Minamitorishima Island, Japan

Minamitorishima Island, Japan

roughly translates to "Southern Bird Island"

Minamitorishima is located about 1,848 kilometers (1,149 miles) southeast of Tokyo, making it one of Japan's most distant territories.
Minamitorishima, also known as Minami Torishima or Marcus Island, is a remote, uninhabited raised coral atoll in the Pacific Ocean.  It is part of the Ogasawara Islands chain, which belongs to Japan.  This small (less than 1 square mile) low lying island (less than 400 ft above sea level) was once mined heavily for guano, serves as a strategic location for airspace and maritime surveillance and is now the site of major sub sea floor rare-earth metal mining research and possibilities.  Rare-earth metals are crucial in the making of high-tech products such as electric vehicles and batteries, and most of the world has relied on China for almost all of its needs.  After China restricted exports of strategic rare-earth oxides (REO's) in 2009 Japan began to explore its sea floor for deposits.   Among the rare metals found around Minamitorishima Island are cobalt and nickel — both essential for lithium-ion batteries.
Manganese nodules found in the seabed around Minamitorishima
Minamitorishima Island samples held by scientists from the University of Tokyo
Minamitorishima is considered Japan’s easternmost territory and plays a role in Japan's control over its exclusive economic zone (EEZ) in the Pacific Ocean.  The island is off limits to civilians except for Japan Meteorological Agency staff, although reporters, documentary makers, and scientific researchers can sometimes get an entry permit. No commercial boat tours or flights visit the island, and civilians are currently not allowed access to Minamitorishima for tours or sightseeing, due to its use by the JSDF as an observation station.
The Research operation investigating the existence, location, and concentration of rare-earth metals has been focusing their efforts to collect samples from the sub-sea floor from around Minamitorishima island because this atoll makes a great base of operations.  In 2013 a deep sea research vessel obtained seven deep sea mud core samples some 5000m below the sea level that revealed extremely concentrated REO in a mud layer 2-4m beneath the seabed around the island. 
Researchers think that the deposits found are the result of hot plumes from hydrothermal vents that over hundreds of thousands of years have pulled materials out of the seawater and deposited them into the muddy seabed.
An effort began in 2018 to create detailed maps of rare-earth elements distribution.   Researchers have found 16 million tons of REO mineralized sediments within the studied area which some say is equivalent to 75-100 years worth of rare-earth materials underneath Japanese waters — enough to supply to the world on a "semi-infinite basis," according to a study published in Nature Publishing Group's Scientific Reports.  That supply term depends on the demand of course and it remains to be seen what and how human demands for products that utilize these REO's will change in time...especially if there are more suppliers than China.
Japanese Research Vessel Kaityo Maru 2 is supporting the acoustic mapping operation around Minamitorishima Island
The mapping and sampling process requires a wide range of specialists and organizations, cutting edge technology and equipment, and time.  There are marine geologists using new high resolution acoustic profiling technology that creates a narrow acoustic beam that transmits information about the soft seafloor 6000m to 11,000m deep.  The beam is then able to penetrate 200m into the sub-seafloor allowing researchers for the first time to gather sub-seafloor data.  Concurrently, researchers have taken hundreds of deep sea core samples which is very slow and difficult work as well.  One sample taken 5000m deep can take an entire day.  Samples are sent to laboratories in Tokyo for analysis.  Together they are building an understanding of the geologic history of the area like never before and hope that they will be able to discover where the soft sediment with the material from the ocean vents has settled.
Deep sea piston coring device.
Piston with lowers the core sampler. 700 samples have been taken in three years.
In addition to the islands particular geology, Minamitorishima is known to have a unique ecosystem, and though 'uninhabited' by humans, it provides a habitat for various bird species, hence the name, "Southern bird Island". Its isolation and distance from the mainland has allowed it to remain relatively undisturbed by human activity, which is important for preserving its natural environment.  The island is also a significant site for marine life, with surrounding waters providing a rich habitat for marine species. With this in mind, while the researchers have made many findings about the geology of the surrounding seafloor, their efforts are colossal and not without impact.  The drivers believe that results could be worth the effort.  In the long term and in the short term one cannot forget to ask, What are the risks?  Will the risks be outweighed by the rewards?  What are the impacts of this work on the surrounding environment, the local, pelagic, and migratory animals.  Could the repeated core sampling affect the plate tectonics?  Could the acoustic beams disrupt other ocean acoustics?  Have they already?  What could be affected that is not being considered or seen at this time?
As all these questions begin to bubble up it is clear is that Minamitorishima’s isolation, strategic role, and environmental uniqueness make it an intriguing part of Japan’s territorial holdings in the Pacific.  Japan is being strategic and hopefully considering so much more than the potential political and economic value of the extracted minerals for the human species.
It was the possibility of darkness that made the day seem so bright. -Stephen King

By Maurisa Descheemaeker on SV WHIRLWIND

 

Sources: https://www.nature.com/articles/d42473-020-00525-x

https://www.japantimes.co.jp/news/2024/06/22/japan/science-health/tokyo-island-rare-metals-find/

https://www.t-borderislands.metro.tokyo.lg.jp/en/minamitorishima/


MANTA RAYS MAJESTIC & MYSTERIOUS

MANTA RAYS : Majestic and Mysterious

Each Manta ray can be identified by their unique markings on their underside.  Photo Credit: SV WANDERLUST

Manta Rays are among the most majestic gentle giants in tropical and sub tropical oceans of the world.  Seeing them swim under water is a magical sight to behold; with their mouths wide open, manta rays silently move through the water in a slow, effortless, gliding motion, feeding on the smallest of living creatures, plankton, that drift in the ocean currents.   Like many species of sharks, mantas are in constant motion to keep water flowing over their gills to breathe.  Additionally, mantas are cartilaginous fish meaning their skeleton is made of cartilage like our ears and noses.

There are two species of Manta Rays: the Reef Manta (Mobula alfredi) and the Oceanic Manta (Mobula birostris).  No matter the species of manta, With their wings outstretched they dwarf all but large sharks or whales.  The reef mantas wings span up to 5 meters while the oceanic mantas wings span up to 7 meters and can weigh up to 2 tons.  Manta Rays have the largest brain to body ratio of all living fish and are known to display high levels of intelligence, have long-term memory, and are able to map their environment using sights and smells.  The markings on their underside are their unique 'fingerprint'.  Much like the marking on the underside of a humpbacks tail, the star-like pattern of whale sharks, and the whisker spots of lions, there are no two exactly alike and these creatures can be identified by their markings that make them unique.

Manta in the pass to Tikihau Atoll, French Polynesia. Photo Credit: Planet Ocean

As seen in this photo above there is a mutualism, or mutually beneficial relationship, between mantas and various small hitchhiker fish like remoras.  The Remora clings onto the Manta Ray for protection, transportation and scraps from the Manta Rays meals. The Remora benefits the Manta Ray by cleaning it’s skin of bacteria and parasites keeping Mantas healthy.  Manta Rays can also be found at 'Cleaning Stations' (or healthy coral patches) sometimes circling close by for up to an hour before moving in for a cleaning and then staying on for hours getting cleaned.  In this case the mantas have a symbiotic relationship with cleaner fish (like the cleaner wrasse fish and the scarlet cleaner shrimp). These small fish and crustaceans swim around the larger animals and inside their mouths to eat the parasites, bacteria, and dead skin cells from their bodies.  One animal is getting fed while the other is getting cleaned.  It's a win-win!  Manta Rays will often return to cleaning stations they 'know'.

Manta rays live up to 50 years.  The female manta becomes sexually mature a bit later than the male: round 8-10 years of age.  Manta rays are ovoviviparous meaning that after fertilization the offspring grows inside an egg (like a bird...but WAIT...there's more)...which the female manta carries inside of her during the pregnancy and give birth to a live fully independent manta ray (live birth like a mammal?!).  Mantas give birth to 1-2 manta every 2-5 years.  Many details are still a mystery as no one has ever documented seeing a live birth in the wild.

The manta ray can be seen in Polynesian art and design

Perhaps because of their size, their grace, their omnipresence in the oceans Manta Rays, and many other characteristics, manta rays have found their way into the art and mythology of many cultures around the world.  In Polynesian mythology, for instance, the manta ray is believed to be the guardian of the ocean and a symbol of knowledge and wisdom.  In ancient Greek mythology, they were believed to be messengers of the sea god, Poseidon.   In ancient Hindu mythology, manta rays are believed to be the manifestation of Lord Vishnu, the creator of the universe. In Japan, manta rays are often associated with the god of the sea, believed to protect sailors and fishermen from danger and provide them good fortune.  Interestingly, they are universally seen as protectors and not aggressors, creators not destroyers.

Sadly, as much as manta rays are widely admired to revered their existence is threatened in various ways.  Being pelagic, they cross 'borders' constantly and live in a warming ocean that is thereby struggling with habitat loss and teaming with industrialized fishing techniques that do not take care to avoid them (mantas are often 'bycatch' and can die due to suffocation as a result of entanglement.).  In some places mantas are specifically sought out for food and bait (for instance in the Sea of Cortez, Mexico) and in the western south Pacific mantas are harvested for their gill plates that are used in Asian Medicine.   It is worth noting that in Indonesia, Peru, and the Philippines there now national laws in place to protect manta rays.

Still, in order to protect animals, we need to understand them.  Efforts are being made to understand manta distribution, mating, and ecology better to help them.  However, Scientific efforts to understand Mantas formally began rather recently around 2008.

Satellite telemetry (tagging) has been used on dozens of marine species. This map highlights the diversity of species tagged in just one study; the Tagging of Pelagic Predators (TOPP) programme. Figure from Block et al., 2011.

According to Mantatrust.org  :

Manta rays often undertake seasonal migrations, travelling tens, hundreds, and sometimes thousands of kilometers. This means that their habitat can encompass large areas, sometimes crossing national boundaries, where conservation management is often more challenging. Therefore, to effectively protect these animals, we must first understand what habitats they are using, when they are there, and what they are doing within it. 

....It is often a sad fact of human nature that the more endangered a wild animal becomes, the greater our desire to possess or consume it. Diminishing stocks drive a lucrative trade (often illegal) to hunt down, trade in, and consume the dwindling populations of these endangered species.

Interestingly, again there is still so much mystery around mantas that citizen scientists are helping with these efforts.  People can communicate directly with the scientists at Manta Trust to help supply information (pictures) to create a 'mantabase' about specific manta individuals to share where they are and begin to help map their health, habitats, and seasonal routes.

If you are a mariner, look out for this incredible species of fish.  Maybe you can appreciate their majesty while unlocking some of their mystery.


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