Nestled in the heart of Philadelphia, Pennsylvania, the Academy of Natural Sciences of Drexel University emanates the aura of a sprawling cabinet of curiosities. Its neoclassical facade is covered in natural motifs—doorways flanked by ammonites, handrails that curl into ferns, bronze door handles shaped like ibis skulls. As the oldest natural science institution in the western hemisphere, the academy has accumulated a trove of remarkable specimens. Among the 19 million or so specimens housed here are plants procured on the Lewis and Clark Expedition, blue marlin reeled in by Ernest Hemingway, and America’s first mounted dinosaur skeleton.
Many of the academy’s most unassuming yet impactful treasures are filed away on its second floor, in an office space crowded with hulking cabinets and microscopes. Next to one of these microscopes, curator Marina Potapova pops open a notebook-sized plastic container brimming with glass slides. To the untrained eye, these unremarkable slides seem filthy—each looks like it’s been smudged by dirty fingers.
But as soon as Potapova slips one under a microscope lens, the slide’s contents dazzle. Dozens of diatoms—microscopic, single-celled algae encased in sturdy silica walls and found wherever there is water—are fixed to the slides in a myriad of shapes.
With over four million specimens, the Academy of Natural Sciences of Drexel University’s diatom collection in Philadelphia, Pennsylvania, is the second largest in the world. Photo by Jack Tamisiea
Some are elongated like baguettes or flattened into saucers while others hook together to resemble translucent centipedes. Others are barbed like harpoons or shaped like pudgy sea stars. Some even resemble ornate stained-glass windows. Under a microscope, a few drops of murky pond water become a kaleidoscope of diatom diversity.
The beauty of diatoms is impressive. But their ecological significance is staggering. Diatoms anchor marine food webs by feeding everything from minuscule zooplankton to mammoth filter feeders. (Case in point: scientists have deduced that the rise of whales some 30 million years ago mirrors a spike in diatom diversity.) Diatoms also have an outsized atmospheric impact. As one of the planet’s most prolific organisms, diatoms siphon harmful gases like carbon dioxide out of the air and produce massive stores of oxygen as they photosynthesize. It is estimated that roughly one-quarter of the air we breathe is created by diatoms.
More than four million specimens of these essential algae are plastered onto hundreds of thousands of slides and housed in the academy’s diatom herbarium. Only London’s Natural History Museum stores more slides of diatoms.
Although the academy’s diatoms no longer feed the planktonic masses or pump oxygen into the atmosphere, they do hold clues about how the aquatic world is changing. As their tough shells sink to the bottom of a body of water, they are stored in the sediment for millennia. When researchers use a sediment core to drill down into the muddy bottom of an estuary, they are collecting diatoms deposited over the eons.
In addition to being plentiful and hardy, diatoms are also a crucial barometer for a variety of environmental conditions. The existence of certain diatom species can help scientists pinpoint everything from industrial pollution to oxygen depletion. Potapova and her colleagues have recently used these water condition time capsules to gauge how accelerating sea level rise is endangering New Jersey’s coastal wetlands.
Diatoms, a type of phytoplankton made of silica and coming in myriad shapes and forms, underpin marine food webs and have an outsized impact on the health of Earth’s atmosphere. Photo by Scenics & Science/Alamy Stock Photo
Thanks to a relative dearth of environmental monitoring, the historical decline of these crucial marshes—which hoard carbon, provide nursery grounds for fish, and buffer the coast from storms—has largely been obscured, making restoration efforts little more than guesswork.
However, the millions of diatoms stored at the academy are helping the researchers track the fall of the coastal wetlands as the ocean rises, which may help anticipate the coast’s future. “Diatoms are absolutely invaluable environmental archives,” Potapova says. “You can infer the future from what they tell you about the past.”
Considering the academy’s history, it is no wonder that the storied institution has become a hub for diatoms. With the advent of accessible microscopy in the 1850s, many of Philadelphia’s gentleman naturalists were captivated by the realm of minute microbes, eventually establishing the Microscopical Society of Philadelphia at the academy.
Because of their striking beauty, diatoms took the microscopical society by storm. To satiate their interest, many of these diatomists headed east to the New Jersey coastline to collect samples, which they mounted onto glass slides using a steady hand and a brush brimming with pig eyelashes. The hobbyists would then gather at the academy to show off their slides at gourmet luncheons.
The academy’s early members were clearly enthusiastic about diatoms, but most were amateurs and published little research on the myriad of specimens they collected. Organizing the mountains of slides compiled by each collector into a cohesive collection proved to be quite the task for Ruth Patrick when she arrived at the academy in 1933. The daughter of an amateur diatomist who received her first microscope at the age of seven, Patrick gravitated toward diatoms early in her childhood and eventually completed her PhD studying the microscopic organisms. Despite her scientific credentials, she was relegated to setting up microscopes and slides for the untrained hobbyists. It took her years to even gain membership in the male-dominated academy. But her persistence paid off, and in 1937 she became curator of the nascent diatom herbarium.
Patrick’s first goal was organizing the amalgamation of different collections into a unified and comprehensive source for taxonomic research. When she was not mounting and organizing slides, she was wading into nearby ponds and streams to collect new specimens in the field, where she gradually gained an appreciation for the ecological importance of diatoms.
Ruth Patrick, the first curator of the academy’s diatoms, works on the collection in the 1940s. Photo courtesy of Academy of Natural Sciences Archives coll. 457
This crystalized during a 1948 expedition to Pennsylvania’s Conestoga River—a body of water heavily polluted by sewage and industrial runoff. As her team collected samples from throughout the creek, she recognized patterns in the diatom composition. Some species’ densities exploded in areas contaminated with sewage, while others thrived in spots tainted with chemicals. Soon, Patrick became adept at using the existence of certain diatoms as a key for diagnosing pollution in lakes and rivers. This supported the idea that greater diatom diversity correlated with healthier freshwater ecosystems—an insight ecologists coined the Patrick Principle.
Patrick revolutionized the use of diatoms to monitor freshwater systems, but using them in coastal wetlands lagged behind. The brackish fusion of fresh and salt water in coastal zones such as estuaries creates habitats that are dynamic and complex with a mixture of inland and oceanic diatoms, according to Mihaela Enache, a research scientist at the New Jersey Department of Environmental Protection (NJDEP).
However, in recent decades, the sea has dominated the once-dynamic coastal margin, propelling farther inland as sea levels rise. Over the last century, the sea level along New Jersey has risen by 0.45 meters, more than double the global average of 0.18 meters. By 2100, the sea could rise by over a meter.
This dramatic rise in sea level has proven disastrous for the patchwork of marshes along New Jersey’s coastline, several of which have already succumbed to the sea. However, the full extent of the loss of these wetlands is difficult to parse because environmental monitoring only dates back a few decades.
Without a sense of a wetland’s natural conditions, ecological restoration is daunting. Having that information is crucial, says Enache. “Without [it], you are in the dark.” Thankfully, some of this missing data is recorded in the academy’s cache of diatoms.
Like most coastal margins, New Jersey is familiar with sea level rise. During the Pleistocene, when New Jersey was blanketed by ice and home to mastodons, sea ice slurped up stores of seawater. Around 18,000 years ago, sea levels sank more than 130 meters below their current levels—extending the New Jersey coastline 110 kilometers farther into the Atlantic Ocean.
The end of the last ice age sparked a steady climb in sea levels. Retreating ice sheets caused parts of New Jersey to sink. This subsidence, combined with glacial melt, proved a potent mix for rapid sea level rise according to Jennifer Walker, a sea level researcher at Rutgers University.
In a study published last year, Walker turned to the past to put New Jersey’s current bout of sea level rise in context. “If we can understand how temperatures, atmosphere, and sea level changes are all interconnected in the past, that’s what we can use to project changes in the future.”
To gauge fluctuating sea levels over the past 2,000 years, her team examined the shells of single-celled protists called foraminifera that are finely calibrated to specific environmental conditions. This makes them a valuable proxy for reconstructing shifts in sea levels. By identifying the presence of certain foraminifera species throughout sediment cores collected from different spots along the Jersey shore, her team concluded that New Jersey’s coast is experiencing the fastest rise of sea level in 2,000 years.
The NJDEP hoped diatoms could serve as a similar tool for understanding how coastal marshes responded to the rising sea. Like foraminifera, each diatom species is extremely sensitive to environmental conditions. For example, species like the rolling pin–shaped Nitzschia microcephala thrive in nitrogen-rich environments, making their shells a common sign of nutrient pollution. Other species, like Diploneis smithii, whose segmented shell resembles a slender trilobite, prefer saline waters. Their existence inland is a good indication of past sea level intrusion and helps researchers deduce which marshes have been prone to flooding in the past.
To pinpoint where these microscopic indicators once existed, the NJDEP deployed a team of researchers into several marshes along the coastline, ranging from heavily polluted wetlands in the north to near-pristine tidal marshes in the south. At each site, they cored into the marsh muck, sampling as deep as two meters in certain spots. Enache compares this method to slicing into a stack of pancakes—as you cut deeper, you are essentially going back in time from the steaming pancake just off the griddle to the soggy pancake deposited at the bottom of the stack. As they dug deeper, the researchers were traveling back decades. In total, they collected nine cores from five wetlands.
The NJDEP then sent the sediment cores to Philadelphia, where Potapova and her master’s student Nina Desianti gauged the diatom diversity of New Jersey’s coastal wetlands through time. Desianti began processing the diatom specimens by soaking the sediment samples in strong acid to dissolve everything but the silica shell before adhering them to slides. The result was an environmental history of each of the five marshes mounted onto thousands of glass slides. Then, by using the specimens already cataloged at the academy, they played a microscopic game of who’s who. But even the sprawling diatom herbarium lacked all the answers—Desianti estimates that over one-third of the 900-odd species they collected from the wetlands are new to science.
Marina Potapova, curator at the Academy of Natural Sciences of Drexel University, samples for diatoms. Photo courtesy of Academy of Natural Sciences of Drexel University
The monumental effort yielded the tome Diatom Flora of the New Jersey Coastal Wetlands in 2019. To the uninitiated, it is an overwhelming mix of intimidating Latinized names and dramatic electron microscope photographs that portray the diatoms in all their infinitesimal glory. To Enache, it’s the key to decoding the decline of New Jersey’s wetlands. By punching the composition of diatom species and modern wetland conditions into modeling programs, Enache is able to illustrate what a wetland once looked like. “Diatom species are a very precious environmental archive because we can go back in time—when nobody could take measurements of nutrients, nobody could take measurements of pH—and actually use the diatom species to get complete numbers,” she says. These figures help her record the increase of everything from agricultural nutrients to industrial chemicals in New Jersey’s water all the way back to the mid-1600s, when Europeans arrived and began to dramatically alter the state.
But while diatoms offer a window into the decline of New Jersey’s marshes, they also offer a glimpse of environmental resiliency to Desianti. Just as the team used the salt tolerance of different diatoms to map past episodes of sea level rise, they could also use the microscopic algae to deduce how these marshes responded to saltwater intrusion.
When it comes to habitats, marshes are particularly dynamic. As the boggy barriers between land and sea, coastal marshes hoard sediment, building vertically to stay above the rising ocean. When sea level rise outpaces their accumulation of sediment, the marshes retreat inland by spilling into coastal forests. As the marsh’s briny water percolates into the groundwater, it kills the trees, creating what ecologists call “ghost forests” of desiccated tree husks.
Potapova examines diatoms sampled from the coast in an Academy of Natural Sciences of Drexel University lab. Photo by Jack Tamisiea
While coastal marshes are naturally pliable, anthropogenic impacts have rendered them brittle. In New Jersey, dams strain out sediment, robbing the marsh of construction material, and retreating marshes butt up against paved roads and vacation homes. “Salt marshes have to compete with us in establishing habitat,” says Desianti, who now uses diatoms to track nutrient pollution for the Wisconsin State Laboratory of Hygiene. “As a result, these salt marshes are squeezed between sea level rise and human pressures.”
The diatoms Potapova and Desianti collected and identified will help the NJDEP not only understand how New Jersey’s coastal wetlands have responded to past bouts of sea level rise but also inform what can be done to restore these vibrant ecosystems.
The deeper you core into the pond muck, the more diverse the diatoms tend to be, which, as Ruth Patrick deduced decades ago, is the trademark of a healthy ecosystem. As you examine a core’s more recent chapters, this diatomic diversity often decreases as certain specialists, like salt-loving marine diatoms, dominate. Understanding where these saline-specializing species persist reveals which ecosystems have succumbed to sea level rise and where restoration efforts, like an influx of sediment, are needed the most.
Diatoms are not a cure for threats like sea level rise and pollution. Instead, they are a key to help combat them. They reveal what pristine habitats were once like long before anyone paid attention and illustrate what has gone awry over the centuries. To enact successful wetland restoration measures, it would be wise to consult these microscopic algae.
Which is why the diatom specimens Potapova and Desianti collected in New Jersey’s coastal marshes are being filed away alongside Patrick’s specimens in the diatom herbarium’s steel cabinets. Similarly to how they persist in sediment for millennia, the diatom specimens stored at the academy will offer invaluable data points for future researchers to make sense of pollution and shifting sea levels.
“The diatom herbarium is an invaluable resource for diatom research,” says Desianti. “I’m sure that in the future, even when I’m gone, people will still access this collection and continue to investigate environmental issues.” She is confident that within the tens of thousands of slides deposited in the recesses of the academy are environmental breakthroughs waiting to be decoded.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
