Fig. 1). The 2015; Ribeiro et al. 2017); however, under in situ sediment samples were collected with a Van veen grab conditions the organisms are exposed to microplastics sampler having a mouth area of 0.1 m2. The sediment throughout their lifetime as compared to the short samples were washed through a 0.5-mm mesh sieve, experimental periods. The continuous ingestion and and the collected organisms were fixed and preserved accumulation of microplastics by the organisms may in neutral formalin–Rose Bengal mixture. The sedi- have potential toxicological effects. ment samples were also collected for particle size India is one of the major plastic consumers in the analysis. world, with an annual consumption of * 5.6 million tonnes (Toxics link 2014). The coastal waters and Sample processing and identification estuarine systems have been recognized as hotspots for of microplastics microplastic pollution (Browne et al. 2010; Wright et al. 2013). However, to our knowledge no studies The sieved benthic macrofauna was examined under a have reported the presence of microplastics in biota binocular microscope (Lawrence & Mayo), and the from the Indian coastal waters. In the present study, an targeted benthic invertebrates, polychaetes [Ster- effort was made to assess the occurrence and type of naspis scutata (5 mm; deposit feeder), Magelona microplastics in benthic invertebrates from the coastal cinta (25 mm; deposit feeder)] and bivalve Tellina waters of Kochi, southwest coast of India, which is sp. (8 mm; suspension feeder), were separated and vulnerable to plastic pollution. used for this study (Fig. 2). For each species, three numbers of organisms were picked and washed by Study area gently shaking in particle free seawater obtained by filtering with 0.22 lm polycarbonate filters (Milli- Kochi with a population of 2.5 million people is the pore) in order to remove sediment particles adsorbed second most urbanized city on the west coast of India, onto the surface of the organism. The washed poly- (UN 2016). The Kochi estuarine system connected to chaetes Sternaspis scutata and Magelona cinta were the southeastern Arabian Sea by two permanent put in a drop of water on an object slide and squeezed openings has a number of chemical industries at the firmly with a cover slip. The bivalve Tellina sp. was upstream region (Balachandran et al. 2006). Further, opened with a sharp knife, and the soft tissue was the prolonged monsoon with an annual rainfall of placed on an object slide. Measures were taken to about 3200 mm results in the wash out of wastes into avoid any contamination while handling and process- the network of rivers, streams and finally into the ing of the samples. All the dissecting tools were rinsed coastal waters of Kochi. In addition, Kochi has an all with Milli-Q water before use. weather natural port that handles a number of 123 Environ Geochem Health Fig. 1 Sampling locations of the benthic invertebrates in the coastal waters of Kochi, Arabian Sea The analytical methods for identification of and an integration time of 10 s. The resulting spectra microplastics in various matrices are still under were compared with the Aldrich Raman condensed development. In a review on the analytical methods phase library for polymers. The OMNIC Software was for microplastics, Shim et al. (2017) suggested the use used to operate the instrument and for data analysis. of Raman spectroscopy for particles less than 20 lm in size. In this study, the prepared specimens were examined using a stereo zoom microscope at 109 and Results and discussion 409 magnification and by the Nikon Upright Fluo- rescent Microscope (Eclipse 80i). The type of polymer The epifluorescence microscopy and DXR Raman the microplastic particles were made of was identified microscope are well-established techniques for the by the DXR Raman microscope (Thermo Scientific, examination and identification of microplastic parti- USA). The operating conditions of the DXR Raman cles in biological organisms and sediments (Cole et al. microscope were as follows: excitation wave length 2013; Imhof et al. 2013; Thompson et al. 2004; Sruthy 532 nm, laser beam power \ 5 mW, grating 900 and Ramasamy 2017). The epifluorescence micro- groves/mm, a 509 long working distance objective scopic examination of the gut content of the sediment 123 Environ Geochem Health Fig. 2 Microscope images of the benthic invertebrates (a Ster- Magelona cinta; h Tellina sp.) and the epifluorescence images of naspis scutata; d Magelona cinta; g Tellina sp.) and correspond- the microplastic particles found in the gut (c Sternaspis scutata; f ing images representing the gut contents (b Sternaspis scutata; e Magelona cinta; i Tellina sp.) deposit feeding polychaetes Sternaspis scutata in laboratory experiments (Thompson et al. 2004; (Fig. 2a) and Magelona cinta (Fig. 2d) and suspension Browne et al. 2008; von Moos et al. 2012) and in the feeding bivalve Tellina sp (Fig. 2g) showed the natural populations (Murray and Cowie 2011; Van presence of fluorescent particles and fibres (Fig. 2c, Cauwenberghe et al. 2015). f, i). This could be due to the ingestion of particles DXR Raman microscope was used to identify the present in the water column by the suspension feeding polymer composition of the blue fluorescent particle bivalve Tellina sp. and from the sediments by the found in Sternaspis scutata (Fig. 2c) and green deposit feeding polychaetes Magelona cinta and fluorescent fibres found in Magelona cinta and Tellina Sternaspis scutata.

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