It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, May 20, 2025
Selenium exposure during pregnancy may reduce childhood streptococcal infections
This study used data collected from the Japan Environment and Children’s Study to show an inverse association between maternal selenium levels during pregnancy and the risk of children developing streptococcal infections by ages 3 or 4. (Illustration: Hiroyoshi Iwata)
Higher maternal selenium levels during pregnancy were associated with a lower risk of streptococcal infections in children, suggesting a potential protective effect.
Scientists from Hokkaido University have discovered that exposure to certain metals and trace elements during pregnancy may affect a child’s risk of developing streptococcal infections, according to a new study published in PLOS ONE. These infections are common in children, especially those caused by Group A Streptococcus, a bacterium that commonly causes illnesses such as strep throat, skin infections, and, in severe cases, more serious complications like scarlet fever or invasive diseases. The findings could contribute to improved strategies for preventing childhood infections.
The research team tracked more than 74,000 mothers and their children from a nationwide study in Japan. They measured the mothers' blood levels of various metals and trace elements, including selenium, mercury, cadmium, lead, and manganese. The researchers then followed the children to see whether they developed streptococcal infections between the ages of three and four. Statistical analysis was used to explore potential links between maternal metal exposure and infection risk in the children.
“We found that mothers with higher selenium levels during pregnancy were less likely to have children who developed streptococcal infections. ” says Hiroyoshi Iwata, the study’s first author, from the Center for Environmental and Health Sciences at Hokkaido University. “This association was strongest among mothers with the highest selenium levels in their blood. However, high selenium concentrations during pregnancy can lead to toxicity and adverse effects, so caution is necessary. As this research is based on a single blood sample provided by pregnant mothers, and the results of this study alone should not be used to recommend selenium intake during pregnancy.”
Selenium is a trace element that plays a key role in immune function, and previous studies have suggested that it may help the body combat infections by strengthening the immune system. These new findings support the idea that sufficient selenium levels during pregnancy could help enhance a child’s immune defenses against bacterial infections.
This study supports the importance of ensuring adequate selenium intake during pregnancy for the benefit of children's long-term health and adds to a growing body of evidence suggesting that selenium plays a vital role in immunity. However, this study specifically analyzed the relationship between maternal selenium levels and streptococcus infections only, and did not evaluate the relationships with other infectious diseases. Further research is needed to fully understand how selenium supports the immune system and to determine the optimal levels during pregnancy.
Association between prenatal exposure to maternal metal and trace elements and Streptococcus infection: A prospective birth cohort in the Japan Environment and Children’s Study
Surprise baby whale sightings reveal there’s still much to learn about humpbacks
A UNSW-led study published today shows humpback whales are being born much further south than previously thought, with sightings extending as far as Tasmania – more than 1500 kilometres ahead of the assumed calving zone.
“Historically, we believed that humpback whales migrating north from the nutrient-rich Southern Ocean were travelling to warmer, tropical waters such as the Great Barrier Reef to calve,” says lead author Jane McPhee-Frew, a UNSW Sydney PhD candidate and whale watching skipper.
The study includes more than 200 sightings of humpback calves from whale watching operators, citizen scientists and government wildlife agencies – across an area extending from Queensland down to Tasmania and across to New Zealand’s South Island. The findings challenge current beliefs of where humpback whales give birth.
“I was working part-time as a skipper on a whale-watching boat in Newcastle when I first spotted a calf in the area,” McPhee-Frew says.
“It seemed out of place,” she says. “The calf was tiny, obviously brand new. What were they doing here? But none of my tourism colleagues seemed surprised.
“This sparked a conversation with my research colleagues, and we realised there was a gap between the scientific literature and the sightings.”
McPhee-Frew says once they started investigating, reported sightings came in from further and further south.
“Eventually, we just ran out of land to see them from,” she says. “So we don't actually know where the limit is. But we had reports right to the bottom of Tassie, the southernmost points of Western Australia and to the South Island of New Zealand.”
This emerging pattern suggests humpbacks may have more complex migration and breeding behaviours than previously thought – which comes with a new set of issues.
Navigating risky waters
McPhee-Frew’s first calf sighting in Newcastle in 2023 was from within a busy shipping lane – the city is home to the largest coal export port in the world.
Most observations of live calves in the study were from 2016 onwards, with two-thirds of observations made in 2023 or 2024.
“It’s not just the sightings themselves that are important,” McPhee-Frew says.
“The pattern we’re seeing is mother whales with calves travelling through some of the busiest shipping lanes and urbanised regions.
“This means these vulnerable animals are exposed to risks like boat strikes, entanglements, pollution – and just general public unawareness.”
The study is an example of how industry, research institutions, government agencies and the wider public work together to improve the understanding and protection of marine life.
Back from the brink
Humpback whales were once close to extinction, with populations in the 1960s plummeting into the low hundreds. On the back of increased protection and conservation efforts, their numbers have risen to around 50,000 today.
McPhee-Frew says while the discovery of baby humpbacks being born so far south of the tropics might seem new, the behaviour itself might not be. It’s probably just newly visible.
She scoured historical records, including 19th-century whaling logbooks and accounts from expeditions like Captain Scott’s Terra Nova. Within these texts were sightings of mothers with calves at similar latitudes to those now being reported.
She says this information on breeding patterns was likely not seen for decades as humpback populations were so low following industrial whaling. The behaviours may also only just be coming into view “with more eyes than ever before looking at the water with technology like drones and with activities like whale watching.”
McPhee-Frew says what this study highlights is the critical need for increased awareness to protect the newborn whales throughout their winter journey north – which, in some cases, could span more than 2300kms.
“Regardless of the health of population now, we can't be in a situation where we're putting any age of whales – especially baby whales – in a situation where they're getting caught in nets, being exposed to chemicals, being hit by boats and being harassed.”
Co-author Professor Tracey Rogers, also from UNSW, says newborn humpbacks are not as strong as adult whales.
“Mums with newborns swim much more slowly,” Prof. Rogers says.
“Newborns are like Great Dane puppies. They have those long, enormous fins that they need to grow into, and they’re not very strong swimmers. So they rest a lot of the time on their mum’s back,” she says.
“Imagine giving birth off Hobart and then swimming up the coast.
“It’s heartbreaking to think of these young whales travelling through busy ports and dangerous shipping lanes with those long, clumsy fins.
“And it's not just happening here in NSW – this is off WA, Victoria, Tasmania, New Zealand – it's something we just didn't know before.”
Keeping a safe distance
“The legislation to protect humpback whales, including mothers and calves, is already in place across all states,” says Dr Adelaide Dedden from the NSW National Parks and Wildlife Service – which collaborated with the UNSW scientists for this study.
“But we do have a gap in public awareness, particularly among recreational water users,” Dr Dedden says.
“People need to be aware that calves are being seen not just on the southern migration but also on the northern one.”
While close-up images of baby humpbacks may give the impression that encounters are guaranteed, these moments are rare and rely on the whales approaching out of curiosity – not pursuit by vessels.
“Humpbacks are charismatic and curious,” Dr Dedden says. “They're going to want to come and check out the boat."
She says NSW waters have numerous whale watch operators. The guidelines are to maintain a 100m distance from adult whales and 300m from mother-calf pairs.
“We’ve been working hard to get this message out to the public and encourage boaters, surfers, kayakers and jet-ski operators to be aware of these guidelines,” Dr Dedden says.
A collaborative effort
McPhee-Frew says partnering with government agencies and sharing information ultimately supports better policies to protect the whales.
She also says whale watching operators, who are regularly out on the water, are critical for providing sightings data as well as educating the public about safe approaches.
In addition, social media platforms like Instagram and Facebook are invaluable tools for citizen science, for sharing images and information about whale sightings.
“The excitement and curiosity around whales are contagious,” McPhee-Frew says.
“We’ve built a huge repository of data just by encouraging the public to share observations.”
An unanswered question
McPhee-Frew says the question remains of why humpback mothers continue to use the ‘humpback highway’ to travel north after giving birth because, “in the tropics, there's really no food for them.”
She says rather than holding a strict view of migratory patterns with fixed endpoints, the focus is shifting to how humpbacks use different marine environments on their journey.
“We still have a lot to learn,” says McPhee-Frew.
“But, you know what? It's such a privilege to see whales. It is such a fantastic aspect of living in Australia.
“We just need to follow the rules so everyone can enjoy.”
The study includes co-authors Holly Raudion and Kelly Waples from the Western Australia Department of Biodiversity Conservation and Attractions, and Dr Vanessa Pirotta from Macquarie University.
It turns out humpback whales’ epic migrations to tropical waters aren’t as essential as we thought for giving birth: calves can be born as far south as Tasmania or New Zealand, 1,500km further south than previously known. Researchers say these results overturn long-held beliefs about humpback migration, and that — to protect these unexpected baby whales — we need to improve awareness of expanded calving areas.
“Hundreds of humpback calves were born well outside the established breeding grounds,” said Dr Tracey Rogers of the University of New South Wales, senior author of the article in Frontiers in Marine Science. “Giving birth along the ‘humpback highway’ means these vulnerable calves, who are not yet strong swimmers, are required to swim long distances much earlier in life than if they were born in the breeding grounds.”
“Alongside my studies, I work as a marine guide,” said Jane McPhee-Frew of the University of New South Wales, PhD candidate and first author. “In July 2023, during a whale-watching tour, I encountered a mum and calf at the mouth of Newcastle Harbor — the busiest shipping port in Eastern Australia. The calf was tiny, obviously brand new. What were they doing there? But none of my tourism colleagues seemed surprised.”
The whales’ way
Inspired by McPhee-Frew’s sighting, the researchers investigated the calving range for humpback whales around Australia and New Zealand. They combined data from citizen science observations, government surveys, and reported strandings. New Zealand’s Department of Conservation Cook Strait Whale Project supplied data from migration surveys, and Australian state wildlife departments supplied information on strandings dating back to 1991.
The scientists identified 209 records of newborn calves, including 11 births — 41 strandings and 168 observations of live calves, representing at least 169 individuals. They had data on the direction of travel for 118, which showed the whales were continuing to migrate north after delivery.
“Humpback whale populations undertake extensive long-distance migrations from the Southern Ocean to breeding grounds in the tropics,” explained co-author Dr Adelaide Dedden of the National Parks and Wildlife Service, Australia. “They rely heavily on body reserves from an enormous amount of Antarctic krill to support the physiological costs of the journey and reproduction.”
The highest-latitude calf was found at Port Arthur, Tasmania, 1,500km further south than we previously thought humpback whales could calve. The highest-latitude birth recorded was witnessed only slightly further north, at Kaikoura, New Zealand.
Most observations of live calves were recorded from 2016 onwards, with two-thirds of observations made in 2023 or 2024. Meanwhile, comparisons with historical texts and whaling logbooks indicate that calves born during migration were observed before the population crashed due to hunting.
“I think it’s very likely that this pattern has always existed, but the low number of whales obscured it from view,” said McPhee-Frew. “The Eastern Australia humpback population narrowly escaped extinction, but now there are 30, 40, or 50,000 in this population alone. It doesn’t happen overnight, but the recovery of humpback whales, and the return of their full range of behaviors and distribution, just goes to show that with good policies built on good science we can have excellent outcomes.”
Migration motives
Migrating costs energy and leaves calves vulnerable to predators. Why do humpback whales risk migrating if they can give birth further south? This study can’t answer that question, but it’s possible other factors drive migration, or the benefits of usually delivering in tropical waters outweigh the risks to a potential calf born on the way. Although data provided by Western Australia’s Department of Biodiversity, Conservation, and Attractions identified a possible nursery area in Flinders Bay, it’s likely most calves are born much further north in the tropics.
The findings do have conservation implications. Some of the calves observed were injured, and the scientists say expanded protected areas, awareness campaigns about protective measures, and more research into the habitats humpbacks use while migrating are needed to safeguard calves.
“This study was based on opportunistic observations,” cautioned McPhee-Frew. “This data is excellent for answering questions like, ‘are there newborn whales here?’ But we can’t stretch the interpretations too far. It might appear that we see more calves the further north we go, or that we have seen more over time. But it could be that there are more people whale-watching in the north, or more cameras and social media sharing in recent years.”
“We can only document what we see,” added co-author Dr Vanessa Pirotta of Macquarie University. “Perhaps there are things happening in our ocean that we are yet to find out.”
A mother and baby whale swim at Kiama, New South Wales, Australia. Vanessa Risku - Instagram: droning_my_sorrows
Worldwide, coastal areas are squeezed between a rising sea level on one end and human structures on the other. The distance between a sandy coastline and the first human structures averages less than 400 meters around the world. And the narrower a coastline is, the lower its biodiversity as well. That is shown by the thesis that coastal ecologist Eva Lansu will defend at the University of Groningen on May 20th. “This coastal squeeze is not only a problem for biodiversity, it also affects our defense against flooding and our drinking water supply”, Lansu says.
All sandy beaches
For her research, Lansu analyzed a huge database, previously created by colleagues at TU Delft and Deltares, of all the world's (ice-free) sandy beaches. On top of that map, she projected another map of all human-built structures and paved roads. With that, she calculated the distance from the high waterline to the first built-up area.
The average 390 meters around the world that resulted from these measurements is shockingly little, Lansu argues. “For a seaside resort like Zandvoort or Scheveningen, it may still sound like a long distance, but when you consider that it's an average that includes the beaches of Walvis Bay in Namibia or the Amazon in South America, we are building remarkably close to the coast.”
Vulnerable to sea level rise
Constructions close to the sea make coastal areas extra vulnerable, Lansu emphasizes in her dissertation. “The narrower a coast, the sooner you will run into problems with rising sea levels.” In addition to those weaker defenses, narrower coasts are also bad news for biodiversity, Lansu found in a comparative study in both the Netherlands and the United States. In the Netherlands, together with colleagues, Lansu visited 35 dune areas. In each of these areas, they walked a transect perpendicular to the coastline and determined plant diversity every hundred meters. She did the same along 12 transects in the states of Florida and Georgia. Lansu: "It was clear that the wider the coast was, the greater the plant diversity. Especially the first two kilometers, that diversity increased rapidly."
In the Netherlands, only coastal areas of at least 3.8 kilometers wide reached their maximum plant diversity. "But unfortunately, such wide zones are rare. Dutch dune areas are on average no more than one kilometer wide, leaving plant diversity stuck at half the possible level," Lansu said.
Manage better or plan smarter
The limited biodiversity in narrow coastal strips can be boosted to some extent by nature management. But much more important, Lansu argues, is spatial planning. "We will have to take into account rising sea levels and avoid further hardening our coasts. We also need to start looking at coastal expansion, as has been done in the Netherlands with the ‘Sand Motor’ near the village of Monster."
The Sand Motor is a place where a gigantic amount of sand was deposited off the coast once in 2011, only to have it spread naturally along the coast. Lansu: "At that spot you can already see quite a few embryonic dunes forming on the newly raised beach. But future coastal expansion could stimulate natural sand dynamics and associated biodiversity even better. After all, biodiversity is not a luxury. It is our insurance for the future, for coastal defense, drinking water supply and in general also for our food supply."
Washington Oaks Florida (USA) coastal squeeze - photo by Orlando Cordero
Vegetation survey in the dunes - photo Eva Lans
Vegetation survey Cumberland Island Georgia - USA - photo Eva Lansu
