Microplastics were found in the digestive tract of four out of every 10 fish in the Gulf of Izmit, according to ongoing research investigating the effects of microplastics on biodiversity.

The Gulf of Izmit, in the east of the Marmara Sea, has become a drainage point for a population of approximately 25 million and has become polluted due to increasing population, industrialization and maritime traffic since the 1970s. Researchers examined 12 fish species, most of which are consumed as food and have an important function in the biogeochemical cycles of the seas.

Lecturer Ülgen Aytan, from the Department of Marine Biology at Recep Tayyip Erdoğan University, conducted research with her team in 2019 on fish in the Gulf of Izmit.

Types of plastic

Plastics contain all kinds of pollutants and are one of the leading pollutants. Aytan stated that the type of microplastics quite common in fish were fibers originating from synthetic textile products. According to the research, microplastics were found in 80% of red mullet, 53% of streaked gurnard, 40% of horse mackerel, 39% of rockfish, 20% of greater weever and 10% of haddock.

Explaining that they evaluated plastics according to their physical and chemical properties in their research, Aytan said the plastic fibers are usually carried by the wind or through the sewage as a result of the laundering of the synthetic textile.

Another type of common microplastic pollution originates from the fragmentation of all kinds of plastic materials, such as detergent bottles, packaging and plastic bags. Pointing out that global plastic production is expected to quadruple by 2050, even if plastic entry into the marine environment is stopped, the plastics that have entered since the 1950s continue to break down, Aytan also pointed out.

Plastic threat

Living things like mussels and anchovies that feed by filtering water are at great risk because they cannot avoid ingesting microplastics and chemicals. "Most of these chemicals are bio-accumulative. They can be transferred from one living thing to another through the food chain. For example, if an anchovy consumes microplastic, the larger fish that feed on it also ingests the microplastics. In addition, sea life can mistake microplastics as natural nutrients and consume them by mistake," Aytan said.

When we look at the previous studies, data shows microplastic pollution in the Marmara exceeds a million particles per kilometer. While the current studies show that Türkiye is on the path to being one of the worst affected by microplastics, Aytan said. "We cannot say that Izmit Bay is in a very bad condition, neither can we say anything positive in this regard but there is a reported range for microplastic consumption."

Emphasizing that research has shown the consumption of microplastics in more than 400 fish species around the world: "More than half of these fish are economically valuable and consumed by people. These fish may pose a greater threat to human health. It is very important to understand the extent of pollution in the environment, to make a risk assessment and to guide decision-makers both in terms of ecosystem and human health and on the measures to be taken."

Solutions

"We urgently need to reduce the plastic in our seas and urge the development of new technologies to remove what is already there. We are now talking about a toxic, persistent pollutant that has spread to the poles. A pollutant with such high buoyancy can be transported to even the most remote ecosystems.

"There is a need for solid waste management and wastewater treatment. The use of single-use plastics should be banned globally. However, while we wait for these regulations, we should not forget that even our personal preferences will create a global change. We must choose carefully when shopping. We all have an important share in this pollution," Aytan emphasized.