Gregory J. Dick, University of Michigan

Federal scientists released their annual forecast for Lake Erie’s harmful algal blooms on June 26, 2025, and they expect a mild to moderate season. However, anyone who comes in contact with toxic algae can face health risks. And 2014, when toxins from algae blooms contaminated the water supply in Toledo, Ohio, was a moderate year, too.

We asked Gregory J. Dick, who leads the Cooperative Institute for Great Lakes Research, a federally funded center at the University of Michigan that studies harmful algal blooms among other Great Lakes issues, why they’re such a concern.

1. What causes harmful algal blooms?

Harmful algal blooms are dense patches of excessive algae growth that can occur in any type of water body, including ponds, reservoirs, rivers, lakes and oceans. When you see them in freshwater, you’re typically seeing cyanobacteria, also known as blue-green algae.

These photosynthetic bacteria have inhabited our planet for billions of years. In fact, they were responsible for oxygenating Earth’s atmosphere, which enabled plant and animal life as we know it.

Algae are natural components of ecosystems, but they cause trouble when they proliferate to high densities, creating what we call blooms.

Harmful algal blooms form scums at the water surface and produce toxins that can harm ecosystems, water quality and human health. They have been reported in all 50 U.S. states, all five Great Lakes and nearly every country around the world. Blue-green algae blooms are becoming more common in inland waters.

The main sources of harmful algal blooms are excess nutrients in the water, typically phosphorus and nitrogen.

Historically, these excess nutrients mainly came from sewage and phosphorus-based detergents used in laundry machines and dishwashers that ended up in waterways. U.S. environmental laws in the early 1970s addressed this by requiring sewage treatment and banning phosphorus detergents, with spectacular success.

Today, agriculture is the main source of excess nutrients from chemical fertilizer or manure applied to farm fields to grow crops. Rainstorms wash these nutrients into streams and rivers that deliver them to lakes and coastal areas, where they fertilize algal blooms. In the U.S., most of these nutrients come from industrial-scale corn production, which is largely used as animal feed or to produce ethanol for gasoline.

Climate change also exacerbates the problem in two ways. First, cyanobacteria grow faster at higher temperatures. Second, climate-driven increases in precipitation, especially large storms, cause more nutrient runoff that has led to record-setting blooms.

2. What does your team’s DNA testing tell us about Lake Erie’s harmful algal blooms?

Harmful algal blooms contain a mixture of cyanobacterial species that can produce an array of different toxins, many of which are still being discovered.

When my colleagues and I recently sequenced DNA from Lake Erie water, we found new types of microcystins, the notorious toxins that were responsible for contaminating Toledo’s drinking water supply in 2014.

These novel molecules cannot be detected with traditional methods and show some signs of causing toxicity, though further studies are needed to confirm their human health effects.

We also found organisms responsible for producing saxitoxin, a potent neurotoxin that is well known for causing paralytic shellfish poisoning on the Pacific Coast of North America and elsewhere.

Saxitoxins have been detected at low concentrations in the Great Lakes for some time, but the recent discovery of hot spots of genes that make the toxin makes them an emerging concern.

Our research suggests warmer water temperatures could boost its production, which raises concerns that saxitoxin will become more prevalent with climate change. However, the controls on toxin production are complex, and more research is needed to test this hypothesis. Federal monitoring programs are essential for tracking and understanding emerging threats.

3. Should people worry about these blooms?

Harmful algal blooms are unsightly and smelly, making them a concern for recreation, property values and businesses. They can disrupt food webs and harm aquatic life, though a recent study suggested that their effects on the Lake Erie food web so far are not substantial.

But the biggest impact is from the toxins these algae produce that are harmful to humans and lethal to pets.

The toxins can cause acute health problems such as gastrointestinal symptoms, headache, fever and skin irritation. Dogs can die from ingesting lake water with harmful algal blooms. Emerging science suggests that long-term exposure to harmful algal blooms, for example over months or years, can cause or exacerbate chronic respiratory, cardiovascular and gastrointestinal problems and may be linked to liver cancers, kidney disease and neurological issues.

In addition to exposure through direct ingestion or skin contact, recent research also indicates that inhaling toxins that get into the air may harm health, raising concerns for coastal residents and boaters, but more research is needed to understand the risks.

The Toledo drinking water crisis of 2014 illustrated the vast potential for algal blooms to cause harm in the Great Lakes. Toxins infiltrated the drinking water system and were detected in processed municipal water, resulting in a three-day “do not drink” advisory. The episode affected residents, hospitals and businesses, and it ultimately cost the city an estimated US$65 million.

4. Blooms seem to be starting earlier in the year and lasting longer – why is that happening?

Warmer waters are extending the duration of the blooms.

In 2025, NOAA detected these toxins in Lake Erie on April 28, earlier than ever before. The 2022 bloom in Lake Erie persisted into November, which is rare if not unprecedented.

Scientific studies of western Lake Erie show that the potential cyanobacterial growth rate has increased by up to 30% and the length of the bloom season has expanded by up to a month from 1995 to 2022, especially in warmer, shallow waters. These results are consistent with our understanding of cyanobacterial physiology: Blooms like it hot – cyanobacteria grow faster at higher temperatures.

5. What can be done to reduce the likelihood of algal blooms in the future?

The best and perhaps only hope of reducing the size and occurrence of harmful algal blooms is to reduce the amount of nutrients reaching the Great Lakes.

In Lake Erie, where nutrients come primarily from agriculture, that means improving agricultural practices and restoring wetlands to reduce the amount of nutrients flowing off of farm fields and into the lake. Early indications suggest that Ohio’s H2Ohio program, which works with farmers to reduce runoff, is making some gains in this regard, but future funding for H2Ohio is uncertain.

In places like Lake Superior, where harmful algal blooms appear to be driven by climate change, the solution likely requires halting and reversing the rapid human-driven increase in greenhouse gases in the atmosphere.

Gregory J. Dick, Professor of Biology, University of Michigan

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

Samantha Thompson, Smithsonian Institution

Everything in space – from the Earth and Sun to black holes – accounts for just 15% of all matter in the universe. The rest of the cosmos seems to be made of an invisible material astronomers call dark matter.

Astronomers know dark matter exists because its gravity affects other things, such as light. But understanding what dark matter is remains an active area of research.

With the release of its first images this month, the Vera C. Rubin Observatory has begun a 10-year mission to help unravel the mystery of dark matter. The observatory will continue the legacy of its namesake, a trailblazing astronomer who advanced our understanding of the other 85% of the universe.

As a historian of astronomy, I’ve studied how Vera Rubin’s contributions have shaped astrophysics. The observatory’s name is fitting, given that its data will soon provide scientists with a way to build on her work and shed more light on dark matter.

Wide view of the universe

From its vantage point in the Chilean Andes mountains, the Rubin Observatory will document everything visible in the southern sky. Every three nights, the observatory and its 3,200 megapixel camera will make a record of the sky.

This camera, about the size of a small car, is the largest digital camera ever built. Images will capture an area of the sky roughly 45 times the size of the full Moon. With a big camera with a wide field of view, Rubin will produce about five petabytes of data every year. That’s roughly 5,000 years’ worth of MP3 songs.

After weeks, months and years of observations, astronomers will have a time-lapse record revealing anything that explodes, flashes or moves – such as supernovas, variable stars or asteroids. They’ll also have the largest survey of galaxies ever made. These galactic views are key to investigating dark matter.

Galaxies are the key

Deep field images from the Hubble Space Telescope, the James Webb Space Telescope and others have visually revealed the abundance of galaxies in the universe. These images are taken with a long exposure time to collect the most light, so that even very faint objects show up.

Researchers now know that those galaxies aren’t randomly distributed. Gravity and dark matter pull and guide them into a structure that resembles a spider’s web or a tub of bubbles. The Rubin Observatory will expand upon these previous galactic surveys, increasing the precision of the data and capturing billions more galaxies.

In addition to helping structure galaxies throughout the universe, dark matter also distorts the appearance of galaxies through an effect referred to as gravitational lensing.

Light travels through space in a straight line − unless it gets close to something massive. Gravity bends light’s path, which distorts the way we see it. This gravitational lensing effect provides clues that could help astronomers locate dark matter. The stronger the gravity, the bigger the bend in light’s path.

Discovering dark matter

For centuries, astronomers tracked and measured the motion of planets in the solar system. They found that all the planets followed the path predicted by Newton’s laws of motion, except for Uranus. Astronomers and mathematicians reasoned that if Newton’s laws are true, there must be some missing matter – another massive object – out there tugging on Uranus. From this hypothesis, they discovered Neptune, confirming Newton’s laws.

With the ability to see fainter objects in the 1930s, astronomers began tracking the motions of galaxies.

California Institute of Technology astronomer Fritz Zwicky coined the term dark matter in 1933, after observing galaxies in the Coma Cluster. He calculated the mass of the galaxies based on their speeds, which did not match their mass based on the number of stars he observed.

He suspected that the cluster could contain an invisible, missing matter that kept the galaxies from flying apart. But for several decades he lacked enough observational evidence to support his theory.

Enter Vera Rubin

In 1965, Vera Rubin became the first women hired onto the scientific staff at the Carnegie Institution’s Department of Terrestrial Magnetism in Washington, D.C.

She worked with Kent Ford, who had built an extremely sensitive spectrograph and was looking to apply it to a scientific research project. Rubin and Ford used the spectrograph to measure how fast stars orbit around the center of their galaxies.

In the solar system, where most of the mass is within the Sun at the center, the closest planet, Mercury, moves faster than the farthest planet, Neptune.

“We had expected that as stars got farther and farther from the center of their galaxy, they would orbit slower and slower,” Rubin said in 1992.

What they found in galaxies surprised them. Stars far from the galaxy’s center were moving just as fast as stars closer in.

“And that really leads to only two possibilities,” Rubin explained. “Either Newton’s laws don’t hold, and physicists and astronomers are woefully afraid of that … (or) stars are responding to the gravitational field of matter which we don’t see.”

Data piled up as Rubin created plot after plot. Her colleagues didn’t doubt her observations, but the interpretation remained a debate. Many people were reluctant to accept that dark matter was necessary to account for the findings in Rubin’s data.

Rubin continued studying galaxies, measuring how fast stars moved within them. She wasn’t interested in investigating dark matter itself, but she carried on with documenting its effects on the motion of galaxies.

Vera Rubin’s legacy

Today, more people are aware of Rubin’s observations and contributions to our understanding of dark matter. In 2019, a congressional bill was introduced to rename the former Large Synoptic Survey Telescope to the Vera C. Rubin Observatory. In June 2025, the U.S. Mint released a quarter featuring Vera Rubin.

Rubin continued to accumulate data about the motions of galaxies throughout her career. Others picked up where she left off and have helped advance dark matter research over the past 50 years.

In the 1970s, physicist James Peebles and astronomers Jeremiah Ostriker and Amos Yahil created computer simulations of individual galaxies. They concluded, similarly to Zwicky, that there was not enough visible matter in galaxies to keep them from flying apart.

They suggested that whatever dark matter is − be it cold stars, black holes or some unknown particle − there could be as much as 10 times the amount of dark matter than ordinary matter in galaxies.

Throughout its 10-year run, the Rubin Observatory should give even more researchers the opportunity to add to our understanding of dark matter.

Samantha Thompson, Astronomy Curator, National Air and Space Museum, Smithsonian Institution

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

Cynthia H. Chuang, Penn State and Carol S. Weisman, Penn State

On June 24, 2022, the U.S. Supreme Court decision in Dobbs v. Jackson Women’s Health Organization eliminated a nearly 50-year constitutional right to abortion and returned the authority to regulate abortion to the states.

The Dobbs ruling, which overturned Roe v. Wade, has vastly reshaped the national abortion landscape. Three years on, many states have severely restricted access to abortion care. But the decision has also had a less well-recognized outcome: It is increasingly jeopardizing access to contraception.

We are a physician scientist and a sociologist and health services researcher studying women’s health care and policy, including access to contraception. We see a worrisome situation emerging.

Even while the growing limits on abortion in the U.S. heighten the need for effective contraception, family planning providers are less available in many states, and health insurance coverage of some of the most effective types of contraception is at risk.

A growing demand for contraception

Abortion restrictions have proliferated around the country since the Dobbs decision. As of June 2025, 12 states have near-total abortion bans and 10 states ban abortion before 23 or 24 weeks of gestation, which is when a fetus is generally deemed viable. Of the remaining states, 19 restrict abortion after viability and nine states and Washington have no gestational limits.

It’s no surprise that women living in states that ban or severely restrict abortion may be especially motivated to avoid unintended pregnancy. Even planned pregnancies have grown riskier, with health care providers fearing legal repercussions for treating pregnancy-related medical emergencies such as miscarriages. Such concerns may in part explain emerging research that suggests the use of long-acting contraception such as intrauterine devices, or IUDs, and permanent contraception – namely, sterilization – are on the rise.

A national survey conducted in 2024 asked women ages 18 to 49 if they have changed their contraception practices “as a result of the Supreme Court overturning Roe v. Wade.” It found that close to 1 in 5 women began using contraception for the first time, switched to a more effective contraceptive method, received a sterilization procedure or purchased emergency contraception to keep on hand.

A study in Ohio hospitals found a nearly 16% increase in women choosing long-acting contraception methods or sterilization in the six months after the Dobbs decision, and a 33% jump in men receiving vasectomies. Another study, which looked at both female and male sterilization in academic medical centers across the country, also reported an uptick in sterilization procedures for young adults ages 18 to 30 after the Dobbs decision, through 2023.

A loss of contraception providers

Ironically, banning or severely restricting abortion statewide may also diminish capacity to provide contraception.

To date, there is no compelling evidence that OB-GYN doctors are leaving states with strict abortion laws in significant numbers. One study found that states with severe abortion restrictions saw a 4.2% decrease in such practitioners compared with states without abortion restrictions.

However, the Association of American Medical Colleges reports declining applications to residency training programs located in states that have abortion bans – not just for OB-GYN training programs, but for residency training of all specialties. This drop suggests that doctors may be overall less likely to train in states that restrict medical practice. And given that physicians often stay on to practice in the states where they do their training, it may point to a long-term decline in physicians in those states.

But the most significant drop in contraceptive services likely comes from the closure of abortion clinics in states with the most restrictive abortion policies. That’s because such clinics generally provide a wide range of reproductive services, including contraception. The 12 states with near-total abortion bans had 57 abortion clinics in 2020, all of which were closed as of March 2024. One study reported a 4.1% decline in oral contraceptives dispensed in those states.

Contraception under threat

The Dobbs decision has also encouraged ongoing efforts to incorrectly redefine some of the most effective contraceptives as medications that cause abortion. These efforts target emergency contraceptive pills, known as Plan B over-the-counter and Ella by prescription, as well as certain IUDs. Emergency contraceptive pills are up to 98% effective at preventing pregnancy after unprotected sex, and IUDs are 99% effective.

Neither method terminates a pregnancy, which by definition begins when a fertilized egg implants in the uterus. Instead, emergency contraceptive pills prevent an egg from being released from the ovaries, while IUDs, depending on the type, prevent sperm from fertilizing an egg or prevent an egg from implanting in the uterus.

Conflating contraception and abortion spreads misinformation and causes confusion. People who believe that certain types of contraception cause abortions may be dissuaded from using those methods and rely on less effective methods. What’s more, it may affect health insurance coverage.

Medicaid, which provides health insurance for low-income children and adults, has been required to cover family planning services at no cost to patients since 1972. Since 2012, the Affordable Care Act has required private health insurers to cover certain women’s health preventive services at no cost to patients, including the full-range of contraceptives approved by the Food and Drug Administration.

According to our research, the insurance coverage required by the Affordable Care Act has increased use of IUDs, which can be prohibitively expensive when paid out of pocket. But if IUDs and emergency contraceptive pills were reclassified as interventions that induce abortion, they likely would not be covered by Medicaid or the Affordable Care Act, since neither type of health insurance requires coverage for abortion care. Thus, access to some of the most effective contraceptive methods could be jeopardized at a time when the right to terminate an unintended or nonviable pregnancy has been rolled back in much of the country.

Indeed, Project 2025, the conservative policy agenda that the Trump administration appears to be following, specifically calls for removing Ella from the Affordable Care Act contraception coverage mandate because it is a “potential abortifacient.” And politicians in multiple states have expressed support for the idea of restricting these contraceptive methods, as well as contraception more broadly.

On the third anniversary of the Dobbs decision, it is clear that its ripple effects include threats to contraception. Considering that contraception use is almost universal among women in their reproductive years, in our view these threats should be taken seriously.

Cynthia H. Chuang, Professor of Medicine and Public Health Sciences, Penn State and Carol S. Weisman, Distinguished Professor Emerita of Public Health Sciences, Penn State

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