Tiny specks of plastic drifting in waterbodies are a growing environmental hazard. Shrimp and other critters ingest the plastic particles, mistaking them for food. These microplastics can accumulate in their guts, impairing the animals’ growth and behavior. Recent research suggests their health may be further compromised as plastics provide surfaces for myriad microorganisms, including disease-causing pathogens, to congregate.
Now, biologists at China’s Ningbo University report that polyvinyl chloride microplastics prolong the survival and replication of the white spot syndrome virus in larval shrimp guts, resulting in greater numbers of shrimp deaths.
In laboratory experiments, Jiong Chen, Lei Lui, and their colleagues found that these microplastics impaired the hosts’ antiviral defense pathway, making them more vulnerable to the viral infection (Environ. Sci. Technol. 2023, DOI: 10.1021/acs.est.3c01566). The study demonstrates how microplastics might impact the crustacean aquaculture industry, which already struggles to contain white spot syndrome virus outbreaks.
“We’re [increasingly] seeing this connection between microplastics and organismal health in the way that it will impact the individuals’ ability to fight off pathogens and remain free of disease,” says Meredith Seeley, a postdoctoral fellow studying ocean pollution and microplastics at the National Institute of Standards and Technology, who wasn’t involved in the study. “It’s more evidence that we should be thinking about what this might mean for us as humans.”
It’s unclear whether it’s the physical presence of the microplastics or the chemicals that may leach out of them that’s making the animals more susceptible to infections. It can be both, Seeley says.
In the study, the researchers observed that shrimp ingesting microplastics 100 µm in length were more likely to be infected by the virus than those exposed to particles of 5 or 10 µm. Larger particles might cause greater irritation to delicate gut tissues, Seeley says, but it’s also possible that chemicals associated with the microplastics may have a role in blunting host defenses, she added.