According to a study by a research team from Bremerhaven, microplastics do not affect the health of fish.
The study by the Thünen Institute in Bremerhaven was funded by the German Federal Ministry of Food and Agriculture (BMEL) and recently published in the journal "Science of the Total Environment". To investigate the effects of microplastics on fish, a team led by fisheries ecologist Jörn Peter Scharsack had first determined the microplastic content in the digestive tract of two species of wild fish. In the flatfish species dab, the scientists found less than ten microplastic particles per fish. They then fed sticklebacks a diet with a comparably high number of microplastic fibres as currently found in the seawater of the North and Baltic Seas for nine weeks. A control group was fed a diet with natural cotton fibres and a third group was fed a diet that did not contain any fibres. The result surprised the researchers: The fish embryos raised on feed containing microplastics also developed unharmed. "According to current scientific knowledge, the small amounts of microplastics ingested by fish in the North and Baltic Seas do not lead to any adverse effects on fish health and do not pose a health risk to consumers," the study concludes. Neither the blood count nor the immune system of the animals had been changed by the plastic, nor had reproduction and offspring been affected. On the question of where the microplastics ingested by fish remain, the scientists explained: "The efficient excretion of the fibres with the faeces probably prevents harmful effects of microplastic fibres on fish - even at fibre concentrations significantly above current measured values in the environment." Scharsack believes the research results are transferable to other fish species: "I would go so far as to say that in principle they can be transferred to all vertebrates". The basic structures of the intestinal system are comparable in all vertebrates. With regard to earlier studies that microplastics harm marine animals, Scharsack says: "Our studies do not show that the increasing littering of the sea with plastic is unproblematic. Only concrete evidence that microplastic ingestion affects fish health or inhibits development has not emerged."
Further information: zur Studie „Less impact than suspected: Dietary exposure of three-spined sticklebacks to microplastic fibers does not affect their body condition and immune parameters“
