Golden oyster mushrooms, known for their bright yellow caps and earthy flavors, are native to Asia. However, these prized edible mushrooms have gained popularity throughout North America, where they’re spreading across forests and displacing native fungal species, a recent study has found.
Aishwarya Veerabahu, lead author and a doctoral student at the University of Wisconsin-Madison, U.S., told Mongabay by email that the study was prompted by a growing number of wild golden oyster observations in North America across citizen science biodiversity databases.
“[T]he public, mushroom enthusiasts, and community scientists were logging their observations of this non-native mushroom on online biodiversity databases like iNaturalist and MushroomObserver,” Veerabahu said. “Local mycologists (Drs. Anne Pringle and Todd Osmundson) were also increasingly noticing this mushroom that they knew to be introduced to the region and were alarmed at how rapidly it was multiplying and spreading.”
By Dec. 31, 2023, observations of the mushroom had been reported from 23 states in the U.S. and Ontario, Canada.
To find out how the golden oyster’s spread could be affecting native fungal species, Veerabahu and her colleagues examined 78 samples of wood from 26 dead elm trees near Madison. Half of the trees had golden oysters growing on them.
The team then used DNA analysis to identify the different fungi that grew on each sample. They found that trees with golden oysters hosted about half as many native fungal species as those that didn’t have them.
“Though we have yet to study downstream impacts, we suspect changes to native fungal diversity in dead trees could potentially affect wood decay processes, rates of carbon emissions from dead wood, and changes to deadwood habitat for birds, mammals, and tree seedlings,” Veerabahu said.
She added that fungal biodiversity in general is poorly documented, so as golden oysters outcompete native fungi, “we may lose species we don’t even know about yet along with their unique chemistry — we may lose undiscovered medicinal compounds that these fungi produce.”
Matthew P. Nelsen, a mycologist at the Field Museum of Natural History in Chicago, who wasn’t involved in the study, told The New York Times that golden oyster mushrooms have been “popping up like crazy all over the place” in the past five years. He added the study “paints a troubling picture of what this means for the diversity of wood-rotting fungi and all the other organisms that rely on these fungi.”
The mushrooms, which were first imported into North America in the early 2000s, are now sold in popular mushroom-growing kits.
“The take home message for people who grow and cultivate mushrooms is that non-native mushrooms are often cultivated in North America but can become invasive, causing devastating effects on native fungal biodiversity,” Veerabahu said. She added that all stakeholders, from mushroom cultivators and sellers to researchers, must come together and jointly develop a management plan for golden oysters.
Banner image: Golden oyster mushrooms. Image by Jordan Cook via Flickr (CC BY-NC 2.0).
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