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.

A new study conducted by researchers from the University of the Free State (UFS), the National Health Laboratory Service, and the University of Venda has revealed for the first time that common brown locusts can carry pathogenic yeasts, including Candida auris, a fungus capable of causing severe infections in humans, particularly in individuals with weakened immune systems or those seriously ill.

The study, titled South African brown locusts, Locustana pardalina, hosts fluconazole-resistant, Candidozyma (Candida) auris (Clade III), uncovers the presence of the disease-causing yeast C. auris in the digestive tracts of locusts. This discovery highlights the potential for locusts to spread this emerging pathogen. The research began in April 2022, with 20 adult locusts collected during a significant locust outbreak in the semi-arid Eastern Karoo region of the Eastern Cape, which lasted from September 2021 to May 2022. The study is currently under peer review.

According to Prof. Carlien Pohl-Albertyn, National Research Foundation (NRF) SARChI Research Chair in Pathogenic Yeasts, the researchers isolated three strains of C. auris from different locusts, two of which also contained strains of Candida orthopsilosis, another potentially pathogenic yeast. “The fact that we were able to isolate C. auris from 15% of the sampled locusts, using non-selective media and a non-restrictive temperature of 30°C, may indicate that C. auris is abundant in the locusts and that specific selective isolation is not mandatory,” said Prof. Pohl-Albertyn.

The study also found C. auris in both the fore- and hindguts of the locusts. The foregut, responsible for food intake and partial digestion, likely serves as the entry point for the yeast via the locust’s feeding activities. The hindgut confirmed that C. auris can survive digestion and may be excreted back into the environment through faeces.

While C. auris poses a significant risk to individuals with compromised immune systems, Prof. Pohl-Albertyn emphasized that healthy humans are not at great risk. “There is currently no proof that ingestion may be harmful to them,” she explained. However, she warned that the yeast could pose dangers to immunocompromised individuals, even though few people in South Africa are in direct contact with locusts.

One of the C. auris strains studied in-depth showed decreased susceptibility to fluconazole, a common antifungal drug, underscoring the need for new antifungal treatments. “This highlights the urgent need to discover and develop new antifungal drugs,” Prof. Pohl-Albertyn added.

The study also raises concerns about how locusts could potentially spread C. auris to other animals, such as birds, and, in some regions, even humans. “The fact that locusts are a food source for other animals could lead to eventual distribution of the yeast to people,” Prof. Pohl-Albertyn noted. In countries where locusts are consumed by humans, direct transmission could be more likely.

This research contributes to understanding the natural hosts of emerging pathogens and their role in spreading these diseases. Prof. Pohl-Albertyn emphasized the importance of understanding how C. auris emerged as a pathogen in multiple countries and how environmental factors may have shaped its evolution. “This has implications for the prevention of the spread of this specific yeast species, as well as our preparedness for new pathogenic yeasts that may be emerging from the environment,” she concluded.

Researchers from the Department of Biological Sciences and Bioengineering at the Indian Institute of Technology (IIT) Kanpur have made a path breaking discovery that could pave the way for new treatments for cancer and respiratory diseases. The team successfully visualized the atomic structure of CXCR2, a crucial human receptor involved in the progression of these diseases. Their findings, published in the prestigious journal Molecular Cell, offer a new perspective on targeting this receptor for therapeutic intervention.

CXCR2 is a key receptor in the immune system, involved in directing immune cells to infection and injury sites through interaction with chemokines—small signaling proteins. CXCR2’s role in inflammatory disorders and cancers such as chronic obstructive pulmonary disease (COPD), asthma, atherosclerosis, and pancreatic cancer makes it a promising target for new drugs.

Using advanced cryogenic-electron microscopy (cryo-EM), the IIT Kanpur researchers captured unprecedented details of the receptor’s “lock-and-key” mechanism, shedding light on how CXCR2 interacts with multiple chemokines. This discovery addresses a fundamental question in biomedical science about how a single receptor can bind to various chemokines and trigger biological responses. The visualization also opens up opportunities for designing novel therapeutics.

“Our findings provide a molecular blueprint for designing next-generation therapeutics that can precisely target CXCR2 and potentially reduce its role in cancer and respiratory diseases. By visualizing this receptor in its active state, we now have the opportunity to develop highly specific inhibitors that can disrupt its function, potentially leading to significant advancements in treatment strategies,” said Professor Arun Kumar Shukla, the lead investigator of the study at IIT Kanpur.

The research team at IIT Kanpur includes Shirsha Saha, Saloni Sharma, Manisankar Ganguly, Nashrah Zaidi, Divyanshu Tiwari, Nabarun Roy, Nilanjana Banerjee, and Ramanuj Banerjee. Their work also involved collaboration with experts from the University of Tokyo, Japan—Fumiya Sano, Hiroaki Akasaka, Takaaki Kobayashi, Yuzuru Itoh, Wataru Shihoya, and Osamu Nureki—along with Andy Chevigne from the Luxembourg Institute of Health.

This study was funded by the DBT Wellcome Trust India Alliance, Science and Engineering Research Board (SERB), Indian Council of Medical Research (ICMR), and LADY TATA Memorial Trust.

Building on this discovery, the IIT Kanpur team is now developing small molecules and antibodies aimed at targeting CXCR2. These therapeutics will undergo laboratory testing, followed by animal studies, bringing the team closer to offering innovative treatments for cancer and respiratory diseases. This achievement further underscores IIT Kanpur’s commitment to pioneering research that has the potential to revolutionize global healthcare and biomedical innovation.