AsianScientist (Feb. 27, 2019) – Plastic pollutants in the ocean serve as platforms for the growth of toxic bacteria, say scientists from the National University of Singapore (NUS). They published their findings in the journal Science of the Total Environment.
There are currently more than 150 million tons of plastics in the ocean. In particular, microplastics—pieces of plastic smaller than five millimeters in size—pose a major problem for marine ecosystems because many marine organisms, such as shrimps, mussels and fish, often mistake these tiny plastics for food.
Compared to microplastics on land, microplastics in aquatic ecosystems take a much longer time to degrade due to the presence of salt and a lower temperature in the ocean. As a result, they present a habitable environment for marine biota to colonize. Yet, despite their prevalence, the distribution of microplastics along the coasts of tropical regions is not well studied.
In this study, researchers led by Dr. Sandric Leong of the NUS Tropical Marine Science Institute conducted a field survey and uncovered toxic bacteria living on the surfaces of microplastics collected from the coastal areas of Singapore.
Between April and July 2018, the research team collected and examined 275 pieces of microplastics from three beaches along the coastline of Singapore, namely Lazarus Island, Sembawang Beach and Changi Beach. By using high-throughput sequencing techniques, the team discovered more than 400 different types of bacteria across all the microplastics collected.
The researchers found that a subset of bacteria found on microplastics can cause coral bleaching and harm humans. These include marine Vibrio, a major cause of wound infections in humans, and species of Arcobacter, known to cause gastroenteritis in humans.
“Microplastics form a large proportion of plastic pollution in marine environments. Marine organisms may consume bits of microplastics unintentionally, and this could lead to the accumulation and subsequent transfer of marine pathogens in the food chain. Hence, understanding the distribution of microplastics and identifying the organisms attached to them are crucial steps in managing the plastic pollution on a national and global scale,” said Leong.
The NUS team also discovered Erythrobacter, which is capable of degrading plastic, and bacteria species Pseudomonas veronii, which have been used to clean up oil spills growing on the plastic waste. Such bacteria may have industrial uses and could be used to clean up pollutants in the ocean.
The researchers intend to conduct further studies to examine the origin of the bacteria species transported by the microplastics. This will allow the identification of non-native species that threaten the existing biodiversity and provide insights on managing the urgent issue of marine plastic pollution.
The article can be found at: Curren et al. (2018) Profiles of Bacterial Assemblages From Microplastics of Tropical Coastal Environments.
Source: National University of Singapore; Photo: Pixabay.
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