Invasive Zebra Mussels Lurking from Aquarium Decor Stores in the US 

Invasive Zebra Mussels Lurking from Aquarium Decor Stores in the US 

Outbreaks of invasive aquatic species usually start from home aquarium. This one can be another almost undoable disaster, but let’s hope that it won’t be the case—so if you’re reading this, spread the awareness. 

So, federal officials in the United States have found invasive zebra mussels hiding in shipments of moss balls. These balls are aquarium accessories sold in pet shops across the country (at least in 21 states). The species itself is a freshwater Eurasian native. 

Moreover, The Conservation Officer Service in BC, Canada, has also reported the mussels in pet shops at around 600 locations. 

To make things worse, this species is small—about the size of a fingernail—so it can go unnoticed. And even though they’re small, these beautifully striped mollusks can do a lot of damage. 

According to US Fish and Wildlife Service (USFWS), once they become established in an environment, “they alter food webs and change water chemistry, harming native fish plants and other aquatic life. They clog pipelines used for water filtration, render beaches unusable, and damage boats.” 

Taking actions 

These tiny creatures can multiply quickly when they find a water source. And, they’re resilient, meaning they’re still going strong even when you flush it down the toilet. 

Zebra mussels have reached the Great Lakes region, where it costs hundreds of millions of dollars annually to deal with them. That amount of money can help other animals in need, don’t you think? 

 United States Geological Survey (USGS) officials said that all aquarium owners/stores that also own/sell moss balls should treat them as if they all contain zebra mussels. Destroying them first before disposing of them properly (sealed in a container) is a wise choice. 

USFWS recommended freezing, boiling, or bleaching any moss balls or other suspected items that may contain these mussels. It may sound so harsh, but it’s better to do this than trying to repair or undo the damages later. 

Per Rick Boatner, invasive species wildlife integrity supervisor at the Oregon Department of Fish and Wildlife, zebra mussel infestation “would be devastating to our environment if these ever got established in Oregon or the Pacific Northwest.” 

So far, the Pacific Northwest has been keeping the species mostly at bay through strict monitoring of boats and other craft. Those two are one of the main causes of mussel introduction to new waters. 

Boatner said that his agency was not expecting zebra mussels from moss balls. 

Discovery in pet stores 

Thanks to a PetCo employee in Seattle last February, awareness of mussel-occupied moss balls could spread today. The employee saw the striped mollusks and reported it to local officials.  

Then, USGS biologist Wesley Daniel went to a pet store in Florida and discovered the small mussel there, also in a moss ball. This suggested that the issue was widespread. Alas, more reports have come in from 21 states. 

PetCo spokesperson Jason Murdock said that the company has immediately paused the sale of all Marimo aquarium moss balls at PetCo locations and its web store. 

Because of the geographic extent of the moss balls, experts have become concerned that the incident could spread the mussels to new areas.  

Executive coordinator for the Washington Invasive Species Council Justin Bush said, “This is one of the most alarming things I’ve been involved with in over a decade of working with invasive species.” 


World’s freshwater fish declining 

If the mussel invasion became worse, then freshwater fish and other species would be in danger. Two recent assessments of the world’s freshwater ecosystems show that the health of habitats that was once rich and biodiverse is declining. I don’t know what will happen if the mussels attack. 

Now, human population keeps growing, and that expansion has reduced biodiversity in more than half of Earth’s freshwater river basins. According to the new research, only 14% remain pristine. 

Conservation organizations have released a global assessment of the world’s freshwater fish species. They found that nearly a third are at risk of extinction.  

This assessment also finds that the biggest types of fish (the ones that weigh more than 27 kilograms) have been declining. Their numbers have plummeted by 94% over the past half century. 

The World’s Forgotten Fishes, the title of this assessment, suggests that this loss won’t only deplete our planet of natural beauty, but puts humans at a disadvantage as well. Per this assessment, 80 species declared extinct and 16 disappeared in 2020 alone. 

Around 200 million people rely on freshwater fish for the protein. And, 60 million people needs the fish to support themselves and their families (and eventually the country economy). 

Researchers behind the other paper observed that the river basins surrounded by heavy human presences got the worse impact. I mean, that’s not so surprising, since us humans can make matters worse.  

Evolutionary biologist at Paul Sabatier University Sébastien Brosse said, “Rivers which have the most economic development around them, like the Mississippi river, are the most strongly impacted.” 

Brosse added that rivers that remain pristine were primarily in Africa and Australia. Probably this happens because of the slower industrialization in Africa and the lack of human populations around rivers in Australia. 

Finding changes in fish biodiversity 

Brosse and his co-authors created an index to know the change in almost 2,500 rivers across the globe (not including the polar and desert regions). Before, attempts to know how humans affect the world’s river ecosystems focused only changes in the number of species. 

On the other hand, new effort incorporates ecological roles and evolutionary relationships of the freshwater species. 

Unsurprisingly, overfishing and climate change are the most significant and main drivers of the global decline in freshwater biodiversity. Other significant factors include blockages created by dams and introduction of non-native species. 

Apparently, dams and other waterway modifications can destroy native species population. It can also make it easier for invasive fish to replace them. Invasive fish like carp, largemouth bass, and tilapia easily thrive on slow-moving waters. Dams turn rivers that flow swiftly into that, giving them the upper hand. 

In 2019 a study found that there’s just around a third of the world’s longest rivers remain free-flowing. The cause are dams that homogenize rivers. Furthermore, another report in 2020 stated that the significantly reduced habitats contributed to the 76% decline of migratory freshwater fish species. 


So we’re left with 14% of pristine rivers—what does that make? Brosse said that number is not enough to maintain global biodiversity of fish because they only contain 22% of the world’s approximately 18,000 freshwater fish species. He said, “We also need to conserve the biodiversity in basins highly impacted by humans.” 

Needless to say, there should be actions. Jeremy Biggs, director of the Freshwater Habitats Trust, stated that a successful conservation plan will need to consider all kinds of waters, from rivers and streams to lakes and ponds. 

“It’s now more urgent than ever that we find the collective political will and effective collaboration with private sector, governments, NGOs and communities, to implement nature-based solutions that protect freshwater species, while also ensuring human needs are met,” said Carmen Revenga, senior fisheries scientist at the Nature Conservancy. 

I don’t know what we should do. Should we need to get rid of human populations near rivers and relocate them somewhere else? I dunno. What actions should we take, according to your opinion? 



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