marine mammals

Removing microplastics from water

April 23, 2025 By EarthWise Leave a Comment

Microplastics come from the breakdown of larger plastics in the environment as well as from direct use in various products such as certain cosmetics. They are found everywhere, from oceans and mountain peaks to the air and water, and alarmingly, in our bodies. They are ingested by all sorts of organisms, from tiny plankton to fish and marine mammals. Microplastics just don’t go away. They don’t biodegrade so they simply accumulate in the environment.

Researchers at North Carolina State University have recently demonstrated proof of concept for a system that actively removes microplastics from water. Such a system has the potential for helping to cleanse oceans and other bodies of water from the tiny plastic particles.

The system makes use of soft dendritic colloids, which are tiny particles that have the ability to stick to just about any surface. These sticky particles can attract microplastics and grab them, even in wet and salty conditions. The colloids are made from chitosan, a harmless and biodegradable polymer made from processed shellfish waste.

The researchers produced small pellets of the colloids that also contain small amounts of magnesium, which makes them bubble up and rise to the surface of water. The pellets are coated with a gelatin layer, which blocks the magnesium. As the gelatin gradually dissolves away, the pellets collect microplastics. Eventually, the result is a microplastic-laden scum that rises to the surface where it can be skimmed away.

The scum itself can be bioprocessed into more chitosan that can create more of these microcleaner pellets to then capture more microplastics. The researchers are investigating how the process can be scaled up to become a valuable tool in dealing with the microplastics problem.

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New Water Microcleaners Self-Disperse, Capture Microplastics and Float Up for Removal

Photo, posted January 17, 2018, courtesy of Bo Eide via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Lighted Nets Protect Marine Wildlife | Earth Wise

March 16, 2022 By EarthWise Leave a Comment

Gillnets are walls or curtains of netting that hang in the water to trap fish. They are one of the most extensively used fishing gear in coastal regions throughout the world’s oceans. While they are very effective at catching targeted fish species, they are not discriminating. As a result, they carry significant risk of bycatch – the accidental capture of unwanted species as well as other interactions with various marine animals.

Researchers from The Wildlife Conservation Society, NOAA Fisheries, Arizona State University, and the National Fisheries and Aquaculture Institute of Mexico have recently published a study showing that using lighted gillnets reduced overall bycatch by 63%, including a 95% reduction in sharks, skates, and rays, and an 81% reduction in Humboldt squid.

Gillnets often catch endangered, threatened, and protected species such as sharks, sea turtles, marine mammals, and seabirds, as well as unwanted species and non-marketable juvenile target fish species. The bycatch animals are often dead or injured and are generally dumped overboard.

Illuminating gillnets with LED lights has emerged over the past decade as an effective tool to reduce bycatch of endangered sea turtles. The new study is the first detailed examination of the effectiveness of illumination for other vulnerable species.

Gillnets are ubiquitous because they are inexpensive and catch everything that passes them. Global populations of sharks, skates, and rays have declined as a result of bycatch and illegal fishing. The results of this study are encouraging because they provide a practical solution for increasing the selectivity of gillnets and avoiding bycatch.

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Lighted Nets Dramatically Reduce Bycatch of Sharks and Other Wildlife While Making Fishing More Efficient

Photo, posted September 19, 2015, courtesy of Jim Bahn via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Whales As Ecosystem Engineers | Earth Wise

December 14, 2021 By EarthWise Leave a Comment

Researchers from Stanford University have been studying the role of large whales on ocean ecosystems with some surprising results.

From 1910 to 1970, people killed about 1.5 million baleen whales in the waters surrounding Antarctica. The whales were hunted for their blubber, baleen, and meat. Baleen is the filtering fringe that certain whales use instead of teeth to capture food from the ocean. A primary food source for these whales is krill, small shrimp-like creatures. One would assume that the decimation of the baleen whale population in the Southern Ocean would have led to a surge in krill populations. But the new research has found that the opposite is the case.

The precipitous decline of large marine mammals has negatively impacted the health and productivity of ocean ecosystems.

New high-tech tagging devices that attach to whales for brief periods allow researchers to record their movements and activities. For the first time, it has been possible to accurately determine how much krill whales actually consume, and the answer is that they eat two to three times as much as previously thought. Interestingly, the same technology shows that fish-eating whales like humpbacks eat somewhat less than previously thought.

Baleen whales are essentially mobile krill processing plants. They eat the krill, digest it, and produce iron-laden excretions that are needed by phytoplankton, which comprise the bottom of the food chain that nourish krill and other small creatures. With fewer whales, there is less nourishment for the krill. In fact, based on the new data, estimates are that the historic abundance of krill in the Southern Ocean had to be about five times what it is today.

Whales are important ecosystem engineers.

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Stanford researchers find whales are more important ecosystems engineers than previously thought

Photo, posted November 18, 2010, courtesy of Dr. Brandon Southall, NMFS/OPR 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.

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.