Harmful algal blooms can occur in warm, nutrient-rich, stagnant waters and are often associated with the rapid reproduction of blue-green algae—a misnomer for cyanobacteria, not algae.

As of 2026, the Great Atlantic Sargassum Belt is the world's largest macroalgal bloom, with seaweed stretching from the Caribbean to West Africa.

Massive blooms of microscopic algae called dinoflagellates produce the neon blue light seen in glowing tides.

Satellite imagery of the massive seaweed blob in the Atlantic

A belt of sargassum seaweed that stretches from the west coast of Africa to the Gulf of Mexico is the largest on record for March.

View the rainbow effect on the waters at First Landing State Park

The phenomenon results from light interacting with a thin film of natural oils on the surface of swamps and marshes at the site, not unlike the coloration seen in soap bubbles. The oils originate from decaying vegetation or from anaerobic bacteria reducing iron in soil. (Some readers may experience a paywall.)

Coral reefs get their colors from zooxanthellae—photosynthetic algae that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Natural toxins produced on plants or consumed by animals may cause food poisoning

When humans eat plants with certain natural toxins on them—including a family of toxins called aflatoxins that fungi produce on crops like peanuts and corn— they can become ill with food poisoning. Toxins can still harm humans even if animals or plants appear fine to the human eye. The World Health Organization advises that we should throw away moldy or discolored foods, refrain from eating wild plants or mushrooms that aren’t definitively nonpoisonous, and remember that just because something is “natural” it’s not always safe to eat.

While major oil spills result from accidental pipeline ruptures or damage to transportation vessels or rigs, as much as half the oil that reaches coastlines has naturally leaked from the seafloor.

To protect the symbiotic algae they rely on for food, some corals absorb ultraviolet radiation and re-emit it as visible light, which these algae can photosynthesize.

Climate change threatens coral reefs by disrupting the symbiotic relationship between corals and algae due to rising ocean temperatures.

The ocean's ability to store carbon long-term is being hindered by marine heatwaves

More than 4,000 robotic floats with biogeochemical data sensors, including oxygen, pH, nitrate, suspended particles, chlorophyll, temperature, and conductivity, have been deployed as part of the Global Ocean Biogeochemical Array. They have identified changes to ecosystem structure affecting the ocean's ability to transport carbon from surface waters into the deep.

Louisiana's 'Cancer Alley,' an area with hundreds of industrial plants and petrochemical production, has cancer rates 50% above the national average.

The world's largest species of marine algae is giant kelp, which can grow as much as two feet per day from depths of about 100 feet up to the ocean surface.

During coral bleaching, corals sacrifice their food source and expel colorful microorganisms to protect themselves, a phenomenon that resembles an organism's immune system attacking itself.

Watch underwater photosynthesis make water look like champagne

In shallow waters where sunlight can reach, photosynthetic reactions absorb water and dissolved carbon dioxide, producing bubbles of oxygen at the surface of plants. As these bubbles rise to the water's surface, a fizzy appearance is created.

Algae can capture carbon dioxide at rates up to 50 times faster than land-based plants and can be grown in tanks that use one-tenth the land footprint of terrestrial plants.

Underwater nighttime photos capture the ocean's diversity

Self-taught photographer Steven Kovacs explores Palm Beach's ocean after sunset, capturing tiny sea creatures in deep waters. Over eight years, he's dived into Florida's eastern coast, drifting from 0 to 100 feet, photographing rarely seen larval fish. Lacking formal marine biology training, Kovacs collaborates globally to identify species like cusk eels and the female blanket octopus, known for its revealing membrane. Check out his photos here.

How microbes limited the damage and helped clean up the Deepwater Horizon oil spill

A bloom estimated to contain about 100 sextillion microbial cells broke down much of the 4.1 million barrels of spilled crude oil into nontoxic compounds in what was one of the most significant bioremediations of a human-made disaster. The microbes involved acted similarly to the first patented genetically modified organism in US history: an oil-eating bacterium engineered in 1971.

A remote Scottish island is awash in forever chemicals even though there are no obvious industrial sources nearby, and scientists suspect the toxic substances are accumulating via sea spray.

Explore a map of coral reefs around the world and the extent of coral bleaching.

Some algae have helped remove microplastics from water after being bioengineered to clump together with these contaminants, forming an easily collectible microplastic-algae sludge.

Forever chemicals accumulate up the food web, with recent research indicating that apex predators have higher concentrations because they're eating prey that also have accumulated the substances.

The risks of bioremediation, from intermediate products to ecological disruption

A step in the series of complex biochemical reactions involved in the implemented bioremediation process may produce dangerous molecules—sometimes more toxic than the initial pollutants—that require ongoing monitoring to ensure optimal conditions for processing these intermediates toward the eventual, safe outputs. Introducing non-native nutrients or species, including GMOs, may alter existing food webs and gene pools.

The Amazon rainforest is considered the 'lungs of the Earth,' but it contributes less than a quarter of the oxygen of phytoplankton—microscopic plants, algae, and bacteria capable of photosynthesis.

Synthetic pheromones may protect coral reefs by attracting their predators

Researchers in Australia and Japan have developed these nontoxic chemicals to attract crown-of-thorns starfish, which consume corals that make up the Great Barrier Reef. As of 2026, synthetic pheromones have been shown to be effective in lab trials, and future field trials will attempt to lure starfish into areas for mass removal.

Molecules derived from algae can be found in foods such as ice cream, salad dressings, brownie mix, and gravies, as well as in products such as toothpaste, multivitamins, and egg substitutes.

Plastic debris across the ocean aids the spread of invasive species

The durable, long-lasting material can serve as a platform for living organisms to latch onto and ride over vast distances. After the 2011 earthquake and tsunami in Japan, a large dock carrying 100 tons of living organisms native to Japan washed up on Oregon's coastline, confirming the ecological threat.

Water is naturally tinted with a slight blue, but sediments and organics can alter its color

The innate coloration comes from water absorbing red light in the visible spectrum more than green or blue, giving shallow waters in some parts of the Caribbean their turquoise hue. If sand is light, it can be churned up by turbulent water, clouding its appearance. Plankton and other organisms can color water by affecting how the rest of the spectrum is absorbed or reflected.

We can get food poisoning from spending time in swimming pools, lakes, rivers, and ponds

Some of the same pathogens that may sicken us in food or water may also sicken us in recreational swimming environments. Bacteria can rub off of people’s (or animal’s) bodies or contaminate the water through a diarrheal episode. Washing your hands for at least 20 seconds before eating food if you are at the beach, pool, or other similar environments and being sure not to swallow the water are ways to help keep safe.

25 million pounds of beads are distributed every Mardi Gras, leading to environmental concerns

The necklaces—which are mostly made from cheap, often toxic, plastic—are believed to be harmful to New Orleans and its residents. Dr. Howard Mielke, an environmental scientist at Tulane University, found that the majority of lead in the city's soil can be found along Mardi Gras parade routes.

Research has found that when their symbiotic algae are not producing oxygen via photosynthesis, corals twirl hairlike structures to circulate water and draw oxygen into their outer tissues.

Scientists have collected critical minerals from ocean water using seaweed, a type of algae that leaves behind a mineral-rich powder called bio-ore after being processed into biofuels.

When diving and snorkeling in environments containing reefs, avoid touching reefs, anchoring on them, or using sunscreen with active ingredients harmful to marine life.

Starting with red, colorful objects will appear to lose their colors the deeper they are submerged because water scatters light, reducing the amount available to reflect off objects and be observed.

Climate change is influencing the spread of disease

Rising temperatures and water levels are forcing animals and pathogens beyond their typical boundaries. This article and its data visualizations explore the proliferation of climate-driven diseases.

Solutions of bioluminescent bacteria can create FOMO-inducing living art

A 2002 exhibition at Montana State University-Bozeman placed the bacteria onto petri dishes that served as macroscopic pixels to create images. Once the bacteria finished eating all the food in the sealed dishes, the light slowly faded away, ending the exhibit.

The Arctic is greening from rising temperatures

This one-minute video summarizes a new study that used satellite data to look at plant life across the entire Arctic area for the first time. It found that from 1985 to 2016, 38% of the areas studied—including parts of Alaska, Canada, and...