Hexbyte Glen Cove A decade of deep-reef exploration in the Greater Caribbean

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Research submersibles permit long-duration dives at any depth with panoramic views of underexplored ecosystems. They are also equipped with devices to collect fishes during those dives. Credit: D. Ross Robertson, Smithsonian Tropical Research Institute

The mysteries of underwater life have long been a source of inspiration for writers, filmmakers, and marine biologists. But scientists interested in understanding the biological diversity of the oceans are often limited by the relatively shallow depths accessible via scuba diving. Small research submersibles, while expensive, allow for the exploration of much deeper waters. A new paper co-authored by researchers at the Smithsonian’s Tropical Research Institute (STRI) and National Museum of Natural History (NMNH), the University of Washington and the Universidad Nacional Autónoma de Honduras describes the important contribution of submersibles to increasing our knowledge about the diversity of deep-reef fishes in the Greater Caribbean.

In 2010, Smithsonian scientists initiated the Deep Reef Observation Project or DROP to explore the ocean surrounding the Caribbean islands of Curacao, Bonaire, Dominica, Sint Eustatius (Statia) and Roatan using two privately-owned small submersibles, Curasub and Idabel. These submersibles can dive to 300 and 900 meters, respectively, about two to six times deeper than a technical scuba dive, and they can stay at maximum depth for much longer than can technical divers relying on tanks of gas mixtures they carry with them.

The new article in Frontiers in Marine Science reveals that, due to DROP research at three sites in the Greater Caribbean (Curacao, Statia, Roatan), the numbers of deep-reef fishes recorded increased about 9-fold and the total numbers of such fishes are two to four times greater than at three sites with little or no similar research effort: Alligator Reef in the Florida Keys, Bermuda and St. Croix.

“DROP research produced two important results: it showed that reef-fish faunas dominated by families of typical shallow water reef fishes extend down far below the mesophotic zone—to about 300 meters—and that the diversity of the deep-reef fish fauna of the Greater Caribbean biogeographic region is at least one third greater than had previously been realized,” said D. Ross Robertson, STRI staff scientist. “These results derive from our collections of such fish using the submersibles, mostly at Curacao and Roatan.”

Although the rate of discovery of new deep-reef fish species began increasing after the advent of scuba, it grew dramatically with the use of research submersibles, as they permit longer-duration dives at any depth with panoramic views of underexplored ecosystems, and are equipped with devices to collect fishes during those dives.

“When DROP first started exploring Caribbean deep reefs using submersibles, we saw a lot of fish species we didn’t recognize,” said Carole Baldwin, chair of vertebrate zoology at the NMNH. “Now, after nearly a decade of submersible collecting at places like Curacao, we can identify almost everything we see from the windows of the sub, much of which we collected, named, and described as new species.”

The use of research submersibles has revealed that the deep-reef fish fauna of the Greater Caribbean region is at least one third greater than had previously been realized. Credit: D. Ross Robertson (Smithsonian Tropical Research Institute) Carole Baldwin (National Museum of Natural History) Luke Tornabene (University of Washington) and Barry Brown (Substation Curacao)

However, such submersible research is at the expensive end of the range of options. Depending on whether or not it is supported by a research vessel, a week-long expedition using submersibles could cost between $30,000 and $200,000. In comparison, similar research using a small industrial ROV (remotely operated vehicle) working to 300 meters and operated from a small fishing vessel would cost around $40,000 for one week’s research.

Baited remote underwater videos (BRUVs) are the cheapest technology and can be used at sites wherever there is boat support. However, since they rely on baits, they tend to attract certain fishes over others and may not gather the same kind of data as other methods.

Closed-Circuit Rebreathers (CCR) are a less expensive option. They allow dives with minimal boat support and, because divers are highly maneuverable, likely are more effective than submersibles at collecting rapidly moving demersal fishes. However, they are limited by human physiology to dives shallower than about 150 meters and require extended periods of decompression after short deep dives.

Differences in deep-reef fishes discovered at different islands ultimately suggest that many parts of the Greater Caribbean likely harbor a myriad of deep-reef fishes waiting to be discovered, a process that could be accelerated by increasing the use of research submersibles, perhaps in combination with other less costly underwater exploration methods.

Funding for the DROP project comes from internal sources at the Smithsonian, from the National Geographic Society’s committee for research and exploration and the Prince Albert II of Monaco Foundation. Fieldwork at Roatan was conducted using additional funds from the University of Washington and the Burke Museum.

Since 2011, the DROP project has published 45 peer-reviewed papers, with more planned. Those include descriptions of 7 new genera and 35 new species of deep-reef fishes, mollusks, crustaceans and echinoderms, with another approximately 10 fish species still to be named and described. DROP discovered and described a new reef ocean zone, the rariphotic, which connects the mesophotic and deep sea. It also acquired almost ten years of temperature data along a reef slope from 15 to 245 meters, documented the first record of invasive Caribbean lionfish preying on previously unknown biodiversity, acquired foundational data on cryptic reef biodiversity at various depths down a tropical-reef slope and developed protocols and methods for deployment and retrieval of collecting devices placed on deep reefs, using robotic arms of ROV/submersibles.



More information:
D. Ross Robertson et al, Submersibles Greatly Enhance Research on the Diversity of Deep-Reef Fishes in the Greater Caribbean, Frontiers in Marine Science (2022). DOI: 10.3389/fmars.2021.800250

Citation:
A decade of deep-reef exploration in the Greater Caribbean (2022, March 4)
retrieved 7 March 2022
from https://phys.org/news/2022-03-decade-deep-reef-exploration-greater-caribbean.html

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Hexbyte Glen Cove Decade after Fukushima, Japan towns struggle to rebuild community thumbnail

Hexbyte Glen Cove Decade after Fukushima, Japan towns struggle to rebuild community

Hexbyte Glen Cove

Masakazu Daibo returned to his hometown in Fukushima just last year to reopen a restaurant established by his grandfather

Masakazu Daibo has reopened his family’s eel restaurant in part of Japan declared a no-go zone after the 2011 nuclear disaster, but so far he has barely a single neighbour.

A decade after radiation forced tens of thousands to flee their homes in Fukushima, some towns in the region are still wrestling with the difficult question of how to rebuild a community from scratch.

After the disaster, 12 percent of Fukushima prefecture was off-limits and around 165,000 people fled their homes either under evacuation orders or voluntarily.

Numerous areas have since been declared safe after extensive decontamination, and incentives are being offered to lure people back. But many are reluctant.

Daibo returned just last year, reopening a restaurant established by his grandfather in the town of Namie, around nine kilometres (5.6 miles) from the .

Namie and 11 neighbouring communities were part of an exclusion zone around the plant, and for years Daibo could enter only on brief visits.

“There were no people but the town remained. It was really like a movie set,” the 65-year-old told AFP.

“I heard no human voices, and saw only wild dogs, cows, pigs.”

The radiation that blanketed the region forced him to discard everything in the restaurant.

Some towns in Fukushima are still wrestling with the difficult question of how to rebuild a community from scratch

Contaminated parts of the walls were removed and he lost everything inside, down to the sauce that had been kept cooking since his grandfather opened the business.

Daibo and his wife hesitated about moving back, but after restrictions were lifted in 2017, they decided they would try to revive the past.

“I want everyone to say ‘Oh, this is a long-forgotten flavour,'” when they taste his food, Daibo said.

“I hope that my presence will shine a light on this town.”

‘Survival is our big issue’

But few others have followed suit.

The restaurant is surrounded by empty lots overgrown with weeds. Wooden signboards are piled up next to a toppled bin in the porch of one abandoned building, in what was once downtown.

Restrictions have been lifted on just 20 percent of Namie, and the town’s population is seven percent its former size of 21,000, despite incentives including reduced rents and money for moving and renovation.

Daibo and his wife hesitated about moving back, but after restrictions were lifted in 2017, they decided they would try to revive the past

Around 36 percent of residents are aged 65 or above, higher than the 29 percent national average, and just 30 students attend local elementary and junior-high schools, compared with nearly 1,800 before.

Japan as a whole is battling low birthrates and an ageing population, but the issue is in stark relief in Namie.

“We feel like the future of 20 years from now has arrived suddenly,” said town official Takanori Matsumoto.

Namie hopes to raise its population to 8,000 by 2035, helped by national subsidies of up to two million yen ($18,500) per new family moving to disaster-hit areas.

“Survival as a community is our big issue,” Matsumoto said.

Just over two percent of Fukushima remains under evacuation orders, with the figure for evacuees officially at around 35,700, though some experts believe there could be nearly twice as many.

But there is no deadline for lifting all the evacuation orders, and doubts persist that Fukushima Daichii can be decommissioned on schedule by 2041 at the earliest.

Namie and 11 neighbouring communities were part of an exclusion zone around the Fukushima Daiichi nuclear plant

‘I can’t go back’

For many, fears over lingering radiation and mistrust of the government’s decontamination process are major obstacles to returning.

“It’s not like I won’t go back. It’s more like I can’t go back,” said Megumi Okada, who was pregnant with her third child at the time of the disaster and left despite being outside the official evacuation zone.

“If I were alone, I would go home,” added the 38-year-old, now a mother of four living in Tokyo.

“But as a mother, I strongly feel that I want to avoid risks for my children.”

Around two-thirds of Fukushima evacuees don’t plan to return, according to a 2020 survey by researchers at Kwansei Gakuin University.

“Many people say they can’t trust the decommissioning target, and their distrust of government measures runs deep,” said Yoko Saito, an associate professor on disaster reduction who jointly conducted the survey.

For Megumi Okada and many others, fears over lingering radiation is a major obstacle to returning

The rate of return to reopened areas varies considerably.

In Kawauchi, which lifted its last evacuation order in 2016, the population is now 68 percent of its pre-2011 figure.

It’s a different story in Futaba, which jointly hosts the crippled plant.

A tiny portion of the town was declared open last year—but not a single person has returned.

All roads into the restricted zone are blocked by barricades, and those entering must wear plastic suits and cover their hair and shoes. Radiation levels on their bodies are measured when they leave.

Crumbling buildings, untended because of radiation, dot the region.

At a ruined inn, an antique clock sits stopped, and fallen teacups litter shelves in a nearby giftshop.

‘A little sad and lonely’

For many in reopened areas, returning has brought conflicting feelings.

Around two-thirds of Fukushima evacuees don’t plan to return, according to researchers

Takao Kohata went back to Minamisoma after authorities lifted restrictions but is still haunted by radiation fears.

Government officials tout strict screening of food in the region, but “many people are still nervous,” the 83-year-old said.

The parents of his four grandchildren won’t let them visit, because they worry about radiation.

“I fully understand their concerns, but I feel a little sad and lonely,” he said.

Some evacuees say they feel forced to return as the government winds up support for the displaced.

“In the end, those who have no place to go and have low incomes are the ones left behind,” said Shohei Yamane, a psychiatric social worker supporting evacuees.

“This disaster will never end as long as there are needy evacuees seeking help,” he added.

Some who have returned have found it takes more than reconstruction to rebuild a community.

Yuko Hikichi helps organise gatherings and group exercise sessions to strengthen community ties in Namie.

“We are just at the starting line… Community-building is not an easy job. It is endless,” she said.

It’s a struggle Masaru Kumakawa knows all too well.

He returned to Namie three years ago, despite losing his wife there in the tsunami, and now lives alone in a new housing district.

The 83-year-old heads a community association, but has struggled to make contact with his neighbours.

“They lived in evacuation for too long,” he said at a newly built community centre.

“We ring doorbells but no one comes out.”



© 2021 AFP

Citation:
Decade after Fukushima, Japan towns struggle to rebuild community (2021, March 9)
retrieved 9 March 2021
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