Climate Solutions Series: Invasive Quagga mussel Is Rewriting Switzerland’s Waterscape

A fingernail‑sized invader is transforming Swiss lakes and the cost of clean water. In this episode, we track the quagga mussel from its arrival in the Rhine to its rapid spread through deep Swiss basins—stripping plankton, stressing fisheries, and clogging water infrastructure. Researchers from Eawag and the University of Konstanz explain the biology behind its takeover and what global case studies reveal about long‑term impacts. 

read more on this story on Quagga mussels  and science from SWI swissinfo

Journalist: Julie Hunt

Host: Jo Fahy
Audio editor/video journalist: Michele Andina
Distribution and Marketing: Xin Zhang

SWI swissinfo.ch is a public service media company based in Bern, Switzerland. 

Transcript

Meet The Quagga Mussel

Jo Fahy 0:52

Swiss Info Podcasts The Quagga mussel is causing many problems in Switzerland and across the Northern Hemisphere, changing ecosystems in its path, attacking water supplies, and causing millions in damage. But is there any way to stop the invasive mussel? That's coming up in this episode of the Swiss Connection Science Podcast. Hello, I'm Joe Fay. Quagga mussels come from the Black Sea region and were first spotted in Switzerland in 2014 in the River Rhine near Basel. Their larvae are invisible to the naked eye and can be carried downstream in rivers or transported by attaching to boats. The mussel can reproduce almost all year round and can inhabit deep water zones where there are few predators. Switzerland, Germany, Austria, and the United States are all countries suffering from an invasive mussel infestation. Researchers there are pooling their findings to better understand the behavior of the quagga. Swissinfo journalist Julie Hunt found out what's being done to stop this invasive species.

Julie Hunt 2:31

A team from the Swiss Federal Institute of Aquatic Science and Technology, EWAG, and the University of Constance take stock of quagga mussels in Lake Constance every autumn. Journalist and diver Sandra Büchi, who films underwater for Swiss Public Television SRF, travel with them around Steckborn.

Sandra Büchi 2:58

Take a look at this. Only mussels wherever you look. There are no spaces between them at all.

Field Survey On Lake Constance

Julie Hunt 3:10

The quagga mussel is convex and has a rounded keel on the side. It measures about 20 millimeters. It's slightly bigger than its relative, the zebra mussel, which often displays a striped pattern. The quagga may have arrived in 2014, but the zebra mussel has been in Europe for 200 years. Lyubov burlakova, a senior research scientist from Buffalo State University in the United States, says both varieties appeared in the Great Lakes in the 1980s.

Lyubov E. Burlakova 4:03

We're monitoring lakes every year on about like 60 stations. So we have the most up-to-date data. Now we know that quagga massel can spread much deeper and occupy much larger areas, especially that's important for deep lakes. So now with this experience from North American lakes, we can use this experience on Swiss lakes and not only Swiss lakes for any deep lakes in Europe that will be colonized with Gawaga mussels. So according to our predictions, they should be a pretty large population so they will be able to completely change their functioning of ecosystem.

Julie Hunt 4:45

Piet Spaak, who leads Eawag's Lake Change Research Project on Lake Constance, told us more about the newest invasive mollusks.

Biology And Supercharged Reproduction

Piet Spaak 4:55

It lives in lakes and in rivers on the bottom and feeds itself through a so-called siphon that that's a kind of tube that goes out of these two uh shells and uh sucks the water in and then the quacker mussel filters its food out of the water. So it's it eats uh algae and plants that grow in the water.

Julie Hunt 5:15

Their great survival skill is their ability to reproduce.

Piet Spaak 5:19

One female muscle can produce up to a million egg cells, uh a male mussel even more sperm. So that means they can produce many, many larvae. Every mussel makes again uh a hundred new mussels, it goes very, very quick. So that is they they are masters in in reproducing.

Julie Hunt 5:37

And there aren't many animals native to Switzerland which can stop the quakers' growth or limit the population.

Piet Spaak 5:44

So they are eaten by um by birds, by ducks, for example, but ducks have to dive, and ducks go only five to ten meters or something like that. They can be eaten by fish, but they are not preferred fish food because they do not have much uh meat. But quacker mussels can go as deep as there is oxygen in lakes, and in clean switch lakes, this is up to the deepest part, so that can be for lake constant, for example, 250 meters.

Julie Hunt 6:14

Seven research institutions from Switzerland, Germany, and Austria are participating in the lake change project. They're focusing on how an invasive species like the quagga affects other life in the lake.

Piet Spaak 6:28

If quacker mussels grow and grow, all the nutrients in a lake that that they accumulate in this quacker mussels, so are not available for the rest of the food chain. So if quacker mussels eat algae all the algae, the algae are not available for the zooplankton. The zooplankton is the food for the fish, means that there is less fish, the fishermen catch less fish, and it also means that biodiversity is at least at at risk. So because if there is only one species in the lake, so there is no space for for for the others.

Food Web Disruption And Biodiversity Risks

Julie Hunt 6:59

Lyubov Bburlakova is currently on a sabbatical at Eawag. Bburlakova estimates that in the Great Lakes, quagga mussels now represent more than ninety-five percent of all biomass. These mussels have affected the whole ecosystem. A deep water crustacean, diaporia, a vital food source for white fish, has declined.

Lyubov E. Burlakova 7:27

They colonized a lot of areas where diaporia used to live. There are several lakes where we can't find diaporia anymore in Great Lakes. So, for example, Lake Ontario.

Julie Hunt 7:37

The mussels are not only a danger to biodiversity, they also disrupt water supplies by clinging to and blocking supply pipes and damaging filters in drinking water systems. Maintenance and removal costs are rising sharply. Andreas Hirt, a manager at energy service Biel Bienne, says the mollusks are virtually unstoppable.

Andreas Hirt 8:09

This means that within three to five years, the body of water is actually completely colonized.

Julie Hunt 8:25

It uses ultrafiltration. But even before the water reaches the ultrafiltration station, the pipe is cleared of mussels using a special pump. Andreas Hirt, a manager at energy service Biel Bienne, says the mollusks are virtually unstoppable.

Andreas Hirt 8:42

It strips off the larvae in the main pipeline and washes them away until they are returned to the lake that they came from. And what's special about this pump is that it can also move backwards. This blocks all of the muscles, unlike other systems, which usually only block 99%, and are therefore not really suitable for removing them.

North American Lessons And Biomass Shift

Julie Hunt 9:11

Andreas Hirt says there's been a lot of interest in Biel Bienne's new pipe cleaning system, but it's very expensive. The new waterworks in Biel that includes the cleaning system costs 100 million francs. But there are other ways to approach the problem. Some Swiss cantons, such as Bern, have introduced cleaning rules for boats that are moved from one lake to another in case any quagga have come along for the ride. So, how is this quagga invasion likely to evolve in Switzerland? Will Quagga completely colonize local waterways? Moritz Heiser from the Department of the Environment writes.

Moritz Heiser 9:49

There are currently no ecologically and economically feasible control measures for lakes the size of Swiss lakes. The quagga mussel can therefore not be removed from a lake, not even with chemicals. 

Julie Hunt 10:25

Lyubov Bburlakova's research is partly focused on predicting when the quagga mussel invasion will reach its peak in Switzerland, with a team of scientists from North America and Europe. She has seen the long-term consequences in these small lakes, which provide some hope.

Lyubov E. Burlakova 10:40

In some lakes which were invaded by zebra mussels that after. For example, 20 years. There are more planktonic organisms in the lake, So there are more algae in the lake, so some parts of the ecosystem can recover after this invasion, after the peak of invasion.

Julie Hunt 10:49

Invasive species eventually deplete available resources in the lake, and their populations then decline. For example, in Lakes Huron, Michigan, and Ontario, in North America, there is now less algae in the water, so quagga populations are falling. Piet Spaak is also basing his predictions for the quagga mussel on what's happening in North America or what hasn't happened.

Water Infrastructure Under Siege

Piet Spaak 11:13

Of course, we always hope that there will be a disease or something or a virus that it that will kill them or will kill part of the population. But but it has not happened in North America the last uh thirty years, so the chances are not not too big, I I would say.

Jo Fahy 11:34

Many thanks to our dear colleague Julie Hunt, who left us this report just before going on early retirement. Gilly, we miss you dearly here, but of course we wish you all the very best and lots of interesting projects for this new phase of life. We've also contacted Piet Spark from EWAG again, who've just heard in this report, to see whether he had any updates on the story. And he'd like us to emphasize that many cantons in Switzerland have increased their efforts to stop the fervor spread of the quagga mussels and are increasingly collaborating in campaigns to raise public awareness. Coming up on this season of the Swiss Connection Science Podcast, we have episodes about a 2000-watt society experiment, about why the Swiss waste more food than they think, and about the challenge of producing semiconductors. In our next episode, though, we're going to Antarctica, which stores information on the Earth's climate from over 1 million years ago. For more science stories, visit our website swissinfo.ch, and you can help others to find our podcast by leaving us a five-star review wherever you get our podcast, or tell a friend about us. Today's episode was recorded and edited by our science and video journalist Michele Andina. For more content, check out our website swissinfo.ch. I'm Jo Fay. Thanks for listening.