(Press-News.org) In the frigid waters surrounding Antarctica, an unusual seasonal cycle occurs. During winter, from March to October, the sun barely rises. As seawater freezes it rejects salts, creating pockets of extra-salty brine where microbes live in winter. In summer, the sea ice melts under constant daylight, producing warmer, fresher water at the surface.
This remote ecosystem is home to much of the Southern Ocean’s photosynthetic life. A new University of Washington study provides the first measurements of how sea-ice algae and other single-celled life adjust to these seasonal rhythms, offering clues to what might happen as this environment shifts under climate change.
The study, published Sept. 15 in the International Society for Microbial Ecology’s ISME Journal, contains some of the first measurements of how sea-ice microbes respond to changing conditions.
“We know very little about how sea-ice microbes respond to changes in salinity and temperature,” said lead author Hannah Dawson, a UW postdoctoral researcher who did the work while pursuing her doctorate in oceanography at the UW. “And until now we knew almost nothing about the molecules they produce and use in chemical reactions to stay alive, which are important for supporting higher organisms in the ecosystem as well as for climate impacts, like carbon storage and cloud formation.”
The polar oceans play an important role in global ocean currents and in supporting marine ecosystems. Microbes form the base of the food web, supporting larger life forms.
“Polar oceans make up a significant portion of the world’s oceans, and these are very productive waters,” said senior author Jodi Young, a UW assistant professor of oceanography. “These waters support big swarms of krill, the whales that come to feed on those krill, and either polar bears or penguins. And the start of that whole ecosystem are these single-celled microscopic algae. We just know so little about them.”
The tiny organisms are also important for the climate, since they quietly perform photosynthesis and soak up carbon from the atmosphere. Polar algae are especially good at producing sulfur-containing molecules that give beaches their distinctive smell and, when lofted into the air in sea spray, promote formation of clouds that can reduce penetration of solar rays.
Antarctic sea ice, though long stable, is at an all-time record low this year.
In other oceans, satellite instruments can capture dramatic seasonal phytoplankton blooms from space — but that isn’t possible for microbes hidden under sea ice. And Antarctic waters are particularly challenging to visit, leaving researchers with almost no measurements in winter.
In late 2018, Dawson and co-author Susan Rundell traveled to Palmer Station, a U.S. research station on the West Antarctic Peninsula. They used a small boat to sample seawater and sea ice at the same nearby sites every three days.
Back on shore, the two graduate students performed 10-day experiments in tanks to see which microbes grew as temperature and salinity were adjusted to mimic sea-ice formation and melt. They also shipped samples back to Seattle for more complex measurements of the samples’ genetics and metabolites, the small organic molecules produced by the cell.
Results revealed how single-celled algae deal with their fluctuating environments. As temperatures drop, the cells produce cryoprotectants, similar to antifreeze, to prevent their cellular fluid from crystallizing. Many of the most common cryoprotectant molecules were the same across different microbial lifeforms.
As salinity changes, to avoid either bursting in freshening waters or becoming desiccated like raisins in salty conditions, the cells change the concentration of salt-like organic molecules. Many such molecules serve a dual role as cryoprotectants, to balance conditions inside and outside the cell to maintain water balance.
The results show that under short-term temperature and salinity changes, community structure in each sample remained stable while adjusting the production of protective molecules. Different microbe species showed consistent responses to changing conditions. This should simplify modeling future responses to climate change, Young said.
Results also hint that the production of omega-3 fatty acids may decline in lower-salinity environments. This would be bad news for consumers of krill oil supplements, and for the marine ecosystem that relies on those algae-derived nutrients. Future research now underway by the UW group aims to confirm that result — especially with the prospect of increasing freshwater input from melting sea ice and glaciers.
“We’re interested in how these sea-ice algae contend with changes in temperature, salinity and light under normal conditions,” Dawson said. “But then we also have climate change, which is completely remodeling the landscape in terms of when sea ice is forming, how much sea ice forms, how long it stays before it melts, as well as the quantity of freshwater input from glaciers. So we're both trying to capture what's happening now, and also asking how that can inform what might happen in the future.”
The study was funded by the National Science Foundation, the Simons Foundation, and the Alfred P. Sloan Foundation. Other co-authors are Anitra Ingalls, Jody Deming, Joshua Sacks and Laura Carlson at the UW; Natalia Erazo, Elizabeth Connors and Jeff Bowman at Scripps Institution of Oceanography; and Veronica Mierzejewski at Arizona State University.
For more information, contact Dawson at firstname.lastname@example.org or Young at email@example.com.
Ground-nesting birds called lapwings use the shape of their nests and surroundings to hide from predators, new research shows.
Many ground-nesting species are in decline due to changes in land management and high populations of predators, such as foxes and crows. Conservation projects can fail because too many eggs and chicks are eaten.
The new study, led by the University of Exeter, assessed the visibility of lapwing nests in terms of cover (also called “occlusion”) and camouflage using models that simulate the vision and viewing angles of various predators.
The findings showed that despite nesting in open fields, lapwings can hide their eggs ...
The review, conducted jointly with researchers from Oxford University, the Royal Berkshire Hospital in Reading, and the Princess Anne Hospital in Southampton, included seven randomised controlled trials involving 2,464 women or couples who had been trying to conceive.
Each month there is a narrow window for successful conception due to the limited lifespan of the sperm and egg, which begins from around five days before ovulation (egg release) and lasts until several hours afterwards.
The period of a woman’s cycle can be identified by different methods, including urine ovulation tests (dipstick ...
A major new study has revealed that American teenagers are more likely than any other nationality to brag about their math ability.
Research using data from 40,000 15-year-olds from nine English-speaking nations internationally found those in North America were the most likely to exaggerate their mathematical knowledge, while those in Ireland and Scotland were least likely to do so.
The study, published in the peer-reviewed journal Assessment in Education: Principles, Policy & Practice, used responses from the OECD Programme for International Student Assessment (PISA), in which participants took a two-hour maths test alongside a ...
Women could be opting to have unnecessary surgery to avoid breast cancer, after being told they are at high risk from genetic test results which do not take family history into account.
The authors of new research led by the University of Exeter have warned that women who discover, outside of a clinical setting, that they carry a disease-causing variant in one of the BRCA genes (BRCA1 or BRCA2) may be told their risk of breast cancer is 60-80 per cent. In fact, the risk could be less than 20 per cent if they do not have a close relative with the condition.
The warning has emerged in a paper published today in the Lancet journal eClinical Medicine. Until recently, women who ...
LISLE, Ill. (September 14, 2023) — The Morton Arboretum in Lisle, Ill., announced it will receive $15 million in federal funding from the U.S. Forest Service through the Inflation Reduction Act (IRA) to expand and improve the tree canopy in disadvantaged communities throughout Illinois. The funding is part of a historic $1 billion investment to boost the nation’s urban tree cover in communities nationwide. The federal grant funding the Arboretum will receive is the largest award in Illinois, the largest award to a public garden in the country and a historic sum for the nonprofit tree-focused organization.
The U.S. ...
A team of scientists with the Department of Energy’s Oak Ridge National Laboratory has investigated the behavior of hafnium oxide, or hafnia, because of its potential for use in novel semiconductor applications.
Materials such as hafnia exhibit ferroelectricity, which means that they are capable of extended data storage even when power is disconnected and that they might be used in the development of new, so-called nonvolatile memory technologies. Innovative nonvolatile memory applications will pave the way for the creation of bigger and faster computer systems by alleviating the heat generated from the continual ...
Rochester Institute of Technology’s Gabriel Diaz, associate professor in the Chester F. Carlson Center for Imaging Science, has earned the Research to Prevent Blindness/Lions Clubs International Foundation Low Vision Research Award (LVRA), in collaboration with researchers at the University of Rochester.
The award is given annually to provide funding for innovative research, which demonstrates out-of-the-box thinking, focuses on the visual system that is damaged, and seeks greater understanding of how the visual system and brain respond to severe and chronic visual ...
ITHACA, N.Y. -- To help respond to emerging and established vector-borne threats, the Northeast Regional Center for Excellence in Vector-Borne Diseases (NEVBD), led by Cornell, has received a five-year, $8.7 million award from the Centers for Disease Control and Prevention (CDC) to train and educate current and future vector-borne disease professionals and to evaluate the effectiveness of community and regional prevention strategies.
The award, effective as of July, follows $10 million in ...
NEW YORK, NY, Sept. 14, 2023--A study led by Columbia obstetricians has shown that a new intrauterine device can rapidly control postpartum hemorrhage, a major cause of severe maternal morbidity and death, in real-world situations.
“Our findings show that the device is an important new tool in managing postpartum bleeding,” says Dena Goffman, MD, professor of obstetrics and gynecology at Columbia University Vagelos College of Physicians and Surgeons and senior author of the study.
“We had ...
Weill Cornell Medicine has been awarded a five-year, $5 million grant from the United States Department of Health and Human Services through the Office of Population Affairs under the Teen Pregnancy Prevention Program to conduct a randomized trial testing whether a bilingual video game called “No Baby No (No Bebé No)” can increase the use of contraception among sexually active Black and Hispanic adolescents.
“Nine out of ten teens play video games. No Baby No empowers Black and Hispanic adolescents to learn about contraception, and the potential consequences of not using it, in a risk-free virtual ...