Remarkable squirting mussels captured on film

jg533 — Sat, 11 Mar 2023 09:00:43 +0000

In spring, female mussels were seen moving to the water’s edge and anchoring into the riverbed, with their back ends raised above the waterline.

Then they squirted out regular water jets, which landed in the water up to a metre away. Squirting cycles lasted 3-6 hours.

This behaviour has never been seen in any other mussel species.

̽��ֱ��jets disturb the river surface and attract fish. Mussel larvae in the jets can then attach to the gills of the fish and complete their metamorphosis into adults.

“Who'd have thought that a mussel, that doesn't even have a head or a brain, knows to move to the river margin and squirt jets of water back into the river during springtime? It’s amazing!” said Professor David Aldridge in the ̽��ֱ�� of Cambridge’s Department of Zoology, lead author of the report published today in the journal Ecology.

Unlike other mussel species, Unio crassus has a limited range of suitable host fishes – including minnows and chub. These species were attracted to the falling water jets.

̽��ֱ��researchers think the mussels squirt water jets to increase the chances of their larvae attaching to the right host fishes. By being squirted into the air and not the water, the larvae are propelled greater distances from the parent mussel.

̽��ֱ��study was carried out during spring in the Biała Tarnowska River, Poland. Six squirts were collected from each mussel for analysis – which confirmed that they contained viable mussel larvae.

Before now, there was only anecdotal evidence of this behaviour. Some scientists thought the water jets might be a way for the mussels to expel faeces.

This behaviour could explain why Unio crassus is an endangered species. Climbing out of the water to squirt makes it vulnerable to floods, destruction of river margins, and predators like mink. And its need for specific host fishes links its survival to theirs.

Understanding how this species completes its life cycle is important for its conservation under changing environmental conditions.

Reference

Aldridge, D C et al: Fishing for hosts: larval spurting by the endangered thick-shelled river mussel, Unio crassus. Ecology, March 2023. DOI: 10.1002/ECY.4026

Cambridge researchers have observed a highly unusual behaviour in the endangered freshwater mussel, Unio crassus.

Who'd have thought that a mussel, that doesn't even have a head or a brain, knows to move to the river margin and squirt jets of water back into the river during springtime?

David Aldridge

Spurting Mussel Movie

Mussel squirting a water jet

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Yes

Conservationists may be unintentionally spreading pathogens between threatened animal populations

jg533 — Mon, 12 Apr 2021 09:00:42 +0000

̽��ֱ��new report published in the journal Conservation Letters focuses on freshwater mussels, which the researchers have studied extensively, but is applicable to all species moved around for conservation purposes.

Mussels play an important role in cleaning the water of many of the world’s rivers and lakes, but are one of the most threatened animal groups on Earth. There is growing interest in moving mussels to new locations to boost threatened populations, or so they can be used as ‘biological filters’ to improve water quality.

A gonad-eating parasitic worm, Rhipidocotyle campanula, which can leave mussels completely sterile, was identified as a huge risk for captive breeding programmes where mussels from many isolated populations are brought together.

“We need to be much more cautious about moving animals to new places for conservation purposes, because the costs may outweigh the benefits,” said Dr David Aldridge in the Department of Zoology at the ̽��ֱ�� of Cambridge, senior author of the report.

He added: “We’ve seen that mixing different populations of mussels can allow widespread transmission of gonad-eating worms – it only takes one infected mussel to spread this parasite, which in extreme cases can lead to collapse of an entire population.”

Pathogens can easily be transferred between locations when mussels are moved. In extreme cases, the pathogens may cause a population of mussels to completely collapse. In other cases infections may not cause a problem unless they are present when other factors, such as lack of food or high temperatures, put a population under stress leading to a sudden outbreak.

̽��ֱ��report recommends that species are only relocated when absolutely necessary and quarantine periods, tailored to stop transmission of the most likely pathogens being carried, are used.

It identifies four key factors that determine the risk of spreading pathogens when relocating animals: proportion of infected animals in both source and recipient populations; density of the resulting population; host immunity; and the life-cycle of the pathogen. Pathogens that must infect multiple species to complete their life-cycle, like parasitic mites, will only persist if all of the species are present in a given location.

“Moving animals to a new location is often used to protect or supplement endangered populations. But we must consider the risk this will spread pathogens that we don’t understand very well at all, which could put these populations in even greater danger,” said Josh Brian, a PhD student in the Department of Zoology at the ̽��ֱ�� of Cambridge and first author of the report.

Different populations of the same species may respond differently to infection with the same pathogen because of adaptations in their immune system. For example, a pack of endangered wolves moved to Yellowstone National Park died because the wolves had no immunity to parasites carried by the local canines.

̽��ֱ��researchers say that stocking rivers with fish for anglers, and sourcing exotic plants for home gardens could also move around parasites or diseases.

“Being aware of the risks of spreading diseases between populations is a vital first step towards making sure we avoid unintentional harm in future conservation work,” said Isobel Ollard, a PhD student in the Department of Zoology at the ̽��ֱ�� of Cambridge, who was also involved in the study.

This research was funded by the Woolf Fisher Trust.

Reference
Brian, J.I., Ollard, I.S., & Aldridge, D.C. ‘Don’t move a mussel? Parasite and disease risk in conservation action.’ Conservation Letters, April 2021. DOI: 10.1111/conl.12799

Moving endangered species to new locations is often used as part of species conservation strategies, and can help to restore degraded ecosystems. But scientists say there is a high risk that these relocations are accidentally spreading diseases and parasites.

We’ve seen that mixing different populations of mussels can allow widespread transmission of gonad-eating worms.

David Aldridge

At-risk species of river mussel

Yes

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Attribution

̽��ֱ�� of Cambridge - Josh Brian

Remarkable squirting mussels captured on film

Reference

Spurting Mussel Movie

Conservationists may be unintentionally spreading pathogens between threatened animal populations