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Prime numbers, the building blocks of mathematics, have fascinated for centuries − now technology is revolutionizing the search for them

Prime numbers, essential in mathematics and history, have been studied since ancient times. They are defined as whole numbers greater than one with only two divisors: one and themselves.

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Last Updated on August 31, 2025 by Daily News Staff

file 20250520 56 lrfedu.png?ixlib=rb 4.1

Prime numbers are numbers that are not products of smaller whole numbers.
Jeremiah Bartz

Jeremiah Bartz, University of North Dakota

A shard of smooth bone etched with irregular marks dating back 20,000 years puzzled archaeologists until they noticed something unique – the etchings, lines like tally marks, may have represented prime numbers. Similarly, a clay tablet from 1800 B.C.E. inscribed with Babylonian numbers describes a number system built on prime numbers.

As the Ishango bone, the Plimpton 322 tablet and other artifacts throughout history display, prime numbers have fascinated and captivated people throughout history. Today, prime numbers and their properties are studied in number theory, a branch of mathematics and active area of research today.

A history of prime numbers

A long, thin shard of bone with small lines scratched into it.
Some scientists guess that the markings on the Ishango bone represent prime numbers.
Joeykentin/Wikimedia Commons, CC BY-SA

Informally, a positive counting number larger than one is prime if that number of dots can be arranged only into a rectangular array with one column or one row. For example, 11 is a prime number since 11 dots form only rectangular arrays of sizes 1 by 11 and 11 by 1. Conversely, 12 is not prime since you can use 12 dots to make an array of 3 by 4 dots, with multiple rows and multiple columns. Math textbooks define a prime number as a whole number greater than one whose only positive divisors are only 1 and itself.

Math historian Peter S. Rudman suggests that Greek mathematicians were likely the first to understand the concept of prime numbers, around 500 B.C.E.

Around 300 B.C.E., the Greek mathematician and logician Euclid proved that there are infinitely many prime numbers. Euclid began by assuming that there is a finite number of primes. Then he came up with a prime that was not on the original list to create a contradiction. Since a fundamental principle of mathematics is being logically consistent with no contradictions, Euclid then concluded that his original assumption must be false. So, there are infinitely many primes.

The argument established the existence of infinitely many primes, however it was not particularly constructive. Euclid had no efficient method to list all the primes in an ascending list.

a diagram showing prime numbers as dots in rows, with composite numbers as dots arranged in rectangles of at least two rows of dots, with the same number of dots in each row.
Prime numbers, when expressed as that number of dots, can be arranged only in a single row or column, rather than a square or rectangle.
David Eppstein/Wikimedia Commons

In the middle ages, Arab mathematicians advanced the Greeks’ theory of prime numbers, referred to as hasam numbers during this time. The Persian mathematician Kamal al-Din al-Farisi formulated the fundamental theorem of arithmetic, which states that any positive integer larger than one can be expressed uniquely as a product of primes.

From this view, prime numbers are the basic building blocks for constructing any positive whole number using multiplication – akin to atoms combining to make molecules in chemistry.

Prime numbers can be sorted into different types. In 1202, Leonardo Fibonacci introduced in his book “Liber Abaci: Book of Calculation” prime numbers of the form (2p – 1) where p is also prime.

Today, primes in this form are called Mersenne primes after the French monk Marin Mersenne. Many of the largest known primes follow this format.

Several early mathematicians believed that a number of the form (2p – 1) is prime whenever p is prime. But in 1536, mathematician Hudalricus Regius noticed that 11 is prime but not (211 – 1), which equals 2047. The number 2047 can be expressed as 23 times 89, disproving the conjecture.

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While not always true, number theorists realized that the (2p – 1) shortcut often produces primes and gives a systematic way to search for large primes.

The search for large primes

The number (2p – 1) is much larger relative to the value of p and provides opportunities to identify large primes.

When the number (2p – 1) becomes sufficiently large, it is much harder to check whether (2p – 1) is prime – that is, if (2p – 1) dots can be arranged only into a rectangular array with one column or one row.

Fortunately, Édouard Lucas developed a prime number test in 1878, later proved by Derrick Henry Lehmer in 1930. Their work resulted in an efficient algorithm for evaluating potential Mersenne primes. Using this algorithm with hand computations on paper, Lucas showed in 1876 that the 39-digit number (2127 – 1) equals 170,141,183,460,469,231,731,687,303,715,884,105,727, and that value is prime.

Also known as M127, this number remains the largest prime verified by hand computations. It held the record for largest known prime for 75 years.

Researchers began using computers in the 1950s, and the pace of discovering new large primes increased. In 1952, Raphael M. Robinson identified five new Mersenne primes using a Standard Western Automatic Computer to carry out the Lucas-Lehmer prime number tests.

As computers improved, the list of Mersenne primes grew, especially with the Cray supercomputer’s arrival in 1964. Although there are infinitely many primes, researchers are unsure how many fit the type (2p – 1) and are Mersenne primes.

By the early 1980s, researchers had accumulated enough data to confidently believe that infinitely many Mersenne primes exist. They could even guess how often these prime numbers appear, on average. Mathematicians have not found proof so far, but new data continues to support these guesses.

George Woltman, a computer scientist, founded the Great Internet Mersenne Prime Search, or GIMPS, in 1996. Through this collaborative program, anyone can download freely available software from the GIMPS website to search for Mersenne prime numbers on their personal computers. The website contains specific instructions on how to participate.

GIMPS has now identified 18 Mersenne primes, primarily on personal computers using Intel chips. The program averages a new discovery about every one to two years.

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The largest known prime

Luke Durant, a retired programmer, discovered the current record for the largest known prime, (2136,279,841 – 1), in October 2024.

Referred to as M136279841, this 41,024,320-digit number was the 52nd Mersenne prime identified and was found by running GIMPS on a publicly available cloud-based computing network.

This network used Nvidia chips and ran across 17 countries and 24 data centers. These advanced chips provide faster computing by handling thousands of calculations simultaneously. The result is shorter run times for algorithms such as prime number testing.

A small rectangle metal chip reading 'nVIDIA'
New and increasingly powerful computer chips have allowed prime-number hunters to find increasingly larger primes.
Fritzchens Fritz/Flickr

The Electronic Frontier Foundation is a civil liberty group that offers cash prizes for identifying large primes. It awarded prizes in 2000 and 2009 for the first verified 1 million-digit and 10 million-digit prime numbers.

Large prime number enthusiasts’ next two challenges are to identify the first 100 million-digit and 1 billion-digit primes. EFF prizes of US$150,000 and $250,000, respectively, await the first successful individual or group.

Eight of the 10 largest known prime numbers are Mersenne primes, so GIMPS and cloud computing are poised to play a prominent role in the search for record-breaking large prime numbers.

Large prime numbers have a vital role in many encryption methods in cybersecurity, so every internet user stands to benefit from the search for large prime numbers. These searches help keep digital communications and sensitive information safe.

This story was updated on May 30, 2025 to correct the name of the Greek mathematician Euclid and to correct the factors of 2047.The Conversation

Jeremiah Bartz, Associate Professor of Mathematics, University of North Dakota

This article is republished from The Conversation under a Creative Commons license. Read the original article.

https://stmdailynews.com/groundbreaking-for-a-sustainable-future-la-metros-southeast-gateway-line-light-rail-project/

https://stmdailynews.com/groundbreaking-for-a-sustainable-future-la-metros-southeast-gateway-line-light-rail-project/

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Association of Black Cardiologists to Celebrate Legacy and Leadership at 16th Annual Spirit of the Heart Awards

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The Association of Black Cardiologists (ABC) is bringing its signature celebration of impact back to New York City this fall—spotlighting leaders and organizations working to make cardiovascular care more equitable, more accessible, and more effective. The 16th Annual Spirit of the Heart Awards Program & Fundraiser is set for Saturday, October 3, 2026 (6:00 p.m.–9:00 p.m.) at Cipriani Wall Street in Manhattan.

For ABC, the evening is more than a high-profile awards program. It’s a cornerstone fundraising event that helps power the organization’s year-round work—supporting medical student scholarships, fellowships, education, and programs designed to strengthen the pipeline of diverse clinicians and researchers while improving outcomes in communities that carry a disproportionate burden of heart disease.

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The official invitation for the ABC 16th Annual Spirit of the Heart Awards Program & Fundraiser, taking place October 3, 2026, at Cipriani Wall Street in New York City.

A fundraising night with long-term stakes

ABC leaders say the Spirit of the Heart Awards is built around a simple idea: celebrating progress while investing in the people who will drive the next wave of change.

Event co-chair Icilma Fergus, MD—Director of the Cardiovascular Disparities Center at Mount Sinai Medical Center and Board Chair of ABC—framed the night as a forward-looking commitment.

“This gathering is about more than one evening of celebration; it is about investing in the future of cardiovascular health for years to come,” Fergus said in the announcement. She added that the support generated through the event helps expand opportunities for aspiring clinicians, researchers, and leaders whose work can transform care and improve lives nationwide.

Honorary Chairperson: Samin K. Sharma, MD

ABC announced Samin K. Sharma, MD as the event’s Honorary Chairperson. Sharma serves as Chief of Clinical Cardiology, Director of the Cardiovascular Clinical Institute, and the Anandi Lal Sharma Professor of Medicine at the Icahn School of Medicine at Mount Sinai.

In the release, ABC highlighted Sharma’s international reputation in interventional cardiology and physician education, noting that he has trained cardiovascular specialists from around the world while advancing the field through research, mentorship, and patient care.

“I am honored to serve as Honorary Chairperson for this important event,” Sharma said. “The Spirit of the Heart Awards Program reflects the power of partnership, philanthropy, and leadership to advance cardiovascular health.”

The Association of Black Cardiologists will host the 16th Annual Spirit of the Heart Awards Oct. 3, 2026 in NYC to honor leaders advancing heart health equity and fund scholarships.
The official invitation schedule for the ABC 16th Annual Spirit of the Heart Awards Program & Fundraiser, taking place October 3, 2026, at Cipriani Wall Street in New York City.

A full weekend of impact, including policy

The awards program is part of a broader weekend of programming. On Friday, October 2, ABC will host its Annual Policy Pulse Summit at Venable LLP in New York City, convening leaders to discuss policy issues shaping the future of cardiovascular health.

What to expect at the Spirit of the Heart Awards

ABC is positioning the evening as both a celebration and a community gathering—bringing together leaders from healthcare, philanthropy, industry, and advocacy.

The event will be co-emceed by:

  • Sandra Bookman, award-winning journalist and anchor of Eyewitness News on ABC7/WABC-TV New York
  • Thomas Cunningham IV, President and Chief Content Officer of BrandCunningham

The program is expected to include:

  • Presentation of the Spirit of the Heart Awards
  • Recognition of medical student scholarship recipients
  • Special guest appearances
  • live auction
  • Musical entertainment

Event co-chair Barbara Hutchinson, MD, PhD, President of Chesapeake Cardiac Care, emphasized the role of sustained collaboration in moving the needle on heart health.

“The Spirit of the Heart Awards Program is a reminder that lasting progress in cardiovascular health is achieved through vision, partnership, and sustained commitment,” Hutchinson said.

How to attend, sponsor, or support

ABC is directing attendees and supporters to its event site for tickets, sponsorship opportunities, and donations:

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About the Association of Black Cardiologists

Founded on the belief that “every heart counts,” the Association of Black Cardiologists works to promote prevention and treatment of cardiovascular disease and to advance health equity by eliminating disparities. ABC’s membership is open to all, regardless of race, ethnicity, or vocation. The organization’s work spans education, advocacy, research, patient and community outreach, and leadership development.

Source and media contact

Media Contact (from the release):

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Consumer Corner

Deed fraud can cause vulnerable Detroiters to lose their homes – here’s why it’s hard to catch the thieves

Deed fraud is rising in Detroit, where forged deeds can strip vulnerable homeowners of their property. Here’s how title theft works, why it’s hard to catch, and what reforms could help.

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A Black woman with long dark curls sits on the steps in from of a yellow brick building. Deed Fraud.
Deed fraud victim Kim Page sits on her front steps in Detroit on June 12, 2026. Nic Antaya/The Conversation, CC BY-ND

Donovan McCarty, Michigan State University

Buying her first home on Detroit’s far east side in 2021 was the moment when a lifelong dream finally came within reach for Kim Page.

“I accomplished something that I always wanted to do,” said Page, who grew up in the city. “I always wanted to buy my own home since I was like 18. I never wanted to rent from anyone.”

Page said she had saved US$15,000 and used $3,800 in cash to buy the single-family brick house on Britain Street. The house, owned by a friend planning to move out of Detroit, was “damaged pretty bad,” Page recalls. But the house was hers to care for, and she was determined to fix what was broken.

For the next several years, Page poured her sweat and paychecks into the property. Working first as a welder at automotive supplier Fisher Dynamics, and later as a phlebotomist, she paid for a dumpster, windows, a door, ceiling repair and an awning above her front porch. Page invested $27,000 in needed repairs and, in 2022, happily moved in.

But in August 2023, a storm damaged her roof. By March 2024, mold had grown inside the property, which made Page struggle to breathe; she moved in with family. She returned to the home in April 2024 for an appointment with a representative from the Federal Emergency Management Agency. That’s when Page noticed the locks had been changed. Perplexed but undeterred, she broke down the back door to get inside and purchased new locks, which she installed.

Then on a hot, summer day in July 2024, Page came home to discover all her locks had been changed again.

Searching for answers, Page called the Wayne County Register of Deeds’ Mortgage and Deed Fraud Unit. The staff confirmed she was a victim of deed fraud – a crime where scammers forge signatures to record a phony transfer of property ownership. Once criminals hijack the title, they can sell the property, rent it out or drain its equity with mortgages, potentially leaving the rightful owner to face the legal and financial fallout.

“I just was in shock,” Page said. “I can’t believe somebody really did this to me.”

A nationwide problem that’s hard to nail down

A small yellow-brick Craftsman bungalow sits in a dense neighborhood.
Like many homes targeted by fraudsters, Kim Page’s was sold in a cash transaction. Nic Antaya/The Conversation, CC BY-ND

Page reached out to me for help in March 2025. I’m a housing attorney, assistant professor at Michigan State University College of Law and director of the Housing Justice Clinic. I have represented dozens of victims of deed fraud.

I have also studied how property recording systems respond – or, more accurately, fail to respond – to fraud. My work examines how procedural gaps in title systems disproportionately harm elderly, low-income and minority homeowners.

Nationwide, deed fraud – also called quit claim deed fraud or home title theft – is a growing problem, including in New York, Boston, Miami and Philadelphia.

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Exactly how big a problem it is, is hard to know. The FBI does not track deed fraud specifically, instead grouping it into a larger category of real estate crimes.

From 2019 through 2023, 58,141 victims in the U.S. reported $1.3 billion in losses relating to real estate crime, the FBI says. However, that number is likely undercounted because many people don’t know where to report it, are embarrassed they were victims or don’t know yet they have been targeted.

In Detroit, deed fraud may be particularly prevalent because so many housing deals are made in cash and many properties owe back taxes. The Wayne County Mortgage and Deed Fraud Unit has tracked more than 13,000 inquiries regarding deed fraud and has opened over 2,300 cases throughout Wayne County since 2005.

Without oversight, the crime often goes undetected

Committing deed fraud is remarkably simple.

A deed is the legal document that transfers ownership of a home or other real property from one person to another. When a home is bought or sold, a deed is legally drawn up to reflect the transfer of ownership. That deed is then recorded with a county register of deeds, providing public notice of who legally owns the property.

A fraudster can forge the signature of the real owner – sometimes someone who is deceased. They can file a deed that appears valid on its face but isn’t.

They then record that false deed with a county register of deeds, the local government office that keeps public land records and other documents showing ownership, claiming title to property they do not actually own.

Fraudsters often target vulnerable people and properties, including elderly owners, families dealing with inherited homes, and houses that appear vacant or neglected, such as those behind on property taxes.

The incentive is clear: Once a fraudster appears to hold title, they can try to sell the property to an investor or an unsuspecting buyer looking for stable housing. I have seen fraudsters secure as much as $50,000 from one deal when they obtained a mortgage based on a fraudulent deed. One notable case of fraud targeted Elvis Presley’s former estate, Graceland.

In Michigan and most other states, recording offices do not have authority to substantively review a deed to determine whether it is fraudulent. If the document complies with technical formatting requirements, such as margin and font size, it must be recorded. Once stamped and indexed, the deed appears legitimate and can easily trick desperate buyers, investors, financial institutions and even police officers, lawyers and judges.

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In other words, the recording process is largely administrative, not investigative. The government office accepts and files the document without first verifying that the person signing it actually had the legal right to transfer the property.

That means a fraudulent deed can enter the public record, look valid to the outside world and remain undiscovered for months or even years.

Detroit is vulnerable

The housing market helps explain why Detroiters are more vulnerable to deed fraud.

Homes in Black neighborhoods nationwide are systematically undervalued compared with similar homes in white neighborhoods. Black borrowers are also more likely to be denied conventional mortgage loans. Detroit is about 73% Black, with a median household income of roughly $39,000 and a poverty rate exceeding 30%.

Man holds sign
In 2011, residents flooded downtown Detroit, demanding an end to home foreclosures and evictions. Jim West/UCG/Universal Images Group via Getty Images

In a market where access to traditional financing is uneven and home prices are relatively low, cash sales accounted for 4 in 10 sales in February 2024.

Lenders, brokers and title companies act as informal gatekeepers when people purchase a home using a mortgage. In cash sales, those actors are absent, and there are fewer opportunities to detect irregularities in the documented history showing how title passed from one owner to the next over time.

Illegal tax practices led to thousands of foreclosed homes

Property tax distress attracts fraudsters. Fraudsters seem to rely on publicly available tax foreclosure lists to identify properties that appear abandoned. They then pay the past-due taxes to remove the property from foreclosure and attempt to sell or mortgage the property using their fraudulent deed.

The fraudsters may also assume that the owner lacks the resources to wage a prolonged legal fight to recover title if they do uncover their scheme. In many cases, that assumption proves correct.

Michigan’s Constitution caps assessments at 50% of market value, but researchers have found that from 2009 to 2015, a majority of Detroit homes were assessed above that limit. Once those inflated bills went unpaid, interest, penalties and fees accumulated, often ending in tax foreclosure.

More than 100,000 Detroit residents lost homes in that crisis, and homeowners were overtaxed by at least $600 million between 2010 and 2016.

In a city already destabilized by unlawful tax foreclosure, fraudsters found opportunity in homes burdened by vacancy and broken chains of ownership.

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The burdens that deed fraud victims face

My first encounter with deed fraud came in July 2023. I received a request for legal assistance from a man who said he had been evicted from a home he claimed to own. Honestly, I didn’t believe him.

But when I pulled the court records and deeds, I learned he was right.

A fraudulent deed had been filed on his property, stripping him of title. The fraudsters then filed an eviction case against him.

The owner had no phone and no internet access to attend the virtual hearings. The court entered a judgment to evict him. A bailiff came, broke down his door and threw his belongings into a dumpster.

It took six months and two separate court cases before he was finally able to return to his home. He never recovered his belongings – and we never found the fraudster.

There are many other hardships for a legitimate owner. A fraudulent deed can prevent homeowners from selling their property, refinancing or accessing financial assistance programs.

To clear title, owners must file a quiet title lawsuit – a court action used to resolve disputes over who legally owns a property.

But quiet title cases are complex legal proceedings.

They require multiple filings, hearings and strict compliance with procedural rules. Even when fraud is obvious – for example, when a deed was signed by someone who was already deceased – courts generally require formal litigation to remove the cloud from the title.

Likewise, the legal process of notifying the defendant can be especially burdensome. Fraudsters often use fictitious names and addresses, making them difficult or impossible to locate. Even uncontested cases typically take months. If a defendant appears and disputes ownership, litigation can stretch for years.

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Filing fees, service costs and other litigation expenses accumulate quickly. Hiring an attorney can cost several thousand dollars, and some victims have reported spending tens of thousands clearing title to their homes.

As for Kim Page, her case is still ongoing. After being locked out of her home, she had to move in with relatives for over a year, putting a strain on their relationship. She was eventually able to return to her home, but the legal dispute over ownership has not been resolved.

A collage of close-ups of repairs needed: in a basement, an unfinished plastic pipe, a ceiling fan with debris inside, a door is boarded up
Repairs that still need to be completed at Kim Page’s home in Detroit. Nic Antaya/The Conversation, CC BY-ND

On top of that, she is facing a counter-lawsuit from the company that filed the fraudulent deed, requesting $50,000 for repairs the company made to the home while Page was locked out, along with property taxes and utility bills that the company says it paid to the county and utility companies on her behalf. The county opened an investigation, but it remains unresolved. As a result, she still has no idea who orchestrated the scheme.

While there are free legal services organizations to help, they have limited capacity, and income thresholds exclude some homeowners who still cannot afford private counsel.

Legal reforms likely won’t resolve systemic issues

Across the country, state legislatures have begun responding. Twenty-one have enacted deed fraud legislation, and 15 more have proposed it.

Another common intervention is fraud alert systems, which notify owners when any documents that impact the title of their property are recorded.

Other reforms increase notarial requirements or enhance criminal penalties.

These measures may deter some misconduct, but they do little to reduce the burden on victims once a fraudulent deed has been recorded.

In my assessment, meaningful reforms focus on empowering registers of deeds to substantively review suspicious documents before recording them; simplifying and expediting quiet title proceedings; and expanding civil remedies so victims can recover the costs associated with clearing their title.

Some jurisdictions like Texas and Florida have adopted streamlined procedures that allow victims to initiate quiet title actions using standardized forms with reduced fees. Others permit recorders, prosecutors or judges to act when fraud has already been established.

In Michigan, I am working with lawmakers and stakeholders to develop comprehensive legislation addressing these issues. Bills are expected to be introduced later this year.

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At the same time, my clinic has begun exploring how technology can help identify fraudulent deeds already in the record. We are working with computer scientists to evaluate whether artificial intelligence tools could flag suspicious filings and potentially prevent fraudulent documents from being accepted in the future.

No property system can eliminate fraud entirely. Preventive and punitive measures may limit fraud, but they cannot eliminate the incentive to commit it. For fraudsters, the payoff can be substantial.

Conversations about the issue often begin and end with the mechanics of the crime or the procedural burdens victims face afterward. Far less attention is paid to the housing market conditions that make some communities especially vulnerable in the first place.

Page, now 42 and working as a transporter for Sinai-Grace Hospital, has been coping with the stress of legal proceedings for the past two years and living with a heart condition so serious that she got a defibrillator.

The longtime Detroiter is fed up – with the lack of police help to find the fraudster, as well as the court system. All she wants is to be the rightful owner of the home.

“Give me my house back,” Page said.

Detroit editor Eleanore Catolico contributed reporting.

Donovan McCarty, Director, Housing Justice Clinic at Michigan State University College of Law, Michigan State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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When your local reflecting pool or pond turns green with algae, don’t reach for chemicals – nature has better solutions

When ponds and reflecting pools turn green with algae, chemical “quick fixes” often fail. Here’s how nature-based solutions like Daphnia and aquatic plants can restore water quality longer-term.

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A man using an underwater vacuum stands knee-deep in the Reflecting Pool with the Washington Monument in the background.
A National Park Service employee uses a vacuum to clean the Lincoln Memorial Reflecting Pool on June 20, 2026. AP Photo/Mark Schiefelbein

Eric Palkovacs, University of California, Santa Cruz

When the Lincoln Memorial Reflecting Pool turned green with algae just days after a US$15 million renovation, the U.S. government scrambled for chemicals and expensive technical solutions to fix the iconic landmark.

Trying to kill algae with chemicals is a common response when community ponds or other water features go green. But as a scientist who studies freshwater ecology, I can tell you there are better solutions that cost far less, last longer and carry less risk of harm to pets and wildlife.

Rather than battling against nature, these alternatives work with nature for long-term solutions. https://www.youtube.com/embed/nkqBQ1r0Kto?wmode=transparent&start=0 If you need to treat a slimy, green, algae-filled body of water, you shouldn’t drain and refill the water, which resets the entire ecosystem. Instead, one solution is quite simple and relies on nature, not chemicals.

What went wrong on the National Mall

The algal bloom that turned the Reflecting Pool a vibrant green shouldn’t have been a surprise.

The pool is big, more than a third of a mile long and around 165 feet wide. But it’s shallow, meaning it warms up quickly in the sun. When it was repainted “American flag blue” during the renovations in spring 2026, the new color darkened the pool, and darker colors absorb more heat.

On top of those conditions, the pool was refilled with water from the nutrient-rich tidal basin of the Potomac River. The combination of warm water and nutrients created prime conditions for algae to bloom, turning the water pea soup green.

A tube into the Reflecting Pool, with the Jefferson Memorial in the background, puts out white bubbles.
In addition to hydrogen peroxide and vacuums, the government ordered nanobubble ozone technology to break up the algae. The nanobubbler contract was for $1.7 million. AP Photo/Jacquelyn Martin

As the national conversation over the Reflecting Pool shifts to political finger-pointing, an important environmental question deserves careful scrutiny: What is the best approach to maintain water quality in a case like this, whether for a national monument or a community water feature or pond?

Trying to chemically or mechanically remove algae can damage the structure of a water feature and may harm species in the water that could actually help solve the problem.

Importantly, chemical and mechanical solutions are only temporary fixes. When the Reflecting Pool is drained and filled again, there’s a good chance that algae will bloom again.

Natural algae control

Limnologists – scientists like me who study inland water bodies – have spent many decades learning why lakes and ponds turn green and how to clear them up.

Often, nutrient-rich waters fueled by fertilizer runoff from farm fields or sewage from cities are the sources that stimulate algal growth.

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However, natural ponds also host grazing zooplankton, which eat algae. For example, a type of zooplankton called Daphnia, known as water fleas because of the way these tiny crustaceans swim, can control algae by consuming it before it becomes a pea soup nuisance. Thus, a thriving Daphnia population can help maintain good water quality in a lake, pond or community water feature, even when nutrient levels spike.

A close-up image of a see-through water creature with eggs inside.
Daphnia are a genus of hundreds of species of tiny, see-through crustaceans that happen to be voracious algae eaters. A female Daphnia magna’s eggs are visible in this magnified image. Hajime Watanabe, PLoS Genetics, March 2011, CC BY

In addition to being highly effective grazers, Daphnia have another superpower – they can evolve rapidly. Urban waterbodies are often harsh environments with a variety of challenges, including high temperatures, low levels of dissolved oxygen, and pollutants. Daphnia can adapt to tough conditions, making these creatures an ideal source of algae control in many urban ponds.

Rooted aquatic plants are also useful for algae control in ponds because they absorb nutrients. Thus, shallow ponds with thick beds of aquatic plants can often resist algal blooms when nutrient levels rise.

Why draining might not be the best solution

One downside to draining and refilling a pond or urban water feature to try to clean it is that doing so resets the aquatic ecosystem, erasing the signature of any past evolution that has taken place.

Imagine Daphnia in a shallow pond that experiences periodic heat waves throughout the summer. Through repeated exposure to high temperatures, natural selection favors heat-resistant genotypes that can thrive in an urban pond.

Daphnia and other grazing zooplankton can also evolve resistance to some types of cyanobacteria, also known as blue-green algae, which produce compounds that are toxic to people and pets. Daphnia that evolve resistance to those toxins can help control harmful cyanobacterial blooms.

If a Daphnia population that evolved to tolerate warm temperatures, low oxygen levels or cyanotoxins is removed, the new population likely won’t be ready to handle those local challenges. This evolutionarily naive population will perform poorly in its new environment, reducing its effectiveness at controlling algal blooms.

As a result, traditional mechanical and chemical approaches may actually work against the goal of minimizing algae in ponds and other water features.

Nature-based solutions

The use of Daphnia to control algal blooms is just one example of solving environmental challenges with nature-based solutions.

Growing urban forests to provide cooling and improve air quality to help reduce the need for more energy-intensive air conditioning is another example. Maintaining urban wetlands can help reduce flooding, protect property and recharge groundwater more effectively and for less money than building and maintaining levees. Coastal marshes similarly reduce erosion, buffer storm surges and support fisheries.

All these urban ecosystems protect biodiversity and support human health and well-being.

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From national landmarks to city parks and backyard ponds, projects of all sizes can take advantage of nature-based solutions. While each specific project is unique, some general principles apply.

Ecosystems are most resilient when they are diverse and connected. So, it is beneficial to use a variety of species and genotypes and provide corridors that support the movement of organisms and their beneficial genes.

Urban climates are changing rapidly, so it helps to use species and genotypes that will thrive under future conditions, including rising temperatures.

Not every solution has to be engineered

The hubbub over the Reflecting Pool holds a mirror up to assumptions about how to solve pressing environmental challenges. The idea of just engineering one’s way out of any environmental crisis has limits.

Understanding ecology and nature’s mechanisms of ecosystem resilience can achieve sustainable solutions that benefit both nature and people.

Eric Palkovacs, Professor of Ecology and Evolutionary Biology, University of California, Santa Cruz

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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