This week in the Planet Earth Podcast – we take a closer look at tiny marine plants, which underpin the entire marine food chain and play a vital role in the Earth’s climate. Also, how scientists are using volcanic ash called tefra to tell how people may have responded to rapid environmental changes in the recent past. Like this podcast? Please help us by supporting the Naked Scientists (https://www.thenakedscientists.com/donate)
I’m Richard hollingham welcome to the planet Earth podcast from the United Kingdom’s most easterly point lowestoft where we’ll be contemplating the color of the North Sea also this time the secrets revealed by volcanic dust every glass from a single eruption has one composition one chemical composition which is Frozen at the time of the explosion and that composition acts like a fingerprint growing up in East Anglia I spent much of my holidays on North Sea beaches in biting wind like this and the water well it’s never looked that inviting here on the beach at lowestoft under to be fair a fairly clear sky the North Sea just looks Brown slopping against the Sandy Beach here but even the clearest seawater is teeming with microscopic life and that’s what Katy Owen from the University of East Anglia is studying you’re looking at phytoplankton now what is a phytoplankton phytoplankton you have to think of them a little bit like the grass of the sea they’re tiny microscopic plants sort of thinner in diameter than a strand of human hair and you find them everywhere in seas and oceans around the world hot cold water they’re tiny little powerhouses they photosynthesize and in dun they remove um carbon dioxide from the atmosphere and convert into organic carbon as part of their bodies so they’re really the base of the food chain in the sea exactly right yeah they underpin everything um they’re eaten by things as varied as crab ly U bacteria all the way up to fishes and whales huge huge range of animals eat them okay well let’s get a bit closer to the water and we’re not going to be able to see them presumably are we no no they’re very small in diameter really really thin thinner than a sheet of cling film so you can’t see them with a nak eye at all let me go get handful of water then whoa so I’ve got a handful of water and wet feet how many planks and are there in there is that is that really just full of Plankton absolutely teeming um you can have as many as sort of 20,000 um individual cells in just a mill of water so huge quantities in a very small amount of volume and you’re interested in this not just because it’s important for the food chain but its role in the global climate exactly right um because they photosynthesized it’s it’s really key they remove this carbon dioxide from the atmosphere and they take it out out of circulation they incorporate into their bodies and then as they die or are eaten by something else in the food web that carbon is recycled or it’s taken to the deep ocean so it’s out of the way it’s removed so it’s a really good way of reducing carbon dioxide levels in the atmosphere are they then a underappreciated sink if you like for carbon yeah I would think so I mean if you think about all of the publicity that the rainforests get which do a similar role but um obviously trees are much more obvious I mean you can take a quick glance and have a look at what’s going on with an ecosystem on land you can see the state of the grass you can see the state of the forest but fighter PL and you look at the sea and you have no idea what’s going on with them so it’s really important that we understand a little bit more about them so what are you doing before I ask that question let’s just move a little further away from the waves uh let me ask that question again what are you doing I use a machine called a flow sitomer um which is borrowed from biomedical research normally it’s used to scan blood cells but um I’m applying it to Marine Science and using it to count these phop Plankton why what what do you what are you trying to find out everything really we know very little about them because they’re so small it’s only really recently with the development of this machine that we’ve been able to count them properly in the past you know since the Victorian times we’ve looked down microscopes to count them but obviously that’s limited to what you can see with a human eye if you do it electronically with a machine you can count them much more accurately um You can count a much larger size range and you can count them a lot faster so using this machine it’s going to give you really sort of detailed image of what’s going on with phop plants and you know where they’re most abundant what makes them tick what nutrients conditions they prefer everything like that and I suppose that’ll give us a better handle on where the carbon is going how it’s moving around exactly it’s all to do with carbon cycling I mean that’s what’s so important we need to know whether it’s all small cells um which are more likely to be recycled within the surface waters or perhaps it’s you know concentrated in larger cells which are more likely to sink through the water column and be deposited in the deep ocean and we you might not see that carbon again unless there’s some kind of storm event could be hundreds of years well let’s get out of the the wind here to your laboratory which is up there on the cliff sure why not well here we are in the molecular biology laboratory at Seas Seas the center for environment fisheries and agriculture science and you have rather helpfully some flasks of phyto Plankton this looks completely green and this is presumably very concentrated this is a very concentrated culture this is um some cells that we grow here in the lab just for testing purposes and you can see how dense that is and normally you wouldn’t get that concentration in a natural sample here’s one that I collected from the North Sea last week and you can see that it is more of that typical North Sea color that’s really just an opaque brownish color yes yeah a lot of that will be sediment but it has been concentrated and there are quite a lot of fop cells in there as well so this one here this almost totally green one that looks almost like a rather nasty synthetic lime Aid that’s a plant essentially a plant in water lots of plants in water lots of tiny microscopic plants all together in um in the special media that we use to grow them so there’s so many of them because we enhance it with sort of the special vitamins that they need to sort of grow happily and next to them on the laboratory bench it’s this curious looking machine it’s about the size of a a beer barrel I suppose but with the outside exposed and it’s full of circuit boards and tubes it does look almost a device out of a a science fiction film yeah I get that a lot actually um it’s not normally like this when I take it to see it’s out of its protective casing um now that I’m here in the lab but it’s it looks horrible it looks really horribly complicated but it’s actually quite a simple principle it’s a machine it uses as a pump and we pump water a stream of water stream of sea water through the path of a laser beam and as the laser beam hits anything in that sea waterer such as debris or hopefully fighter plants and that laser light is scattered and we collect that information which gives us um a lot of details on the size and the shape and the structure and also the pigment content of the phytop planton cells so of individual phytoplankton so you can count them but you can also see the the size and the shape of them yeah that’s right yeah something that um we’ve been doing for a little while now here at CEST traditionally cfest is a great place for phop taxonomy we have a whole Lab which is dedicated to Counting phyter cells light microscope which is as I mentioned earlier something that we’ve done for hundreds of years now but the problem with that is that it only covers a very small range of sizes things that we call the Nano and the net Plankton which are from 20 to 200 microns but there’s a real whole wealth of phop planton below that size range something called the picop planton which are less than three microns so you know we’re talking a fraction fraction of the size of a human hair follicle and you can’t see them with a light microscope and they’re just just too small to be counted or identified at accurately so this machine is not only capable of measuring them we can also approximately identify them and um do thousands of these cells within a few minutes and so these Pico planks and have they been overlooked do you think yes definitely I mean we know very little about them within the North Sea just because they’re so hard to count we only really discovered that they existed about 20 years ago in in the 1980s the end of the 1980s um and we’re still discovering new species in fact this machine here not this one exactly but a machine like this discovered what is now a hugely important species called sne coccus and proclus which we just didn’t know existed and now is essentially vital in carbon cycling so are phytoplankton something we should all learn to appreciate a lot more definitely me I find them fascinating but you know I’m probably slightly biased but I find it amazing that things that are so small and so tiny um we know just so little about they’re so important and and we sail on them we swim amongst them every day but we know very little information about them so I think it’s really key that they become more appreciated and loved a little bit more Katy Owen thank you very much this is the planet Earth podcast you can see some photos of Katie and the beach here at lower stof on our Facebook page and for the latest news and features on the science of the natural world do visit planet Earth online to find both search for planet Earth online when a volcano explodes it ejects material known as tefra now this can range from rocks the size of cars to the smallest particles of Ash this ash can travel thousands of miles forming an invisible layer on the landscape but by studying these microscopic grains scientists can date archaeological sites and this can help clarify the effects of environmental and climatic change or even determine get this the movement of the human population within the last 100,000 years well Su Nelson met up with Dr Christine Lane and Victoria Cullen at the University of Oxford’s research laboratory for archaeology ology to find out more as they both work on the reset project which is investigating the response of humans to abrupt environmental transitions these are some samples that I collected in the field from various places which are from close to volcanic sources so a bit different to what we look at normally in this bag I’ve got two samples from leari which is one of the aolan islands from Italy and one of them is a pmus bit like you’d use in the bath very light light Rock full of air oh yes it’s it’s incredibly light and it’s got that rough scaly feel that you know you want to put on some hard skin oh and this is black and shiny yeah this rock is what we call an obsidian and it’s actually made of exactly the same material as this pmus it’s glass but it’s um got no air bubbles in it so it’s really heavy and it’s much denser so even though past is about the same size you’ll feel that’s a much heavier Rock W so they’re exactly the same yeah the composition is exactly the same they’re both formed from the magma from the eruption one flows out of the volcano and cools very quickly which creates a glass and one is erupted with a lot of gas in the eruption which causes a very explosive eruption so it’s full of bubbles all of these examples were found fairly close to the volcano itself but what we’re looking at in the lab here it’s the same material but it’s traveled maybe thousands up to maybe 3 to 5,000 kmers from the source so what we’re looking at now is volcanic ash rather than puses so it’s again it’s the same material just much smaller and you can see it looks much more like dust just particles of dust or very small grains like sand siiz grains and you have a specific name for this sort of scale this size of Ash don’t you all material erupted from a volcano when it’s erupted explosively we call tea and tea is actually the Greek word for ash so we use the word tea generally when we’re talking about this material in particular when it’s traveled a long way from the volcano Victoria you’re going to show me I want you exactly what that looks like as Christine says it’s actually glass and if you can imagine when you you break a glass in your house it fractures in very distinct ways very sharp edges and in some locations you get these Bubbles as well which also kept with in these glass yards so if I get some slides out for you now we can actually look at what it looks like down the microscope here we go if I get you to look down there and you can see some very pinky purpley looking shards of glass do you know what it reminds me of a child’s Kaleidoscope yeah very much it’s quite mesmerized if you were to find this in an archaological or environmental site you wouldn’t actually be able to see it physically looking at the site it’s invisible to an naked eye so this is why it’s called crypto or hidden secret tea also known as microa so when we look at certain sites because it’s traveled so far it’s so fine it’s so small when it’s deposited it’s just invisible to naked eye so we have to take samples down these sites take them into a laboratory process the samples and then we come onto microscope and actually look if te is there in first place so now that we know obviously that we’ve got tea because these are samples where you know they’ve got them where do you go from here we take them down to the micro probe and we analyze them for their chemistry every glass from a single eruption has one composition one chemical composition which is Frozen at the time of the explosion and that composition acts like a fingerprint so we can identify from a tea the composition of a te Shard which eruption it came from this looks like a sort of giant microscope effectively more than a meter high but with computer screens on either side and and a console yes this is our Electro microbe it is like a giant microscope but it works at much higher resolutions much smaller sizes but it also has four different what we call spectrometers and these are effectively the detectors that record the composition of the material we put in there okay if I just two the little grain to focus in on we can now um on the computer comp console we can have a look at that here and it looks quite complicated cuz there’s a lot of different columns on it but the one we want to look at is this column here which is the weight percent oxide um and this tells us for each element this sodium magnesium aluminium silicon these are all in Ash yeah these are just the what we call the major and minor elements so these are the main constituents of this ash there are other elements Trace elements in there but we can’t analyze those on this machine but usually with in this case nine or 11 elements we can fairly well characterize our eruption so you can see that the greatest composition is silica they’re silicate um materials like all volcanic rocks so silica aluminium sodium iron and potassium and sometimes calcium are the main elements that we’re measuring there’s one I don’t quite recognize TI it’s titanium titanium yeah titanium oide so some volcanic centers such as islandic ones have quite a lot of titanium oxide in their systems and what can you actually learn from analyzing these bits of Ash is tea we’re looking in records where we have a story already so we might have an archaeological site which tells a story of what the population in that site have been doing when they’ve been there what sort of um Behavior they’ve been doing what tools they’ve been making or we might be working in environmental records so sediments accumulated in the bottom of a lake over time which record changes in vegetation or the landscape around the lake Basin and by finding these te layers or the same te layers in different sites we can link link up those records so where we have a population in a cave and we find evidence for them just below a te layer if we find the same te layer in a late record that tells us what the climate was doing at the time that eruption took place we can infer that that was also that the climate at the time of that homin population was there so we’re using them as marker layers to transfer climatic and environmental information between sites Victoria you’re you’re looking at the same type of Ash the same tefra but slightly further field what I’m trying to do with my research is to use these teal a to look at sites in a specific region in the caucuses so that’s Georgia arm asan a small part of Southern Russia and the atias and it’s just between the Black Sea and the Caspian Sea our little land mass there and what we’re finding from these sites there is that sites that have been redated using radiocarbon um and now showing that the coexistence of these two species isn’t as much as we had previously thought so what I’m trying to do is use these teas to try and test about further because we can look at different sites from the same region on one time level with these teas I can see well first of all uh people or homies occupying the same space at the same time so I might find one te a in an upper pic cave site and then in another upper pic cave site might not find that now is that because it’s not getting into there or is that because there’s actually different times when people are exploiting this landscape so I’m trying to build up a picture about how people move around around this landscape and it actually can we prove that these two species co- inhabited the same space in the same time in this one region so does the ash help with everything else be it archaeological radiocarbon dating what have you does it is it act as sort of an extra test in a way in terms of learning whether different species coexisted yeah so the wondrous thing about teenology this ash dating is the fact it’s a blanket of time so we can look at sites across a massive geographical region and including environmental sites on one plane of time and see what was happening at that one time across say Europe for example so if I find an ash in one cave site and then find the same Ash in another cave site I know that was deposited at the same time so then I can look at the archaeology in both sites and actually start to directly compare them and whether that’s coexistence or not that’s where the questions come from Victoria Cullen and Dr Christine Lane from the University of Oxford talking to Su Nelson and we’ll put some pictures of Christine and Victoria on our Facebook page meanwhile right now on planet Earth online you can read about the engineering that goes into orangutang nests and discover how many emperor penguins there are in Antarctica among other things and that’s the planet Earth podcast it’s produced for the natural environment research Council I’m Richard hollingham thanks for listening