dolphins

How much nanoplastic is in the oceans?

August 1, 2025 By EarthWise Leave a Comment

It is unfortunately well-known that microplastics are pretty much everywhere on Earth. They are also increasingly found in living things like birds and dolphins as well as in human brains and placentas. The oceans are polluted with plastic, and for the first time, there is now an estimate for the volume of nanoplastics – which are even smaller than microplastics and invisible to the human eye – found in the North Atlantic.

According to a study published in the journal Nature by the microplastics and nanoplastics research group at the Helmholtz Center for Environmental Research in Germany, there are at least 30 million tons of nanoplastics in the North Atlantic, which is more than the weight of all wild land mammals on Earth.

The same researchers have analyzed plastic in lakes, urban air, and even the air in very remote places, but the new study reveals a missing part of the plastics story.

Nanoplastics are microscopic fragments smaller than one micron, about the size of small bacteria. There has been ongoing concern about nanoplastics in ocean water, but there wasn’t the technology available to really investigate it. While nanoplastics were expected to be found in the ocean, the sheer amount of it was surprising.

The average concentration of nanoplastics near coastlines is about 25 milligrams per cubic meter of water, about the weight of a single large bird feather. Nanoplastics are tiny enough that they can easily infiltrate the bodies of living creatures. For fish and other ocean animals, that means constant exposure that builds up over time.

It is highly unlikely that plastic pollution is going to stop any time soon, but there is a United Nations meeting on the subject in August in Geneva.

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Tons of Invisible Plastic Pieces Lurk in Ocean Water

Photo, posted June 24, 2020, courtesy of G.P. Schmal / NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Toxic algae and West Coast marine life

June 5, 2025 By EarthWise Leave a Comment

Over the first several months of this year, hundreds of sea lions, dolphins, and seabirds have fallen ill or died after eating sardines or anchovies that had been feeding on an algal bloom along the California coast since winter. The biotoxin in the algae accumulates in the feeder fish.

Two cases of whales dying from the biotoxin have been confirmed by two nonprofit organizations tasked with testing dead mammals. These were a humpback that washed ashore in Huntington Beach in January and a minke whale found dead in Long Beach in April.

This is the fourth year a row that California has experienced major algal blooms. Warmer waters are causing blooms to be bigger and more damaging than they have been before. They enter into new areas and contaminate the food web for longer. The warmer waters accelerate algae growth that is further fueled by nutrients that rise to the surface from deeper colder waters driven by winds that blow parallel to the coast. This year’s algae event started earlier than usual and is lasting longer than normal.

More than a dozen animal rescue and rehabilitation groups that form NOAA’s West Coast Marine Mammal Stranding Network are providing resources to try to respond to the situation. At the Marine Mammal Care Center in Los Angeles, more than 80 sea lions and seals were being treated for domoic acid poisoning, the result of ingesting algae neurotoxin. Since February, it has cared for more than 300 poisoned animals.

Marine mammals are sentinel species for humans who also consume seafood. The West Coast ocean ecosystem is currently filled with toxins.

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California Toxic Algal Bloom Blamed for Months-long Marine Life Poisoning

Photo, posted March 26, 2025, courtesy of Marnee Jill via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Elephants have names

July 11, 2024 By EarthWise Leave a Comment

Elephants are considered to be very smart creatures. They have the largest brain of any land animal and have three times as many neurons as humans. Of course, a lot of that brain hardware is needed to control those big elephant bodies, but elephants have also demonstrated impressive mental capabilities on many occasions.

A new study by an international team headed by researchers from Colorado State University has found that elephants call each other by name and respond when they hear others call their name.

The researchers analyzed hundreds of elephant calls recorded over more than a year in Kenya. With machine learning techniques, they were able to identify specific sounds that elephants made when calling each other. When the researchers played recordings of these sounds, the elephants responded to the sound of their own name by calling back or moving toward the loudspeaker. Their response to other names was much less enthusiastic.

Very few animals use names at all, and, in most cases, it is more a matter of imitation. For example, dolphins refer to other dolphins by mimicking their unique sounds.

These findings at least suggest that elephants may be capable of abstract thought and perhaps may have a vocabulary beyond names for each other. The researchers are investigating whether elephants can identify food, water, or locations using their calls. The great hope is that it might ultimately be possible to communicate with elephants directly. It would be wonderful to be able to alert them to poachers or other threats. The lead author of the study said that he would like to be able to tell elephants things like “Do not come here. You’re going to be killed if you come here.”

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Elephants Have Names for Each Other, Study Finds

Photo, posted April 24, 2016, courtesy of Neil Ransom via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Humanity Weighs On The World | Earth Wise

April 6, 2023 By EarthWise Leave a Comment

There are countless ways in which humankind has had disproportionate effects on our planet and most of those effects have been negative. A recent study led by the Weizmann Institute of Science in Israel looked at the total combined weight of various groups of mammals on Earth. The results are that human beings and our domesticated mammals are the overwhelming majority of the total mass of mammals.

We think of large land mammals – elephants, bears, bison, wildebeests, and so on – as adding up to a massive amount of animal matter. The study determined that all wild land mammals put together add up to about 22 million metric tons. Wild marine mammals – such as dolphins and whales – add up to about 40 million tons in total. These sound like pretty big numbers until we look at the human and human-created side of the equation.

The study found that humans weigh about 390 million metric tons, while domesticated mammals – like sheep, cows, and pigs as well as dogs and cats – weigh about 630 million metric tons combined.

All told, wild mammals account for only 6% of all mammals by weight. People and their domesticated animals make up the other 94%. This enormous imbalance is an indication of how profoundly humans have reshaped life on Earth. House cats total twice the weight of African elephants and pigs add up to twice the weight of all wild land animals combined.

The conclusion to draw from the big picture here is that wild animals on Earth are not doing very well. We already knew this from many other perspectives, but this census by weight presents a stark picture of the extent to which we have taken over the planet and its ecosystems.

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Total Weight of Wild Land Mammals Less Than One-Tenth Weight of All Humans

Photo, posted December 27, 2006, courtesy of Nigel Hoult via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

What’s Killing Orcas? | Earth Wise

January 18, 2021 By EarthWise Leave a Comment

With their characteristic tall dorsal fins and black and white color patterns, orcas are one of the ocean’s most iconic species. Measuring up to 32 feet long and weighing as much as 6 tons, orcas have one of the largest geographic distributions of any species. They live in all latitudes, in all oceans, from the Arctic to Antarctica.

While they are often referred to as killer whales, orcas are actually not whales at all. Orcas are the largest dolphin species and one of the most powerful predators on the planet.

But human interference has made life significantly more difficult for orcas in recent years. According to pathology reports on more than 50 orcas stranded over nearly a decade in the northeast Pacific and around Hawaii, the predators face a myriad of mortal threats. Many of those threats stem from human interactions.

Researchers from the British Columbia Ministry of Agriculture analyzed these orca pathology reports in a new study, which was recently published in the journal PLOS ONE,. Of 52 orcas stranded between 2004 and 2013, causes of death were determined for 42%. For example, one orca died after receiving a halibut hook injury. Two orcas died from the blunt force trauma of vessel strikes. While there was no singular common cause of death, the study found a common theme: human-caused deaths occurred in every age class – from juveniles to adults.

The researchers also note that humans aren’t just indirectly hurting orcas with things like lack of salmon or legacy toxins. Humans are also directly killing killer whales with boat strikes and fishing gear.

These findings will help establish a baseline of information to assess future orca conservation efforts.

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What’s killing killer whales?

Photo, posted July 5, 2009, courtesy of Rennett Stowe via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Decline Of Earth’s Largest Freshwater Creatures

September 23, 2019 By EarthWise Leave a Comment

While nearly 70% of the globe is covered by water, only 2.5% of it is freshwater. The rest is saline and ocean-based. And only 1% of our freshwater is easily accessible, with much of it locked away in snowfields and glaciers.

Despite freshwater only making up a small fraction of all water on the planet, it’s home to one third of all vertebrate species. Some have survived hundreds of millions of years, but many of the world’s largest freshwater creatures – including fish, reptiles, amphibians, and mammals – may soon find themselves on the brink of extinction.

According to a study recently published in the journal Global Change Biology, scientists from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries and international colleagues have quantified the global decline of freshwater megafauna for the first time. In four decades since 1970, the global populations of these freshwater giants have declined 88% – twice as much as the loss of vertebrate populations on land or in the oceans.

Freshwater megafauna include all freshwater animals that weigh 30 kilograms (about 66 pounds) or more, such as certain dolphins, beavers, crocodiles, turtles and sturgeons.

Overexploitation is one of the main threats to freshwater megafauna. (These animals are often targeted for their meat, eggs, and skin). The other main threat is the loss of free-flowing rivers. Many of the world’s large rivers are already highly fragmented, which impacts access to spawning and feeding grounds. The research team says another 3700 large dams are planned or under construction, including 800 in habitats rich with freshwater megafauna, including the Amazon, Congo, and Ganges river basins.

Current conservation measures are clearly failing our freshwater creatures.

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88 percent decline of big freshwater animals

Earth’s largest freshwater creatures at risk of extinction

Photo, posted March 25, 2012, courtesy of the U.S. Fish and Wildlife Service via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Keeping Lights On For Turtles

August 8, 2019 By EarthWise Leave a Comment

Gillnets are one of the most common types of fishing gear and are used extensively in most places where people fish for food. They operate by suspending a wall of netting in the water column.

Unfortunately, they are not selective in the species they catch. Sea turtles are one of the most common bycatch species that become entangled in these nets. When turtles are caught in gillnets, they can drown and die. Marine mammals, seabirds, and sharks are also frequently caught in gillnets.

Recently, researchers have been experimenting with illuminating the nets with LED lights to see if increasing net visibility reduces sea turtle bycatch.

Studies in Mexico show green sea turtle bycatch is reduced between 40-60% with no changes in target catch. Studies in Peru show green sea turtle bycatch is reduced between 65-80% with no changes in target catch. Studies in Indonesia show green olive ridley, and hawksbill sea turtle bycatch is reduced by 60% with increases in target catch and catch value.

Recent research shows that net illumination also reduces bycatch of other protected species such as seabirds, sharks and rays, as well as dolphins and porpoises.

The use of illuminated gillnets could prove beneficial to both sea turtles and fisherman by reducing the bycatch that can damage fishing gear.

Studies are now underway off the coast of North Carolina, where state gillnet fisheries are carefully managed to reduce turtle bycatch. Initial studies show that net illumination does not change target catch rates and may even decrease the bycatch of unwanted fish species. When it comes to protecting sea turtles, it looks like a good idea to keep the lights on.

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Illuminated Nets Could Provide A Brighter Future For Sea Turtles

Photo, posted June 2, 2016, courtesy of NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Dolphins

May 27, 2019 By EarthWise Leave a Comment

We don’t think of heatwaves as something that affects the ocean, but increasingly, as the planet warms, there have been instances where ocean water temperatures become much higher than normal for extended periods of time. There has been much discussion of this phenomenon with regard to coral reefs where the catastrophic rise in coral bleaching events has been the result.

Recently, a study at the University of Zurich looked at the effects of ocean heatwaves on marine life higher in the food chain. They studied the well-known dolphin population in Shark Bay, Western Australia.

In early 2011, a heatwave caused water temperatures in Shark Bay to rise more than 4 degrees above the annual average for an extended period. This led to a substantial loss of seagrass, which is a driving factor in the Shark Bay ecosystem.

The researchers investigated how this environmental damage affected survival and reproduction of dolphins, using long-term data on hundreds of animals collected over a ten-year period from 2007 to 2017.

Their analysis showed that dolphins’ survival rate dropped by 12% and female dolphins were giving birth to fewer calves. That phenomenon that began in 2011 lasted at least until 2017.

The researchers were surprised by the extent and the duration of the influence of the heatwave, especially the fact that the reproductive rate of dolphins had not returned to normal even after 6 years.

This study shows for the first time that marine heatwaves not only affect organisms at the lower levels of the food chain, but also might have considerable long-term consequences for the animals at the top, such as dolphins.

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