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The Great Atlantic Sargassum Belt

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Sargassum is a free-floating brown seaweed that can drift together in vast mats, sometimes stretching for miles across the ocean’s surface. For centuries, these blooms have been a natural part of the Atlantic, creating food and shelter for many marine creatures.  Sargassum was once thought to be confined mainly to the Sargasso Sea in the western Atlantic, but scientists now know it grows rapidly and spreads widely, driven both by natural forces and by nutrients from human activities.

Scientists at Florida Atlantic University have reviewed 40 years of data on sargassum seaweed. Their study, which was recently published in the journal Harmful Algae, points to the rise of what is now called the Great Atlantic Sargassum Belt – a massive seaweed bloom stretching from West Africa to the Gulf of Mexico. First spotted in 2011, it has since appeared every year except in 2013.  This past May, the bloom reached a record 37.5 million tons, a number that does not include the 7.3 million tons in the Sargasso Sea.

Sargassum thrives in nutrient-rich waters.  Under ideal conditions, controlled studies found sargassum can double its biomass in just eleven days!  According to the scientists, nutrient pollution from agriculture and wastewater has fueled these record blooms.

In the ocean, sargassum provides habitat for fish, turtles, and other marine life.  But along the coast, it piles up in smelly heaps, clogs waterways, disrupts tourism, and can even threaten power plants.

Understanding why sargassum is spreading so rapidly is key to tackling a problem that now spans an entire ocean.

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A monster seaweed bloom is taking over the Atlantic

Photo, posted December 24, 2014, courtesy of Roban Kramer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Dark chocolate is not so dangerous

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Last year, Consumer Reports published a story stating that a third of chocolate products contain potentially dangerous amounts of heavy metals, in particular lead and cadmium. Since it contains much more cacao, dark chocolate was singled out as the most worrisome product.  Needless to say, chocolate lovers found this report quite alarming.

A new study by Tulane University published in Food Research International employed a larger sample size, expanded the scope of testing to 16 metals, and included a risk assessment of toxic metals as well as accounted for the nutritional contribution of essential minerals.

The conclusions of the study were that dark chocolate poses no adverse risk for adults and contains nutritionally beneficial levels of essential minerals.  Some risks remain for very young children, but only from a very small number of chocolate products and only when large quantities are consumed.

The study sampled 155 dark and milk chocolates from various global brands sold in the United States.  It modeled the risk of eating one ounce of the chocolate per day or two large whole bars a week.

Only one brand exceeded the international limit for cadmium; four had cadmium levels that could pose a risk for a child weighing less than 33 pounds.  Only two bars contained lead levels above California interim standard, but neither posed adverse risks for anyone.

Lead in chocolate comes from post-harvest processing; cadmium comes from the soil.  South American chocolates generally have higher levels of metals than chocolates from Asia and West Africa.  Most dark chocolate in the U.S. is sourced from West Africa.

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A dark side to dark chocolate? New study finds very minimal risk for kids from metals in chocolates

Photo, posted February 19, 2012, courtesy of Bodo via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The global chocolate supply is threatened

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The world is facing the biggest deficit of cocoa in decades. Most cocoa beans are grown in West Africa, where climate change-induced drought has ravaged crops.  Harvests are forecasted to fall short for the third consecutive year. 

The harvest shortfall has triggered a steep rise in cocoa prices.  In fact, cocoa prices have more than doubled in the first four months of this year, and have more than tripled in the past 12 months.

But drought isn’t the only threat:  A rapidly spreading virus is also threatening the future of chocolate.   

Approximately half of the world’s chocolate originates from cacao trees in Ghana and the Ivory Coast.  The Cacao Swollen Shoot Virus Disease is spread by small insects called mealybugs, which eat the leaves, buds, and flowers of cacao trees.  The virus is attacking cacao trees in Ghana, resulting in harvest losses of 15-50%. 

Pesticides don’t work well against mealybugs.  Farmers can vaccinate trees to inoculate them from the virus.  But the vaccines are expensive, and the vaccinated trees produce a smaller harvest of cacao.

According to a new paper recently published in the journal PLOS ONE, an international team of researchers has developed a new strategy to combat these pests: using mathematical data to determine how far apart vaccinated trees need to be planted in order to stop mealybugs from hopping from tree to tree.  The researchers developed two models that allow farmers to create a defensive ring of vaccinated trees around unvaccinated trees

The research team hopes its models will help farmers protect their crops and achieve better harvests in the future. 

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Cacao sustainability: The case of cacao swollen-shoot virus co-infection

Will rising cocoa prices trigger a chocolate crisis?

Photo, posted April 1, 2019, courtesy of Konrad Lembcke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Manatees And Pollution | Earth Wise

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Manatees are large, gentle, and curious marine mammals measuring up to 13 feet long and weighing up to 3,300 lbs.  There are three living species of manatees:  The Amazonian Manatee, the West African Manatee, and the West Indian Manatee, which is commonly found in Florida and the Gulf Coast.  Manatees inhabit the shallow, marshy coastal areas and rivers of the Caribbean Sea, the Gulf of Mexico, the Atlantic coast, the Amazon basin, and West Africa. 

The West Indian Manatee, which includes the Florida Manatee, is protected under the Endangered Species Act.  Today, the range-wide population is estimated to be at least 13,000 manatees, with more than 6,500 in the southeastern United States and Puerto Rico.

In Florida, an uptick in nutrient loading from nonpoint sources is triggering algal blooms in Indian River Lagoon and neighboring areas.  These algal blooms have decimated seagrass, manatees’ primary food source. 

As a result , manatees have starved to death by the hundreds along Florida’s east coast.  The state has recorded 974 manatee deaths in 2021, shattering previous annual all-time highs with still approximately two months to go.  Manatees, which need to eat between 100-200 pounds of seagrass daily, are now eating the seagrass roots, which permanently kills the aquatic plants.

Efforts are being made to replant seagrass and to restore clam and oyster beds so that the mollusks can help clean the water.  But manatees face a myriad of additional threats, including collisions with boats and ships, temperature changes, disease, and crocodile predation.

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Florida lawmakers hear Fish & Wildlife agency response to manatee death ‘catastrophe’

West Indian manatee

Preliminary 2021 Manatee Mortality Table by County

Photo, posted May 7, 2010, courtesy of Jim Reid/USFWS 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.

The Price of Chocolate

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The Ivory Coast has lost more than 80% of its forests in the last 50 years, mainly as a result of cocoa production.

The Ivory Coast is a West African country the size of New Mexico and it produces more than a third of the world’s cocoa.  But around 40% of the country’s cocoa crop – supplying more than a tenth of the world’s chocolate bars – is grown illegally in the country’s national parks and 230 supposedly protected government-owned forests. 

Over the decades, as many as one million landless people from drought-stricken places like Mali and Burkina Faso moved into national parks and protected forests and started farming cocoa.  The Marahoue National Park alone has 30,000 illegal inhabitants.

Most cocoa is grown in monocultures of what is known as the full-sun system, which requires the removal of all surrounding trees.  As a result, many allegedly protected areas have been completely converted into farms.  Most of the cocoa in the Ivory Coast is grown on small farms, typically plots of 7 to 10 acres.  The farmers are caught in an exploitative and corrupt system of cocoa trading and land appropriation, and most earn less than a dollar a day.  Meanwhile, government agencies charged with protecting the forests are more interested in collecting bribes than safeguarding woodlands.

The Ivory Coast government is unveiling a plan to actually remove protection from most of its remaining forests and hand them over to the world’s chocolate traders.    The claim is that this will protect other forests by improving cocoa productivity in already deforested areas.  Needless to say, conservation groups are dubious that the new plan will positively impact an already terrible situation.

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The Real Price of a Chocolate Bar: West Africa’s Rainforests

Photo, posted April 17, 2015, courtesy of Tom Coady via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Endangered Chocolate

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There are many scary stories floating about with regard to dire potential consequences of climate change, but one that should really strike fear into many of our hearts is the prediction from scientists at the National Oceanic and Atmospheric Administration that cacao plants are likely to go extinct as early as 2050 as a result of the changing climate.

[Read more…] about Endangered Chocolate

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