SAN DIEGO — Researchers have uncovered how rising water temperatures in San Diego Bay accelerate a deadly herpes virus in juvenile Pacific oysters. A marine biologist said the virus doesn’t harm humans, but it can be fatal to oysters.

Marine biologist Emily Kunselman did a study using farmed oysters and exposed them to the virus, Ostreid herpesvirus 1, or OsHV-1, via water. She put the oysters in four different water temperatures: 50, 64, 70 and 75 degrees Fahrenheit. At the coldest temperatures, she said the virus was not able to kill any oysters. In the warmer temperatures, she said the oysters died within days. The virus was first found locally in 2018 at an oyster nursery in the San Diego Bay and found again in 2020.

“Previously, a temperature threshold of 20° C (68° F) was imposed where the farm [a local oyster nursery] was not going to be able to grow oysters when temperatures went above that,” Kunselman said.

Kunselman, a doctoral graduate from the Scripps Institution of Oceanography at UC San Diego and current researcher with the Hubbs Seaworld Research Institute, said she wanted to do this study to check the temperature limit for growing or farming oysters was reasonable since it would eliminate the summer months for growing. She said the data would help keep the efforts of aquaculture going.

Data shows 70-85% of the seafood the U.S. consumes is imported, and Kunselman said finding ways to safely grow seafood locally, such as aquaculture, will help keep up with the demand for seafood.

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