Professor Alex Ford smiling wearing blue shirt on beach, Life Solved logo in left hand corner

Professor Alex Ford explores how behaviour of sea creatures changes when zombie-like parasites thrive in polluted waters

  • 16 November 2020
  • 16 min listen

When you pour a medicine down the sink or flush it down the loo, where do the chemicals end up? Professor Alex Ford has been exploring how the behaviour of sea creatures changes when zombie-like parasites thrive in polluted waters, even causing their hosts to change sex.

You can listen to Life Solved on all major podcast players, whether via Apple, Spotify, Google Podcasts or other apps. Just search for 'Life Solved' and press the subscribe button.

Headache tablets, statins, things for cholesterol or things for hay fever or contraceptive pill.... they end up into the nearest river...we drink that water. We use this water recreationally.

Professor Alex Ford, Professor of Biology

Episode transcript:

Narrator: Thanks for downloading this podcast from the University of Portsmouth. Wherever you are, the chances are you're listening to this because you're the sort of curious person that can't resist a new idea, a little intrigue, a way of doing things differently. And whatever your interests, we hope not to disappoint. Research taking place here at Portsmouth is changing the world. Experts and innovators here collaborate with the finest minds in education and industry to make a difference. A biology PhD was studying creatures in polluted waters when he noticed a strange effect on the local shrimp population. It was to become an investigation that would span his career. Our interviewer John Worsey found out more.

Alex Ford: We found at those polluted sites there was no aquatic crustaceans that didn't look quite male, didn't look quite female. When we looked more into that, it was quite a confusing picture because these are parasites and some of these parasites we later found out, had the ability to change the sex of a male to a female.

Narrator: No, this isn't the latest Jurassic Park reboot. This is real life. Zombie parasites are taking over sea creatures, changing their behaviour and even changing their sex.

Alex Ford: We've found quite a few number of new species of parasites that change sex and change behaviour. Out on the shore out here, there's a little crustacean about this big and it has a parasite in its body that makes it swim out into the light. And it does that because it needs to be eaten by a bird or fish to complete its life cycle.

Narrator: That's Professor Alex Ford, a marine biologist at the University of Portsmouth. He discovered this bizarre event happening right under our noses along the British coastline. But it begged a serious question. If these mystery parasites are causing such dramatic changes in the creatures at the bottom of the food chain, what does it mean for the rest of us? This is what happened when one scientist set out to find where the parasites were coming from and how they were taking over the sea creatures. He wanted to find out how they might be passed on up the chain and crucially, what sort of effects could these zombie parasites have upon you and me?

Alex Ford: We're very fortunate here to be right on the coast and to have the Institute of Marine Sciences. We're one of the only universities to have a facility right on the sea where we have seawater on tap and have the lab facilities we've got. We have protected sites, special areas of conservation and around the coastline here. So we've got lots of protected areas, but we've got lots of impacted areas as well.

Narrator: Professor Alex Ford has been at the University of Portsmouth since 2008. For some time, marine biologists have been concerned with just what impact chemicals can have on environments when human action puts them in places they shouldn't be. Sadly, the consequences of seemingly innocuous uses are often only evident after the damage has been done.

Alex Ford: We banned paints: Tributyltin that used to be on boats in the 1980s because it was causing sex changes in snails and it wiped out snail populations around the world, hundreds of different species of snails around harbours and ports where there are lots of boats because this paint was rather toxic to female snails and it made them grow a penis and then they die.

Narrator: Poor old snails. Although the population is slowly returning to the harbour, some 30 years later, pollutants can remain in seabeds and soils for a long time, and activities like dredging can bring them up all over again. Alex began to study the parasites and quickly found out that they controlled the behaviour of the shrimp by acting on their serotonin levels. Serotonin is found in human bodies too. This neurotransmitter hormone affects our behaviour and some commonly used human drugs are designed to act upon it for this reason.

Alex Ford: So in the past, we were concerned about chemicals that act like oestrogens getting into the water and changing the sex of fish, for instance. Now we're concerned about other chemicals that might interfere with behavioural hormones in aquatic organism and change the behaviour. That got me interested instead of drugs that might be involved in changing the sex of aquatic organisms, to drugs that might be involved in changing the behaviour. So then we started researching the effects of antidepressants on aquatic organisms because antidepressants control serotonin. Some of the crustaceans we studied get more active and they appear to spend more time in the light than they do in the dark. Other people have done studies where they've shown fish have become more or less aggressive or they've shown greater exploratory behaviours. So if you've got a fish tank in your house and you go and buy a new fish from the pet shop, when you put it in your tank, it will sort of stay hiding in the corner for some time and then it ventures out. If you give some of these fish some drugs that control their anxiety, they'll move into the centre of the tank a lot quicker. If I had a tank here with the parasites in that could change the behaviour, all the ones without the parasites would be at the bottom, all the ones with the parasites would swim near the top. Or if I had a little stone in that tank, the ones that without parasites would be underneath the stone.

Narrator: So antidepressant chemicals in the water can influence the behaviour of the sea creatures just as much as they do humans with the same neurotransmitter pathways. Its discoveries like this that make it worth exploring the impact of human activity on our marine environments. But there is a bigger picture at stake too.

Alex Ford: Headache tablets, statins, things with cholesterol or things for hay fever or contraceptive pill, we take these, they don't get fully broken down by our stomachs, they come out with our urine, end up in a sewage treatment plant. They don't get fully broken down there because of those sewage treatment plants weren't designed to cope with these pharmaceutical drugs. And then they end up into the nearest river and then into the estuaries. And even though they're in minute concentrations, they quite biologically active compounds. So they don't need to be in high doses to have an effect on the things that are swimming in them and drinking them. We drink that water, we use this water recreationally, the food that we eat, a lot of people eat fish and a lot of fish is taken around coastal areas or in rivers and things. So this all feeds into the food webs which is all very much dependent on those things lower down the food chains. It's incredibly important you knock out the food and our food sometimes disappears as well.

Alex Ford: We have made over thousands and thousands of manmade chemicals, many which were put out into the environment before there were proper processes in place to test what the impacts, what might be in the environment. So we've let loose all these chemicals in the environment, which many of which we don't know how harmful they are. And they were put out before legislation that came in where you have to put them through strict tests before they were given licences to be let in the environment. So it's very much playing catch up because there's just so many chemicals. It's impossible to go and look at them all. So it's trying to design ways of going, what are the priority, which are the ones that we should focus our attention on? And that is probably what we need to work out, where we are with that? How do we go about that best?

Narrator: Part of that catch up is using new scientific techniques to be able to understand the impact of pollutant chemicals on the world around us. It's this sort of development that has allowed Alex and the team at Portsmouth to break new ground and deepen our understanding of just how our chemical waste and water supply is connected to the health of everyone and everything involved.

Alex Ford So when we started off, we had a small little shrimp of which we knew nothing about. We were able to sequence all the genes in that shrimp and not only sequence them, we could differentially look at what genes were switching on and off in a shrimp which did or didn't have parasites which could change the sex or were exposed to chemicals that could change that sex as well. So one of the things that we contributed to is creating this toolkit of things that we could measure, that we could tell, whether its reproductive system was being impacted, its nervous system, its immune system, which we never had before because nobody had those molecular tools. So now we've got them, it's kind of opened up whole new areas of where our science can go, which is fantastic.

Narrator: So how to use this tool kit and where should we begin?

Alex Ford: I think it's probably in applying now what we've learnt and using these tools to go back into the environment and see whether we can see these changes going on because in the past, we couldn't we didn't have the things to measure in the environment to see whether things would changing. Now we've got these, from all our laboratory work, we can now go back into the field and see those changes.

Alex Ford: And the other thing that's quite interesting is, is seeing how organisms adapt over time. We go to lots of very polluted sites, but there are still organisms there. So while they have this amazing capacity to adapt to change and all the nasty things as humans do to them. So it's kind of learning how are they changing, have they got this ability to live in this chemical soup that they live in?

Alex Ford: We've had a number of projects running at the moment. One of them has been looking at the effects of radiation at Chernobyl and Fukushima, to see whether there is still lasting effects of the nuclear plant that exploded 30 years ago in Chernobyl and the accident that happened in Fukushima more recently. Whether we can detect abnormalities in the invertebrates that live in the lakes and shores around Fukushima. We have been looking at the effects of pollutants that come out of sewage treatment works, both in the U.K., we look upstream and downstream of sewage treatment plants in here and in areas across Europe to see whether they're affecting the aquatic invertebrates, which, of course, are the food for all the fish. We've had studies that look at and try to develop ways of analysing the behaviour of aquatic organisms.

Narrator: There are still plenty of questions to be answered as to how we can use our discoveries to moderate the use of certain drugs. But how do you choose which one to study first?

Alex Ford: There's no point looking at the effects of a drug in the environment if it's hardly prescribed and harder to get into the environment. So we know what drugs are more prescribed than others. So you can start looking at them because they're perhaps more likely to be found in the environment. We can look at how quickly they break down in the environment because if it breaks down really quickly, then that can be a good thing. Unfortunately, a lot of these drugs don't break down very quickly because they've been designed to actually be taken orally and survive going through your stomach before they get into your body. So they've been designed in the opposite way and that's one of the problems, is that they don't break down sewage treatment plants either and then get into the environment. But you can also have an inkling that if there's a drug like antidepressants, for instance, because the nervous systems are very conserved throughout the animal kingdom, so a crustacean has the same neurotransmitters as a human that controls its behaviour. So you can kind of make an assumption that if this drug affects this hormone in us, it could well affect this hormone in this crustacean as well. We don't know what effects it might have. It's because that hormone might have multiple functions in crustaceans and many of them do like serotonin is involved in our behaviour, but in a crustacean, serotonin could be involved in the metabolism of sugar. It can be involved in their behaviour, their ability to grow and moult and the colour changeability. So you can have a hormone in a human that can be involved in colour change, so it can have multiple effects in another organism.

Narrator: It's true that a great deal of damage can be done when we harness natural or synthetic chemicals to solve one problem and inadvertently create another. How do we halt the potentially irreversible damage done by human chemicals entering our waters every day? Alex explained what he thinks needs to change.

Alex Ford: One of the things is awareness. You can see how the change in behaviour with plastic has changed people's behaviour, and that comes around by just awareness and education. All of us will probably take in many plastic bags every single week out of our supermarkets. We managed to stop that pretty quickly, I think by 90% in England, Wales and Scotland. So we can change. We do have this ability to change. People are stopping using plastic straws and various different things and just thinking, I think and it's the same with any products that we use that may potentially harm the environment. A lot of people still chuck their pills down the toilet when they don't use them, or chuck them in the bin, whereas we could take them back to our pharmacy and they'll get appropriately disposed of. Most people I know don't. And that's very varied that take up of taking pills back to the pharmacy across Europe, it's hugely variable, it doesn't have that much. And that's one way we can stop some of these pharmaceuticals ending back up in the environment. Sewage treatment plants could be upgraded, but they cost billions to run that out across a region. So there are improvements that can be made technologically to improve. There are behavioural changes that can be done with humans where we could just not end up chucking things into the environment unnecessarily.

Narrator: Plenty of fascinating answers, but a few more questions too. How will different nations and environment agencies interpret the findings to regulate the distribution of chemicals into the natural environment, and what legislation needs to come into force to make sure that can happen? There's still a long way to go before the crucial findings from the research of Alex and his contemporaries can impact our natural world. But it seems there's no time to lose when the stakes are this high.

Alex Ford: Where do they set the benchmark what they aren't and are allowed in? So most pharmaceutical drugs don't have any benchmarks. Oestrogens do because of the work that was done in the 1990s on feminisation of fish. The vast majority still haven't. For instance, you might be exposed to a chemical which might have no effect on you but it might affect your offspring, or it might affect your offspring's offspring. And these tests cost a lot of money to do for companies. They're very complicated and sometimes they need to be done.

Narrator: Thanks for listening to this episode of Life Solved from the University of Portsmouth. You can find out more about the work of Alex and his team, as well as our other projects, by going online to

Narrator: Next time we'll be delving into the research that's future proofing a fundamental part of modern medicine.

Anastasia Callahan: We're trying to understand molecules that are important in antibacterial resistance so that we can have the next generation of antibiotics.

Narrator: Make sure you subscribe in your podcast app to get every episode of Life Solved automatically. And please do tell us what you think with a review and rating if you get a moment. From the team in Portsmouth, thanks for listening. We can't wait to share another fascinating discovery next time.

Previous episode

Next episode