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, October 26, 2021
Fish consumption still safe despite initial fears over mercury levels
The benefits of consuming traditional foods tend to outweigh the risks of possible mercury contamination, according to a recent study.
The research, which was part of a larger biomonitoring project to address community concerns about environmental contaminants in traditional foods, such as fish, also found that mercury exposure in people may be low even when it is sometimes present in elevated levels. Additionally, the researchers discovered that mercury levels in people in northern regions vary by season and region.
"Previously, elevated levels of mercury were found in some fish species in some lakes and therefore, communities wanted to know if these sometimes-elevated levels in fish also meant they were elevated in people," said Sara Packull-McCormick, a PhD candidate at the University of Waterloo's School of Public Health Sciences.
"The good news is that generally, the exposure in communities we studied was low. It means the benefits of consuming these foods tend to outweigh the risks, which is important for these communities since fish consumption has nutritional, cultural and economic benefits."
In conducting the study, the researchers obtained 443 blood samples and 276 hair samples to determine mercury levels present in the body. Generally, the measured human mercury exposures were relatively low. They also used a Food Frequency Questionnaire to assess fish intake, with 170 people participating. The responses showed that total fish intake peaked in late summer, decreased during the winter and increased again in the spring. Hair mercury levels seemed to follow the same seasonal pattern as fish intake but peaked in the fall.
The advantage of blood monitoring is that it provides an accurate snapshot of recent mercury levels. However, blood samples are more invasive, require specialized personnel to draw them, as well as consistent refrigeration. The researchers wanted to see if hair samples, which are easier to collect and show mercury levels over a larger span of time, could be used at the individual level. They found that the ratios between blood and hair mercury levels were inconsistent, meaning blood levels cannot be accurately estimated for an individual based on a hair sample.
Elevated levels of mercury can have negative effects on human development and health, including increased risk of cardiovascular disease and neurodevelopmental impairment. The Canadian Health Measures Survey measured mercury in human biological samples but did not include participants from the Canadian territories or Indigenous peoples living on reserves.
"This study is important because it provides these communities with the information they need to help guide their decision-making," said Brian Laird, a professor in the School of Public Health Sciences and principal investigator. "Mercury can pose serious risks to people's health, but these communities now have a baseline to see what changes occur in the future, especially taking into account those that may be caused by climate change."
The study was published in Environmental Research.
More information: Sara Packull-McCormick et al, Hair to blood mercury concentration ratios and a retrospective hair segmental mercury analysis in the Northwest Territories, Canada, Environmental Research (2021). DOI: 10.1016/j.envres.2021.111800
THAT'S WHY YOU PRAY BEFORE EACH MEAL TO BEG FORGIVENESS
How do we keep on eating meat if we wish animals no harm?
by The Polish Association of Social Psychology
Many of us experience the 'meat paradox', whereby we simultaneously care for animals such as these cows, yet also consume them as meat. Credit: Doruk Yemenici via Unsplash
While Greta Thunberg, the climate activist, laments that animal products are 'stealing' her future, humanity keeps consuming meat. In fact, approximately between 90-97% of us eat meat, with worldwide meat consumption currently on the rise. Yet, the majority of people are concerned, at least to an extent, with animal welfare. In fact, research has shown that many are inclined to empathize more with dogs than with fellow adults.
A new literature review by UK researchers from the Societies Research Hub at Anglia Ruskin University (ARU) and Nottingham Trent University, led by Sarah Gradidge, explores this "meat paradox"—namely the coexistence of eating meat and caring for animals.
The researchers recognize two main psychological processes within the meat paradox: triggers and restorative strategies. Triggers make meat consumers feel uncomfortable about their own meat consumption. For example, this could be when a meat eater is reminded about meat originating from the flesh of slaughtered animals. However, those thoughts can be countered by certain strategies, so that the person can escape the paradox and resolve their feelings of discomfort.
The researchers list the most common strategies of dealing with the meat paradox, such as when a person regards "food" animals to be of low status and hence incapable of thinking, feeling or understanding. Alternatively, some people justify meat consumption as "natural", "necessary", "nice" and "normal" (the "4Ns"). Another common approach is to dissociate meat from animals by using alternative descriptions, such as "livestock", "pork" and "poultry". Some behaviors, such as presenting vegetarianism as illogical, are also often used to justify meat consumption.
Interestingly, the researchers also report that people with different demographics and attitudes utilize different strategies to overcome the meat paradox. For example, one study identified cross-cultural differences, whereby Americans dissociated meat from animals more than people from Ecuador, perhaps because in the latter country it is more common for meat to be served with the animal's head still attached. Similarly, another study found that French people were more likely to deny that animals have their own mind compared to Chinese people.
People may also justify their meat consumption because it is part of their religious traditions. For example, some people linked it to God's abundant provision of food, while in a separate study others pointed out the existence of ethical slaughter within Islam.
Disengagement from animals appears to be significantly more prevalent in men than in women, concludes the review. However, the researchers note that this is likely due to traditional gender attitudes. For example, military men and women think of meat consumption as inherently masculine and associate it with the "man as hunter" gender stereotype. On the other hand, those who do not believe as much in traditional masculinity (including males) demonstrate greater engagement with animals.
In the review, the authors state that "this research evidences how masculinity stereotypes necessitate males, and/or those wishing to be 'masculine', to disengage from consumed animals, perhaps explaining why females identify as vegetarian and vegan more than males." For example, 63% of vegans are female, compared to only 37% being male.
In terms of political ideologies, greater conservatism appears to be linked to viewing vegetarianism and veganism in negative ways and justifying meat consumption as "natural", "necessary", "nice" and "normal", with individuals holding right-wing political beliefs being more willing to consume meat. On the other hand, left-wing participants see vegetarianism and veganism more positively, including in ethical and environmental context.
The main conclusion from the review is that "some people are more likely to engage with animals than others, including: females; those who value masculinity less; have less traditional gender attitudes and males who value 'new masculinity'. Thus, people from these groups may be more responsive to meat reduction interventions."
Sarah Gradidge, the lead author, says that "it is exciting to present the first comprehensive structured literature review of the 'meat paradox', and we hope it will inform both the 'meat paradox' literature and behavior within the real world, such as meat reduction. The work will be of interest not only to 'meat paradox' researchers, but also to people and organizations aiming to reduce meat consumption and even to meat consumers themselves who wish to better understand their psychological relationship to meat. This review is especially timely given urgent requirements to reduce meatconsumption in order to save the environment, and we therefore hope the review informs these efforts."
The research was published in Social Psychological Bulletin.
More information: Sarah Gradidge et al, A structured literature review of the meat paradox, Social Psychological Bulletin (2021). DOI: 10.32872/spb.5953
Provided by The Polish Association of Social Psychology
HEY GOV DESANTIS FEED THE MANATEE
Florida manatees dying in record numbers amid food scarcity
by Curt Anderson
In this Dec. 28, 2010, file photo, a group of manatees are in a canal where discharge from a nearby Florida Power & Light plant warms the water in Fort Lauderdale, Fla. Florida is experiencing an unprecedented die-off of manatees this year, with 959 documented deaths as of mid-October. Credit: AP Photo/Lynne Sladky, File
Florida fishing guide and environmental activist Paul Fafeita says a highlight for his charter customers is spotting the manatees that forage for seagrass in shallow waters. It's not so thrilling when they come across the emaciated carcass of a manatee that starved to death.
"It's not good when you've got clients on the boat and all of a sudden there's a dead manatee," Fafeita, president of the Clean Water Coalition of Indian River County, said during a recent excursion in the Indian River Lagoon, a favorite hangout for the marine mammals along Florida's east coast. "They're wanting to see them. They don't want to see them dead."
Florida is experiencing an unprecedented die-off of manatees this year, with 959 documented deaths as of Oct. 1. That's already more than any full year on record, and colder weather soon to come could bring another wave of deaths in a population that numbers between 7,500 and 10,200 along both Florida coasts, according to state estimates.
"There is a huge sense of urgency," said Gil McRae, director of the state Fish and Wildlife Research Institute. "We're uncertain how long it's (high manatee deaths) going to be."
The reason? Seagrass on which the so-called sea cows depend also is dying as water quality declines due to fertilizer runoff, wastewater discharges and polluted water that is increasingly diverted on purpose from Lake Okeechobee to coastal estuaries.
These manmade pollutants can cause algae blooms so thick that seagrass can't get the sunlight it needs to survive, jeopardizing the manatees' main food supply. Since 2009 about 58% of the seagrass has been lost in the Indian River Lagoon, state estimates show.
"The cold hard fact is: Florida is at a water quality and climate crossroads, and manatees are our canary in the coal mine," said J.P. Brooker, Florida director for the Ocean Conservancy environmental group, in an opinion piece published by The Invading Sea, a collaboration of 26 Florida news outlets focused on climate change impact.
"They are dying off in record numbers because we humans have made Florida waters inhospitable to them," Brooker said. "It's not just our manatees at risk, it's a coast-wide ecological problem."
State and federal environmental officials are beginning a manatee habitat restoration program, armed with $8 million in state money approved this year by Florida legislators. They say with cooler winter months on the way, the tendency of manatees to congregate in warmer waters could mean many more of the creatures will starve before the restoration work is completed.
"Seagrass restoration doesn't happen overnight. We can't really start planting seagrass until we have water quality improvements," said Michael Sole, vice chairman of the Florida Fish and Wildlife Conservation Commission. "The winter is coming."
The commission is asking state lawmakers to approve another $7 million in the upcoming legislative session for seagrass restoration, manatee rehabilitation centers and other projects. At a committee hearing last week, McRae said researchers also are studying whether humans can feed manatees without harming them.
"Those of you that have paid attention to feeding wildlife know that almost universally, it does more harm than good," McRae told lawmakers. But if the manatees' numbers keep plummeting, "there's a possibility some level of supplemental feeding might be in order," he said.
Manatees have struggled to withstand humans for decades. Boat strikes kill dozens of the slow-moving animals despite no-wake zones in areas the animals frequent, and many more bear lifelong scars from such encounters. There are also threats from red tide outbreaks—and unusually cold weather.
In this Thursday, April 2, 2020, file photo, a manatee comes up for air is it swims in the Stranahan River, in Fort Lauderdale, Fla. Florida is experiencing an unprecedented die-off of manatees this year, with 959 documented deaths as of mid-October. Credit: AP Photo/Wilfredo Lee, File
They are gentle round-tailed giants, weighing as much as 1,200 pounds (550 kilograms) and living as long as 65 years or so. Manatees are Florida's official state marine mammal and are closely related to elephants.
Perhaps the best-known and oldest manatee in captivity, a male named Snooty, died at age 69, drowning after a hatch malfunctioned in his aquarium at a Bradenton museum in 2017.
Manatees were listed as endangered beginning in 1966 by the U.S. Fish and Wildlife Service, a designation downgraded to the less-stringent threatened category in 2016. A new push is on to list manatees as endangered once again to increase their long-term recovery chances.
"Florida manatees desperately need us to help them by cleaning up and protecting their habitat," said Jaclyn Lopez, Florida director and senior attorney at The Center for Biological Diversity, a St. Petersburg-based nonprofit intent on saving imperiled species. The center and other groups plan to sue the U.S. Fish and Wildlife Service to boost habitat protections for the manatee.
So far, the threatened designation has remained in place. A 2017 federal-state analysis pegged the chance of manatee extinction in Florida at less than a half-percent within the next 100 years.
Yet to environmental groups, the struggle of the manatee is a signal that humans are wrecking the coastal estuaries they and many other creatures need to survive.
The state Department of Environmental Protection has set in motion a program aimed at sharply reducing the load of harmful releases into the Indian River Lagoon by 2035.
The focus is on cutting introduction of nitrogen and phosphorous that is responsible for the seagrass-killing algae blooms. Projects to date have reduced releases of these nutrients by 37% of the ultimate goal, according to the state environmental agency.
Meanwhile, efforts to rescue and rehabilitate starving manatees continue at locations such as the SeaWorld theme park in Orlando to the Tampa zoo.
The Clearwater Marine Aquarium in September announced plans for a $10 million manatee rescue and rehabilitation facility, the fifth of its kind in Florida.
A coalition of 16 environmental and business groups called this summer for Republican Gov. Ron DeSantis to declare the manatee die-off an emergency, which could focus resources and attention on the problem. DeSantis hasn't done it, contending at a news conference it would "spook a lot of people" and possibly trigger economic harm.
"We have a lot of money at our disposal," the governor said.
Back out on the water, fishing guide and activist Fafeita said it's not just the manatees—seagrass reduction also affects other species such as blue crabs and speckled sea trout.
SpaceX needs to tame toilet trouble before weekend launch
by Marcia Dunn
In this Saturday, April 24, 2021, file photo made available by NASA, the SpaceX Crew Dragon capsule approaches the International Space Station for docking. SpaceX is scrambling to resolve toilet spills in its capsules before it launches another crew for NASA. Liftoff is currently set for early Sunday, Oct. 31, from Florida's Kennedy Space Center. Credit: NASA via AP, File
SpaceX is taming some toilet troubles in its capsules before it launches four more astronauts.
The company and NASA want to make sure the toilet leaks won't compromise the capsule launching early Sunday from Kennedy Space Center or another one that's been parked at the International Space Station since April.
During SpaceX's first private flight last month, a tube came unglued, spilling urine onto fans and beneath the floor, said William Gerstenmaier, a SpaceX vice president who used to work for NASA. The same problem was recently discovered inside the Dragon capsule at the space station, he told reporters Monday night.
As a permanent fix, SpaceX has welded on the urine-flushing tube that's inside the company's newest capsule, named Endurance by its U.S.-German crew. NASA isn't quite finished reviewing the last-minute fix.
As for the Dragon capsule in orbit, less urine pooled beneath the floor panels than the one that carried a billionaire and three others on a three-day flight, Gerstenmaier said. That's because the NASA-led crew only spent a day living in it before arriving at the space station.
SpaceX is conducting tests to make sure the spilled liquid didn't weaken the orbiting capsule during the past six months, Gerstenmaier said. Any structural damage could endanger astronauts during their flight back to Earth next month. The final tests should be completed later this week, he noted.
In the meantime, the one German and three NASA astronauts fly in from Houston on Tuesday for the countdown. Like their predecessors, they'll spend six months at the space station.
This will be SpaceX's fourth launch of NASA astronauts and its fifth passenger flight overall. NASA turned to SpaceX and Boeing to transport crews to and from the space station, following the retirement of the shuttle fleet in 2011. U.S. astronauts hitched rides on Russian rockets until SpaceX took over the job last year.
Study detects the presence of flame retardants inside homes, offices and schools
by Universitat Rovira i Virgili
Credit: Pixabay/CC0 Public Domain
Flame retardants are chemicals found in furniture, textiles, coatings, and plastics such as cell phones, laptops, televisions, etc., and are intended to prevent or delay the spread of a fire. The first ones came onto the market in the 1970s and since then the number of different ones has expanded. Flame retardants can be released into the environment through high temperatures, friction or cleaning and can thus accumulate in the air or dust inside buildings, leading to human exposure through inhalation, ingestion and skin contact.
Some flame retardants have been shown to have adverse effects on health and since 2004 have been banned by European legislation and replaced by new ones, called emerging flame retardants, thehealth effectsof which have not yet been studied. The URV's TecnATox research group has now detected the presence of seven emerging flame retardants in the air in a pioneering study in Europe. The results of this research have been published in the scientific journal Science of The Total Environment.
The study, which is part of the FlameRISK project, has assessed the possible health risks, especially among children, whose tendency to put their hands or objects in their mouths, play on the floor and crawl on all fours increase their likelihood of exposure to these substances. To carry out the research, the research team analyzed samples from twenty interior spaces of homes, offices and schools in the province of Tarragona. Air was collected for 24 hours using sensors that emit a stream of air and retain flame retardants in a filter. Samples of dust accumulated on furniture surfaces and electronic devices in the same spaces were also available. They were subsequently analyzed to determine the levels of 41 different types of emerging or controlled flame retardants.
The results confirmed the presence of seven emerging flame retardants (TEP, TCIPP, T2IPPP, TPPO, DCP, TMCP and B4IPPPP) in the air for the first time in Europe, including at high levels. Controlled flame retardants were also detected in the samples, although in smaller amounts than the emerging ones. This is because in many interior spaces there are still products (furniture, paints, devices, etc.) that were manufactured with these flame retardants before they were banned in 2004.
The results were used to calculate the levels of exposure and the health risks for adults and children living in these indoor spaces. The risk was found to be higher for the child population, close to the limit considered dangerous by the legislation. "This shows the potential of these chemicals, particularly the flameretardant TClPP, to affect human health," says Roser Esplugas, a researcher in the URV's Department of Chemical Engineering who participated in the study. If the permitted limits are exceeded, these retardants can cause cancerous diseases and toxicological effects such as altered hormonal and neurological systems, among others.
"It should be stated that the study did not examine people's exposure to these compounds in other indoor spaces, such as vehicles, where the presence is greater than in homes. Consequently, we may assume that the real risk is even greater ", warns the researcher. Nor did the study look at their ingestion by humans, which is another major source of exposure. The widespread use of these compounds means that they can enter the food chain and, therefore, also be ingested through food.
The results of the study confirm the importance of continuing to measure flame retardants in different environments and assessing their effects on health in order to provide scientific literature on the possible risks to the population.
More information:Roser Esplugas et al, Emerging and legacy flame retardants in indoor air and dust samples of Tarragona Province (Catalonia, Spain),Science of The Total Environment(2021).DOI: 10.1016/j.scitotenv.2021.150494
A new way to detect early signs of harmful blue-green algae, which bloom in lakes, rivers and reservoirs around the world, has been developed by researchers at the University of Birmingham together with researchers at the Culture Collection of Algae & Protozoa (CCAP), based at the Scottish Association of Marine Science.
Blue-green algae, or cyanobacteria, present huge environmental problems. Large scale break-outs, or blooms, spread across bodies of water, depleting the oxygen supply and reducing light, killing fish and other aquatic animals. In addition, some algae can produce toxins that are harmful to animals and humans.
Detecting these blooms – at a sufficiently early stage to prevent them reaching dangerous levels – is not straightforward because of the thousands of different species of algae that could be present. As algae are a vital part of many water systems, it is only those species which become harmful that may need these preventative measures.
Researchers in the University of Birmingham’s School of Biosciences have designed a new approach which uses mass spectrometry – a way of identifying specific molecules by their mass – to identify key protein features within the algae that are unique to each species, enabling them to be rapidly identified. Using recently developed, high resolution techniques, the team found they were able to produce highly specific ‘fingerprints’ that each correspond to specific cyanobacterial species.
The technique is also successful in identifying combinations of different cyanobacteria at low pre-bloom concentrations. This means that the cyanobacteria can be identified before significant quantities of blue-green algae have developed.
Lead author, Dr Aneika Leney, explained: “This is an exciting first step towards developing useful tools that can be used to keep harmful blue-green algae blooms at bay, while leaving non-toxic species untargeted.”
Future work to develop this technique would involve creating a large database of spectral fingerprints for all the different cyanobacteria species currently known. Thus, when a match is found, the species can be identified rapidly.
The technique can also be used to check the authenticity of cyanobacterial products, such as spirulina extracts, that are consumed as health and food supplements.
IMAGE: LITTLE MOSES, AN OUTCROP SPRING AT THE DOONGMABULLA SPRINGS COMPLEX, QUEENSLAND, AUSTRALIA. PHOTO R KEEGAN-TRELOAR, FLINDERS UNIVERSITY.view more
CREDIT: PHOTO R KEEGAN-TRELOAR, FLINDERS UNIVERSITY.
New research led by Flinders University is renewing calls to protect the source of water and aquifers supporting the ecologically significant Doongmabulla Springs Complex in central Queensland from a proposed Carmichael coal mine in the Galilee Basin.
As work on the Bravus (previously Adani) mine progresses, leading groundwater scientists warn more research is needed to measure and fully understand the aquifer sources that potentially feed the spiritually and environmentally significant springs located near the large inland mine site about 300km from the east coast of Australia.
“Even if the springs’ source aquifer is partially dewatered for mining operations, there is a serious threat of permanent damage,” says Flinders University PhD candidate Mr Robin Keegan-Treloar, the lead author of a new paper in the international Journal of Hydrology.
“Our study expands on existing water level data, undertaking the most rigorous analysis so far, and even now we cannot definitively identify the source of water to the springs.
Mr Keegan-Treloar says that without better knowledge of the hydrogeology of the area, the springs are at risk of “irreversible decline.”
“These concerns have been raised in this study, as well as CSIRO and Geoscience Australia studies, about threats to the springs from the Carmichael mine,” he says.
Despite previous warnings, and remaining uncertainties over the effects of nearby mining operations, the mine is still going ahead, says senior author, Flinders University Professor Adrian Werner, from the National Centre for Groundwater Research and Training.
“These findings have important implications given that the Permian Formations will be dewatered by the operation of the nearby Carmichael coal mine,” Professor Werner says.
“Lowering the uncertainty of permanent damage to the springs will require new drilling and seismic studies to adequately identify the hydrogeological regime between the mine site and the springs.”
The research group says the techniques used in the latest study help to identify and quantify conceptual model uncertainties, although further work is needed.
Research is ongoing, with follow-up studies being conducted using water chemistry, geophysics and numerical modelling.
“The latest study have important implications given that the Permian Formations will be dewatered by the operation of the nearby mine,” Mr Keegan-Treloar says. “Lowering the uncertainty of permanent damage to the springs will require new drilling and seismic studies to adequately identify the hydrogeological regime between the mine site and the springs.”
Field work (IMAGE)
FLINDERS UNIVERSITY
CAPTION
Field work at the Doongmabulla Springs Complex in 2019 shows Professor Adrian Werner surveying the elevation of a spring, and Flinders University graduate Dr Dylan Irvine (now Charles Darwin University) collecting a water sample. Also shown is a v-notch weir measuring spring discharge. Photo Flinders University.
Application of Indicator Kriging to hydraulic head data to test alternative conceptual models for spring source aquifers
ARTICLE PUBLICATION DATE
16-Aug-2021
COI STATEMENT
The authors declare no conflict of financial or personal interest
Long-term study of elephant seal reproduction shows population’s resilience
Researchers found that a female elephant seal’s age and experience were more important than ocean conditions in determining the condition of her pup at weaning
IMAGE: RESEARCHERS FOUND THAT AS THE DENSITY OF AN ELEPHANT SEAL BREEDING COLONY INCREASES, THE SIZE OF THE PUPS AT WEANING DECLINES, AND THIS EFFECT IS MORE PRONOUNCED FOR YOUNGER FEMALES.view more
CREDIT: PHOTO BY DANIEL COSTA
A new study based on four decades of data from the elephant seal colony at Año Nuevo Reserve has enabled researchers to disentangle the effects of environmental conditions, population density, and maternal traits on reproductive success in northern elephant seals.
The study, published October 13 in Proceedings of the Royal Society B, focused on how much the pups weighed when they were weaned (weaning mass), because higher weaning mass increases a pup’s chance of survival. First author Rachel Holser, a postdoctoral researcher at UC Santa Cruz, said she expected major oceanographic events that affect the abundance and distribution of the seals’ prey to have a big effect. To her surprise, however, other factors turned out to be much more important.
“The single most important factor in determining the weaning mass of pups was the age of the mother,” Holser said. “That was more important than the mother’s size, which is a measure of her foraging success, and certainly more important than conditions in the ocean. We expected major El Niño events and other oceanographic events to have more impact than they did.”
The mother’s age is important for several reasons, she noted. One is that older females produce milk with higher fat content at the start of lactation than young females do. But the mother’s experience is also crucially important. A more experienced female is better able to choose and defend a good location on the beach for rearing her pup, and she is better able to keep her pup from getting lost and wasting its energy.
“When she gives birth to this tiny pup, it’s got four weeks to put on as much fat as it can, which means it needs to spend as much time as possible nursing and resting,” Holser said.
This gets harder as the population grows and more and more animals are crowded together on the beach. “When the colony becomes more dense, there are more interactions—sometimes the females are fighting, or the males will cause a disturbance—and pups end up getting lost and wasting energy trying to find their mother,” she said.
The study found that higher population densities led to smaller pups overall, but this effect was more pronounced for younger females than for the older, more experienced ones.
Holser noted that, while it is often assumed that a larger female will have larger pups, the mother’s age is actually more important than her size. “There’s a lot of variability in size, and the data show that what’s really important is the experience of having been through multiple reproductive cycles,” she said.
Ocean conditions—such as El Niño events, the Pacific Decadal Oscillation, and marine heatwaves—do matter, she said, but their effects on weaning mass are relatively small compared to other factors. “It’s not that it doesn’t play a role, but it’s not nearly as important as those onshore conditions—who your mother is and how dense the colony is,” Holser said.
This resilience in the face of changing environmental conditions is largely due to the elephant seals’ reproductive strategy. Female elephant seals spend months at sea traveling vast distances across the North Pacific Ocean to feed and put on weight before returning to the colony to give birth. While nursing their pup, they do not leave the beach to feed, relying on the stored energy acquired during the foraging migration.
Other species, such as the California sea lion, depend on regular feeding forays while they are nursing their pups, so a change in conditions that makes it harder to find prey off the coast can be disastrous.
“During a major El Niño, you can see almost complete reproductive failure in some years for species like sea lions,” Holser said. “With elephant seals, we don’t see that kind of boom and bust effect. Even in a poor year, they manage to be pretty successful.”
She cautioned, however, that the effects of ocean conditions on elephant seals can be seen in some measures of the population’s health other than weaning mass. In bad years, some females will skip breeding entirely to restore their body condition rather than rearing a pup. There may also be a decrease in the survival rate of adult females.
“Previous work has shown that ocean conditions impact the ability of the mother to invest in her young, but this study shows that age and, more importantly, experience can compensate for those environmental changes,” said coauthor Daniel Costa, professor of ecology and evolutionary biology and director of the Institute of Marine Sciences at UCSC. “As a senior scientist, it’s good to know that experience matters!”
Northern elephant seals were hunted to near extinction by the early 1900s, but the population has made a remarkable recovery since the end of commercial sealing. Thousands of pups are now born every year at the breeding colony at Año Nuevo Reserve, part of the UC Natural Reserve System.
The long-running elephant seal research program at UC Santa Cruz has been studying this colony since the 1960s, yielding an invaluable trove of data. Begun by Professor Emeritus Burney Le Boeuf, the program has continued under Costa’s leadership.
“This study was only possible because of the work of hundreds of people who have been taking these measurements for over 40 years,” Holser said.
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In addition to Holser and Costa, the coauthors of the paper include Daniel Crocker at Sonoma State University, Patrick Robinson at UC Santa Cruz, and Richard Condit at the Field Museum of Natural History in Chicago.
JOURNAL
Proceedings of the Royal Society B Biological Sciences
