Earth
How Tuna and Swordfish Hunt in the Deep; MIT Oceanographers find the answer
A new study reveals that tuna and swordfish are making regular, long-distance plunges into the twilight zone, a mysterious and dark layer of the ocean, to fill their stomachs

Imagine diving into the ocean’s depths, descending further than the eye can see, into a cold, almost completely dark world where every movement feels like a gamble. For some of the ocean’s most formidable predators—like tuna and swordfish—this is no mere adventure; it’s a necessity. A new study reveals that these apex hunters are making regular, long-distance plunges into the twilight zone, a mysterious and dark layer of the ocean, to fill their stomachs. And what they’re finding there could change the way we think about ocean ecosystems and the future of commercial fishing.
For decades, oceanographers knew that large fish like tuna and swordfish occasionally ventured into the depths of the ocean, but the purpose of these dives remained unclear. Were these predators hunting for food, or were they just exploring? A recent breakthrough by MIT oceanographers has answered that question—and the results are more astonishing than anyone could have imagined.

In a pioneering study published in ICES Journal of Marine Science, an MIT team led by Ciara Willis has found that these fish are relying heavily on the twilight zone, a dark, cold layer between 200 and 1,000 meters below the surface, for as much as 60% of their diet. This discovery reveals a much deeper connection to this enigmatic zone than scientists previously realized.
“We’ve known for a long time that these fish and many other predators feed on twilight zone prey,” says Willis, a postdoc at the Woods Hole Oceanographic Institution, in a press statement. “But the extent to which they rely on this deep-sea food web for their diet has been unclear.”
The Hidden Feast
The twilight zone—often overlooked in marine research—has been gaining attention for its rich ecosystem. It’s a vast, underexplored region teeming with strange creatures, from tiny lanternfish to massive squid, all adapted to live without sunlight. While the surface waters are teeming with life, they offer less concentrated food for large predators. By contrast, the twilight zone is like a dense buffet, providing predators like bigeye tuna, yellowfin tuna, and swordfish a more reliable food source.
“This is a really understudied region of the ocean, and it’s filled with all these fantastic, weird animals,” Willis says. “We call it the ‘deep ocean buffet.’”
The deep sea creatures in the twilight zone have evolved to migrate vertically—swimming to the surface to feed at night and returning to the depths by day to avoid predators. For the big predators of the open ocean, this behavior creates a prime opportunity to feast. Bigeye tuna, yellowfin tuna, and swordfish dive regularly into these depths to hunt. But until recently, scientists didn’t know just how important this food source truly was.
“We saw the bigeye tuna were far and away the most consistent in where they got their food from,” Willis explains. “The swordfish and yellowfin tuna were more variable, meaning that if large-scale fishing were to target the twilight zone, bigeye tuna might be the ones most at risk.”
The Price of Overfishing the Deep
This discovery comes at a critical time. The growing interest in commercial fishing in the twilight zone, despite its often unpalatable fish species, has raised alarms. These creatures are increasingly being harvested for fishmeal and fish oil, products commonly used in animal feed and other industries. However, as researchers point out, this could have dire consequences for tuna and swordfish populations.
“There is increasing interest in commercial fishing in the ocean’s twilight zone,” says Willis. “If we start heavily fishing that layer of the ocean, our study suggests that could have profound implications for tuna and swordfish, which are highly reliant on this region.”
The team’s findings underscore the need for careful management of the twilight zone’s resources. Given that tuna and swordfish rely on this zone for up to 60% of their food, disruptions to the ecosystem here could have cascading effects on the open ocean and the global fishing industry.
“Predatory fish like tunas have a 50% reliance on twilight zone food webs,” Willis warns. “If we start heavily fishing in that region, it could lead to uncertainty around the profitability of tuna fisheries.”
As the twilight zone becomes a target for increasing commercial interest, scientists are calling for greater caution in how we approach the deep ocean’s complex food web. What lies in the shadows of the ocean’s depths may be far more crucial to our marine ecosystems than anyone has realized.
Earth
Biofilms impede free build up of microplastics
New insights could guide cleanup strategies in rivers and coastal zones.

Understanding where microplastics end up in our ecosystem, can help with efforts at environment monitoring amidst widespread plastic pollution. In a recent study, researchers at the Massachusetts Institute of Technology (MIT) have discovered a surprising factor that could help predict microplastic hotspots — biofilms.
Biofilms are thin, sticky layers of biopolymers secreted by microorganisms – are commonly found along riverbeds and seashores. The study, published in the journal, Geophysical Research Letters, suggests these biological coatings can significantly influence whether microplastics settle into sediments or get carried away by water flow.
“Microplastics are definitely in the news a lot,” Heidi Nepf, a professor of civil and environmental engineering at MIT, the study’s senior author, said in a media statement. “And we don’t fully understand where the hotspots of accumulation are likely to be. This work gives a little bit of guidance.”
The study used a controlled flow tank experiment simulating natural riverbed conditions. The researchers found that microplastics were far less likely to accumulate in sandy beds that contained simulated biofilms. In these cases, particles that landed on the surface were more exposed and easily swept away by water.
“These biological films fill the pore spaces between the sediment grains,” Hyoungchul Park, a postdoc at MIT and the study’s first author, explained. “That makes the deposited particles more exposed to flow forces, making it easier for them to be resuspended.”
The experiment involved pumping water mixed with fluorescent microplastic particles through tanks with different bed compositions—some with clean sand and others with added biological material mimicking biofilm. The results showed a clear trend: microplastics stuck more to sand beds without biofilms and less to those with the sticky biological layers.
“The biofilm is blocking the plastics from accumulating in the bed because they can’t go deep into the bed,” Dr. Nepf said. “They just stay right on the surface, and then they get picked up and moved elsewhere.”
The findings may have important implications for environmental monitoring and microplastic mitigation efforts. For instance, in mangrove ecosystems, where outer edges tend to be sandy and interiors richer in biofilm, the sandy outer zones could become key areas for microplastic buildup.
“These results suggest the sandy outer regions may be potential hotspots for microplastic accumulation,” Dr. Park noted in the media statement, pointing to possible priority areas for targeted cleanup or protective measures.
While the interaction between biofilms and microplastics is just one piece of the puzzle, the study offers a useful lens for researchers and policymakers trying to trace and manage plastic pollution in aquatic environments.
“It gives guidance to where you should go to find more plastics versus less,” Dr. Nepf added, suggesting that knowing how sediments interact with flow and biology could improve predictions and cleanup strategies.
Earth
World Environment Day 2025: “Beating plastic pollution”
Although the environment day is arguably symbolic, the occasion lends platform to milestones achieved in past successive year, bringing spotlight to concerns why plastic pollution is worth consideration, and to also showcase stellar efforts from across the world, in terms of advocacy and solutions proposed to tackle plastic produce and waste.

For the 193 member countries of the United Nations Environment Program (UNEP), today marks the World Environment Day.
This year, South Korea’s Jeju city hosts the event, addressing the widespread plastic pileups accumulating in our ecosystems. In 2018, India hosted the UNEP event under the same theme.
Although the environment day is arguably symbolic, the occasion lends platform to milestones achieved in past successive year, bringing spotlight to concerns why plastic pollution is worth consideration, and to also showcase stellar efforts from across the world, in terms of advocacy and solutions proposed to tackle plastic produce and waste.
Moreover, this year’s environment day comes exactly two months before the second session of UNEP convenes in August, to negotiate a legally binding international treaty on plastic pollution. Amongst consideration on the agenda would be dealing with microplastics.
The hazards of using plastic
Plastic is a chemical polymer, with repeating molecular units linked by carbon bonds. It is a synthetic byproduct of a chemical reaction involving parent organic compounds, notably fossil fuels, aka petroleum and natural gas.
Burning plastic, only releases toxic fumes including a ton of greenhouse gases involved in its manufacture, inadvertently contributing to the climate crisis. As the world phases out fossil fuels to combat global warming and climate change, plastic production cease, and be confined within a circular economy.
Nonetheless, it poses an environmental risk, since they are not degradable in nature. According to a UNEP report, about 400 million metric tones of plastic waste are produced annually. Only 10% are ever recycled. Many, amounting to some 8 million tones of plastic waste leak into the oceans.
Spent plastic packages disposed in landfills, rivers and oceans merely pile up in quantity, increasing encounters where humans and marines accidentally ingest plastic. Plastic accounts for 85% of all marine waste. Not only does that affect marine life but also alter the ecosystem’s resilience to the changing climate.
There here have been efforts to erase plastic’s footprint completely. Common engineering solutions hypothesized involves using enzymes produced by bacterial species found in nature which can selectively attack chemicals in plastic. However, these discoveries have remained confined to the lab. Mass-scale solutions are still a work in progress.

On microplastics, we have “real reasons to be concerned.”
As microscopic particles, plastic can easily enter the food chain and circulate far and wide amongst humans and other animals. They are a common appearance in our daily diets, when consuming seafood in addition to other meat. But it remains unclear whether they can be similarly toxic.
“Scientists are still trying to understand the potential impact on our health but there are real reasons to be concerned,” Susan Gardner, who heads the UNEP’s ecosystems directive, says.
For a fact, these microplastics don’t exist in a thin vacuum. Chemical additives binding plastic manufactures, especially heavy metals, can be carcinogenic as well. In the last decade, studies have shown how microplastics can seep through sensitive skin and blood-brain barriers in our body.
Global South dominates plastic polluter charts
Combating plastic pollution is not purely a top-down approach as world governments pursue today. Rather, it ultimately succeeds because it inspires bottom-up, civic action.
That is why the environment day has a special draw upon students, scientists, environmental activists, and entrepreneurs from across the world to recognize conserving the environment, as a societal and civic responsibility.
The Indian President, Draupadi Murmu, took to social media X to promote the World Environment Day in the country. She posted, “Every action for the environment makes a difference and our collective efforts can lead to a greener earth for future generations.”
A study published in the journal Nature found India contributes some 9 million metric tones annually, topping the plastic polluter’s chart. More damningly, it is thought these are underestimations, since the “official statistics do not include rural areas, the open burning of uncollected waste, or waste recycled by the informal sector,” Down to Earth reports.
Saying that the problem is more complex, with the Global North where the industrialized nations reside, affording better waste management programs. Countries in the Global South, historically underdeveloped, including India, face a natural disadvantage. However, eco-entrepreneurs have suggested a more inspiring means to confront what is ultimately a cultural problem.
Living in harmony with nature
“Nature doesn’t need our social media posts on Environment Day. It needs our consistent action, our lifestyle choices and our respect,” Radhakrishnan Nair, co-founder at the Enviro Creators Foundation, said to students at a deemed to be university in Mangalore, was cited in The Hindu report earlier today.
Mr. Nair, who had won global acclaim for his efforts developing some 100 Miyawaki forests, including the largest such one in the world, was subject of EdPublica’s central feature piece back in April 2025.
“Why use a straw when you can drink directly? I carry my own steel plate and tumbler with me wherever I go,” the Malayali native was reported having said in The Hindu. “If each of us made small changes like this, the planet would breathe easier.”
Earth
Glaciers Are Dying: Global Conference in Tajikistan Sounds Alarm on Looming Water Crisis
Glaciers currently store about 70% of the world’s freshwater. Their meltwater sustains hundreds of millions downstream during the dry season

The accelerating disappearance of the world’s glaciers—often called the “water towers” of our planet—is now a full-blown global emergency, warned experts and leaders gathered in Tajikistan for the International Conference on Glaciers’ Preservation. Underway in Dushanbe from 29 May to 1 June in Dushanbe, the event has brought together heads of state, UN officials, scientists, and development partners in a clarion call to put glacier protection at the top of the global climate agenda.
“Glaciers preservation is not just a problem of countries with glaciers but rather a global crisis that deserves the immediate attention of the international community,” said Tajikistan’s President Emomali Rahmon in his opening address.
The urgency is clear. According to a statement issued by the World Meteorological Organization (WMO), five of the past six years have seen the most rapid glacier retreat on record. Glaciers are now the second largest contributor to sea-level rise after ocean warming.
“Our glaciers are dying,” said WMO Secretary-General Celeste Saulo. “The death of a glacier means much more than the loss of ice. It is a mortal blow to our ecosystems, economies, and social fabric.”
Recent disasters highlight the stakes. Just this week, a glacier collapse in the Swiss Alps unleashed a torrent of ice and debris that buried parts of the village of Blatten. Early warnings prevented fatalities—but many developing nations lack such systems. “We need to bridge science and services, and forecasts and action,” Saulo urged.

The conference will culminate in the release of the Dushanbe Glaciers Declaration, a strategic document outlining commitments and partnerships to be presented at COP30 in Brazil later this year. It is a key milestone in the International Year of Glaciers’ Preservation.
UN Deputy Secretary-General Amina Mohammed cited devastating findings from the WMO’s latest climate report. “2021 to 2024 represents the most negative three-year glacier mass balance period on record,” she said, pointing out that glaciers have lost over 9,000 billion tons of ice since 1975—equivalent to an ice block the size of Germany, 25 meters thick.
Glaciers currently store about 70% of the world’s freshwater. Their meltwater sustains hundreds of millions downstream during the dry season. But that lifeline is fading. In the Himalayas, a 2023 report from the International Centre for Integrated Mountain Development (ICIMOD) warned that the region could lose up to two-thirds of its glaciers by 2100. Tajikistan alone has lost nearly 30% of its glaciers over the last century.
The Vanj Yakh Glacier (formerly Fedchenko), the largest continental glacier, has retreated by over 1 km and shrunk by 44 km²—enough to fill 6.4 million Olympic swimming pools.
“Melting glaciers threaten lives on an unprecedented scale – including the livelihoods of more than 2 billion people in Asia alone,” said Asian Development Bank Vice-President Yingming Yang. “ADB is committed to helping the region adapt and transition to clean energy without compromising development.”
UNESCO Director-General Audrey Azoulay highlighted the cultural and ecological loss as well. “In 2022, a UNESCO study found that glaciers in one third of world heritage sites are projected to disappear by 2050,” she said. “It is a stark reminder of the need for bold and immediate climate action.”
Key conference themes include scientific monitoring, water cooperation, and adaptation investment. The message is clear: the world cannot afford to lose its glaciers—or the freshwater, stability, and security they provide.
As Celeste Saulo put it: “Observing, predicting, and effectively communicating glacier changes are vital to mitigating their impacts on people, economies, and ecosystems.”
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