Unique lakes help demonstrate a better way to measure nitrogen loss in aquatic ecosystems

Iowa State University

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Iowa State's Elizabeth Swanner collects dissolved gas from Brownie Lake near Minneapolis in May 2025.

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Credit: Photo provided by Elizabeth Swanner, Iowa State department of Earth, atmosphere and climate.

AMES, Iowa – “The lake surface is calm, and the still air is glorious on this cool, cloudless August morning,” Iowa State University’s Elizabeth Swanner wrote about a research trip to a 60-foot deep, 13-acre lake within Itasca State Park and the Mississippi River headwaters of north-central Minnesota.

 

It’s true, she wrote, that park visitors generally don’t pay much attention to Deming Lake. 

 

But Swanner and her research group, rowing across the surface, pay a lot of attention.

 

“Modest Deming Lake offers more than meets the eye for me,” wrote Swanner, an Iowa State professor of Earth, atmosphere and climate, in an October 2023 account of her field work published by The Conversation.

 

Now Deming Lake, surrounded by forest, and its urban cousin, Brownie Lake, just off Interstate 394 and a few miles west of downtown Minneapolis, are contributing measurements to a research study published in the journal Science.

 

Both lakes are meromictic, meaning they’re permanently stratified. Unlike 99% of all other lakes, their deepest waters never rise and mix with surface waters, and their surface waters never sink to the bottom. The stratification creates a low-oxygen environment at the bottom of the lake.

 

“These systems are unique,” Swanner said. “We can see the effects of processes much more clearly. These are good testbeds.”

 

Swanner usually studies the lakes’ deep water for clues about the Earth’s early oceans, which also lacked oxygen. But for this project, her research group took samples to measure an extremely rare version of dinitrogen gas containing two 15N isotopes, a double-atom, clumped isotope of nitrogen, 15N15N.

 

Isotopes are varieties of elements that contain differing numbers of neutrons. In this case, each of the nitrogen atoms contain seven protons and eight neutrons. This “clumped isotope” version makes up 0.0016% of abundant dinitrogen (N2) gas in the atmosphere. 

 

The work of a geochemist

Leading the research project are Jiarui Liu, who conducted the research as a postdoctoral fellow at the University of California, Santa Barbara and the University of California, Los Angeles; David Valentine, of UCSB’s Marine Science Institute; and Edward Young, of UCLA’s department of Earth, planetary and space sciences. The project includes a large team of collaborators, including Swanner. The various collaborators collected samples for clumped nitrogen measurements from lakes, aquifers, coastal basins and marine sediments.

 

The samples helped determine how the nitrogen isotope can be used to more precisely measure how much dinitrogen gas is formed from nitrate through the process of denitrification, a natural process caused by microbes converting nitrate into the common, atmospheric gas.

 

Current methods rely on indirect substitutes to determine how much dinitrogen gas is produced. The mixing of atmospheric dinitrogen can obscure how much nitrate was converted. 

 

It’s the kind of project that fits Swanner’s expertise as a geochemist.

 

“Geochemists are interested in why elements are where they are and in what form they’re in,” Swanner said.

 

In this case, nitrogen is an important nutrient supporting the growth of aquatic plants and algae.

 

In Iowa, nitrogen fertilizer is applied to farm fields to feed crops. Some of that fertilizer can be lost when it leaks into nearby streams, potentially raising nitrate levels in drinking water, which can affect human health, particularly in infants and the elderly. Natural denitrification can reduce the amount of nitrate in runoff, and Swanner said better quantifying how much occurs could help fine-tune best management practices.

 

Measuring ‘an essential component of life’

The new method to measure nitrogen loss across various water bodies is a solution to an important problem in science, Swanner said.

 

“There are many ways to measure denitrification, but this clumped-isotope method seems to be able to see through other issues and arrive at a more tightly constrained estimate,” she said.

 

The method depends on analysis by the Panorama mass spectrometer at UCLA, a unique and powerful instrument designed to measure rare, clumped isotopes of elements. Because the instrument is so unique, widespread testing for the rare isotopes isn’t currently possible.

 

Prior work with the Panorama team is how Swanner’s research group connected with the project to more accurately measure nitrogen loss. A member of Swanner’s research group had been taking samples of clumped isotopes of methane for analysis by the instrument. That led to requests for samples of clumped nitrogen isotopes from Deming and Brownie lakes.

 

Now those samples, collected during the summer of 2025, are helping answer important questions about aquatic systems around the globe.

 

“Nitrogen is an essential component of life,” the researchers wrote in their Science paper, “and the balance between its sources and sinks in aquatic environments regulates ecosystem productivity, water quality, and the long-term stability of the global fixed-N (nitrogen) inventory.”

 

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Journal

Science

DOI

10.1126/science.aei0940

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Natural 15N15N abundances constrain fixed nitrogen loss

Article Publication Date

8-Oct-2026

 

Genetic analysis reveals that some specialty coffee seeds do not match their commercial identity

The study examined plants grown from Sidra and Gesha seeds and found discrepancies in two of the four morphotypes analyzed

Universidad Tecnica Particular de Loja

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The study examined plants grown from Sidra and Gesha seeds and found discrepancies in two of the four morphotypes analysed.

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Credit: Universidad Técnica Particular de Loja (UTPL)

Genetic analysis revealed that several seeds from a batch sold as Sidra were not, in fact, Sidra: their genetic profile was closer to that of Batian, a Kenyan variety. The finding comes from a study by researchers at the Universidad Técnica Particular de Loja (UTPL), who analysed four morphotypes of plants grown from seeds marketed as Sidra and Gesha on a farm in southern Ecuador. Only two of the four morphotypes matched the variety declared at the time of purchase.

In specialty coffee, a variety’s identity is linked to genetic traits that can influence its growth, productivity and cup quality. Verifying that identity, however, can be costly or difficult for producers to access. In the case studied, the seeds had been purchased without genetic or phytosanitary certification. The plants grew for approximately three years before differences observed in the field led the researchers to verify their identity through genetic analysis and morphological characterisation.

To identify the varieties planted on the farm, a genetic analysis was commissioned from a specialist in coffee genetics. This analysis used molecular markers, small regions of DNA that allow different organisms to be compared genetically. In addition, the research team recorded visible, easily recognisable morphological traits, such as plant architecture and the shape of the leaves, branches and fruits. The analysis identified four morphotypes, two of which matched the expected commercial identity of Sidra. However, one morphotype within the Sidra batch showed a genetic profile consistent with Batian, a variety of Kenyan origin that does not belong to the same genetic group as the Ethiopian landraces to which Sidra is related.

The second case concerned the plants purchased as Gesha. Genetic analysis showed that they belonged to an Ethiopian landrace; although they fell within the same genetic group, they were not identical to the CATIE reference accession in Costa Rica known as Geisha T.02722.

Another notable finding concerns the extent to which physical traits could help to distinguish between varieties. Internode length – the length of the branch segments between two growth points – was one of the physical traits that contributed most to telling them apart. Taken together, the physical characteristics assessed allowed a high proportion of plants to be correctly assigned to their variety on the farm studied.

A mistake that can take years to detect

Coffee plants can take three to four years to reach significant levels of production. During that period, producers invest in purchasing seed, establishing plants and managing the crop, in the expectation of a harvest with specific characteristics, destined for a particular market.

If the planting material does not correspond to the expected variety, the discrepancy may only come to light after years of work and investment. In this case, the plants had been grown for around three years before the differences observed prompted verification of their identity.

‘The study does not allow us to determine how common this type of discrepancy is in Ecuador, as it was carried out on a single farm with a limited number of plants. Nevertheless, this case highlights the need for identification tools and certification systems that are accessible to producers.’

The next step will be to extend the analysis to a larger number of plants and farms in order to establish more robust genetic and morphological references. With more samples and material of confirmed identity, it will be possible to determine more precisely the traits that distinguish varieties and to develop mechanisms for verifying planting material before it reaches the field.

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Journal

Frontiers in Plant Science

DOI

10.3389/fpls.2026.1868034

Method of Research

Case study

Subject of Research

Not applicable

Article Title

What you plant may not be what you bought: morphological and genetic discordance in specialty Coffea arabica L. cultivars from Ecuador

 

The story behind the butterfly’s enhanced visual world of color

Researchers discovered the genetic switch that produces extra light-detecting cells that led to the ability to recognize more colors in flowers and other butterflies

University of California - San Diego

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A new study discovered how the insect's flexible brain was able to adapt to an elevated need to recognize color in flowering plants.

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Credit: Perry Lab, UC San Diego

Many insects see the world through hundreds of tiny lenses that are grouped together in a visual organ known as the compound eye. Behind each lens sits a cluster of eight light-detecting cells arranged in a pattern that scientists believe has existed for hundreds of millions of years.

Butterflies are the rare exception. They are equipped with nine light-detecting cells, which gives them the ability to visually navigate a much richer world of color, compared with insects such as flies, and allows them to locate nectar and potential mates.

University of California San Diego scientists in School of Biological Sciences Associate Professor Michael Perry’s lab have discovered the genetic modification that gave butterflies this visual advantage.

“Butterflies see far more color than flies do because at some point in their evolution they added a photoreceptor to every unit of their compound eye — a rare break from an eye design that has otherwise been conserved across insects for hundreds of millions of years,” said Perry, a faculty member in the Department of Cell and Developmental Biology. “We found the genetic switch that did it.”. “We found the genetic switch that did it.”

In a study published in the journal Science Advances, Perry and his coauthors identified the genetic steps involved in the emergence of the ninth photoreceptor in painted lady butterflies, the most widespread butterfly species in the world. While flies feature light-sensing cells known as photoreceptors R1-R8, butterflies expanded their color vision by adding a second R7 photoreceptor to each unit of the eye, the researchers found. To test whether that genetic change was enough on its own, they recreated it in a fruit fly — switching on a gene in cells that normally keeps it off, and timing it to the brief window when the eye is being built. This produced a “butterfly fly” that grows its eyes on the butterfly plan, with nine cells per eye unit instead of eight.

A new light detector in the eye would be of no use if the brain is not able to connect to the new information provided by that detector. The scientists assumed that adding a sensory input such as a new photoreceptor unit should require the brain to slowly evolve a matching neuron partner that would receive information on the other end. That didn’t happen, the researchers found. To their surprise, no adaptive change was needed.

The fly brain regularly overproduces neurons that die off if they fail to find a connection. The brain of the butterfly-fly, they found, knew precisely how to handle the new photoreceptor by using its extra “standby” neurons and put them in play.

“When we gave those spare neurons something to connect to, they survived and wired up correctly — immediately — with no further genetic change,” said Perry. “In other words, the brain was ready before the eye asked. This is a rare, concrete case of evolution making use of neurons that were otherwise going to die.”

The new study’s findings provide a glimpse of how insects, with a flexible brain framework, were able to accommodate new inputs to evolutionarily adapt to an emerging need in their environment: an elevated ability to visualize flowering plants.

The team also found a hawkmoth that appears to be partway through the same transition: the lower half of its eye is butterfly-like, with two of these cells per unit, while the upper half is fly-like, with one. That is roughly what you would expect if the change began in one region of the eye and spread.

The research team is now exploring further unanswered questions, such as the difficult-to-study issue of whether the butterfly-fly can in fact see more vivid color with the additional photoreceptor, as butterflies do.

Stains (IMAGE)

University of California - San Diego

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Antibody stains in a developing butterfly retina show that each unit eye contains two R7 color photoreceptors.

Credit

Perry Lab, UC San Diego

Postdoctoral Scholar Ke Gao investigates butterfly color vision in the Perry Lab, Department of Cell and Developmental Biology.

Credit

Perry Lab, UC San Diego

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Journal

Science Advances

DOI

10.1126/sciadv.aei7570

Article Title

Sensory receptor expansion and neural accommodation in butterfly color vision

Article Publication Date

7-Oct-2026

 

Bees struggle to smell flowers when air pollutants combine

University of Reading

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Flowers become harder to smell for bees, moths and other pollinating insects in polluted air, according to research led by the University of Reading. 

Scientists analysed 22 experimental studies on how the air pollutants ozone and nitrogen oxides (NOx) affect pollinators. Both pollutants make it harder for pollinators to find flowers by breaking down or altering the scents that flowers give off. 

The new research, published in the journal Frontiers in Ecology and the Environment, found that elevated ozone reduced pollinator performance by an average of 42%, while NOx cut performance by 46%. When the two pollutants occurred together, the average reduction was 68%. Only a few studies tested both pollutants together, and in those the extra harm from combining them was smaller than the averages suggest. This is because the two gases react with each other in the air and partly cancel each other out. 

Diesel vehicles produce most NOx pollution and can stay on roads for more than 20 years after the last new one is sold. The UK's delayed ban on new petrol and diesel cars, pushed from 2030 to 2035 risks extending the damage to pollinators. 

Dr James Ryalls, lead author of the study at the University of Reading, said: “Ozone levels are projected to keep rising until around 2050, even as NOx emissions begin to fall as the world moves away from fossil fuels. This creates a difficult period for pollinators over the next two-to-three decades. Once cleaner fuels take over fully, ozone levels should decline, giving pollinators a chance to recover. 

“How quickly that recovery happens depends on the choices governments make now. Cutting NOx emissions faster, especially from diesel vehicles, could shorten the difficult period and speed up recovery. 

"Most of the food we grow depends on healthy pollinators, so protecting them from pollution cannot wait until 2050." 

The study also found:  

• Specialist pollinators reliant on one plant's scent, such as some moths, are more at risk than generalists like many bees. 

• Day-active pollinators such as bees and butterflies face higher ozone levels, while night-active pollinators (including many moths) encounter higher nitrogen oxides. Both need protection. 

• Most evidence came from Europe, leaving a gap in understanding the risks to pollinators in more heavily polluted regions such as parts of Asia. 

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Journal

Frontiers in Ecology and the Environment

DOI

10.1002/fee.70076

Article Title

Pollinator risks and recovery from air pollutant interactions during the fossil fuel transition

Article Publication Date

8-Oct-2026

 

Your favorite music could help reduce the pain of small medical procedures

Scientists find that playing patients’ favorite music during a cannulation minimizes pain

Frontiers

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If you hate needles, music might make you feel better during a cannula insertion… but it has to be the right kind of music. Although different musical interventions have repeatedly been reported to help with pain and stress, the evidence varies widely for different types of music and it’s hard to figure out what works best. To investigate, scientists played different kinds of music for patients about to undergo an intravenous cannula before an MRI — either Mozart, relaxation music, or the patients’ own favorite tunes. They found that playing patients’ favorite music worked best.  

“Although a needle puncture is a minor procedure, the level of pain can vary significantly from person to person,” said Dr Andrei Cristinel Dragnea of University Hospital Zürich, lead author of the article in Frontiers in Pain Research. “In modern medicine, the goal of treating physicians is not only to provide a successful diagnosis and therapy, but also to ensure that the procedure causes as little discomfort as possible.” 

“I would recommend listening to music to patients, especially patients who like music in general,” said Dr Meritxell Garcia Alzamora of University Hospital Zürich, senior author of the article. “In view of our results we will increase the application of music in venous punctures performed for radiological procedures, especially in anxious or claustrophobic patients.” 

Sweet music? 

The scientists recruited 204 patients undergoing a non-emergency MRI of the brain, spine, or head and neck. These patients’ procedures called for a contrast agent inserted into their veins with a cannula, which can hurt. A quarter of them acted as a control group, meaning they listened to no music, while three other groups listened to either their favorite music, music specifically designed for relaxation, or a piece of Mozart, Sonata KV448, which several studies have found to have therapeutic properties.  

Before the procedure started, patients assigned to the ‘favorite music’ group were asked to name an artist or song they would like to hear, and all patients were shown a visual scale that describes pain from a level of one (no pain) to 10 (worst pain of their life). This allowed the researchers to ask patients to rate their pain before and during the procedure, and then at two points afterwards — 30 seconds and two minutes later.  

“From the four conditions we examined, only favorite music and Mozart showed a positive effect,” said Garcia Alzamora. “Favorite music manifested a significant pain reduction effect both in patients with and without baseline pain — i.e. with preexisting pain before needle puncture. Mozart only showed significant pain relief in patients with preexisting pain.”  

Patients who were listening to their favorite music experienced less pain both 30 seconds and two minutes after the cannula was inserted. In a subgroup of patients who reported preexisting pain before cannulation, listening to their favorite music also reduced pain at the time of needle insertion, and listening to Mozart reduced pain two minutes after needle insertion.  

Pain levels seemed to improve more two minutes after cannulation than at the earlier time points, although this data can’t explain why. It could be that the initial discomfort of the cannula pulled people’s attention from the music, or that the mechanisms which make music helpful for pain reduction need some time to kick in.  

Relaxation music doesn’t soothe 

However, Mozart only seemed to work for the patients who reported being in pain before the cannulation, and the patients who listened to relaxation music or no music didn’t experience any change in their pain. 

“Relaxation music is usually characterized by a slow speed and low volume, and does not show noticeable dynamics,” said Garcia Alzamora. “These characteristics may have contributed to the patients disregarding relaxation music, which would explain the lack of pain relief.” 

“The intervention — in this case the venous puncture — consisted only of a very short-term pain with a small needle, although this can be very painful for some patients,” cautioned Dragnea, adding that it would be worth evaluating the benefits of music for patients undergoing procedures that are more painful and last longer. “Additionally, a technician accompanying and talking to the patient could be regarded as a confounder, as the mere presence of a person talking to you may be perceived as calming and distracting. However, all patients were exposed to the same conditions, so this confounder should not be over-interpreted.” 

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Journal

Frontiers in Pain Research

DOI

10.3389/fpain.2026.1923943

Article Title

Effect of Music on short-term Pain Perception during peripheral intravenous Cannulation

Article Publication Date

9-Oct-2026