Keeping endangered animals parasite free

Trying to keep animals safe has a lot of pitfalls. Sometimes threatened animals are moved from one place to another, to keep them safe. And a new study from the University of Cambridge published in Conservation Letters, looking at fresh water mussels, has shown that it can be very easy to transport parasites and other pathogens, along with the animals you’re trying to protect. Josh Brian spoke to Adam Murphy about protecting these mussels...

Josh - Well, they get a whole range of things, and what we've found is that often we don't understand the full range that these mussels get, but some of the main ones are castrating worms. So these worms live inside the gonad of the mussel, castrate the mussel, and then use them basically as a factory to produce their own reproductive stages for the rest of the mussel's life. They also have mites which can eat the gills. And what we're seeing now, especially from the US, is that there's a lot of emerging evidence of viruses and bacteria which can spread through these muscles very, very quickly.

Adam - And why is protecting them so important?

Josh - Well, these freshwater mussels are hugely important in terms of ecosystems, so they were known as "ecosystem engineers''. So they modify the sediment, they help with nutrient cycling, and they're also massive filter feeders. So my favourite stat about freshwater mussels is that the entire volume of the river Cam that flows through Cambridge is filtered through freshwater mussels every two weeks. So they do a massive job of cleaning the water. In addition, because they form these massive mussel beds along the banks, they can help prevent erosion and things like that as well. But on the whole freshwater mussels are actually one of the most threatened animal groups in the whole world. So it's really important that we understand all the threats facing them and take appropriate steps to protect them.

Adam - Say an infected mussel got into an uninfected group, how much damage could that do?

Josh - Well, it could do a whole lot of damage, especially if it's something which can spread straight from mussel to mussel. You know, if the mussels in the recipient population maybe don't have the same immune response that the previous mussel that that was introduced to it does, this could spread very quickly from mussel to mussel, and do a whole lot of damage. However, sometimes it'll also depend on the life history strategy of the parasite. You know, some parasites need multiple hosts in their life cycle. And so if those hosts are present or not, that'll determine how much damage these parasites can do. So we really need to understand not only our mussel populations, but also really need to look more at parasites and their life histories.

Adam - And so I get why this is important for mussels and how important mussels are, but is this work applicable beyond them to other animals?

Josh - Absolutely. So the principles that we talk about in our paper, we think they're relatable to any sort of translocation that we see. What we really want to emphasise in our paper is that, you know, an individual organism isn't actually just one individual, it's a whole community. It's a community of all the bacteria, viruses, worms, ticks, mites, et cetera, that live on it and in it. And if we want to transport organisms appropriately, we really need to appreciate that they do comprise these whole communities, and this will be true for any single animal that's moved. So it's not just mussels that this could be a threat to, any animal could carry parasites or diseases if we move it around and introduce it to new organisms.