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Microplastics Could Worsen Viral Fish Disease



Microplastics Could Worsen Viral Fish Disease

(CTN News) – “Microplastics and pathogens are everywhere,” says Seeley, “but they’re most common in densely populated aquatic environments, like fish farms.”

Microplastics could affect how severe IHNV infections are in aquaculture. Aquaculture includes rainbow trout, steelhead trout, chinook salmon, and sockeye salmon.

Researchers wanted to see if microplastics, viruses, and fish mortality had a causal relationship. Thus, Seeley and colleagues exposed rainbow trout in aquariums to low, medium, and high concentrations of three different types of microparticles.

They then added the IHN virus to half the tanks. In addition to polystyrene foam (found in floats, buoys, home insulation, and food containers), they chose nylon fibers (found in fishing nets, fishing lines, and clothing).

Spartina alterniflora, a common saltmarsh cordgrass, was also exposed to infected and healthy fish. No viruses or microparticles were found in the control tanks.

Fish were hatched and reared in accordance with Institutional Animal Care and Use Committee guidelines.

Results? “We found that nylon fibres increased disease severity when co-exposed to microplastics and viruses,” says Seeley. It is the first time this interaction has been documented and emphasizes the importance of testing multiple stressors.

Seeley’s doctoral advisor at VIMS, Dr Rob Hale, agrees. Microplastic toxicity must be considered in combination with other environmental stressors, he says.

Dr Andrew Wargo, an expert in infectious diseases, says IHNV is a worldwide problem. Salmonid aquaculture and conservation are affected by this disease, which originated in the Pacific Northwest.

IHNV and microplastics interact, according to our study. How this interaction plays out in aquaculture or wild environments depends on the amount of plastic pollution and IHNV in any given area.

Microparticles aren’t all the same

They suspect that microparticle exposure increases disease severity by physically damaging the delicate tissues of the gills and gut lining, making it easier for the virus to colonize.

Microplastics made from synthetic materials – nylon and polystyrene – had a greater impact than Spartina microparticles. The most durable microfibers are made of nylon. It might be because they’re taller, longer, or harder than plants.

“Nylon microfibers are larger and may damage delicate tissues in the gills and gut lining,” says Seeley. “That could facilitate virus entry and stress the host, ultimately increasing disease virulence.”

The implications are broader

Fish farming is not the only application of the team’s research. “Our research question is relevant to aquaculture, but it can also be applied to natural environments,” explains Seeley.

Currently, microplastics are found worldwide, so many natural pathogens are also co-occurring with them.

Seeley says the team’s results may have implications for human health as well. She says indoor environments are dense with microplastics, such as household dust.

We wonder how indoor microplastic contaminants may affect airborne diseases such as Covid-19.”



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