Podcast: Drugs and marine life
20 January 2015 by Richard Hollingham
This week in the Planet Earth podcast, Alex Ford and Stephen Short of the University of Portsmouth explain why we need to understand the effects of contraceptives, anti-depressants and other prescription drugs on marine organisms to protect our environment.
To assist those who find text-based content more accessible than audio, a transcript of this recording is available below.
Richard Hollingham: This time in the Planet Earth podcast, the creatures that are resisting a sex change. Hello, this is Richard Hollingham and I've come to the Institute of Marine Sciences at the University of Portsmouth which couldn't be better located. Just beneath the laboratory is the beach, the pebble beach overlooking the harbour. I've got Hayling Island ahead of me, the South Downs, to the left and the Solent over to the right and there's just gently lapping water and a very slight breeze this morning, even some sunshine. I am here to meet marine biologist, Alex Ford and Stephen Short who study the feminisation of marine organisms. Now, Alex, what do we mean by 'feminisation'?
Alex Ford: Well, we've known for quite some time that pollution in the environment can feminise a wide variety of organisms and in the past there have been some quite high profile cases of feminisation in fish caused by estrogenic substances such like in the contraceptive pill. We've known that over in the US that there has been alligators showing signs of reproductive abnormalities and even below our feet just here we have some snails which back in the 1970s and 1980s were completely eradicated by some chemicals that masculinised female snails and these chemicals were in paint-based substances.
Richard Hollingham: And these are tiny concentrations of these chemicals, and we're talking about here, it's the sea, it's not even a river from a sewage works or anything.
Alex Ford: Pollution can enter the sea from many sources. Obviously a lot enters rivers and then the ultimate repository of rivers is estuaries and then down into the sea. It gets diluted as it goes but some of these chemicals we're talking about can have an effect at extraordinarily low concentrations.
Richard Hollingham: Now, Stephen, your latest research focuses on a particular organism, a crustacean that you've also sequenced the genetic code for and we've got it here this little organism.
Stephen Short: Yes. We know so little about the molecular basis of these organisms and we know so much more about vertebrates, we know very little about these, so the first thing to do was to actually sequence, in fact, what we call the transcriptome, all the genes that are being expressed in all the tissues just so we have a resource that we can use to monitor reproductive dysfunction and any other kind of dysfunction actually.
Richard Hollingham: We should describe this - it is shrimp-like, not a shrimp but shrimp-like. We've got it in a dish here and you can find them on seaweed all around the beach and I suppose it is about the width of my little finger, something like that.
Stephen Short: Yes, they come in various sizes, so you do get versions in the deep sea that are huge but this is the average run of the mill amphipod - we would call that. Yes, they occur in estuarine, fresh water, inter-tidal environments which is quite useful actually because those are the environments that you tend to impact with pollution and effluent, so in that sense they are well placed for monitoring those environments and they are easy to find as well, easy to collect.
Richard Hollingham: Now, I said shrimp-like, what is it actually called?
Stephen Short: It's an amphipod. Shrimp just means 'small thing' really so shrimp is good for me, I have no issue with shrimp. Technically an amphipod.
Richard Hollingham: You've sequenced the DNA of this, the genetic code of this, and you have found it is doing something interesting with this issue of feminisation; it seems to be locking in its maleness, if you like.
Stephen Short: Yes. So we looked at animals we call intersexes and they are clearly feminised, they have brood plates on the outside which is normally in females and they a oviduct on their testes, but actually when you look at the molecular level, yes, there are a lot of females genes switched on as you would expect but we couldn't find any decrease in the male genes. So, in other words, they seem to be able to be completely male whilst having an awful lot of feminisation going on.
Richard Hollingham: So it might look slightly feminine but actually when you probe down and look at the genetics it is actually pretty male?
Stephen Short: Yes. I would say it is probably best to describe the intersexuality as feminisation superimposed on a normal male effectively - that's how I would describe it. It is quite important in trying to work out whether the intersexuality is dysfunction. I mean are these animals that are intersex are somehow not reproducing correctly, and so to understand what is happening to its male genes is obviously quite important. What, Alex, do you think is going on looking at what Stephen has found with this research?
Alex Ford: Well, when we go and look in the environment and we've done this over a decade now and when we look in clean and polluted sites we do find an increase number of these crustaceans that showed signs of reproductive abnormalities. We haven't had the resources in the past to actually go and determine which chemicals, if any, is the cause of these reproductive problems such as intersexuality that Stephen referred to. Now we know that some of the intersexuality in these populations of these little creatures is caused by parasites and there is a fantastic little parasite that has the ability to feminise these crustaceans and convert a male entirely into a female and when it doesn't quite do the job correctly it leaves them half male and half female as an intersex. So we know we have an increase in these parasites and polluted sites but we also see an extra proportion of the population which we intersex but don't have the parasite.
Richard Hollingham: I love this word 'intersexuality'. When you were looking at this, Stephen, there is an evolutionary pressure already on these to combat, if you like, this feminisation because of this parasite.
Stephen Short: Well, yes, quite possibly. I mean it could well be that there are strong evolutionary pressures on the animal to prevent itself from being feminised and is useful from the point of view of its battle with the parasite, but it is also potentially useful if there are feminising contaminates in the environment, it may have some capacity to maybe reduce the impact of those kind of chemicals.
Richard Hollingham: So, Alex, what are the implications of this research? I understand you are quite at early stages at the moment but you've done a lot of background work already on feminisation of various species in the marine environment.
Alex Ford: Now we have this toolkit to go and assess where the crustaceans are being feminised, being masculinised in their environment. We've gone back to a number of key locations around the UK and selected some specimens and we're going to look at the genes in them to see whether there is any indicators of them becoming less male, more female and whether we can attribute that to a polluted estuary versus a clean estuary.
Richard Hollingham: What can you actually do with this information? Is it something for policymakers to use?
Alex Ford: Yes, certainly. Whenever a new chemical comes on the market and it has to get a licence to be released into the environment we want to know whether it is going to be safe, whether it is going to impact the organisms which might come into contact with it. So in the past we would never have been able to assess whether a chemical might affect the reproductive health of a crustacean, now we have the tools to do that.
Richard Hollingham: Now there is another aspect to this. We've talked about feminisation and the chemicals such as contraceptives causing that or leading to that. Antidepressants in the environment are another factor as well.
Alex Ford: Yeah, here at the University of Portsmouth we have been doing quite a number of these recently where we've been looking at effects of antidepressants. Just as you've mentioned we have found contraceptive pills, we find anti-cholesterol drugs in the environment, we also find a lot of anti-depressants as well and by sequencing the whole transcriptome of this little amphipod we've got just the reproductive genes, we've got the nervous system genes, we've got the immune system genes, we are now able to find and determine the effects of chemicals on those other biological systems within these organisms and it just so happens that antidepressants do affect the gene, the behaviour, the physiology of the shrimp as well.
Richard Hollingham: Are all these things we should be concerned about and can do something about, ultimately, removing them perhaps from the environment or stop putting them into the environment.
Alex Ford: I think there are a number of things we can do. We can probably improve the sewage treatment process because a lot of the drugs that we consume end up in the sewage treatment plant, they don't get fully broken down and they up being put back into the environment. There is probably technology improvements that can be made there, although they are very expensive. Us as consumers of these pharmaceutical drugs we could maybe dispose of them better. In some countries it is mandatory for people to take them back to a pharmacy for them to be disposed of appropriately, whereas I think in the UK they tend to end up in somebody's waste bin or in the local landfill site or something like or even flushed down the loo which then just goes back to the sewage treatment plant.
Richard Hollingham: But by decoding the gene of this tiny little creature that is swimming around in your Petri dish there, so we are going to release before the end of the podcast? Are you actually making progress do you think or least understanding what is going on?
Alex Ford: Yes, certainly. I think we are really getting a handle on how low some of these chemicals can be that can actually effect some of these organisms which then in turn will feed back into policy in ways that we can better protect our own environment.
Richard Hollingham: Alex Ford and Stephen Short here at the University of Portsmouth, thanks very much, and we're going to release now the amphipod... and there it goes. Pictures of our recording today, as ever, on Facebook and Twitter... I've just realised I've failed to take a picture of the amphipod! And for more news from the natural world do visit Planet Earth online and that is the Planet Earth podcast from the Natural Environment Research Council. I am Richard Hollingham from the beach here in Portsmouth - thanks for listening.