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MMF study shows manta rays form social bonds

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Manta rays form social relationships and actively choose their social partners, a new study has revealed. Research published today by scientists from the Marine Megafauna Foundation, Macquarie University, the University of Papua, and the University of York is the first to describe the structure of social relationships in manta rays.

Sharks and rays are often thought to be solitary creatures, but reef manta rays typically form groups at shallow-water feeding and cleaning sites. The researchers studied the structure of more than 500 of these groups over five years, in Indonesia’s Raja Ampat Marine Park, one of the most biodiverse marine habitats on Earth. They found two distinct but connected communities of rays living together. These social communities were quite differently structured, one being made up of mostly mature female rays, and the other a mix of males, females and juveniles.

Two groups social reef mantas from high up © Rob Perryman

We still understand very little of how mantas live their lives, but we know they are socially interactive, and these interactions seem important to the structure of their populations. Understanding social relationships can help predict manta ray movements, mating patterns and responses to human impacts. That’s essential for conservation and ecotourism efforts,” said lead author Rob Perryman, a researcher for Marine Megafauna Foundation and PhD student at Macquarie University.

The study, published in the journal Behavioral Ecology and Sociobiology used social network analysis to show that manta ray communities contain a web of many weak acquaintances, with some stronger, longer-lasting relationships. Though they do not live in tight-knit social groups, the team noticed that female mantas tend to make long-term bonds with other females, while males did not have many strong connections. This could be due to different reproductive strategies or dispersal patterns.

Like dolphins, manta rays are intelligent and perform collective behaviors such as foraging and playing. They are curious, often approaching humans, and individuals appear to have different personalities. It turns out that reef manta rays actively choose to group with preferred social partners,” Perryman added.

To identify social structures, the researchers took identification photos of all rays present in each group, and monitored whether individuals were more likely to be seen together (at different times and in different locations) than expected if encounters were random.

The locations used by the rays seemed to be important to their social relations. Manta rays form groups at cleaning stations where they are attended to by cleaner wrasse and other small fish. The team observed that certain social groups were regularly seen together at these sites, and so may be using them as social meeting points. Some rays had very strong affinity to certain cleaning stations. The researchers were surprised to find this given the close proximity of all sites and that mantas are generally mobile and wide-ranging animals. They concluded that the rays left and returned to preferred sites where they formed groups through a ‘fission-fusion’ social process.

Like many sharks and rays, manta rays are internationally threatened animals and population declines have been reported in various locations worldwide. They are hunted for their valuable gill plates used in traditional Chinese medicine. Other anthropogenic threats include injuries or entanglement in discarded nets and lines, pollution and habitat destruction.

© Rob Perryman

It is important to find the right balance between preserving a species and encouraging sustainable wildlife viewing that brings economic benefits. “Knowing how mantas interact is important, particularly in areas where they are susceptible to increasing dive tourism,” said Dr Andrea Marshall, co-founder and principal scientist at the Marine Megafauna Foundation. “The increasing number of boats and scuba divers around reef mantas in Raja Ampat, particularly at cleaning stations, could break apart their social structures and have impacts on their reproduction.”

Dr. Ricardo F. Tapilatu, a co-author working at the University of Papua and the main Indonesian counterpart for the project said: “Pristine marine environments such as the manta ray aggregation sites in Raja Ampat are of increasing interest to tourists. This collaborative research is set in the extremely biodiverse region of the Coral Triangle, located in the Indo-Pacific, where we set up science-based conservation management for such unique natural systems.”

In Indonesia, manta rays are protected since 2014 but artisanal fishing remains an issue, and there is still little awareness of the threats they face. The team hopes that showing the social nature of manta rays will help broaden support and public enthusiasm for their protection around the world.

“Collecting more information about their social relationships and structures will be needed to develop sustainable ecotourism and conservation initiatives that allow mantas to coexist with humans in their natural habitats,” concluded Perryman.

This research was supported by Papua Explorers Dive Resort, Raja Ampat SEA Centre, University of Papua and Barefoot Conservation, and carried out under a RisTek-Dikti permit.

The study by Rob Perryman et al, titled ‘Social preferences and network structure in a population of reef manta rays’ is published in the journal Behavioral Ecology and Sociobiology on 22 August 2019 and will be available here.

To find out more about the Marine Megafauna Foundation visit their website by clicking here.

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Scubaverse UWP Winners Gallery: Christian Horras

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Each month we give the winner of the Scubaverse Underwater Photography competition the opportunity to show off a little more of their work in a gallery. The March winner was Christian Horras and you can see their winning image at the top of this page.


What do you love about diving & underwater photography?

For me it is all about showing the beauty of our world underwater to people that don’t dive and thus can’t see it for themselves. I want to share my own passion for the amazing ecosystem that is so much older than everything we know living on land. As I am from Germany, there are only a few people in my surroundings that have ever seen a coral reef or a shark with their own eyes. It is a big privilege to be able to go diving all over the world and in return it should be our task to arise awareness of this fragile and endangered ecosystem.

What equipment do you use?

I use a Nikon D810 in a Isotta Housing and various lenses, depending on the subject: a Sigma 15mm F2.8 Fisheye, a Nikon 16-35 mm F4 and two Nikon Macro lenses (60mm and 105mm), as well as a WeeFine +13 Diopter. The Fisheye is my main lens, as it allows me to get really close and still cover a big field of view. For lighting I use two Retra Pro Strobes and a Retra Snoot.

Where can our readers see more of your work?

Website: www.christianhorras.com
Instagram: www.instagram.com/christian.horras/


To enter the latest Scubaverse Underwater Photography competition, with a chance to win some great prizes as well as have your own gallery published, head over to the competition page and upload up to 3 images.

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Emperor Divers reaches halfway in Covid Diver Heroes Initiative with fourth award

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Emperor Divers have reached the halfway point with their #coviddiverheroes initiative and are still receiving worthy nominations every day! Here, they recognise their 4th winner, another awesome hero from the diving community with an inspirational story of selflessness through the pandemic. Nominated by David White, Phuong Cao wins a free liveaboard trip in the Maldives when she can finally take some time off, and here is her story:

I, David White, would like to nominate Phuong Cao (36) for her tireless efforts fighting this pandemic. Not satisfied with being a frontline hospitalist in New York she took a second job on the COVID team in Guam to treat patients under even tougher conditions on her weeks off! She continues to commute 7750 miles each way and apply herself to both jobs for three months already and counting. Her energy level has no limits and she’s only happy when those in her care are on the mend. I think she definitely deserves a break! I guess the Maldives would be the best choice for her as I know she has dived with you in the Red Sea already.

Phuong Cao

We have been in touch with Phuong who had this to say: “Wow what a surprise! Thank you for the recognition. Holding my breath until I get back underwater!”

The halfway point is a good chance to remind people that the initiative is still running and the Emperor Divers team would love to hear about more heroes, as there are four more to award in the next 2 months!

Do you know a diver who has been heroic this past year? Emperor know that, worldwide, people have had to step up during this pandemic which has affected so many lives. They want to reward some real heroes with free liveaboard trips in the Red Sea or Maldives.

Luke Atkinson, Emperor’s Red Sea Manager, said: “This initiative is our way of saying ‘thank you’ to all those hundreds of people who have taken a selfless interest in looking after the vulnerable in their community. Examples could include healthworkers, carers or those who have come out of retirement to volunteer locally, but really we know there are many other ways people have been heroic.“

Emperor want to hear from people who know a heroic diver who would love to have a free liveaboard trip to look forward to in the future. People need to nominate a Covid Hero Diver and tell Emperor (in 100 – 200 words) why they deserve a free trip, and whether they would prefer the Red Sea or the Maldives. A multinational panel of Emperor’s most loyal and compassionate staff will judge the entries and pick a winner every 2 weeks for the next 2 months. There are two remaining Red Sea and two more Maldives liveaboards to be earned, so get nominating and give that hero a reward for their amazing work!

Winners will be announced by 14th (Maldives) and 28th (Red Sea) of each month. Final entries for Red Sea by 20th May ‘21 and Maldives 5th June ’21.

Entries, comments and questions should be sent to heroes@emperordivers.com.

Terms & Conditions apply: Please contact heroes@emperordivers.com for details.

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