water quality

The pandemic was good for Hanauma Bay

October 8, 2025 By EarthWise Leave a Comment

Hanauma Bay is a marine sanctuary near Honolulu that is a popular snorkeling spot and is home to vibrant marine life and well-preserved corals. Its popularity grew in the 1970’s and 1980’s and its visitor attendance peaked at an estimated 10,000 people a day. A new management plan in 1990 reduced visitation, improved facilities, established an education program, and banned the feeding of fish. In 2019, average daily attendance was still about 3,000 people – about a million a year – and the impact on the reef ecosystem was considerable.

In 2020, because of the Covid pandemic, the preserve was completely closed to the public for seven months. This provided a unique natural experiment to study the effect of removing human interference from a natural ecosystem.

Researchers from the Hawaii Institute of Marine Biology found that the reef in Hanauma Bay quickly returned to having better water quality, more monk seal sightings, greater fish abundance, and significant changes in fish behavior. The fact that the ecosystem responded quickly indicated that everyday human presence can have a real and measurable effect on reef health.

The research serves as a valuable case study for marine managers around the world. Putting limits on the number of visitors to reefs – especially those that are currently unregulated – could help restore lost ecological function and reduce human-induced pressure while still maintaining access. Tourism to reefs generates billions of dollars annually, so there needs to be ways to protect reefs without making them entirely off limits.

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When crowds left, reefs came alive at Hanauma Bay

Photo, posted December 13, 2011, courtesy of Dalton Reed via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Tree plantings and climate impact

October 1, 2025 By EarthWise Leave a Comment

Planting trees is a key strategy in the fight against climate change. Trees absorb carbon dioxide, regulate temperature, support biodiversity, and improve air and water quality, offering benefits that extend well beyond their boundaries.

But according to a new study by researchers from University of California – Riverside, where those trees are planted makes a big difference. The study, which was recently published in the journal Climate and Atmospheric Science, found that tree plantings are almost always a net positive for the climate because trees pull CO2 out of the atmosphere. But the impact of trees on temperature varies a lot by region.

In tropical regions, trees deliver the biggest cooling benefits. They not only absorb carbon but also cool the air through a process called evapotranspiration. Roots draw water from the soil, and when it evaporates from the leaves, it cools both the tree and the air around it. This also raises humidity, which can lead to more clouds. Both effects block some sunlight from reaching the ground, which adds to the cooling.

The researchers estimated that tropical tree plantings could cool regions like central Africa by as much as eight-tenths of a degree Fahrenheit.

In contrast, planting trees at higher latitudes may have a slight warming effect. Darker tree canopies absorb more sunlight, which can offset some of the cooling. In some places, such as Canada and the northeastern U.S., trees may even increase fire risk. But this does not mean trees in those regions are unhelpful. They provide many other benefits for biodiversity, ecosystems, and the environment.

But one thing is clear: planting trees in the tropics offers the strongest returns for the climate.

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Trees in the tropics cool more, burn less

Photo, posted September 15, 2024, courtesy of Jan Helebrant via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Harmful algal blooms and climate change

September 5, 2025 By EarthWise Leave a Comment

An algal bloom is a rapid increase in the density of algae in an aquatic system. Harmful algal blooms occur when bodies of water get overloaded with nitrogen and phosphorus runoff from agriculture and other human activities. These excess nutrients can facilitate the out-of-control growth of cyanobacteria, also known as blue-green algae.

Some species of blue-green algae produce a toxin called microcystin. These toxins pose a serious health hazard to people, animals, and the environment. Microcystin affects liver function and can cause death in animals, as well as humans in rare instances. A notable incident occurred in the summer of 2014, when cyanobacteria contamination in Lake Erie left 500,000 residents in Ohio and Michigan without water for 72 hours and sickened more than 100 people.

According to a study led by researchers from Carnegie Science, as climate change warms the earth, higher-latitude regions will be at a greater risk for microcystin produced by algal blooms. The study found water temperatures of 68 to 77 degrees Fahrenheit as being at the greatest risk for developing dangerous levels of microcystin.

In the study, which was published in the journal Nature Water, the research team also demonstrated that the areas most susceptible to high toxin concentrations will continue to move northward. And in some areas, researchers say the relative risk of exceeding water quality guidelines will increase by up to 50% in the coming decades.

The research team hopes its findings raise more awareness about water sustainability, and the need to focus on the quality of the water as much as the quantity of water.

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Geographic redistribution of microcystin hotspots in response to climate warming

Photo, posted October 27, 2010, courtesy of Nara Souza / Florida Fish and Wildlife Commission via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wildfires and water quality

August 11, 2025 By EarthWise Leave a Comment

Hotter and drier conditions driven by climate change are leading to an increasing number of wildfires in North America and around the world. The damage wildfires cause – to forests, homes, and communities – is well-known. But long after the flames are gone, the effects can linger, especially in rivers and streams, where water quality may suffer for years.

A new study by scientists at the CIRES institute at the University of Colorado Boulder analyzed more than 100,000 water samples from more than 500 sites across the Western U.S. and found that wildfires can degrade water quality for up to eight years after a fire. The research, which was recently published in the journal Nature Communications Earth & Environment, found elevated levels of organic carbon, nitrogen, phosphorus, sediment, and turbidity – the cloudiness of water – in basins affected by fire.

This large-scale analysis reveals watersheds take longer to recover from wildfires than previously thought, with widespread, long-lasting impacts often going undetected for years.

Organic carbon, phosphorus, and turbidity remain elevated for one to five years after a fire. Nitrogen and sediment levels stay notably high for up to eight years. Fire-driven impacts are worse in more forested areas.

Each watershed in the study responded differently depending on local conditions. In some places, sediment levels surged to as much as 2,000 times normal levels, while others remained relatively unchanged.

The research team hopes its findings can help guide future planning efforts to improve wildfire resilience.

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Wildfires threaten water quality for years after they burn

Photo, posted April 6, 2017, courtesy of Bonnie Moreland via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Tearing down small dams to restore rivers

March 11, 2025 By EarthWise Leave a Comment

There are more than 31,000 dams in the northeastern United States. More than 4,000 of them are in the Hudson River watershed. Most of these dams are quite small and were built in the 19^th century to form ponds and to power grist, textile, paper, saw, and other kinds of mills as the region developed its industrial infrastructure. The nonprofit organization American Rivers estimates that 85% of U.S. dams are unnecessary at best and pose risks to public safety at worst.

Dam removals have been occurring for over 100 years, but the vast majority have taken place since the mid-2010s and have increased dramatically since the 2021 Bipartisan Infrastructure Law, which provided funding for such projects.

So far, 806 Northeastern dams have come down and hundreds more are in the pipeline.

Dam removals improve aquatic fish passage, water quality, watershed resilience, and habitat for all the organisms in river ecosystem food chains, ranging from insects to fish to otters to eagles. Small dams have degraded habitat and altered downstream hydrology and sediment flows. They have created warm, stagnant, low-oxygen pools that trigger algal blooms and favor invasive species.

But removing even small dams is not an easy matter. Projects range in cost from $100,000 to $3 million and qualifying for funding – whether federal or state – requires projects to meet a variety of requirements including community support. Not all dams can be removed, but many more should.

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How Tearing Down Small Dams Is Helping Restore Northeast Rivers

Photo, posted September 20, 2010, courtesy of Doug Kerr via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Thawing permafrost in the Arctic

February 18, 2025 By EarthWise Leave a Comment

Permafrost covers about a quarter of the landmass in the Northern Hemisphere. It stores vast quantities of organic carbon in the form of dead plant matter. As long as it stays frozen, it is no threat to the climate. But as permafrost thaws, microorganisms start breaking down that plant matter and large amounts of carbon are released into the atmosphere in the form of carbon dioxide and methane.

Scientists estimate that there could be two and a half times as much carbon trapped in Arctic permafrost as there is in the atmosphere today.

Thawing permafrost poses various risks to the Arctic environment and the livelihoods of its people. According to a new study led by researchers from the University of Vienna in Austria, Umeå University in Sweden, and the Technical University of Denmark, thawing permafrost threatens the way of life of up to three million people.

To identify these risks, the research team studied four Arctic regions in Norway, Greenland, Canada, and Russia between 2017 and 2023. The research, which was recently published in the journal Communications Earth and Environment, identified five key hazards posed by the thawing permafrost: infrastructure failure, disruption of mobility and supply, decreased water quality, challenges for food security, and exposure to diseases and contaminants.

These are present developments – not future dangers. Global scientific cooperation, policy interventions, and investment in research are critical to mitigate the impact of thawing permafrost and address the broader consequences it brings.

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A transdisciplinary, comparative analysis reveals key risks from Arctic permafrost thaw

Thawing permafrost threatens up to three million people in Arctic regions

Photo, posted February 9, 2017, courtesy of Benjamin Jones / USGS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wind farms and sea farms

August 5, 2024 By EarthWise Leave a Comment

There has been increasing use of agriculture coexisting with solar farms. This dual use of land is a win-win situation. Recently, Danish researchers have been investigating the potential for farming marine products at offshore wind farms.

Scandinavia’s largest wind farm, Kriegers Flak, is the site of a four-year-old project in which long lines are stretched between the wind farm’s pylons and are used to grow mussels and seaweed. With the first harvest that has taken place after 18 months, it is showing signs of early success.

Seaweed and mussels are low trophic aquaculture crops. That means that that they don’t need to be fed or fertilized. They take up nutrients from the sea and produce healthy foods.

The 328-foot lines spread between the turbines can be used to grow substantial quantities of the underwater seafood. According to modeling by Aarhus University – the institution conducting the study – using just a tenth of Denmark’s wind park area could produce tons of seafood annually while using only the naturally-available resources. This form of aquaculture captures emissions instead of producing them.

Researchers say that it is time to develop guidelines to encourage companies to plan for multiple uses of the ocean because countries are ramping up production of clean energy from offshore wind farms. Denmark was the first country in the world to install a commercial offshore wind park in 1991. Over 30 years later, nearly half of the country’s electricity comes from wind turbines.

The benefits of such sea farms combined with offshore wind farms go beyond food production and clean energy production. They also help improve water quality and capture carbon. It is another win-win situation.

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Beneath offshore wind turbines, researchers grow seafood and seaweed

Photo, posted August 5, 2007, courtesy of Andreas Klinke Johannsen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Palm oil and water quality

June 3, 2024 By EarthWise Leave a Comment

Palm oil is the world’s cheapest and most widely used vegetable oil. In fact, more than 86 million tons of palm oil was consumed last year alone. Even though few of us cook with it, palm oil can be found in approximately half of all packaged grocery items – everything from ice creams and pizzas to detergents and cosmetics.

This massive global demand for palm oil is driving tropical deforestation around the world. While many studies have shown how converting rainforests to oil palm plantations causes biodiversity loss, researchers from UMass Amherst are the first to demonstrate how these plantations also cause wide-ranging disturbances to nearby watersheds.

In the study, which was recently published in the journal Science of the Total Environment, the research team focused on the Kais River watershed of West Papua, a province in the far east of Indonesia. Approximately 25% of the watershed has been turned into oil palm plantations. The watershed is also one of the oldest continually inhabited homes for different groups of Indigenous Papuans.

The researchers found that the conversion of tropical rainforest to oil palm plantation has increased precipitation, runoff, and soil moisture. Water quality in the watershed has also gotten dramatically worse: sedimentation has increased by 16.9%, nitrogen by 78.1%, and phosphorus by 144%.

The research team hopes regulators will work to limit the use of pesticides, conduct continuous water quality monitoring, and ensure that downstream communities have access to water quality information.

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Oil Palm Plantations Are Driving Massive Downstream Impact to Watershed

Photo, posted December 13, 2008, courtesy of Fitri Agung via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Hope for amphibians

May 6, 2024 By EarthWise Leave a Comment

There are more than 7,000 known species of amphibians, the group of animals that includes frogs, toads, and salamanders. Over the past 25 years, more than 90 species are believed to have gone extinct and at least 500 more have declining populations.

There are many factors contributing to the decline of amphibian populations but the most alarming is a fungus called Batrachochytrium dendrobatidis – or Bd – that ravages the skin of frogs and toads and eventually causes heart failure. The fungus has been devastating amphibians on nearly every continent.

In a recent paper in the journal Current Biology, scientists at the University of California Riverside documented the discovery of a virus that infects Bd and could be engineered to control the fungal disease.

The researchers were studying the population genetics of the Bd fungus with DNA sequencing technology and uncovered the virus inside the fungal genome. Some strains of the fungus are infected with the virus and others are not. They are now looking for insights into the ways that the virus operates to see how it gets into the fungal cells. The goal is to engineer the virus to infect more strains of the fungus and potentially end the global amphibian pandemic.

Frogs and toads control bad insects, crop pests, and mosquitos. If their populations around the world collapse, it could be devastating. They are already having difficulty coping with warmer temperatures, stronger UV light, and worsening water quality in many places.

Some amphibian species are already acquiring resistance to Bd. The UCR researchers are hoping to assist nature in taking its course.

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Discovery could end global amphibian pandemic

Photo, posted August 25, 2010, courtesy of Kev Chapman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Flower power in agriculture

January 5, 2024 By EarthWise Leave a Comment

Agriculture is the world’s largest industry. When managed sustainably, agricultural operations can provide many environmental benefits, such as protecting watersheds and habitats, and improving soil health and water quality. Sustainable agriculture also embraces biodiversity by minimizing its impact on wild ecosystems and incorporating numerous plant and animal varieties into farm ecosystems.

A new study of farms in India has demonstrated the power of incorporating flowers into farming practices. According to the research by ecologists from the University of Reading in the U.K. and the M.S. Swaminathan Research Foundation in India, planting flowers beside food crops attracts bees, boosts pollination, and improves both the yield and quality of crops.

The study, which was recently published in the Journal of Applied Ecology, is the first of its kind in India. The researchers focused on moringa – which is a nutrient-packed superfood native to South India, and bees – the plants’ essential pollinators.

Working alongside farmers, the researchers planted marigold and red gram crops alongside moringa trees across 12 moringa orchards. They found that flower-visiting insect numbers and diversity were 50% and 33% higher, respectively, in orchards with floral interventions compared to those without them. Floral interventions also led to larger moringa pods and a 30% increase in harvestable fruits.

India has many crops of high economic and nutritional value. The study highlights how farmers can significantly improve crop pollination services and boost yields, while also managing their lands in a more sustainable manner.

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Flower power on Indian farms helps bees, boosts livelihoods

Floral interventions on farms boost pollinators and crop yields

Photo, posted June 24, 2008, courtesy of Jim via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate A Winner In The Elections | Earth Wise

December 22, 2022 By EarthWise Leave a Comment

The dominant issues in midterm elections in November were the economy and abortion rights, but at the same time there were also ballot initiatives in various cities and states across the country related to climate. What some describe as the ‘silent surprise’ of the election was that these initiatives generally passed and, in some cases, by large majorities.

The most significant of these ballot measures was in New York, where two-thirds of voters passed the largest environmental bond measure in state history. The measure funds up to $4.2 billion for environmental improvement projects including increasing flood resiliency, reducing greenhouse gas emissions, electrifying school buses, and creating more green and open spaces.

The Clean Water, Clean Air, and Green Jobs Environmental Bond Act provides up to $1.5 billion for projects aimed at climate change mitigation. Another $1.1 billion is targeted for flood risk reduction and waterway restoration. $650 million goes for water quality and infrastructure improvement.

Rhode Island voters passed a green bonds act that will allow the state to invest in climate resiliency at the municipal level, as well as local recreation, open space protection, brownfields remediation, and forest and habitat restoration.

Other climate-related ballot measures passed in Boulder, Colorado and in El Paso, Texas. There were however a few climate measures that lost. Proposition 30 in California that would have taxed very high-income residents to encourage sale of electric vehicles failed. So did Arizona Proposition 310, which would have increased sales taxes by 0.1% to fund fire districts.

But overall, it was a good election for the climate.

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Voters pass historic climate initiatives in ‘silent surprise’ of US midterms

Photo, posted September 24, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Climate Change And The Color Of Lakes | Earth Wise

October 19, 2022 By EarthWise Leave a Comment

**According to a new study recently published in the journal Geophysical Research Letters, blue lakes around the world are at risk of turning green-brown if climate change continues unabated.**

For the study, the research team used over five million satellite images of more than 85,000 lakes and reservoirs around the globe between 2013 and 2020 in order to determine each lake’s most common water color. Since lake color can change seasonally, the researchers assessed the most frequent lake color during those seven years.

Algae and sediments affect the color of lakes. But the study found that precipitation, air temperature, lake depth, and elevation also play major roles in determining a lake’s most common water color.

The research team found that blue lakes account for less than one-third of lakes worldwide. Blue lakes tend to be deeper and are often found in cool, high latitude regions with high precipitation and winter ice cover. Meanwhile, green-brown lakes, which account for 69% of all lakes, are found in drier regions, continental interiors, and along coastlines.

As global temperatures rise, lakes will warm, and warmer water produces more algal blooms. As a result, the researchers expect the changing climate to decrease the percentage of blue lakes, many of which are found in the Rocky Mountains, northeastern Canada, northern Europe and New Zealand.

Water color is a simple but viable way to measure water quality that can be done on a global scale using satellites. This approach provides researchers with a way to study how lakes – even the remote ones – are changing.

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Climate change is making lakes turn green-brown

Photo, posted August 27, 2011, courtesy of Paul Schultz via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cleaning Up Urban Rivers With Nature’s Tools | Earth Wise

October 7, 2022 By EarthWise Leave a Comment

Fifty years after the passage of the Clean Water Act, urban waterways across the United States are continuing their comeback and are showing increasing signs of life. A strategy that is being adopted in many places is to use natural restoration techniques focused on bolstering plants and wildlife to improve water quality.

A nonprofit called the Upstream Alliance has focused on public access, clean water, and coastal resilience in the Delaware, Hudson, and Chesapeake watersheds. Working with the Center for Aquatic Sciences and with support from the EPA and the National Fish and Wildlife Foundation, the alliance has been repopulating areas of an estuary of the Delaware River near Camden, New Jersey with wild celery grass, which is a plant vital to freshwater ecosystems.

In many places, scientists, nonprofits, academic institutions, and state agencies are focusing on organisms like bivalves (typically oysters and mussels) along with aquatic plants to help nature restore fragile ecosystems, improve water quality, and increase resilience.

Bivalves and aquatic vegetation improve water clarity by grounding suspended particles, which allows more light to penetrate. These organisms also cycle nutrients both by absorbing them as food and by making them more available to other organisms.

Underwater restoration projects have been underway in New York Harbor for more than a decade, where the Billion Oyster Project has engaged 10,000 volunteers and 6,000 students.

The hope is that bringing back bivalves and aquatic plants can create a lasting foundation for entire ecosystems. It is restoring nature’s ability to keep itself clean.

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How Using Nature’s Tools Is Helping to Clean Up Urban Rivers

Photo, posted December 19, 2019, courtesy of Scott via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Beavers Are Flooding The Warming Arctic | Earth Wise

March 14, 2022 By EarthWise Leave a Comment

The accelerating warming in the Arctic has transformed the region into a warmer, wetter, and more diverse environment. Warming temperatures have encouraged the increasing growth of vegetation, particularly shrubs that provide beavers with bark to eat and branches to build with. Warming temperatures also mean that lakes and streams freeze solid for shorter periods of time or not at all, allowing beavers to pursue their construction projects for longer periods during the year.

Prior to the mid-1970s, residents of the Alaskan Arctic encountered few beaver ponds. In 2018, researchers using satellite imagery mapped 12,000 beaver ponds in Alaskan tundra.

Beavers are causing major changes in the streams and floodplains that many small Alaskan villages depend upon for food, water, and navigation. As the rodents transform lowland tundra ecosystems, they are eliminating food sources, deteriorating water quality, and making it difficult to navigate waterways.

The migration of beavers across the Arctic landscape is largely a result of climate change. But it is also becoming one of the factors amplifying climate change. Scientists are trying to figure out the degree of permafrost thawing that beaver dam-and-den building is causing and how fast these defrosted organic soils will degrade and release trapped carbon and methane.

Beaver dams alter the hydrology of streams by slowing the flow, storing and spreading water to create wetlands, raising the water table, and lowering the oxygen content of the water.

Climate-driven changes in species distributions affect human well-being as entire ecosystems continue to change. Shifts in animal habitat stimulated by climate change could have profound consequences across the globe.

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Beavers Are Flooding the Warming Alaskan Arctic, Threatening Fish, Water and Indigenous Traditions

Photo, posted June 12, 2018, courtesy of Peter Pearsall/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Restoring Seagrass In Virginia | Earth Wise

December 10, 2020 By EarthWise Leave a Comment

Seagrass is found in shallow waters in many parts of the world. They are plants with roots, stems, and leaves, and produce flowers and seeds. They can form dense underwater meadows that constitute some of the most productive ecosystems in the world. Seagrasses provide shelter and food to a diverse community of animals including tiny invertebrates, fish, crabs, turtles, marine mammals and birds.

In the late 1920s, a pathogen began killing seagrasses off the coast of Virginia. In 1933, a hurricane finished them off completely. For nearly 70 years thereafter, the bay bottoms of the Virginia coast were muddy and barren, essentially devoid of fish, shellfish, mollusks and other creatures that inhabit seagrass meadows. The local scallop industry was no more.

The largest seagrass restoration project ever attempted has changed all that. During the past 21 years, scientists and volunteers have spread more than 70 million eelgrass seeds within four previously barren seaside lagoons. This has spurred a natural propagation of meadows that have so for grown to almost 9,000 acres, the largest eelgrass habitat between North Carolina and Long Island Sound.

The long-term research conducted by the team from the University of Virginia shows that the success of the seagrass restoration project is improving water quality, substantially increasing the abundance of fish and shellfish in the bays, and capturing carbon from the water and atmosphere and storing it in the extensive root systems of the grasses and in the sediment below.

The study shows that marine restorations are possible on scales that contribute directly to human well-being.

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Some Good News: Seagrass Restored to Eastern Shore Bays is Flourishing

Photo, posted May 17, 2019, courtesy of Virginia Sea Grant via Flickr. Photo credit: Aileen Devlin | Virginia Sea Grant.

Earth Wise is a production of WAMC Northeast Public Radio.

Excluding Climate Change From Infrastructure Planning | Earth Wise

January 14, 2020 By EarthWise Leave a Comment

According to a new Trump administration proposal, federal agencies would no longer need to take climate change into account when evaluating infrastructure projects. The proposed changes to the 50-year-old National Environmental Policy Act (NEPA) are aimed at speeding up approvals for highway construction, pipelines, oil and gas leases, and other major infrastructure projects.

Under NEPA, federal agencies are required to consider how their proposed actions would affect everything from water quality to wildlife to greenhouse gas emissions. They’re also required to understand how rising seas and other consequences of climate change might affect a given project. These requirements have proven to be an obstacle to projects like the Keystone XL pipeline, for example.

According to reporting in the New York Times, the administration also plans to narrow the range of projects that require environmental review in the first place. That could make it more likely for projects to be approved without having to disclose plans to do things like cut down trees, discharge waste, or increase air pollution.

The administration says that the changes would improve the environmental review and permitting process while ensuring a safe, healthy, and productive environment. Environmentalists say the proposed changes would weaken critical safeguards for air, water, and wildlife.

The proposed changes to NEPA would revise the rules that guide the implementation of the law, as opposed to amending the act itself. Once these proposed changes appear in the federal register, the public will have 60 days to comment on them.

A decision on whether or not to weaken the nation’s benchmark environmental law is expected before November.

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