Microplastics found in marine animals in S'pore's coral reefs, mangroves, seagrass beds
Microplastics have been found in marine animals across Singapore's coastal areas in a new study, with researchers discovering these plastic bits not just in the animals' digestive tracts, but also in their respiratory organs and bodily fluid.
Microplastics enter the animals not just through the food they consume, but also when they breathe or move through water, said the researchers from the NUS Tropical Marine Science Institute (TMSI).
The study also showed that microplastics are widespread across Singapore's coastal habitats - including mangroves, coral reefs and seagrass beds - and they could potentially be transferred from one organism to the next.
Previous studies had focused mostly on the presence of microplastics - referring to tiny plastic particles smaller than 5mm - in Singapore's environment, said the study's co-principal investigator Neo Mei Lin, a senior research fellow at TMSI.
For example, a recent study had found that 97 per cent of macro- and microplastics on Singapore's shores came from marine-based sources.
The TMSI researchers wanted to find out more about the presence, distribution, abundance and composition of microplastics in local marine organisms. Their study is part of a larger project that examines the impacts and hazards of marine plastics in the coastal environments.
As an emerging field of study, not a lot is known about microplastics and their impacts yet, according to the US National Oceanic and Atmospheric Administration (NOAA).
However, laboratory studies have shown that microplastics and chemicals in plastics may impact animals by delaying their developmental stages, cause problems with reproduction, and may even make it difficult for them to fight off disease, NOAA noted on its website.
In fiddler crabs, microplastics likely accumulate through respiration and direct contact with contaminated seawater. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS
Four marine species were selected for the TMSI study: the orange fiddler crab (Gelasimus vocans), porcelain fiddler crab (Austruca annulipes), garlic bread sea cucumber (Holothuria scabra) and synaptid sea cucumber (Synaptula recta).
These species "typically consume and process large amounts of sediments", making them good indicators for researchers to gauge the extent of microplastic pollution in marine sediments, said Dr Neo.
"Their abundant presence indirectly suggests their importance in the ecosystem, and being common across multiple study sites allows us to compare and infer the impact of microplastics," she said.
Only the guts of the synaptid sea cucumbers were assessed as they lack respiratory trees. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS
They are also commonly found in the South-east Asian region, according to study co-author Dr Jenny Fong, who was involved in the study when she was a research fellow at TMSI.
A total of 153 live samples across the four species were collected between November 2021 and May 2022 from mangroves, seagrass beds and coral reefs at seven sites across Singapore.
The sites are Pasir Ris Park, St John's Island, Kusu Island, Small Sister's Island, Pulau Semakau, Changi Beach and Pulau Hantu Besar.
The researchers said they prioritised safety, accessibility and abundance of the target species in choosing these sites, citing the presence of saltwater crocodiles and snakes in other locations as a deterrent.
The animals were dissected and microplastic samples from their organs were collected.
The gills, hepatopancreas - a digestive gland which performs functions similar to those of the liver and pancreas in humans - and guts of the fiddler crabs were examined.
In the case of the garlic bread sea cucumber, researchers studied its respiratory trees - a branching network of tubes for breathing - guts and coelomic fluid, which is a bodily fluid crucial in transporting nutrients and gases.
Only the guts of the synaptid sea cucumbers were assessed since they lack respiratory trees.
A total of 1,266 microplastic samples were found in these organs. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS
A total of 1,266 microplastic samples were found in these organs, which the team carefully analysed and categorised into four shape types - fibres, fragments, films and spheres, listed in order of prevalence. Most particles were less than 1mm in size.
Polymers commonly used in everyday life, such as in plastic bottles, packaging, synthetic textiles and automotive parts, were identified.
"The shapes of microplastics provide hints on the potential sources of plastics... and it tells us what kind of microplastics affect (the animals) the most," said Dr Neo, who added that fibres were the most common shape found.
Knowing the most common plastic type helps researchers identify which ones marine animals are likely to ingest, said fellow researcher Ashwini Suresh Kumar, a TMSI research fellow.
"This information could be valuable for policymakers, particularly when considering regulations around additives commonly used during the manufacturing of these polymers, with the aim of reducing bio-accumulation and environmental impact," she said.
Researchers suggest that in fiddler crabs and garlic bread sea cucumbers, microplastics likely accumulated through respiration and direct contact with contaminated seawater.
The smallest particle, approximately 60 micrometres in size, was found in the respiratory trees of a garlic bread sea cucumber, said Dr Neo.
The hepatopancreas of both fiddler crab species generally had the highest number of microplastics, likely from ingestion as the primary pathway of entry, according to the findings.
With an additional pincer-like claw compared with males, female fiddler crabs exhibit faster and more frequent feeding behaviours - patterns that researchers associate with higher microplastic contamination in their organs.
Synaptid sea cucumbers, which are often seen feeding on the excretion of marine sponges, may ingest microplastics accumulated on these surfaces after the sponges feed by filtering seawater. This suggests that microplastics may be transferred up the marine food chain.
Asked what the findings could mean for the safety of locally grown seafood, Dr Neo said more studies need to be done.
She noted that the guts of contaminated animals are "typically removed and cleaned before (the animal) goes for sale", adding that "the sweeping statements of humans eating microplastics need to be carefully discerned".
"While we do not have any plans to examine the long-term impacts through surveys and sampling, our current work has led us to new research questions such as developing new approaches to studying microplastic distribution in organisms," she said.
In June 2022, Singapore launched a national action strategy aimed at reducing land- and sea-based sources of plastic waste that end up as marine litter.
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Straits Times
01-06-2025
- Straits Times
Mirxes, Singapore's billion-dollar biotech firm led by life sciences scholar Zhou Lihan, lists in Hong Kong
Mirxes CEO Dr Zhou Lihan, his wife Yeap Su Phing, parents and two children at the Hong Kong Stock Exchange in Central after the Singapore biotech firm launched its IPO on May 23. PHOTO: MIRXES – Singapore has produced its first billion-dollar biotechnology start-up, 25 years after it began formally building its life sciences industry. Mirxes, which invented and produces the world's first blood test kit to detect early stage gastric cancer, is helmed by Dr Zhou Lihan, a naturalised Singaporean from the country's maiden batch of life sciences graduates. He arrived on the Lion City's shores as a wide-eyed 15-year-old PRC (People's Republic of China) scholar, navigating life and studies in a foreign country. Today, the 42-year-old is chief executive officer and co-founder of Mirxes (pronounced 'm'raek'sis'). It is the first South-east Asian biotech start-up to achieve a valuation of more than US$1 billion (S$1.29 billion), when on May 23 it launched its initial public offering (IPO) on the Hong Kong Stock Exchange (HKEX). The company's market capitalisation is HK$8.29 billion, or US$1.06 billion. It has been trading around HK$30 per share, up 28 per cent from its listing price of HK$23.30. It is also South-east Asia's first biotech firm to list on HKEX. The microRNA-based cancer-detection start-up, which was spun out of Singapore's public sector R&D agency A*Star in 2014, has yet to become a household name in the country. But it is already a big player in the regional biotech industry. Now, the company has reached a critical level in its development where it can build on its success only by leveraging on an expansive fund-raising platform with a mature base of investors familiar with the industry. That is why, instead of listing in Singapore, Mirxes opted to do so first in Hong Kong, Dr Zhou told The Straits Times. He does not, however, discount the possibility of Mirxes listing in Singapore eventually. Dr Zhou's life story in the Republic tracks closely with some of the country's strategic economic policies over the years. 'I left China in 1998 after learning, through the Suzhou-Singapore Industrial Park project, about the opportunity to take on a scholarship to come to Singapore,' the Suzhou-born Dr Zhou told ST in an unmistakably Singaporean accent. Dr Zhou (second from left) with his fellow PRC scholars studying in Singapore's Anglican High School in 1998. PHOTO: COURTESY OF ZHOU LIHAN The project was launched in 1994 for China to adapt the Republic's development experiences to its own context, and for Singapore to develop an external wing to its economy. The PRC scholarship system is a Singapore Government-sponsored scheme for top Chinese teenage students since the 1990s, aimed at having them eventually contribute to economic development and potentially set down roots in the country . Finding love at NUS After going through the local education system at Anglican High School and Temasek Junior College, Dr Zhou enrolled at the National University of Singapore (NUS) in 2003, among the first batch of life sciences students. The life sciences programme was introduced as part of a government initiative in 2000 to develop the Republic into a regional biomedical hub. 'Because I spent most of my formative years in Singapore, all my friends and family are in Singapore. I even met my wife in NUS on shuttle bus A2, heading from the arts faculty to (university hostel) Prince George's Park,' Dr Zhou recalled with a laugh. Dr Zhou (top row, second from left), with Associate Professor Too Heng-Phon (far right) and fellow researchers from Prof Too's lab during their university days in 2008. PHOTO: COURTESY OF ZHOU LIHAN His wife, a Malaysian-born Singaporean, was an NUS arts student whom he got to know better in the students' union , he explained. They have a son and a daughter, aged eight and three, respectively. The family, including Dr Zhou's parents who have also moved from Suzhou to Singapore , were at HKEX in the central business district to witness Mirxes' IPO launch on May 23. Mirxes' history dates back to Dr Zhou's days at NUS, where he obtained his PhD in biochemistry and molecular biology at the Yong Loo Lin School of Medicine in 2012. During his PhD studies, he, fellow scientist Zou Ruiyang and their mentor, Associate Professor Too Heng-Phon, developed the technology to detect microRNA (micro ribonucleic acid), the smallest genetic material ever found in living things. Dr Zhou with his mentor, Prof Too, on his graduation day in 2007. PHOTO: COURTESY OF ZHOU LIHAN Their research, which the trio took with them to A*Star when they joined the agency in 2010, proved so ground-breaking that they set up an enterprise three years later with the agency's support and a government grant to commercialise their technology. Thus, Mirxes was born: a three-person start-up with Dr Zhou as CEO, Dr Zou as chief technology officer, and Prof Too as chief scientific adviser, aimed at developing an accurate, affordable and easily accessible early detection system for various cancers and other diseases. In the decade since, Mirxes has grown into a 350-strong company with a presence in China, Japan, Malaysia, the Philippines and the United States, and partnerships with global biotech giants including Johnson & Johnson and Pfizer. Dr Zhou (left) and Mirxes' co-founder, Dr Zou Ruiyang, at the biotech startup in the initial years after it spun off from A*Star. PHOTO: MIRXES The firm's flagship invention, GastroClear, in 2019 became the world's first molecular blood test approved for early detection of gastric cancer in high-risk populations. It was developed in close collaboration with the Singapore Gastric Cancer Consortium. The test – available in Singapore for less than $150 at public hospitals or around $250 in private clinics – is less expensive and invasive than an endoscopy, the traditional diagnostic procedure for stomach cancer, which can cost between $400 and $3,000. GastroClear has an 87 per cent accuracy, better than any other blood-based tests for the detection of gastric cancer. Patients who test positive are recommended to undergo an endoscopy for more specific results. The test is less expensive and invasive than an endoscopy, the traditional diagnostic procedure for stomach cancer, which can cost between $400 and $3,000. PHOTO: NATIONAL UNIVERSITY HEALTH SYSTEM Listing in Hong Kong Months of careful consideration preceded Mirxes' decision to list in Hong Kong over Singapore. Ultimately, it came down to two key factors. 'Firstly, our flagship product GastroClear is focused on stomach cancer, a very Asian disease,' Dr Zhou said. 'China alone accounts for half of all stomach cancer cases worldwide.' The Hong Kong platform provides a gateway into mainland China, the biggest market not just for stomach cancer tests, but also for the scale and speed of cancer clinical trials to accelerate the firm's research and development efforts. 'So listing in (the Chinese territory of) Hong Kong makes sense, because the investors here will understand our product's value to them.' Secondly, he added, HKEX's dedicated biotech listing regime has built up an investor base that 'understands how to look at biotech firms' financials without getting scared off'. Mirxes is still in the red, reporting net losses exceeding US$92 million for 2024 – 30 per cent more than the previous year. It is already generating revenue, although the US$20 million it reported for 2024 is a 16 per cent drop from that in 2023. 'People get worried that Mirxes is losing money,' Dr Zhou said. 'But if we want to be competitive globally, we have to invest in R&D and innovation. But that's something that our South-east Asian investor base is not yet familiar with.' HKEX's investors, on the other hand, are no strangers to promising yet still-loss-making start-ups. Hong Kong in 2018 started allowing yet-to-be-profitable biotech firms to list on its main board under the exchange's Chapter 18A regulations, to attract companies in cutting-edge industries. Since then, more than 70 such firms – which would otherwise not have qualified to list – have launched their IPOs in the city, gaining access to much-needed funds to grow their fledgling technologies and innovations . Mirxes CEO Dr Zhou Lihan (right) with a Hong Kong Stock Exchange representative at the IPO ceremony in Hong Kong on May 23. PHOTO: MIRXES The 18A rules recognise these start-ups' potential for growth, granting them access to capital as long as they have one core product past the concept phase, HK$1.5 billion in expected market value, and two years of financial records, among other criteria. In Asia, biotech start-ups that have yet to bring in revenue can also choose to list on subsidiary boards that cater to such firms, like China's ChiNext, Singapore's Catalist and Korea's Kosdaq. But the drawbacks include lower trading volumes and hence lower funding , and less visibility . Rebuilding ties in China HKEX's listing reforms, like Chapter 18A, have over the years opened new pathways for a broader range of companies around the world to raise funds in the city. It is on track to be the world's top IPO destination by the end of 2025, according to Swiss investment bank UBS. Its IPO market has raised HK$76 billion so far in 2025, more than seven times that in the same period a year ago, Financial Secretary Paul Chan said on May 25. The city is further cementing its status as a leading fund-raising hub for the tech and biotech sectors. In early May, it set up a scheme to streamline the IPO process for such firms, offering them 'a more efficient pathway' to listing and allowing them to file confidentially to avoid drawing competitors' attention. But some companies seeking a Hong Kong listing may still face a lengthy approval process from the China Securities Regulatory Commission, under rules introduced in March 2023 that also pertain to firms with principal business operations in mainland China. Mirxes, which has laboratories in Hangzhou, filed to list in Hong Kong in July 2023. One of Mirxes' laboratories in Singapore. It has a presence in China, Japan, Malaysia, the Philippines and the United States. PHOTO: MIRXES Dr Zhou said that while his China background is 'definitely helpful' in bringing Mirxes to the world's second-biggest economy, 'honestly, I had to rebuild all my connections there as I had left China as a secondary school student'. These days, he is a 'weekend dad', travelling around mainland China, Hong Kong and South-east Asia for work and seeing his family in Singapore only on weekends. 'Most people – my parents included – will not be able to fully comprehend the technical details of what we do at Mirxes,' Dr Zhou said. The firm will allocate some of its IPO funds to promote awareness and the use of GastroClear in China and South-east Asia. The cash will also fund ongoing research into its colorectal and multi-cancer detection tests, among other plans. Reflecting on Mirxes' journey from fledgling start-up to IPO, Dr Zhou said the listing 'would not have been possible without the Singapore Government's strong support and consistent investment in life sciences over the years'. 'It proves a point that our Singapore technologies and companies are as good, if not better, than others,' he said. 'But we tend to be a little too humble, and not as patient .' The vibrant ecosystem of biotech firms in Boston or San Francisco, for example, was built up over 50 years, the CEO noted. 'In Singapore, we started only some 20 years ago … We are reaching a point where we should see more companies like Mirxes taking their next steps .' Dr Zhou hopes Mirxes' IPO will go a long way in enhancing the company's global credibility. 'If the public sees that this biotech firm has been vetted, has gone public, and everything about it is transparent and fully disclosed, that will add a layer of trust,' he said. 'And in the healthcare business, trust is very important.' Magdalene Fung is The Straits Times' Hong Kong correspondent. She is a Singaporean who has spent about a decade living and working in Hong Kong. Join ST's Telegram channel and get the latest breaking news delivered to you.
New Paper
22-05-2025
- New Paper
Microplastics found in marine animals in S'pore's coral reefs, mangroves, seagrass beds
Microplastics have been found in marine animals across Singapore's coastal areas in a new study, with researchers discovering these plastic bits not just in the animals' digestive tracts, but also in their respiratory organs and bodily fluid. Microplastics enter the animals not just through the food they consume, but also when they breathe or move through water, said the researchers from the NUS Tropical Marine Science Institute (TMSI). The study also showed that microplastics are widespread across Singapore's coastal habitats - including mangroves, coral reefs and seagrass beds - and they could potentially be transferred from one organism to the next. Previous studies had focused mostly on the presence of microplastics - referring to tiny plastic particles smaller than 5mm - in Singapore's environment, said the study's co-principal investigator Neo Mei Lin, a senior research fellow at TMSI. For example, a recent study had found that 97 per cent of macro- and microplastics on Singapore's shores came from marine-based sources. The TMSI researchers wanted to find out more about the presence, distribution, abundance and composition of microplastics in local marine organisms. Their study is part of a larger project that examines the impacts and hazards of marine plastics in the coastal environments. As an emerging field of study, not a lot is known about microplastics and their impacts yet, according to the US National Oceanic and Atmospheric Administration (NOAA). However, laboratory studies have shown that microplastics and chemicals in plastics may impact animals by delaying their developmental stages, cause problems with reproduction, and may even make it difficult for them to fight off disease, NOAA noted on its website. In fiddler crabs, microplastics likely accumulate through respiration and direct contact with contaminated seawater. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS Four marine species were selected for the TMSI study: the orange fiddler crab (Gelasimus vocans), porcelain fiddler crab (Austruca annulipes), garlic bread sea cucumber (Holothuria scabra) and synaptid sea cucumber (Synaptula recta). These species "typically consume and process large amounts of sediments", making them good indicators for researchers to gauge the extent of microplastic pollution in marine sediments, said Dr Neo. "Their abundant presence indirectly suggests their importance in the ecosystem, and being common across multiple study sites allows us to compare and infer the impact of microplastics," she said. Only the guts of the synaptid sea cucumbers were assessed as they lack respiratory trees. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS They are also commonly found in the South-east Asian region, according to study co-author Dr Jenny Fong, who was involved in the study when she was a research fellow at TMSI. A total of 153 live samples across the four species were collected between November 2021 and May 2022 from mangroves, seagrass beds and coral reefs at seven sites across Singapore. The sites are Pasir Ris Park, St John's Island, Kusu Island, Small Sister's Island, Pulau Semakau, Changi Beach and Pulau Hantu Besar. The researchers said they prioritised safety, accessibility and abundance of the target species in choosing these sites, citing the presence of saltwater crocodiles and snakes in other locations as a deterrent. The animals were dissected and microplastic samples from their organs were collected. The gills, hepatopancreas - a digestive gland which performs functions similar to those of the liver and pancreas in humans - and guts of the fiddler crabs were examined. In the case of the garlic bread sea cucumber, researchers studied its respiratory trees - a branching network of tubes for breathing - guts and coelomic fluid, which is a bodily fluid crucial in transporting nutrients and gases. Only the guts of the synaptid sea cucumbers were assessed since they lack respiratory trees. A total of 1,266 microplastic samples were found in these organs. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS A total of 1,266 microplastic samples were found in these organs, which the team carefully analysed and categorised into four shape types - fibres, fragments, films and spheres, listed in order of prevalence. Most particles were less than 1mm in size. Polymers commonly used in everyday life, such as in plastic bottles, packaging, synthetic textiles and automotive parts, were identified. "The shapes of microplastics provide hints on the potential sources of plastics... and it tells us what kind of microplastics affect (the animals) the most," said Dr Neo, who added that fibres were the most common shape found. Knowing the most common plastic type helps researchers identify which ones marine animals are likely to ingest, said fellow researcher Ashwini Suresh Kumar, a TMSI research fellow. "This information could be valuable for policymakers, particularly when considering regulations around additives commonly used during the manufacturing of these polymers, with the aim of reducing bio-accumulation and environmental impact," she said. Researchers suggest that in fiddler crabs and garlic bread sea cucumbers, microplastics likely accumulated through respiration and direct contact with contaminated seawater. The smallest particle, approximately 60 micrometres in size, was found in the respiratory trees of a garlic bread sea cucumber, said Dr Neo. The hepatopancreas of both fiddler crab species generally had the highest number of microplastics, likely from ingestion as the primary pathway of entry, according to the findings. With an additional pincer-like claw compared with males, female fiddler crabs exhibit faster and more frequent feeding behaviours - patterns that researchers associate with higher microplastic contamination in their organs. Synaptid sea cucumbers, which are often seen feeding on the excretion of marine sponges, may ingest microplastics accumulated on these surfaces after the sponges feed by filtering seawater. This suggests that microplastics may be transferred up the marine food chain. Asked what the findings could mean for the safety of locally grown seafood, Dr Neo said more studies need to be done. She noted that the guts of contaminated animals are "typically removed and cleaned before (the animal) goes for sale", adding that "the sweeping statements of humans eating microplastics need to be carefully discerned". "While we do not have any plans to examine the long-term impacts through surveys and sampling, our current work has led us to new research questions such as developing new approaches to studying microplastic distribution in organisms," she said. In June 2022, Singapore launched a national action strategy aimed at reducing land- and sea-based sources of plastic waste that end up as marine litter.
Straits Times
18-05-2025
- Straits Times
Microplastics found in marine animals in S'pore's coral reefs, mangroves and seagrass beds: Study
The animals were dissected and microplastic samples from their organs were collected. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS Microplastics were found in the digestive and respiratory organs of the animals. Microplastics found in marine animals in S'pore's coral reefs, mangroves and seagrass beds: Study SINGAPORE - Microplastics have been found in marine animals across Singapore's coastal areas in a new study, with researchers discovering these plastic bits not just in the animals' digestive tracts, but also in their respiratory organs and bodily fluid. Microplastics enter the animals not just through the food they consume, but also when they breathe or move through water, said the researchers from the NUS Tropical Marine Science Institute (TMSI). The study also showed that microplastics are widespread across Singapore's coastal habitats – including mangroves, coral reefs and seagrass beds – and they could potentially be transferred from one organism to the next. Previous studies had focused mostly on the presence of microplastics – referring to tiny plastic particles smaller than 5mm – in Singapore's environment, said the study's co-principal investigator Neo Mei Lin , a senior research fellow at TMSI. For example, a recent study had found that 97 per cent of macro- and microplastics on Singapore's shores came from marine-based sources. The TMSI researchers wanted to find out more about the presence, distribution, abundance and composition of microplastics in local marine organisms. Their study is part of a larger project that examines the impacts and hazards of marine plastics in the coastal environments. As an emerging field of study, not a lot is known about microplastics and their impacts yet, according to the US National Oceanic and Atmospheric Administration (NOAA). However, laboratory studies have shown that microplastics and chemicals in plastics may impact animals by delaying their developmental stages, cause problems with reproduction, and may even make it difficult for them to fight off disease, NOAA noted on its website. In fiddler crabs, microplastics likely accumulate through respiration and direct contact with contaminated seawater. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS Four marine species were selected for TMSI study: the orange fiddler crab (Gelasimus vocans), porcelain fiddler crab (Austruca annulipes), garlic bread sea cucumber (Holothuria scabra) and synaptid sea cucumber (Synaptula recta). These species 'typically consume and process large amounts of sediments', making them good indicators for researchers to gauge the extent of microplastic pollution in marine sediments, said Dr Neo. 'Their abundant presence indirectly suggests their importance in the ecosystem, and being common across multiple study sites allows us to compare and infer the impact of microplastics,' she said. Only the guts of the synaptid sea cucumbers were assessed since they lack respiratory trees. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS They are also commonly found in the South-east Asian region, according to study co-author Dr Jenny Fong, who was involved in the study when she was a research fellow at TMSI . A total of 153 live samples across the four species were collected between November 2021 and May 2022 from mangroves, seagrass beds and coral reefs at seven sites across Singapore. The sites are Pasir Ris Park, St John's Island, Kusu Island, Small Sister's Island, Pulau Semakau, Changi Beach and Pulau Hantu Besar . The researchers said they prioritised safety, accessibility and abundance of the target species in choosing these sites, citing the presence of saltwater crocodiles and snakes in other locations as a deterrent. The animals were dissected and microplastic samples from their organs were collected. The gills, hepatopancreas – a digestive gland which performs similar functions to the liver and pancreas in humans – and guts of the fiddler crabs were examined. In the case of garlic bread sea cucumbers, researchers studied its respiratory trees – a branching network of tubes for breathing – guts and coelomic fluid, which is a bodily fluid crucial in transporting nutrients and gases. Only the guts of the synaptid sea cucumbers were assessed since they lack respiratory trees. A total of 1,266 microplastic samples were found in these organs. PHOTO: CMBS PHOTOGRAPHY TEAM, LEE KONG CHIAN NATURAL HISTORY MUSEUM, NUS A total of 1,266 microplastic samples were found in these organs, which the team carefully analysed and categorised into four shape types – fibres, fragments, films and spheres, listed in order of prevalence. Most particles were less than 1mm in size. Polymers commonly used in everyday life, such as in plastic bottles, packaging, synthetic textiles and automotive parts, were identified. 'The shapes of microplastics provide hints on the potential sources of plastics... and it tells us what kind of microplastics affect (the animals) the most,' said Dr Neo, who explained that fibres were the most common shape found. Knowing the most common plastic type helps researchers identify which ones marine animals are likely to ingest, said fellow researcher Ashwini Suresh Kumar, a TMSI research fellow. 'This information could be valuable for policymakers, particularly when considering regulations around additives commonly used during the manufacturing of these polymers, with the aim of reducing bio-accumulation and environmental impact,' she said. Researchers suggest that in fiddler crabs and garlic bread sea cucumbers, microplastics likely accumulate through respiration and direct contact with contaminated seawater. The smallest particle, approximately 60 micrometres in size, was found in the respiratory trees of a garlic bread sea cucumber, said Dr Neo. The hepatopancreas of both fiddler crab species generally had the highest number of microplastics, likely from ingestion as the primary pathway of entry, according to the findings. With an additional pincer-like claw compared with males, female fiddler crabs exhibit faster and more frequent feeding behaviours – patterns that researchers associate with higher microplastic contamination in their organs. Synaptid sea cucumbers, which are often seen feeding on the excretion of marine sponges, may ingest microplastics accumulated on these surfaces after the sponges feed by filtering seawater. This suggests that microplastics may be transferred up the marine food chain. Asked what these findings could mean for the safety of locally grown seafood, Dr Neo said more studies need to be done. She noted that the guts of contaminated animals are 'typically removed and cleaned before (the animal) goes for sale', adding that 'the sweeping statements of humans eating microplastics need to be carefully discerned'. 'While we do not have any plans to examine the long-term impacts through surveys and sampling, our current work has led us to new research questions such as developing new approaches to studying microplastic distribution in organisms,' she said. In June 2022 , Singapore launched a national action strategy titled aimed at reducing land- and sea-based sources of plastic waste that end up as marine litter. Join ST's WhatsApp Channel and get the latest news and must-reads.
