Scientists put a salt marsh in a giant wave-machine: here's what they learned

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0:37AI has turned the threat landscape into quicksand, moving too fast for any human to fully predict. That's why an agentic cyber resilience platform matters. Automated recovery, clean data, a business that keeps moving no matter what hits. One platform, not a patchwork of stitched together tools and gaps. Don't wait for the next attack. Secure and accelerate your business at Rubric.com. Again, Rubric.com.

1:26Welcome back to the Nature Podcast. This week, simulating how salt marshes respond to storms and learning more about what Denisovans looked like. I'm Benjamin Thompson.

1:48Salt marshes are a particular type of ecosystem. them. They're found in coastal areas all over the world, and they're tidal, meaning they regularly get flooded or inundated by the sea, hence the salt. These landscapes, often dominated by grasses, are vital habitats for animals like seabirds. A lot of salt marshes have disappeared due to things like land reclamation, but they're increasingly being considered as important parts of coastal defences against storm events. In some cases, artificial defences like dikes, levees or seawalls weren't designed for a changing world or haven't been adapted in the face of it, and big waves during a storm surge can overrun them.

2:37Salt marshes, however, can help. They're often higher ground than the surrounding seabed, and the plants that live there act as natural breaks, slowing oncoming water and attenuating, or taking the energy out of, waves. But while a lot of research has gone into understanding how salt marshes can act as coastal defences during regular storm events, there's not as much known about what effects these ecosystems might have, and indeed whether they might stand up to, truly monster storms. The kind of once-in-a-hundred years or once in a thousand years extreme events that are expected to become more common as time goes on.

3:18One of the issues with figuring this out has been that, well, these events don't happen very often. So to find out how salt marshes might fare, a team of researchers has come up with a different approach. So yeah, the storm wasn't brought to the marsh, but we brought the marsh actually to a facility where we were able to create this kind of super storm indeed. This is Pim Willemsen, from Wageningen University and Research and from Deltares, both in the Netherlands. He's part of a group who have used an enormous wave machine called the Delta Flume to pummel a sample of salt marsh in simulated storms.

3:57I called him up to find out more about the research and he explained the efforts the team went to to set up their experiment. We tried to get this marsh, intact pieces transported from the Wallen Sea area, so all the way to the north of the Netherlands, back to Delft, which is actually close to the southwestern delta of the Netherlands. We had to really put this in a restricted time window because we had to wait until breeding season was over to not disturb the birds. And we had to get out before the storm season started because yeah, then the chances are rather high that a marsh gets inundated again.

4:37And we had to be on the marsh with trucks with 50 ton cranes to lift out almost 70 blocks of two by two meters with a depth ranging from 40 to 70 centimeters. So we transported 20 truckloads from the marsh towards the delta flume. Wow. And talk me through this facility then. In this Delta Air's Delta Flume is a wave basin. So let's say a big swimming pool with a length of 300 meters and a height of 9.5 meters. And there's a big paddle at one side that is called the wave generator. And that is able to generate these high waves and move all this water. So I think it can hold 9 million litres of water, which is the equivalent of almost four Olympic swimming pools.

5:29And you've used it to do a series of runs where the salt marsh you built, essentially recreated in the flume, was subjected to waves of different heights. What did you see then in these runs? So when the flume was drained, we really saw that after each run, a lot of vegetation was still straight up. And we also saw that after the really high waves of two meters, a lot of the vegetation was still straight up, but it did progressively damage over time. Still at the end of the full study, we saw at every block that we collected that vegetation stamps were standing and were able to contribute to wave attenuation.

6:09And in addition to that, we saw that the substrate also remained intact. Of course, mud particles and sand particles got up. But on average, we didn't saw a lot of erosion. The erosion was only seven millimetres on average. So the sediment survived these storms and the plants did too, but obviously got damaged. What did these plants actually do then to attenuate, to lower these waves? The wave went travelling over the marsh. Fuels, friction and results in a decreasing wave height. We saw that the vegetation with waves of 75 centimeters was, at the start of the experiment, able to attenuate 20 % of this wave height.

6:53But also the higher waves at the end of the experiment with a lot of vegetation damage, there was still a couple of percentage of the wave height that was attenuated by the vegetation. And can you imagine it's just sticks standing straight up, let's say, or stems with a bit of leaves. and that is apparently able to attenuate a little bit of the wave of two meters that is yeah going over this vegetation and i guess that could actually make a big difference in terms of does the water go over the top of the human built structure that sort of thing yeah exactly that might help a lot and it is for these two meter waves it was at the potential peak of a storm only a couple of percentages but at the same time for the lower waves a lot has attenuated so if 20 % of a wave of 75 centimeters is attenuated.

7:41Well, that is quite a lot. And to give a practical example, the results are also being used in a dike strengthening project in the Netherlands where the dikes need to be improved, let's say up in the north where we took the marsh. And there it really results at some locations that the clay layer on top of the dike might be 10 centimeters smaller. And then you can say, well, 10 centimeters is not quite a lot. But if you do that over a dike stretch of 15 kilometers for a dike that has a height of, let's say, eight meters, well, then the savings go towards millions. So in that sense, if the salt marsh is already there and we now prove that it remains in place and that the vegetation can contribute also during these extreme waves, well, then it really starts to count.

8:30And we've talked a lot about what you've seen there in the Netherlands, I suppose, like these salt marshes are very good at attenuating the strength of the wave height of moderate storms, not quite as effective at very big storms, but still have some effect. You've actually taken the data that you've gained here and tried to extrapolate it out to other places. Now, obviously, there are many environments like this around the globe. What was the sort of take home message from that bit? What we then globally observed was if we extrapolate our results using a statistical model, we really saw that with these lower waves heights up to one meter, the marshes are able to contribute as much as in some locations, 50 % of wave attenuation.

9:11But as soon as the wave gets higher, it attenuates up to 10%. percent. But still, we saw from this practical example in the Netherlands that it can still contribute a lot to how you build a dike at the back of this marsh then. And so you've got your data then, which is based on a salt marsh on the coast of the Netherlands in winter. From what I understand, this marsh is dominated by one sort of plant, by one sort of grass. And it obviously has the sediment that is present. I'm imagining that salt marshes around the world do look very different so how applicable is what you found here do you think to other places around the world yeah so that is very fair to say what we did was wait till the end of the storm season to start the test so the natural degradation of the vegetation through a winter season already happened so in that sense we got a conservative estimate of the state of the vegetation we didn't test it at the end of the growing season for example and it is still strong and green and so on and we did also additional tests in the flume that is described in another paper where we added lots of different vegetation species and also there we saw that the biomass only decreased by a 30 percent every wafer and so we really saw the same results then so from a vegetation species i think we are rather on the conservative sides the substrate we have here has been built up year after year layer after layer the growth is mainly driven by minerals there are other marshes globally that are driven by organic growth by the vegetation themselves so that also results in a different erodibility so the global assessment that we did it gives first insights of where potentially vegetation can contribute to wave attenuation but it definitely needs a local assessment as well and that then maybe informs what build defenses need to look like in addition to the salt marshes Is that fair?

11:08Yeah, or you can see it the other way around, what we can prevent in terms of structures and how we can better use the salt marshes that are already there. And if we now prove that these salt marshes actually have this additional function, we might better think about how to keep them the way they are. This is a very positive message in how this ecosystem is not only good for biodiversity, which is already very important to start with. but you can gain more from it by leaving it there as it is already. Pim Willemsen there. To read his paper, look out for a link in the show notes. Coming up, what the study of ancient proteins is revealing about one of our enigmatic ancient relatives.

11:55First though, it's time for the research highlights with Dan Fox.

12:02Orangutans are the most solitary of the great apes. But despite this, a new study has found that orangutan mothers will go out of their way to arrange playdates for their kids. Researchers analysed 15 years of behavioural and movement data from 31 mother-offspring pairs of Bornean orangutans in Indonesia. They found that mothers with similarly aged young tended to spend more time in the same areas of forest than did does whose young were further apart in age. Young orangutans who were close in age also tended to play together more often than did does with a larger age gap. And on days when their offspring played with peers, mothers travelled farther and spent less time feeding than on other days.

12:49They also tended to move towards potential playmates the day before an encounter, returning to their usual territory afterwards. The authors say these findings suggest a previously overlooked way in which orangutan mothers support their young's social development. Arrange a date to read that research in the Proceedings of the National Academy of Sciences of the United States of America.

13:18Traces of lead preserved in human teeth have provided a snapshot of inequality in medieval Europe. The Peak District in the UK was one of the largest lead-producing regions in Europe during the Middle Ages. To better understand the labour dynamics during this period, researchers analysed teeth from 15 people who lived and were buried in the Peak District in the early 7th to early 16th centuries. The team looked at chemical signatures in the tooth enamel. Lead accumulates in enamel early in life and doesn't dissipate over time, acting as a time capsule of childhood exposure. People buried with high-status goods, such as crystal amulets and swords, had lower levels of tooth lead than did does with less decorated burials.

14:07This indicates that the latter grew up and worked in lead-tainted environments, suggesting that lower-status citizens were responsible for mining and smelting lead, whereas wealthy elites had less direct exposure. You can find that paper in Antiquity.

14:32there's a paper out in nature this week that's looking to shed some more light on a group of our ancient relatives namely the denisovans nature's rachel fieldhouse has been covering the story and she joins me now from sydney australia rachel thanks as always for being here thank you for having me so yes this story is ultimately about denisovans but also it's about helping to solve a mystery of sorts related to some ancient hominin remains discovered in Shujao Yao in China in the 1970s. Tell me about this trove of remains that was discovered. So we had this collection essentially of 20 cranial fossils and teeth, jaws that were found in northern China.

15:12And they were also found with some cultural artifacts and some animal remains. As far as we know, they're at least 130 ,000 years old. So they're one of the earlier examples of ancient humans that we have. But we, until recently, have not been able to identify who they were or what kind of human they were. And so what species these bones belong to was something of a mystery then, and folk attributed them to various different ancient hominins, right? And so to try and maybe figure out what they were, in this paper, the researchers looked at a couple of bones that had been uncovered then back in the 70s and studied the proteins that they could find?

15:50Yes. So they started off by doing a technique called paleoproteomics, which is the analysis of ancient proteins. One of the benefits of this technique is that proteins tend to last a little bit longer than ancient DNA does. So it can use a bit of insight for older samples where the ancient DNA might've already degraded and be too poor of a condition to actually be analysed. What they did was they looked at tiny pieces of proteins called peptides that were from some of these fossils. And when they compared the Xu Jiao fossils to other Denisovans samples, they found that in particular, a single amino acid change on some of the peptides was also found in some of the samples that are known to be Denisovans.

16:33So from that, they were able to conclude that the Xu Jiao samples were Denisovans. And of course, contamination is always a potential pitfall in studies like these. But in this case, the researchers were looking for the hallmarks of how a couple of amino acids could become chemically altered over time. So yes, they were looking at a particular process called deamidation. So this tends to happen as proteins age. By looking for peptides that had these residues, they could be sure that the peptides were actually from the fossils themselves and had been aging over time. They weren't contaminants. They weren't any other thing that was potentially modern human, or just anything that wasn't actually belonging to that fossil.

17:15Now, researchers only uncovered the existence of Denisovans about, what, 20 years ago, and that was via, I think, a single finger bone found in a cave in Siberia. And other bones have been found since, and researchers have been trying to piece together more about this branch of our family tree. What does this work do in that regard? What light does it shed on the Denisovans? Well, part of it is that it shows that the territory and where Denisovans were is a lot bigger than we'd previously thought. So there was more of these Denisovans in East Asia. And additionally, this work gives us a sense of who they were at like a molecular level and also at a physical level when they started to look at the morphology of the actual bones and how they compared to modern humans and Neanderthals and sort of what made Denisovans special.

18:03Right, because a lot of these bones that were uncovered in the 70s were cranial bones, were pieces of skull. And the researchers have tried to piece these together to give an idea of what some Denisovans at least might have looked like. That's right. So this study gave us a general idea of what the Denisovan looked like. Maybe you frame it as sort of the average Denisovan, because previously this team had a single individual, the Harbin individual, and they've since taken that one and the Shuja Yao fossils, and they started to get a picture of the common traits. So for instance, Denisovans had a low sloping forehead, a pronounced brow ridge, and then for the bridges of their nose, it was a flat, but moderately elevated bridge.

18:44And they then compared what they were seeing there with what we can see in Neanderthal skulls and modern human skulls. And they found actually that Denisovans had a mix of different features, some found in Neanderthal, some found in modern humans, and also some other ancient species like Homo erectus. That's another one that has since gone extinct. But for example, with the Homo erectus, they shared a thick cranial vault. That's the thick part of the skull that encases the brain and protects it. And this work continues to shine a light on how our ancient relatives may have lived. And of course, now maybe what they would have looked like in terms of the Denisovans.

19:19What have researchers you've spoken to about this work told you? They've been generally very excited. It's very exciting to them that we can finally, as one researcher put it to me, start to put a face to the Denisovans' name, really. And they were also excited because, I mean, this team has shown that using paleoproteomics is a viable and useful tool and it can complement existing tools that we already have. The researchers behind the study, when I spoke to them, they were quite excited and really looking forward to using this technique and were hopeful that this technique could be really useful for identifying more fossils that were denisophant, so fossils we've already discovered but have an unknown identity, and also the potential use for new fossils that have emerged that are very old but have only recently been discovered and being able to quickly identify who they are rather than leaving them in this mystery category.

20:11For the Shuja Yao samples, they've been in this mystery category for decades. They were also telling me too that one of the outcomes from this study for them has been settling the debate about who these humans were, who they belonged to, who their relatives were, and how they were related to us. nature's Rachel Fieldhouse there head over to the show notes for links to her story and the research paper we talked about and that's all for this time if you'd like to stay in touch with us you can we're on email podcast at nature.com or you can find us on social media at nature podcast I'm Benjamin Thompson thanks for listening

20:58State fair food is getting smaller and pricier. We'll have room for fried cookies. Okay, you never overspend on food. What's your deal? What's his deal? He went to Metro and got$450 in value on the new Samsung Galaxy A37 5G for free. And no activation fees. Free phone? Oh, sign me up. Get that more for your money feeling. Only on Metro by T-Mobile. Free your number and activate$40 period plan. $450 based on device discount waived activation fee. Not available if with Metro or T-Mobile in the past 180 days. Rubrik is the security and AI operations company built for what happens after an attack hits, not just the moments before.

21:35AI has turned the threat landscape into quicksand, moving too fast for any human to fully predict. That's why an agentic cyber resilience platform matters. Automated recovery, clean data, a business that keeps moving no matter what hits. One platform, not a patchwork of stitched together tools and gaps. Don't wait for the next attack. Secure and accelerate your business at Rubrik.com. Again, rubric.com.