The swimming habits of gelatinous animals are inspiring underwater vehicle design

Peer-Reviewed Publication

UNIVERSITY OF OREGON

 

IMAGE: PHYSONECT SIPHONOPHORES, MARINE ANIMALS RELATED TO JELLYFISH, SWIM VIA JET PROPULSION. view more 

CREDIT: PLEASE CREDIT THE SUTHERLAND LAB.

A gelatinous sea creature could teach engineers a lesson or two.

Nanomia bijuga, a marine animal related to jellyfish, swims via jet propulsion. A dozen or more squishy structures on its body pump water backwards to push the animal forward. And it can control these jets individually, either syncing them up or pulsing them in sequence.

These two different swimming styles let the animal prioritize speed or energy efficiency, depending on its current needs, a team of University of Oregon researchers found. The discovery could inform underwater vehicle design, helping scientists to build more robust vehicles  that can perform well under a variety of conditions.

The UO team, led by marine biologist Kelly Sutherland and postdoctoral researcher Kevin Du Clos, report their findings in a paper publishing November 28 in Proceedings of the National Academy of Sciences.

“Most animals can either move quickly or in a way that’s energetically efficient, but not both,” said Sutherland. “Having many, distributed propulsion units allows Nanomia to be both fast and efficient. And, remarkably, they do this without having a centralized nervous system to control the different behaviors.”

Nanomia shares the gelatinous, ethereal form of its jellyfish relatives. But it’s a little more structurally complicated: Each one is technically a colony of individuals. For instance, each of Nanomia’s jets is produced by an individual unit called a nectophore. The nectophores are clustered on a stalk-like structure at the front of the animal. Meanwhile, wispy tentacles trail behind, carrying structures specialized for feeding, reproduction, and protection.

While many marine creatures move via jet propulsion, squid and jellyfish included, most just have one jet. Nanomia often has ten to twenty—the exact number varies colony-to-colony.

“We're interested in why multi-jet swimming is useful, and what we were really interested in here was the timing,” Du Clos said. Nanomia can pulse its nectophores all at once, or activate them in a sequence. Du Clos and his colleagues wanted to see how those different modes impacted the animals’ swimming style, possibly illuminating an evolutionary advantage to having multiple jets.

At Friday Harbor Labs in Washington, the researchers scooped Nanomia out of the ocean and put them in tanks in the lab. Then, they used video recordings and computer models to analyze the swimming patterns.

The two different swimming modes are suited to different situations, the team found.

Synchronous pulsing sends Nanomia forward very quickly—perfect for an expeditious escape from a predator. Asynchronous pulsing moves the animal a little more slowly, but more steadily, and the researchers’ modeling experiments suggested that it’s a more energy-efficient way to swim. So with Nanomia sometimes traveling hundreds of meters per day, asynchronous pumping might be better suited for everyday use.

The intricacies of Nanomia’s movement could be useful for engineers turning to nature for inspiration.

“It gives a framework for developing a robot that has a range of capabilities,” Du Clos said. For instance, an underwater vehicle could have multiple propulsors, and simple changes in propulsion timing could allow that one vehicle to move either quickly or efficiently as the need arises.

In future work, the researchers plan to dive more into Nanomia’s features, next focusing on better understanding how the arrangement of the animal’s tentacles affects its feeding.

Colonial animals are quite common in the open sea due to their potential hydrodynamic advantages, Sutherland added. The team is currently looking beyond Nanomia at other species of colonial swimmers, to figure out how diverse arrangements of swimming units influence animals’ movement.

 

 

---

JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2202494119 

ARTICLE TITLE

Distributed propulsion enables fast and efficient swimming modes in physonect siphonophores

California Academy of Sciences researchers reveal how extinct Steller’s sea cow shaped kelp forests

To uncover “sea cow effect,” researchers developed new Past-Present-Future modeling approach that could inform more effective conservation strategies across ecosystems

Peer-Reviewed Publication

CALIFORNIA ACADEMY OF SCIENCES

 

IMAGE: A DRAWING OF A STELLER'S SEA COW, AN EXTINCT MARINE MEGAHERBIVORE. (BIODIVERSITY HERITAGE LIBRARY, CC BY 2.0, VIA WIKIMEDIA COMMONS) view more 

CREDIT: BIODIVERSITY HERITAGE LIBRARY, CC BY 2.0, VIA WIKIMEDIA COMMONS

SAN FRANCISCO, CA (November 28, 2022) — For millions of years, the Steller’s sea cow, a four-ton marine mammal and relative of the manatee, shaped kelp forests along the Pacific coast of North America by eating massive quantities of kelp fronds from the upper canopies, thus allowing light to spur productivity in the understory. In a paper published today in Frontiers in Ecology and Evolution, researchers from the California Academy of Sciences—as part of the Academy’s Thriving California initiative—reveal what historical kelp forests may have looked like in the presence of the marine megaherbivore, which went extinct in the 1700s just 27 years after its first encounter with Europeans due to overhunting, and suggest how kelp forest conservation efforts can take its absence into account.

“Kelp forests are highly productive ecosystems. They act as storm buffers, are economically important for fishing, and are home to countless marine organisms, yet they are in steep decline throughout the Pacific,” says study author and Academy Curator of Geology and Invertebrate Zoology Peter Roopnarine, PhD. “When kelp forests were evolving millions of years ago, there were large marine herbivores like the Steller’s sea cow, which are now extinct. So when it comes to what’s driving their widespread decline, there might be a major component we’re missing.” 

This tendency to evaluate the state of modern ecosystems based on their recent past is known as shifting baseline syndrome and can obscure how an ecosystem may have existed over much longer periods of time. 

“We already see the consequences of this thinking with things like wildfire management,” Roopnarine says. “In the short-term, wildfires have been seen as something to suppress because of the damage they bring to forest ecosystems. But recently we have learned that, in the long run, wildfires are a natural part of those systems that can lead to healthier, more resilient forests.”  

 

A new approach to address shifting baselines

In the paper, the researchers propose—and advocate for—a new way of evaluating the overall health of ecosystems to avoid the pitfalls of shifting baseline syndrome, called the Past-Present-Future (PPF) approach. 

As opposed to evaluating an ecosystem based on its current state, the researchers say the PPF approach, which combines historical lines of evidence from museum specimens and the fossil record with Indigenous traditional ecological knowledge and modern scientific data, can lead to mathematical models that more accurately depict natural systems. Importantly, these models can then be operationalized for more effective conservation. 

"Today, we are surrounded by severely degraded ecosystems, places that were far healthier a mere century ago, let alone a millennium or more,” says study author and Academy Executive Director Scott Sampson, PhD. “Growing numbers of these ecosystems are now in danger of collapse, even if we protect them. So if we are to help guide a given place toward a flourishing future, we must understand not only its current state of health, but past states as well, and then apply these insights toward calculated, regenerative interventions. This Past-Present-Future approach to conservation has the potential to be revolutionary."

 

Uncovering the “sea cow effect”

To get a better picture of kelp forests of the past—and therefore a better baseline from which to compare against the state they are in today and predict how they might change in the future—the researchers built a mathematical model using historical and modern data to simulate how the ecosystem might respond under different scenarios. 

First, the researchers input the effects different players in the ecosystem have on kelp forests, such as predation of kelp by sea urchins or predation of urchins by sea otters. The model was then compared against pre-existing data on kelp forests to ensure it reproduced how the ecosystems function in real life. 

Once the researchers refined the model, they were then able to explore how the Steller’s sea cow impacts kelp forests by adding them to the model and seeing how the ecosystem responded over time. 

“One of the more important and surprising findings was that including the Steller’s sea cow resulted in a totally different type of kelp forest,” says study author and postdoctoral researcher at the Academy and the University of Nevada Las Vegas Roxanne Banker, PhD. “Instead of kelp-dominated, which is what we think of with modern forests, the sea cow’s presence and predation of the upper canopy would have resulted in more of a balance between kelp and algae as more sunlight would have reached the sea floor.” 

Banker adds that this finding is of particular significance when reflecting on the current state of kelp forests, which are heavily degraded due in part to overpredation from sea urchins. “Algae would provide an additional food source for urchins, potentially reducing their impact on kelp,” she says. 

The study also showed that when the sea cow was present, the kelp forests as a whole were often more resilient: Even under adverse conditions, such as ocean warming or disease outbreaks, kelp forests may have been less likely to transition to the barren urchin-dominated state that is often seen today, and when they did they more quickly recovered to a forested state. This effect, which the researchers dubbed the “sea cow effect,” provides actionable insights for current kelp conservation efforts. 

“If our model was further validated through experimentation on test plots, it could allow us to build more resilience into kelp forests by modeling the efficacy of different interventions,” Roopnarine says. “Selectively harvesting the upper fronds of the kelp canopy, for instance, to recreate the role that was lost with the Steller’s sea cow.” 
 

Media Contact: 
Skylar Knight, sknight@calacademy.org 
Interviews with researchers available upon request.

###

About the California Academy of Sciences
The California Academy of Sciences is a renowned scientific and educational institution with a mission to regenerate the natural world through science, learning, and collaboration. Based in San Francisco’s Golden Gate Park, it is home to a world-class aquarium, planetarium, and natural history museum, as well as innovative programs in scientific research and environmental education—all under one living roof. Museum hours are 9:30 am – 5:00 pm Monday – Saturday, and 11:00 am – 5:00 pm on Sunday. Admission includes all exhibits, programs, and shows. For daily ticket prices, please visit www.calacademy.org or call (415) 379-8000 for more information.

 

About Research at the California Academy of Sciences
The Institute for Biodiversity Science and Sustainability at the California Academy of Sciences is at the forefront of efforts to regenerate the natural world through science, learning, and collaboration. Based in San Francisco, the Institute is home to more than 100 world-class scientists, state-of-the-art facilities, and nearly 46 million scientific specimens from around the world. The Institute also leverages the expertise and efforts of more than 100 international Associates and 450 distinguished Fellows. Through expeditions around the globe, investigations in the lab, and analysis of vast biological datasets, the Institute’s scientists work to understand the evolution and interconnectedness of organisms and ecosystems, the threats they face around the world, and the most effective strategies for ensuring they thrive into the future. Through deeply collaborative partnerships and innovative public engagement initiatives, they also guide critical conservation decisions worldwide, inspire and mentor the next generation of scientists, and foster responsible stewardship of our planet.

---

JOURNAL

Frontiers in Ecology and Evolution

DOI

10.3389/fevo.2022.983558 

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Impact of the extinct megaherbivore Steller's sea cow (Hydrodamalis gigas) on kelp forest resilience

Positive media coverage of cannabis studies regardless of therapeutic effect

Peer-Reviewed Publication

KAROLINSKA INSTITUTET

In cannabis trials against pain, people who take placebos report feeling largely the same level of pain relief as those who consume the active cannabinoid substance. Still, these studies receive significant media coverage regardless of the clinical outcome, report researchers from Karolinska Institutet in Sweden in a study published in JAMA Network Open.

“We see that cannabis studies are often described in positive terms in the media regardless of their results,” says the study’s first author Filip Gedin, postdoc researcher at the Department of Clinical Neuroscience, Karolinska Institutet. “This is problematic and can influence expectations when it comes to the effects of cannabis therapy on pain. The greater the benefit a treatment is assumed to have, the more potential harms can be tolerated.”

The study is based on an analysis of published clinical studies in which cannabis has been compared with placebo for the treatment of clinical pain. The change in pain intensity before and after treatment were the study’s primary outcome measurement.

The analysis drew on 20 studies published up to September 2021 involving almost 1,500 individuals.

The results of the study show that pain is rated as being significantly less intense after treatment with placebo, with a moderate to large effect. The researchers also observed no difference in pain reduction between cannabis and placebo, which corroborates results from another recently published meta-analysis. 

“There is a distinct and clinically relevant placebo response in studies of cannabis for pain,” says Dr Gedin.

The researchers also examined a possible connection between the magnitude of the therapeutic effect shown by the cannabis studies and the coverage they receive in the media and in academic journals. Media presence was measured through Altmetric, which is a method of evaluating mentions in the media, in blogs and on social media. Academic impact was measured in terms of citations by other researchers.

The analysis of media presence included a total of 136 news items in traditional media and in blogs and was categorised as positive, negative or neutral, depending on how the results were presented concerning the effectiveness of cannabis as a treatment for pain.

The researchers found that the cannabis studies received much greater media attention than other published studies. The coverage was substantial regardless of the magnitude of the placebo response and regardless of the therapeutic effect of cannabis. They also observed no link between the proportion of positively described news about a study and the effect it reported. 

The researchers add the caveat that their study combined trials of varying designs and quality and therefore the results should be interpreted with caution.

This research was financed by Riksbankens Jubileumsfond (Karin Jensen). The researchers report no potential conflicts of interest.

Publication: “Placebo Response and media attention in randomized clinical trials assessing cannabis-based therapies for pain: A systematic review and meta-analysis”, Filip Gedin, Sebastian Blomé, Moa Ponten, Maria Lalouni, Jens Fust, Andreé Raquette, Viktor Vadenmark Lundquist, William H. Thompson and Karin Jensen, JAMA Network Open, online 28 November, 2022, doi: 10.1001/jamanetworkopen.2022.43848

---

JOURNAL

JAMA Network Open

DOI

10.1001/jamanetworkopen.2022.43848 

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

“Placebo Response and media attention in randomized clinical trials assessing cannabis-based therapies for pain: A systematic review and meta-analysis”

Biodiversity in Africa and Latin America at risk from oil palm expansion, new report warns

Peer-Reviewed Publication

UNIVERSITY OF YORK

 

IMAGE: GHANA SUVANNA view more 

CREDIT: KATE PARR, UNIVERSITY OF LIVERPOOL

Zero deforestation commitments may inadvertently leave vital habitats in Latin America and Africa vulnerable to agricultural expansion, a new study has found. 

The study highlights how sustainability commitments, which play an important role in preventing the destruction of tropical rainforest, fail to protect nature in tropical grassy and dry forest habitats such as the Llanos in Colombia, Beni savanna in northern Bolivia, and Guinean and Congolian savannas in West and Central Africa. 

The research team, led by the University of York, calculated that if oil palm producers cleared these habitats to make way for new plantations, a third of vertebrates on the International Union for Conservation of Nature’s red list of threatened species could be affected, including the blue-throated macaw in Bolivia, the giant pangolin in Congo, and the Hellmich's Rocket Frog in Colombia. 

For the study, researchers mapped the areas around the globe that are at risk from new oil palm plantations. They identified 167 million hectares that are potentially suitable for the crop while still meeting the Roundtable on Sustainable Palm Oil’s (RSPO) definition of 'zero deforestation'. Of those 167 million hectares, 95 million are in grasslands and dry forests, mostly in South America and Africa. 

As global demand for agricultural land increases researchers are calling for urgent protections for these habitats, which support a rich array of species and act as an important carbon store. 

Co-author of the study, Professor Jane Hill from the Department of Biology and the Leverhulme Centre for Anthropocene Biodiversity at the University of York, said: “Palm oil is at the sharp edge of debate on how we can balance the need to feed the world and sustain livelihoods, while protecting nature. 

“With a yield estimated to be six times higher than many other vegetable oils such as oil seed rape, palm oil is regarded as a miracle crop and it supports the livelihoods of millions of people in tropical countries around the world. So rather than avoiding or banning palm oil, we need to ensure effective international policies and governance to protect, not just tropical rainforest, but tropical grasslands and dry forests too.  

“Our study highlights how current sustainability commitments could have the unintended consequence of putting areas of remarkable biodiversity at risk from the expansion of oil palm agriculture.” 

Since 2018, many oil palm companies have signed up to the RSPO’s zero deforestation commitments, which means they cannot expand plantations into tropical rainforest or peatlands. 

While concern from buyers and consumers about the environmental impact of palm oil has helped to drive membership of the scheme, many oil palm producers are yet to sign up to these commitments.

First author, Dr Susannah Fleiss, who carried out the study while researching her PhD at the University of York, said: “Although we found that oil palm yield in areas currently covered by grassland and dry forest would be lower than in tropical rainforest, these sites would still be attractive for the expansion of oil palm agriculture. We also found that irrigation would improve yield in many of these locations, potentially making them more attractive for expansion. 

“Clearing these areas for plantations would have a serious impact on biodiversity, potentially reducing the ranges of one quarter of vertebrate species that are currently threatened with extinction. Plantation development would replace the existing habitat in these areas, disrupting the ability of the species present to find food and water, and affecting their migration routes. 

“Large numbers of people live in tropical grassy and dry forest regions, where they often play a critical role in ecological processes such as burning and grazing. The expansion of oil palm agriculture in these areas could lead to a number of interlinked issues for local people and biodiversity. 

“Our study highlights the strong need for internationally-coordinated governance to protect these habitats, in addition to the existing global efforts to protect tropical rainforest.” 

Co-author Dr Phil Platts, Honorary Fellow at the University of York and Director of Earth Observation at BeZero Carbon, said: “Sustainability guidelines for palm oil were developed in the context of Southeast Asia’s rainforests, and so reflect the structure and function of those habitats. Now expansion is shifting to different ecological contexts, the scope of sustainability commitments must similarly expand, in line with the distinct biodiversity and carbon stocks now under threat.” 

The research, published in the journal Nature Ecology and Evolution, is funded by Unilever,  in collaboration with the University of Liverpool, Oxford, the Potsdam Institute for Climate Impact Research, Unilever and BeZero Carbon.  

---

JOURNAL

Nature Ecology & Evolution

Ethiopian schools study suggests COVID has “ruptured” social skills of the world’s poorest children

Primary school pupils were less confident talking to others and found it harder to make friends after the pandemic. Two interlinked studies, involving 8,000 primary pupils altogether, indicate children lost at least a third of a year in learning.

Peer-Reviewed Publication

UNIVERSITY OF CAMBRIDGE

School closures during the COVID-19 pandemic have “severely ruptured” the social and emotional development of some of the world’s poorest children, as well as their academic progress, new evidence shows.

In a study of over 2,000 primary school pupils in Ethiopia, researchers found that key aspects of children’s social and emotional development, such as their ability to make friends, not only stalled during the school closures, but probably deteriorated.

Children who, prior to the pandemic, felt confident talking to others or got on well with peers were less likely to do so by 2021. Those who were already disadvantaged educationally – girls, the very poorest, and those from rural areas – seem to have been particularly badly affected.

Both this research and a second, linked study of around 6,000 grade 1 and 4 primary school children, also found evidence of slowed academic progress. Children lost the equivalent of at least one third of an academic year in learning during lockdown – an estimate researchers describe as “conservative”. This appears to have widened an already significant attainment gap between disadvantaged pupils and the rest, and there is some evidence that this may be linked to the drop in social skills.

Both studies were by academics from the University of Cambridge, UK and Addis Ababa University, Ethiopia.

Professor Pauline Rose, Director of the Research in Equitable Access and Learning (REAL) Centre at the Faculty of Education, University of Cambridge, said: “COVID is having a long-term impact on children everywhere, but especially in lower-income countries. Education aid and government funding must focus on supporting both the academic and socio-emotional recovery of the most disadvantaged children first.”

Professor Tassew Woldehanna, President of Addis Ababa University, said: “These  severe ruptures to children’s developmental and learning trajectories underline how much we need to think about the impact on social, and not just academic skills. Catch-up education must address the two together.”

Both studies used data from the Research on Improving Systems of Education (RISE) programme in Ethiopia to compare primary education before the pandemic, in the academic year 2018/19, with the situation in 2020/21.

In the first study, researchers compared the numeracy test scores of 2,700 Grade 4 pupils in June 2019 with their scores shortly after they returned to school, in January 2021. They also measured dropout rates. In addition, pupils completed the Children’s Self Report Social Skills scale, which asked how much they agreed or disagreed with statements such as “I feel confident talking to others”, “I make friends easily”, and “If I hurt someone, I say sorry”.

The second study measured relative progress during the pandemic using the numeracy scores of two separate cohorts of Grade 1 and Grade 4 pupils. The first of these cohorts was from the pre-pandemic year; the other from 2020/21.

The results suggest pupils made some academic progress during the closures, but at a slower than expected rate. The average foundational numeracy score of Grade 1 pupils in 2020/21 was 15 points behind the 2018/19 cohort; by the end of the year that gap had widened to 19 points. Similarly, Grade 4 students started 2020/21 10 points behind their predecessor cohort, and were 12 points adrift by the end. That difference amounted to roughly one third of a year’s progress. Similar patterns emerged from the study of children’s numeracy scores before and after the closures.

Poorer children, and those from rural backgrounds, consistently performed worse academically. Dropout rates revealed similar issues: of the 2,700 children assessed in 2019 and 2021, more than one in 10 (11.3%) dropped out of school during the closures. These were disproportionately girls, or lower-achieving pupils, who tended to be from less wealthy or rural families.

All pupils’ social skills declined during the closure period, regardless of gender or location. Fewer children agreed in 2021 with statements such as “Other people like me” or “I make friends easily”. The decline in positive responses differed by demographic, and was sharpest among those from rural settings. This may be because children from remote parts of the country experienced greater isolation during lockdown.

The most striking evidence of a rupture in socio-emotional development was the lack of a predictive association between the 2019 and 2021 results. Pupils who felt confident talking to others before the pandemic, for example, had often changed their minds two years later.

Researchers suggest that the negative impact on social and emotional development may be linked to the slowdown in academic attainment. Children who did better academically in 2021 tended to report stronger social skills. This association is not necessarily causal, but there is evidence that academic attainment improves children’s self-confidence and esteem, and that prosocial behaviours positively influence academic outcomes. It is therefore possible that during the school closures this potential reinforcement was reversed.

Both reports echo previous research which suggests that lower-income countries such as Ethiopia need to invest in targeted programmes for girls, those from rural backgrounds, and the very poorest, if they are to prevent these children from being left behind. Alongside in-school catch-up programmes, action may be required to support those who are out of school. Ghana’s successful Complementary Basic Education initiative provides one model.

In addition, the researchers urge education policy actors to integrate support for  social skills into both catch-up education and planning for future closures. “Social and emotional skills should be an explicit goal of the curriculum and other guidance,” Rose said. “Schools may also want to think about after-school clubs, safe spaces for girls, and ensuring that primary-age children stay with the same group of friends during the day. Initiatives like these will go some way towards rebuilding the prosocial skills the pandemic has eroded.”

Ruptured School Trajectories is published in the journal, Longitudinal and Life Course Studies. Learning Losses during the COVID-19 Pandemic in Ethiopia, is available on the REAL Centre website.

---

JOURNAL

Longitudinal and Life Course Studies

ARTICLE TITLE

Ruptured school trajectories: Understanding the impact of COVID-19 on school dropout, socio-emotional and academic learning using a longitudinal design

Mussel survey reveals alarming degradation of River Thames ecosystem since the 1960s

Peer-Reviewed Publication

UNIVERSITY OF CAMBRIDGE

 

IMAGE: ONE OF THE MUSSELS GATHERED IN THE RIVER THAMES SURVEY view more 

CREDIT: UNIVERSITY OF CAMBRIDGE

Scientists replicated a 1964 River Thames survey and found that mussel numbers have declined by almost 95%, with one species – the depressed river mussel – completely gone.

The detailed study measured the change in size and number of all species of mussel in a stretch of the River Thames near Reading between 1964 and 2020.

The results were striking: not only had native populations severely declined, but the mussels that remained were much smaller for their age – reflecting slower growth.

Mussels are important in freshwater ecosystems because they filter the water and remove algae. As filter feeders they’re exposed to everything in the water, and this makes them a valuable indicator of ecosystem health. Mussel shells also provide places for other aquatic species to live.

“Mussels are a great indicator of the health of the river ecosystem. Such a massive decline in mussel biomass in the river is also likely to have a knock-on effect for other species, reducing the overall biodiversity,” said Isobel Ollard, a PhD student in the University of Cambridge’s Department of Zoology and first author of the report.

She added: “The depressed river mussel used to be quite widespread in the Thames, but this survey didn’t find a single one - which also raises concerns for the survival of this species.”

The study also recorded new arrivals: the invasive, non-native zebra mussel, Dreissena polymorpha, and Asian clam, Corbicula fluminea - both absent from the original 1964 survey - were present in high numbers. The scientists say invasive species probably hitched a ride on boats as they sailed up the Thames, and established themselves in the river.

The results are published today in the Journal of Animal Ecology.

“This dramatic decline in native mussel populations is very worrying, and we’re not sure what’s driving it,” said Professor David Aldridge in the University of Cambridge’s Department of Zoology, and senior author of the report.

He added: “While this might seem like a rather parochial little study of a single site in a single river in the UK, it actually provides an important warning signal about the world’s freshwaters.”

The invasive species could be behind the decline in the native mussel populations: zebra mussels are known to smother native species to death. But the scientists say more work is needed to be sure. Other causes could be changes in land use along the river, or changes in the fish populations that mussels depend on as part of their life cycle.

Many empty shells of the depressed river mussel, Pseudanodonta complanata, were found in the survey, indicating that the species had been living at this site in the past. The depressed river mussel is one of the most endangered mussel species in the UK.

The survey found that the population of duck mussels, Anodonta anatina, had decreased to just 1.1% of 1964 levels, and the painter’s mussel, Unio pictorum, decreased to 3.2%.

The scientists think the mussels’ reduced growth rate may reflect the river’s return to a more ‘natural’ state. Since 1964, levels of nitrate and phosphate in the river water have fallen due to tighter regulation of sewage treatment. A reduction in these nutrients would reduce the growth of algae, limiting the food available to the mussels.

Mussel species are threatened globally. The scientists say that regular population surveys of key species, like this one, are essential to tracking the health of rivers and guiding their management.

To ensure the survey was an exact replica of the original, Ollard contacted Christina Negus – who had done her survey while a researcher at the University of Reading in the sixties. Negus, who is no longer a scientist, shared details of the methods and equipment she had used. Her report, published in 1966, continues to be cited extensively as evidence of the major contribution mussels make to ecosystem functioning in rivers.

These mussels were gathered in the River Thames survey

CREDIT

University of Cambridge

Isobel Ollard

Ollard conducted the survey of River Thames mussels

CREDIT

University of Cambridge

---

JOURNAL

Journal of Animal Ecology

DOI

10.17863/CAM.80071 

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Declines in freshwater mussel density, size and productivity in the River Thames over the past half century

Seagrass crucial to stemming the tide of coastal erosion

Peer-Reviewed Publication

UNIVERSITY OF GOTHENBURG

 

IMAGE: SEAGRASS´ ROOT MATS CAN REDUCE COASTAL EROSION UP TO 70 %. RESEARCHERS AT UNIVERSITY OF GOTHENBURG HAVE MADE TEST IN WAVE TANK THAT SHOWS THAT THE ROOTS MAKES BINDS THE SAND DUNES. view more 

CREDIT: PHOTO: PEKKA TUURI

The sea devours large tracts of land when storms wash sand out to sea from the coast. In a new study involving a researcher from the University of Gothenburg has shown that seagrass can reduce cliff erosion by up to 70% thanks to its root mats binding the sand.

Coastal erosion is a global problem that is often combated by replenishing the coast and beaches with new sand in locations where storms wreak the greatest havoc. According to a 2016 survey conducted by the Geological Survey of Sweden, 12 per cent of Skåne’s coastline in southern Sweden is vulnerable to increasing rates of coastal erosion. It is an even bigger issue in other countries. In the Netherlands, the coastline is protected through the construction of dikes made from stone and mud. Another solution is to utilise nature’s own defences against coastal erosion. In this new study, researchers examined the importance of seagrass for preserving the coastline.

“We have seen that seagrass meadows in the coast are valuable assets in mitigating erosion. We already know that their long canopies serve as breakwaters, but now we can show that their root mats also bind together the underwater sand dunes, effectively reinforcing them,” says Eduardo Infantes, a Marine Biologist at the University of Gothenburg and the lead author of the study which has been published in the journal Marine Ecology Progress Series.

More powerful storms in the future

Common eelgrass is a seagrass species that grows along Sweden’s coasts, and there are areas with large seagrass meadows growing on the bottom sediments, such as in Skåne. In other places, the seagrass has disappeared altogether. This not only represents an ecological loss, it can also mean that the coast becomes more vulnerable to erosion. As the climate changes, storms risk becoming more powerful, which in turn can lead to an increase in coastal erosion. Approximately 8% of the world’s population live in areas at an elevation of fewer than 10 metres above sea level. Rising sea levels may see many people affected by coastal erosion.

“This is why it is even more important to preserve those seagrass meadows that still exist today and to replant seagrass in those places where it has disappeared. In our research, we have made successful attempts to restore common eelgrass meadows on the Swedish west coast, but if such replanting efforts are to succeed, there is a need for detailed studies of the current status seabed environment,” says Eduardo Infantes.

In this study, the researchers took samples of sandy sediments with and without common eelgrass from a number of sites and placed them in a large tank capable of simulating waves. The experiments demonstrated that the sand is eroded far less by waves when seagrass is growing in it. The researchers also took samples from muddy seabeds but found that the effect of the seagrass there was less. However, this matters less since muddy seabeds are most commonly found in fjords and other areas that are less exposed to waves.

More factors in field tests

The next step will be to move out of the laboratory environment and take measurements of sand erosion on an exposed shoreline along the coast. Other factors such as currents, traffic on the water, inflows from rivers etc. can then affect the erosion.

“It’s more complicated in the field, but we have created realistic storm waves in our experiments and the seagrass has clearly shown a protective effect against erosion. I think we will be able to demonstrate the similar effects in field tests,” says Eduardo Infantes.

---

JOURNAL

Marine Ecology Progress Series

DOI

10.3354/meps14196 

METHOD OF RESEARCH

Experimental study

ARTICLE TITLE

Seagrass roots strongly reduce cliff erosion rates in sandy sediments

Indonesia raises volcano warning to highest after Semeru erupts - media

Published: 04 Dec 2022 -

Mount Semeru spews smoke and ash in Lumajang on December 4, 2022. 

(Photo by Agus Harianto / AFP)


JAKARTA: Indonesian authorities raised the warning on Semeru volcano to the highest level on Sunday, Kompas TV reported, after an eruption spewed a column of ash high into the air.

The evacuation of people living near the volcano in East Java province had begun, a top regional administrator, Thoriqul Haq, told the broadcaster.

The plume from the volcano reached a height of 50,000 feet (15 km), said Japan's Meteorology Agency, which was monitoring for the possibility of a tsunami there.

Indonesia's Center for Volcanology and Geological Hazard Mitigation, PVMBG, raised the level of volcanic activity to IV from III, Kompas TV reported. The centre could not immediately be reached for comment.

The eruption on the eastern part of Java island, some 640 km (400 miles) east of the capital Jakarta, follows a series of earthquakes on the west of the island, including one last month that killed more than 300 people.

"Most of the road accesses have been closed since this morning. Now its raining volcanic ash and it has covered the view of the mountain," Bayu Deny Alfianto, a local volunteer told Reuters by phone.

Small eruptions were continuing and it was raining in the area, he said.

With the higher alert level, authorities warned residents not to conduct any activities within 8 km (5 miles) of Semeru's eruption centre, Kompas TV said.

The volcano began erupting at 2:46 a.m. (1946 GMT on Saturday), Indonesia's disaster mitigation agency, BNPB, said in a statement. Videos posted on social media showed grey ash clouds in nearby areas.

With 142 volcanoes, Indonesia has the largest population globally living in close range to a volcano, including 8.6 million within 10 km (6 miles).

The deadly late-November quake that hit West Java's Cianjur was a shallow temblor of 5.6 magnitude. A much deeper quake on Saturday in Gurat of 6.1 m

 

Brown University takes firm stand on caste-based harassment

Ivy League institution of US makes provisions for stringent punishment, including expulsion or termination of employment, for violations

Brown University

---

Basant Kumar Mohanty   |   New Delhi   |   Published 04.12.22, 03:33 AM

---

Brown University, an Ivy League institution based in Rhode Island in the US, has added caste-based harassment to its non-discrimination policy and made provisions for stringent punishment, including expulsion or termination of employment, for violations. 

Earlier, Harvard, California State University and Brandeis University in the US had acted similarly against caste-based discrimination, said to be prevalent among South Asians in American institutions.

According to a statement, the Corporation of Brown University, the varsity’s governing body, voted in Fall 2022 to adopt a change to the University’s Corporation Policy Statement on Equal Opportunity, Non-discrimination and Affirmative Action to insulate the varsity community from caste oppression and to “call attention to a subtle, often misunderstood form of structural inequality”.

The policy seeks to prevent discrimination, harassment or retaliation based on a person’s race, colour, religion, sex, age, nationality, disability, sexual orientation or caste.

“Failure to comply with this and related policies is subject to disciplinary action, up to and including suspension without pay, expulsion, or termination of employment or association with the University, in accordance with applicable (eg, staff, faculty, student) disciplinary procedures,” the policy said.

The statement quoted the vice-president for institutional equity and diversity, Sylvia Carey-Butler, as saying that as the  South Asian population in the US increases, caste discrimination is becoming a growing issue on college and university campuses across the country.

“University students who are members of the castes classified as lower often report facing discrimination at educational institutions in the diaspora,” it added.

The Equity Lab, a South Asian-American human rights forum in the US, conducted a survey on caste in the country in 2016 and found that one in three Dalit students reported discrimination during their education in the US while two out of three Dalits reported being treated unfairly at their workplaces.

Sixty per cent said they had experienced caste-based derogatory jokes or comments while 40 per cent of Dalits said they felt unwelcome at places of worship because of their caste. Sukhadeo Thorat, former chairman of the University Grants Commission, said it was unfortunate that people from dominant castes continued to exercise their caste status even on foreign soil despite obtaining higher education. He said the societal norms in India were the main source of the bias, which stayed with people throughout their lives.

Effective measures are required at various levels to sensitise caste Hindus on the subject, he said. “Social norms that are discriminatory should be changed. People from the forward castes have to take the initiative.

It can happen if there is sustained action by government and non-government organisations, political parties and the media. Such actions are very negligible,” Thorat said.

Harvard and California State University included caste in their non-discrimination policy last year while Brandeis University did so in 2019.

LA REVUE GAUCHE - Left Comment: Search results for HINDUISM IS FASCISM