Why shark attacks are on the rise in Réunion

For decades residents of Reunion, a small French Territory in the middle of the Indian Ocean, lived in relative harmony with the surrounding ocean and its inhabitants.

However, since 2011, a rise in shark attacks has forced many to come to terms with the spike in fatal encounters with sharks and turn to science to address this unexplained phenomenon

From The Economist by S.M.M.S.

When Julian Creedon moved from Jersey to Réunion in 2006 the island seemed like a surfer’s paradise: “White beaches, epic waves, it was perfect.”
But last month Alexandre Naussance, a 26-year-old fellow surfer, became the eighth person to be killed by a shark in the waters around the island since 2011.
In the past six years 20 people have been attacked by sharks in Réunion.
In terms of deaths, the tiny island takes first place.
Why have the waters around Réunion become so dangerous?

Saint Leu spot

A decade ago, shark attacks in Réunion were rare.
They also mainly occurred away from the island’s western coastline, the most popular with tourists and surfers.
“Everything changed in 2011,” says Mr Creedon.
That year alone there were six shark attacks, five of which took place around the tourist hub of St-Gilles-les-Bains.


Since then the numbers have steadily risen, with three attacks within six months in 2013, including two fatalities.
One of these was a 15-year-old French girl who was swimming just five metres out from the beach in St Paul when she was attacked.
Her death caused a public outcry.
Local authorities implemented a ban on swimming and water sports across almost all of Réunion’s beaches.
Despite the rising death toll, locals and tourists continue to ignore warnings (though in the case of Mr Naussance the warning signs had been sawed off the previous weekend).

Le Reunion island with the GeoGarage platform (SHOM chart)

The sharp rise in attacks is the cause of much debate in Réunion.
Many locals blame the government’s ban on shark meat in the 1990s, or the creation of a protected marine nature reserve along the west coast in 2007.
Experts say it is unlikely that either of these factors is responsible.
Some argue that the overfishing of other species has had an impact on shark behaviour.
Dwindling fish stocks make hungry sharks more likely to come in to shore in search of food.
Others suggest environmental damage caused by Réunion’s growing population, and urban development along its western coastline.
The geology of the island also contributes: steep volcanic slopes mean rainfall quickly washes waste and debris down into the sea.
The murkier water is appealing to bull sharks, the prime culprits.
The sharp drops and deep waters around the island also allow both bull and tiger sharks, which usually remain in the ocean’s depths, to glide all the way up to the beaches with ease.

Reunion Island continues to improve beach safety as more anti-shark nets installed

The island is paying a high price.
The government has spent millions on anti-shark defences, with limited success.
The attack count continues to rise, while tourism to the island, a French overseas department with one of the highest unemployment rates in France, continues to suffer.
Despite a slight resurgence last year, the number of visitors has not returned to 2011 levels.
With just 450,000 visitors in 2016, the tourist economy of Réunion is dwarfed by that of neighbouring Mauritius, which received over 1m people.
Since this latest attack, there have been renewed calls for a large-scale shark cull around Réunion to protect surfers and, with them, the struggling tourist industry.
Conservationists and marine biologists however say this would only be a short-term fix; such a cull would harm the ecosystem.
In the long run more research into shark behaviour could help predict attacks—but would be costlier than culling.

Links :

• The Guardian : Surf champion Kelly Slater calls for daily shark cull on Réunion
• EarthTouchNews : Kelly Slater, sharks and surfers: How do we move forward? 
• The Smithsonian : Why Is This Indian Ocean Island a Hot Spot for Shark Attacks?
• The Independant : Humans and global warming to blame for sharp rise in shark attacks, study finds

Scientists and engineers turn ocean plastic into new products

Each pair of sunglasses manufactured by Norton Point bears the latitude and longitude of its ocean plastic's origin.

In addition to Haiti, the company has identified ocean plastics from Indonesia and Hong Kong as potential collection streams.

Credit: Amy Ware

From Phys by Terry Hasting

Two years ago, socially conscious entrepreneurs Rob Ianelli and Ryan Schoenike founded their company, Norton Point, to manufacture sunglasses made from the huge amounts of plastic cleaned up from ocean coastlines.

Their goal was to be a part of the solution to one of the planet's greatest challenges: the 8 million tons of plastic entering Earth's oceans each year.
Moreover, they wanted to reinvest their profits in research, education and development efforts that help reduce the impact of ocean plastic.

Now, engineers and polymer scientists with the University of Georgia's New Materials Institute are helping Norton Point, which is based in Martha's Vineyard, Massachusetts, with testing of its "ocean plastics" products and finding new product applications.
"Packaging represents about half of all plastics produced, and single-use plastic items make up the majority of what is found on beaches," said Jenna Jambeck, associate professor of engineering and director of Center for Circular Materials Management in the New Materials Institute.

The amount of plastic pollution in the oceans is staggering and Dell’s innovative approaches to packaging provide an opportunity to begin addressing the problem.

Her study of ocean plastics, published in the journal Science in 2015, quantified for the first time the amount of plastics flowing into the earth's oceans, drawing worldwide attention to the issue.
Jambeck's study was published at an opportune time for the Norton Point founders, who had been exploring the idea of manufacturing sunglasses from ocean plastics.
"But we were concerned about doing it right," said Schoenike.

They connected for the first time with Jambeck last year at an Oceans conference, and since then, Schoenike said, the New Materials Institute has "moved our goals and the issue forward" together.
Jambeck explained that one of the plastics used in single-use plastic products is high-density polyethylene, or HDPE, which doesn't biodegrade.
"It only breaks down in the environment by creating smaller and smaller fragments," she said.
Jambeck said we need to ask how we can recapture the valuable resources in materials like littered plastics-that is, repurpose them into new products.
"By changing the way we think about waste," she said, "valuing the management of it, collecting, capturing and containing it, we can open up new jobs and opportunities for economic innovation, and in addition, improve the living conditions and health for millions of people around the world and protect our oceans."

Adidas launches trainers made from recycled ocean rubbish

and Swimwear Collection made from recycled ocean plastics

New Materials Institute researchers will work with Norton Point to help make "green" products from re-purposed plastics obtained from locations around the globe.
"Norton Point wants to know how the recycled materials respond to different manufacturing processes like extrusion and injection molding, and how they compare with virgin petroleum-based high-density polyethylene in terms of qualities like impact-resistance, toughness and durability," said Jason Locklin, director of UGA's New Materials Institute and associate professor of chemistry and engineering at UGA.
The institute also is looking to help Norton Point identify new types of products that make the best use of the material properties of ocean plastics.
In the same way that claims on other types of post-consumer waste are regulated, the New Materials Institute plans to explore the potential for certification and labeling of ocean plastics.

Links :

• The Inertia : This Sunglasses Company Makes Eyewear out of Trashed Ocean Plastic
• FastCoExist : What will it take to keep plastic out of the oceans 
• Parley for the Oceans : Facing ocean plastic 
• BBC : Plastic from tyres 'major source' of ocean pollution
• GeoGarage blog : Our seas have become a plastic graveyard - but can technology turn the tide? / "A Plastic Tide" film depicts shocking plastic pollution ... / 'Biodegradable' plastics are a big fat lie / A plastic ocean / We can solve the ocean plastic problem / Invisible ocean: plankton & plastic / Study finds rising levels of plastics in oceans / Full scale of plastic in the world's oceans revealed for first ... / Book review: Plastic Ocean

Nazaré, black Carnival

Nazaré - Black carnival from Kylian Castells

During last carnival a few riders confronted one of the last truths in the world: big ocean exploring. 

« I don’t believe people are looking for the meaning of life as much as
they are looking for the experience of being alive. » 

--Joseph Campbell (Reflections on the Art of Living book)

Links :

• GeoGarage blog : Big surf in Nazare : a closer look /  Big wave surfing Nazaré Portugal / Searching for monsters : Nazaré - Big Sunday / Surfer rides 90 foot wave (World Record) / Surf spots roar back to life as strong Atlantic swell hits Western Europe : big surf reality check

Natural power : strength of the ocean

Fierce seas have lifted a 50-tonne concrete block and dumped it on the breakwater
at Atlantic french resort St-Jean-de-Luz.


The block, spotted on top of the centre Artha breakwater, was thrown up by waves earlier this week during the violent storms ('Ekaitz' in Bask language) that lashed the length of the Atlantic coast.
- above photos Dominique Reis -

 photo Paco Elissalde

An ocean wave "casually" lifted a 50 ton block of concrete onto one of Saint Jean de Luz town's piers (digue de l'Artha) during Feb 28th's storm 
photo : Mathieu Mengaillou / Komcébo

Image taken from page 103 of 'La Terre: description des phénomènes de la vie du globe. I. Les Continents. II. L'Ocean, l'Atmosphere, la Vie' -1868-

Saint Jean de Luz bay, scanned marine map (#3647), published in 1878 
Survey from 1876 by M. A. Bouquet De La Grye, hydrograph, assisted by M. Favé, student engineer.
-courtesy of SHOM old maps- 

Note : the Artha dike was not completely built at that time.

 extract from 'Plan de la Baie de St Jean de Luz' (Artha massif)
Survey in 1873 by Mr A. Bouquet de la Grye
full plan on BNF/Gallica

 St- Jean -de- Luz plan, with the different building projects for the bay, by Thouars & Dupuis, 178x
 map on BNF/Gallica

In 1857, Napoleon III approved the construction of three dikes (Sokoa, Artha and Sainte Barbe), which began in 1863.
15 years and 7,400 blocks of 50 tons were needed to raise up the Artha massif (see pictures above), located at depths varying from 6 to 14 m and then again 10 years to build a 250 m long masonry of 32,000 cubic meters.

The final work was completed only in 1895, so more than 30 years after with the Sainte Barbe dike.
(see above)

 Saint Jean de Luz bay with the GeoGarage platform (SHOM chart)

 Pleiades image CNES 2012

Saint-Jean-de-Luz and its characteristic seashell-shaped bay
-photo taken by Thomas Pesquet, ISS on January 1st, 2017- credit : ESA/NASA

Saint Jean de Luz/Ciboure bay in winter
video : Gaël Duval

Measuring the same size as a small car – the block was thrown about 20m by the waves which came as orange alerts for ‘vagues-submersion’ were in force,
The storm waves plus a strong north-westerly current combined to lift the block.

A concrete block of 4 meters long, about 2.5 meters wide and 2 meters thick (20 m3), 
so a weight of 50 tons !

This phenomenon has already occurred during the storm of December 27/28/29th, 1951 and has not since been renewed : a concrete block was also thrown on to the breakwater – and then washed it off a few days later.

Links :

• Sud-Ouest : Baie de Saint-Jean-de-Luz : un bloc de 50 tonnes déposé sur la digue de l’Artha par l’océan /  Un cadeau de l'océan
• Alain Miranda diaporama
• YouTube : Inspection of the Artha breakwater  
• Histoire de la Baie de Saint-Jean-de-Luz Ciboure (book of Guy Lalanne) 
• BNF/Gallica Saint Jean de Luz maps : XVIIth century / ? / 1614 / 1749 / 1872
• BRGM : Etude de l'érosion de la Côte Basuqe, synthése bibliographique
• GeoGarage blog : Image of the week : the Basque Country corniche

Why is the sea salty?

From Cosmos by Jake Port

The water on the Earth’s surface was once fresh.
How that changed ?


It is estimated there is enough salt in the world’s oceans to cover all the planet’s land surfaces with a layer about 40 stories thick.
But seawater wasn’t always so salty; when the Earth’s oceans first formed about 3.8 billion years ago, as the surface of the planet cooled enough to allow water vapour to liquify, the oceans were mostly fresh water.
So where did all the salt come from?

Satellite view of La Plata River discharge to the Atlantic Ocean.

One way minerals and salts are deposited into the oceans is from outflow from rivers, which drain the landscape, thus causing the oceans to be salty.

It came from rock, laden with elemental salts including sodium, chlorine and potassium, that was spewed forth as magmatic material by massive volcanos from the depths of the planet.

Enter erosion, the process liberating these salts from their rocky prison, thanks to an atmosphere dominated by gases including nitrogen and, importantly, carbon dioxide.

 

When mixed with water (H2O), carbon dioxide (CO2) can form carbonic acid (H2CO3), a weak but corrosive acid.
This carbonic acid rained down on salt-rich rock, slowly breaking through and releasing the trapped salt into rainwater.
The runoff slowly carried the salt to nearby lakes and rivers, which in turn carried it to the seas.
Although the amount deposited by any one outlet was small, the contribution of millions of outlets over millions of years gradually raised the salinity of the oceans. The process continues.

Along the way from rock to sea, a fair proportion of the salt released from rock is used by living things.
Salt is crucial to both plant and animal life, regulating the amount of fluid in cells and neuron function.
When an organism dies and decomposes, the salt is freed to continue its seaward journey.

The Mariana Arc is part of the Ring of Fire that lies to the north of Guam in the western Pacific.

In 2004, scientists exploring the NW Eifuku volcano near the Mariana Islands reported seeing small white chimneys emitting a cloudy white fluid near the volcano's summit, as well as masses of bubbles rising from the sediment around the chimneys.

In this picture you can see masses of minerals and carbon dioxide escaping from the earth's crust into the ocean.

These vents contribute dissolved minerals to the oceans, which is one reason the oceans are salty.

Acid rain isn’t the only way the seas are fed with salt.
Ongoing volcanism still has an important role to play.
Hydrothermal vents allow seawater that has seeped though the rock of the oceanic crust to return to the surface.
The water is superheated from magma below, and as it travels up it dissolves minerals locked in the crust, erupting as mineral-rich steam.

A similar process involves the interaction of submarine volcanoes with surrounding seawater. Submarine volcanoes are comparable to their above-ground relatives except that their lava cools much more rapidly, allowing for speedy growth.
Magma erupting through submarine fissures boils the surrounding water, which then dissolves salts in the cooling rock to escape in a manner similar to hydrothermal vents.
Many of the worlds islands were formed by this process, releasing thousands of tons of salt in the process.

While seawater contains, on average, about 35 grams of salt per litre, the oceans and seas are not uniformly salty; generally the closer you get to the poles the less saline the water becomes, as fresh water released from the ice of the frozen poles dilutes the concentration of the salt.

When you are swimming in the ocean or sea, the last thing you want is a big mouth full of water.

Its horrible because it is really salty.

But why is it salty?

This video looks into why the sea is salty and how it gets there

There is still one question left: if most of the salt in the sea comes via rivers and streams, why are they not also salty?
The simple explanation is that they do contain salt, but the concentration is much lower, and the salt flows rather than accumulates.
It is estimated that each year four billion tons of dissolved salts are carried to the sea by rivers.

So is the ocean getting saltier?
The answer right now is probably not.
The input of salts is balanced by salts being buried underground by the movement of tectonic plates, the flow of freshwater and a host of other processes.

Links :

• BBC : Why is the sea so salty
• USGS : Why is the Ocean salty ? 
• NOAA : Why is the ocean salty?
• YouTube : Our World: Why are Oceans Salty? (NASA)