Scientists seeking cause of huge freshwater mussel die-off

A pile of recently dead freshwater mussels are piled along the shore of the Clinch River near Wallen Bend, Tennessee. (AP)
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Updated 17 December 2019

Scientists seeking cause of huge freshwater mussel die-off

  • Freshwater mussels range from about the size of a large button to the size of a billfold
  • Mussels benefit the people who use their rivers as a source of drinking water

KYLES FORD, Tennessee: On a recent late fall afternoon at Kyles Ford, the white branches of sycamore trees overhung the banks of the Clinch River, leaves slowly turning yellow. Green walnuts covered the ground.

The shallow water ran fast and cold over the rocky bottom, but it was littered with the white shells of dead mussels.

Freshwater mussels range from about the size of a large button to the size of a billfold, but the work they do for ecosystems is enormous. They can filter around 8-10 gallons of river water each day, cleaning it of algae, silt and even heavy metals and making the whole river a better environment for fish, amphibians, plants and bugs. Mussels also benefit the people who use their rivers as a source of drinking water.

That’s why scientists are working quickly to discover the cause of a massive mussel die-off on the Clinch and understand whether it is related to similar die-offs on at least five US rivers and another in Spain.

The Clinch River, winding 300 miles through Appalachia, is home to 133 species of fish and is one of the most important rivers for freshwater mussels in the world, with 46 different species — more than in all of Europe.

“I always try to get people to call this area a temperate Amazon, because the biodiversity here really is off the charts,” biologist Jordan Richard, with the US Fish and Wildlife Service, said recently as he stood in waders, surveying the mussel population at Kyles Ford, a rural community of around 525 near the Virginia border.

Richard slogged through thigh-deep water in search of pheasantshell mussels, until recently one of the most abundant species on the river. He spots them easily although to the untrained eye, they aren’t so obvious. Mussels bury themselves in the riverbed, digging in with their single foot and leaving only a crescent of their shells visible.

In 2016, Richard noticed the pheasantshells were dying in large numbers — the population dropping from 94,000 in 2016 to less than 14,000 this year on a 200-meter (219-yard) stretch. He estimates hundreds of thousands, possibly millions, have died in the larger river.

Richard found reports of similar die-offs over the years in rivers around the world, but he didn’t find many answers.

Over the past century, mussel populations everywhere have declined steeply due to pollution, habitat loss and climate change, yet the current decline looks to be something different.

Richard and a team of scientists suspect an infectious disease. By comparing healthy pheasantshell mussels with dying ones, the team is narrowing down a list of suspected pathogens.

“All living things are chock-full of microorganisms, and we don’t have any sort of map for what is healthy inside a mussel,” Richard said.
University of Wisconsin epidemiologist Tony Goldberg is helping with the investigation. He specializes in wildlife diseases of unknown cause — and recently he’s been busy.

“Along with invasive species, we’re seeing invasive pathogens,” Goldberg said. “Often it’s the coup de grace for a species that is holding on by a thread.”
Disease is a big part of the global extinction crisis, he said. For example, white nose syndrome was first discovered in a single New York cave in 2007 and has since killed millions of bats, and chytrid fungus is responsible for the demise of tree frogs and about 200 other amphibian species worldwide.

But Goldberg is hopeful the freshwater mussel team, which includes scientists from the US Geological Survey and a nonprofit conservation group, will be able to find the cause of the mussel die-offs and a way to stop them.

“I see it as a race against time, not an impossible task,” Goldberg said. “We’re all motivated by the sinking realization that if we lose these mussels, the rivers we all love are never going to be the same.”

The Clinch, which is relatively pristine on its upper reaches, has seen 10 mussel species go extinct — it used to have 56. Another 20 species there are endangered, including mussels with evocative names such as fluted kidneyshell, snuffbox, birdwing pearlymussel, and shiny pigtoe.

Preliminary results indicate that whatever is killing the pheasantshell mussels on the Clinch is not the culprit in other die-offs under investigation in Wisconsin, Michigan, the Pacific Northwest and Spain.

“There’s not some mussel Ebola sweeping across the world to take out every mussel everywhere,” Goldberg said.

That also means there’s no single cure for what’s killing them.

In Spain, biologist Rafael Araujo is working with Goldberg to figure out what is killing the last of the endangered Spengler’s freshwater mussels in the Imperial Canal on the Ebro River.

“We know that the problem is environmental (dams, water pollution, excess fertilizers, pesticides, exotic species, lack of water, etc.), but we also think that there could be a pathogen (bacteria and/or virus) that is making things worse,” Araujo wrote in an email.

In Oregon and Washington, Emilie Blevins is studying the die-off of western pearlshell mussels in her role as a biologist with the Xeres Society for Invertebrate Conservation.

Blevins likens mussel beds to coral reefs in terms of their diversity and contributions to other aquatic life. But she acknowledges, “They just don’t get the spotlight of some other big, beautiful species. A big part of all of our work is ... spotlighting how important they are because if we don’t value them, they’re not going to be around.”


Spiraling COVID-19 infection rates loom over US elections

Updated 30 October 2020

Spiraling COVID-19 infection rates loom over US elections

  • Donald Trump brushed aside worries about the virus and simply promised to vanquish it, moving on to talk about economic growth under his watch
  • Joe Biden is heavily focused on tackling COVID-19, vowing to prioritize science and refusing to run “on the false promises of being able to end this pandemic by flipping a switch”

NEW YORK: For the past month, life seemed to be slowly but surely edging toward normality for restaurants in Manhattan’s East Village neighborhood. For outdoor dining, streets were lined with makeshift cubicles, tables separated by plexiglass out of an abundance of caution and lights were strung over the tent-shaped patios.

It looked almost festive: Chatter filled the air as New Yorkers took to eating outside, happy to break the monotony of the past months and hoping, with their patronage, to save the remaining local businesses, 30 percent of which had already closed shop for good due to the coronavirus disease (COVID-19) pandemic.

But all it took was one day of heavy rain for the now-familiar desolation to descend on the streets again, a harbinger of a coming winter during which many are expecting an even deeper economic pain to unfold. As of last month, indoor dining was allowed, with contact tracing being implemented on all premises, but many New Yorkers still do not feel safe enough to dine in closed spaces.

In the home stretch before Election Day, the COVID-19 specter remains omnipresent.

President Trump, trailing in the polls, is sticking to a whirlwind schedule of rallies, attended by thousands, some wearing masks and practicing social distancing but many not. Trump brushed aside worries about the virus and simply promised to vanquish it, moving on to talk about economic growth under his watch.

His rival, former Vice President Joe Biden, is heavily focused on tackling COVID-19, vowing to prioritize science and refusing to run “on the false promises of being able to end this pandemic by flipping a switch.”

Over the summer, as New York’s infection rates dipped to lows unseen in most states since, it appeared the former world epicenter of the pandemic had cracked the code to containment.

Now, with the US smashing its own daily case record for the third time in a week, no state has been immune from the latest surge sweeping the nation. 

The 71,000 new cases per day that the US averaged over the past week were the most in any seven-day stretch since the crisis started.

As colder weather moves in and the holidays hit, Dr. Anthony Fauci, the nation’s top infectious disease expert, warned that if these trends did not change, there would be a “whole lot of pain in this country with regard to additional cases and hospitalizations and deaths.”

In New York, the numbers have been creeping up again. The total number of hospitalizations is the highest since June, topping 1,000 for the fourth day in a row. Back in early September, that number was 410. The highest total was 18,825 on April 12.

Twelve people were confirmed to have died from the virus yesterday.

Governor Andrew Cuomo has enforced a new lockdown plan to deal with the alarming rise in infections in so-called micro-clusters of the city and state, which are now targeted for further restrictions.

“Because we’re so aggressive, every time we see the virus pop up, we run and hit it down,” said Cuomo, touting his micro-cluster strategy. “It’s like Whack-A-Mole.”

This strategy appears to have been working. Despite recent upticks, the Empire State has the nation’s second-lowest infection rate, according to data from Johns Hopkins University.

Cuomo also announced that California has been added to New York State’s travel advisory, bringing the total number of states on the list to 41, which constitutes around 90 percent of the US.

The advisory requires individuals who have traveled to New York from areas with significant community spread to quarantine for 14 days.

For his part, Mayor Bill de Blasio urged New York City residents to avoid holiday travel unless it is “absolutely necessary.” He expressed concerns over the recent growth of the city’s seven-day rolling positivity average.

Today, it hit 1.92 percent, and while that is low compared with other major American cities, it is still the highest average for New York in months — and dangerously close to the 2-percent threshold de Blasio said could lead to the closure of indoor dining across the city.

“Big picture here is there has been a danger of a full-blown second wave in New York City. We still have to keep a vigilant eye on that,” the mayor said. “We do fear more and more [COVID-19] coming in from outside. [We] must be really strong at this moment.”

Earlier this month, Cuomo announced that he was limiting attendance at houses of worship, closing schools and shuttering nonessential businesses in six parts of the state where infections have spiked.

The decision to reinstate restrictions was met with protests, some of which turned violent. In Brooklyn’s Hasidic neighborhood, some viewed the lockdowns as anti-Semitic.

Several class-action lawsuits have been filed against the state of New York, Governor Cuomo and other public officials, by large groups of restaurant owners, gym owners, and small performing arts venues, all seeking to overturn executive orders from Cuomo that have barred those businesses from opening.

But the Democratic governor has been adamant that the return of restrictions is the way to go.

“This is not rocket science,” Cuomo said. “It’s a virus. When you reduce congregate activity and people wear masks… you stop the spread of the virus. That’s how it works. That’s how it’s always worked. You just have to do it.”