Plastic pollution threatens the health of Nile Tilapia, study finds

The Nile, renowned globally, serves as the principal source of freshwater in Africa. It traverses 11 countries, providing a habitat for approximately 300 million individuals. A significant portion of this population relies on the Nile’s resources for their livelihood, particularly in agriculture and fishing.

The Nile is composed of two primary tributaries: the Blue Nile and the White Nile, which converge in Sudan’s capital, Khartoum. Over the years, Khartoum has experienced substantial growth, evolving into a major urban center.

Nile branches meet in Khartoum

Like all rivers, the Nile is affected by pollution. One big problem is plastic waste. Over time, this plastic breaks down into tiny pieces called microplastics. These are very small plastic particles that can be as small as a nanometer. A recent study found that rivers can carry up to 25,000 tons of plastic to the sea every year. More than 80% of this is microplastic.

Microplastics are bad for the environment and the climate. When they break down, they release greenhouse gases. Microplastics in the air can affect the climate by changing how sunlight and heat are absorbed and reflected. This can make the air warmer or cooler. Microplastics are also harmful to animals and people. Studies have shown that they can be toxic.

To address the lack of research on microplastics in Africa’s inland waters, a study was conducted on the Nile in Khartoum. This study focused on Nile tilapia, a prevalent fish species in Africa that plays a significant role in the fishing industry of many African countries, including Sudan. The research involved searching for microplastics within these fish.

The results were not good. We found 567 microplastic particles in the 30 fish we examined. This shows that the Nile is polluted with microplastics. These can be eaten or absorbed by tilapia and other water animals.

The fish in this study were caught near Al-Mogran, where the two Niles meet. They were bought fresh from the Al-Mawrada fish market in the Omdurman area, which is also near the Nile.

The fish were dissected to remove their digestive tracts. These tracts were treated to digest any organic matter they contained, which didn’t interfere with the microplastics analysis. After another extraction procedure, physical and chemical analyses were conducted.

Microplastics in fish affect humans

Microplastics were found in the digestive tract of every fish. The number of microplastics ranged from five to 47 particles per fish, with a total of 567 particles identified. This is high compared to other studies on tilapia in other rivers and lakes. There is currently no global guideline or standard for what might be an “acceptable” number of microplastics.

Different sizes (0.04mm to 4.94mm), shapes (fibers, fragments, films, foams, and pellets), and colors of microplastics were detected. The most common were very small (less than 1mm), fibrous, and colored.

These characteristics are related to how fish and other aquatic organisms feed. Nile tilapia eat a variety of organisms, which puts them at a high risk of ingesting microplastics. They are also more likely to consume particles that are similar in size, shape, and color to their natural prey.

Smaller microplastics can carry other pollutants like heavy metals, which can cause additional health risks. Their small size also makes it easier for them to move into organs like the liver. Microplastics have been found in the tissues, muscles, livers, blubber, and lungs of other aquatic and marine mammal species.

Fibers, the most common shape found in the specimens, stay in the intestine longer than other microplastic shapes, which can lead to health problems for the fish. Colored microplastics contain dyes, many of which contain toxic chemicals.

This has serious implications for human health, as people who catch and eat the fish are introducing those microplastics and associated chemicals into their bloodstreams.

Plastic waste pollutes Khartoum environment

Plastic pollution comes from various sources in Khartoum. About 65% of plastic waste ends up in open dumps, where it spreads to water bodies and other parts of the environment.

The city's wastewater treatment plants, like Karary, Wd-Daffiaa, and Soba, are outdated and don't meet standards. This means untreated waste from homes, industries, and farms adds to microplastic pollution.

Recreational spots along the Nile, like Nile Street, contribute too. These areas lack proper waste management, so plastic from activities like water sports and cafes ends up in the river.

Solving this problem isn't easy. It needs better technology and efforts from everyone—consumers, producers, governments, and scientists.

Consumers can use less plastic, like choosing reusable bags and containers. Recycling is also important.

Governments should enforce waste rules, raise awareness, and have policies to deal with microplastics.

Scientists can study more about microplastics and find ways to stop their harm. They also need to share their findings with others.

This content is originally published under the Creative Commons license by The Conversation. The Ground Report editorial team has made some changes to the original version.

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