Invasive zebra mussels detected on Marimo moss balls prompts collaborative response
In August, a Renton fish wholesaler spotted suspicious mussels hitching a ride on Marimo moss balls, a popular aquarium and water garden decoration. Aware of the threat of aquatic invasive species (AIS), they alerted the Washington Department of Fish and Wildlife (WDFW) and asked their retail network to quarantine the moss balls.
The wholesaler’s swift action activated a WDFW AIS early detection monitoring team who arrived the same day to collect samples of the mussels, moss ball s, and eDNA, as well as plankton tows. The team’s rapid response was made possible by $3.62 million in additional funding from the Washington State Legislature and federal partners to increase prevention and monitoring efforts for invasive mussels.
After alerting the U.S. Fish and Wildlife Service (USFWS) and U.S. Department of Agriculture (USDA), WDFW provided aquarium decontamination guidance to the wholesaler. Samples were submitted to the WDFW Genetics Lab, with samples and images taken from a microscope camera sent to independent experts.
Within two days, the suspicious mussels were confirmed to be zebra mussels, a prohibited aquatic invasive species not known to be established in Washington. Zebra mussels and their close relative, quagga mussels, pose an imminent threat to Washington’s economy, environment, agriculture, health, and critical infrastructure. If established, mitigation and management costs to vital infrastructure, like drinking water and hydropower, are estimated to cost hundreds of millions annually.
“I would like to thank our industry partner for their vigilance and quick notification,” said Justin Bush, Aquatic Invasive Species Policy Coordinator for WDFW. “Our agencies worked together quickly to address the incident and keep invasive species out of Washington’s waters.”
The discovery of the highly invasive mussels prompted the Washington State Department of Agriculture (WSDA) and WDFW to request the fish retailer issue a voluntary recall which they did immediately. WDFW contacted retailers who may have received the contaminated moss balls to raise awareness of the voluntary recall and provide additional information.
Thanks to the USDA’s ability to trace products, additional retailors were identified and notified. All potentially contaminated moss balls were accounted for. In September, voluntary compliance visits were made to retailers by WDFW, WSDA, and USDA to obtain additional samples.
“WSDA works hand-in-hand with nurseries and plant retailers to protect Washington’s agriculture,” Scott Brooks, WSDA Plant Services Program Manager, said. “However, this incident was unique and crossed agency and state lines. This is a great example of private industry and the public sector coming together to protect our environment from invasive species.”
Final lab analysis confirmed that the adult and juvenile specimens collected were dead and no microscopic larvae were detected. Whether the zebra mussels were dead when imported to the U.S. or died during transportation to Washington is unknown.
The Marimo moss balls were collected in and exported from the zebra’s mussels native Ukraine. The moss balls were then illegally imported to Florida and shipped across the nation. USDA and USFWS are investigating the illegal introduction.
Due to the wholesaler’s awareness and report, the incident which was first reported in Washington state ended up impacting at least 19 states and Canada. The Washington response and collaborative effort between agencies and industry serves as a national model for future incidents.
“Identifying and reporting suspected invasive species is critically important.” Said Bush. “The report may be a new invasive species not established in Washington and trigger rapid response, preventing hundreds of thousands to millions in management costs and damage to the economy and environment.”
Reflecting on things to be thankful for this season, WDFW and WSDA are grateful for the Renton fish wholesaler’s vigilance and partnership in preventing the introduction of invasive species to Washington. Additionally, thanks to our partners at the USDA and USFWS for their assistance. By agencies and industry working together, we can keep Washington free of quagga and zebra mussels.
Learn more about aquatic invasive species prevention and threats by visiting the WDFW’s AIS webpage.
Learn more about protecting plant health and Washington’s agriculture from pests and diseases at the Plant Services Program webpage.
