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The Decline Of Earth’s Largest Freshwater Creatures

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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.

A Giant Seaweed Bloom

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Scientists using data from NASA satellites have discovered and documented the largest bloom of seaweed in the world, stretching all the way from West Africa to the Gulf of Mexico.  The gigantic macroalgae bloom has been dubbed the Great Atlantic Sargassum Belt. 

The brown seaweed floats in surface water and in recent years has become a problem to shorelines lining the tropical Atlantic, Caribbean Sea, Gulf of Mexico, and east coast of Florida.  The stuff carpets popular beach destinations and crowded coastal waters. In 2018, more than 20 million tons of it floated on the ocean surface.

Scientists have been studying the Sargassum algae using satellites since 2006, but the major blooms have only started appearing since 2011.  They have occurred every year between 2011 and 2018 except for 2013.  Before 2011, most of the free-floating Sargassum in the ocean was primarily found in patches around the Gulf of Mexico and the Sargasso Sea located on the western edge of the central Atlantic Ocean.

Sargassum provides habitat for turtles, crabs, fish and birds, and produces oxygen via photosynthesis.  However, too much of it can crowd out many marine species.

According to researchers, the ocean’s chemistry must have changed in order for the bloom to get so out of hand.  The factors involved include a large seed population left over from a previous bloom, nutrient input from West Africa, and nutrient input from the Amazon River.  The increase in nutrients may be a result of deforestation and fertilizer use.

Climate-change effects on precipitation and ocean currents ultimately do play a role in this, but increased ocean temperatures do not.  Unfortunately, these giant seaweed blooms are probably here to stay.

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NASA Satellites Find Biggest Seaweed Bloom in the World

Photo courtesy of NASA.

Earth Wise is a production of WAMC Northeast Public Radio.

Keeping Lights On For Turtles

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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.

Edible Six-Pack Rings

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There has much talk about plastic straws and their harmful effects on the environment.  But much like the straws, plastic six-pack rings are also enemies of the ocean.  While straws and six-pack rings account for only a tiny fraction of all the plastic trash in the ocean, images of marine animals tangled up in the rings have sparked public backlash against these common items.  The soft but tough plastic rings are transparent which means that in the water animals don’t even see them.  They end up tangled in the loops, which can cut into their skin and constrict parts of their bodies, leading to serious injury or death.  Birds, turtles, and otters are among the frequent victims of six-pack rings.

Plastic straws have readily available alternatives such as paper straws and reusable straws.  But the plastic rings that have been available for more than 40 years are not as easy to replace.  By law, six-pack rings are photo-degradable, so they do gradually disintegrate when exposed to direct sunlight.  But even then, they remain quite dangerous at least for a while.

The Saltwater Brewery in Delray Beach, Florida, recently has released edible six-pack rings, representing a brand-new approach to sustainable beer packaging.  The rings are 100% biodegradable and edible.  They are actually made from barley and wheat ribbons from the brewing process.  This packaging can be safely eaten by animals that may come into contact with them in the wild.

Producing the edible rings represents a big investment for a small brewery but the company hopes to influence larger brewers and inspire them to get on board with the safer packaging.

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Saltwater Brewery Creates Edible Six-Pack Rings

Photo courtesy of Saltwater Brewery.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving Beaches With Seagrass

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Almost a quarter of the Gross Domestic Product of places around the Caribbean Sea is earned from tourism.  Preserving the beaches in the region is an economic imperative.  With increasing coastal development, the natural flow of water and sand is disrupted, natural ecosystems are damaged, and many tropical beaches simply disappear into the sea.

With such high stakes, expensive coastal engineering efforts such as repeated replenishing of sand and the construction of concrete protective walls are common strategies.  Rising sea levels and increasingly powerful storms only increase the threat to tropical beaches.

Researchers from The Netherlands and Mexico recently published a study in the journal BioScience on the effectiveness of seagrass in holding onto sand and sediment along shorelines.

Seagrasses are so-named because most species have long green, grass-like leaves. They are often confused with seaweeds but are actually more closely related to flowering plants seen on land. Seagrasses have roots, stems and leaves, and produce flowers and seeds. Seagrasses can form dense underwater meadows and are one of the most productive ecosystems in the world. Seagrasses provide shelter and food to an incredibly diverse community of animals, from tiny invertebrates to large fish, crabs, turtles, marine mammals and birds.

The researchers performed measurements of the ability of seagrass along Mexico’s Yucatan Peninsula coastline to keep sand in place and prevent erosion.  They found that the amount of erosion was strongly linked to the amount of vegetation.  Quite often, seagrass beds have been regarded as a nuisance, rather than a valuable asset for preserving valuable coastlines.  The study opens opportunities for developing new tropical beach protection schemes in which ecology is integrated into engineering solutions.

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Seagrass Saves Beaches and Money

Photo, posted October 13, 2010, courtesy of NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Australian Plastic Bag Ban

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Last summer, the two largest supermarket chains in Australia – Coles and Woolworth’s – decided to stop offering single-use disposable plastic bags to customers.  The initial public reaction was decidedly negative.   However, within just three months after the radical change, the country’s National Retail Association reported an 80% drop in the consumption of plastic bags nationwide.

In that three-month period, it is estimated that 1.5 billion bags have been prevented from use.   Some retailers are reporting reduction rates as high as 90% in the use of the bags.  The move by the big supermarkets has paved the way for smaller businesses to follow suit. The smaller businesses typically can’t afford to risk the wrath of their customers with a major change like this. Customers have to learn to bring their own bags or buy reusable bags at the store.

In much of Australia, the phase-out of plastic bags has been legislated, but the state of New South Wales, home to Sydney, the country’s largest city, has not enacted such legislation. So, supermarkets themselves are doing the work of getting rid of the bags.

The change has not been without hiccups.  For the first couple of months after the plastic bag ban was put in place, Woolworth’s saw poor sales in its stores.  However, customers eventually got used to the new way of doing things and sales levels returned.

Disposable plastic bags often find their way into the oceans where they break down into microparticles. Studies have shown that these plastic bits are ingested by a wide variety of marine life.  For example, a UK study found that 100% of sea turtles in the Pacific and Atlantic oceans as well as the Mediterranean Sea had plastic in their digestive systems.

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Australia-wide ban leads to ’80 per cent drop’ in plastic bag consumption

Photo, posted September 18, 2018, courtesy of Matthew Paul Argall via Flickr.  

Earth Wise is a production of WAMC Northeast Public Radio.

Corals Like Plastic

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Microplastics, which are tiny pieces of weathered plastic less than 5 millimeters in diameter, have been accumulating in the oceans for the past 40 years and are now ubiquitous in the marine environment.  They are a major threat to many kinds of marine life, including numerous species of birds, turtles, fish, marine mammals and invertebrates who ingest the stuff causing a variety of problems.

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Sea Turtle Populations Are Rebounding

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The increasing disappearance of so many plants and animals around the world has made many scientists believe that we are experiencing a sixth mass extinction.  Despite ongoing conservation efforts, living things are struggling with habitat loss, climate change, and many other natural and man-made pressures.  Conservation success stories seem to be rare events.

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Turtles Delay Flights

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Recently, we talked about the problems New York’s native turtles have during their mating season as they cross roads and highways seeking places to lay their eggs.   The state Department of Environmental Conservation even issued recommendations for how people can help turtles avoid getting crunched by cars.

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Save The Turtles

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New York is home to 11 native species of land turtles.  Many of the species can’t breed until age 10 and then they lay just one small clutch of eggs each year by digging in a suitable patch of sandy soil.  As a result, breeding females are at a premium for the welfare of the species.  Overall, turtles are on decline in the Empire State.

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Ghost Forests

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Coastal floodplains across the southeastern and mid-Atlantic regions of the United States are at the leading edge of climate change’s effect on what were largely freshwater ecosystems.    Because of the low elevation and flat or gently sloping characteristics of coastal forests in these areas, they are among the most vulnerable globally to saltwater intrusion.

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Why Do Animals Eat Ocean Plastic?

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It’s no secret that there is a lot of plastic debris in our oceans.  In fact, scientists estimate that there is more than 165 million tons of plastic trash swirling about in our oceans today, with an additional 8.8 million tons flowing in every year.  And as the oceans swell with plastic litter, hundreds of marine species are ingesting the stuff – often with dire consequences.

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Light Pollution

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The luminous glow of the Milky Way, the galaxy that contains our Solar System, has inspired everything from stories and songs to paintings and poems for centuries.  But now one third of the people on the planet – including 80% of Americans and 60% of Europeans – cannot see the Milky Way at night because of light pollution.  Nighttime light pollution now covers nearly 80% of the globe.   

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