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Giant manta rays found to be predators of the deep ocean

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A new scientific study by the Marine Megafauna Foundation (MMF), the University of Queensland (UQ) and Proyecto Mantas Ecuador has been published in Royal Society Open Science today, providing novel insights into the food sources of giant manta rays found in the eastern equatorial Pacific.

The giant manta ray (Manta birostris) is a filter-feeding and highly migratory marine species found in tropical and temperate waters worldwide. The large majority of existing information about the species’ diet is based on observational data limited to feeding activities at the sea surface during daylight at well-known aggregation sites.

This new study focused on Isla de la Plata, an island off Ecuador, which seasonally hosts the largest known aggregation of giant manta rays in the world. Manta ray muscle and surface zooplankton were examined through stable isotope analysis, and revealed that the species’ dietary intake largely comes from the mesopelagic zone (200 to 1,000 meters below the ocean surface) rather than from surface zooplankton as previously thought.

MMF’s manta ray researcher Katherine Burgess, who authored this study as part of her PhD project at the University of Queensland, commented: “Manta rays are one of the most iconic marine animals, yet we still know very little about their feeding habits. The study reports much-needed information on the diet of this elusive species.”

katherine-burgess-taking-a-tissue-sample-of-a-giant-manta-ray-in-ecuador-copyright-andrea-marshall

Katherine Burgess taking a tissue sample of a giant manta ray in Ecuador. Copyright: Andrea Marshall

“We studied the giant manta rays’ diet using biochemical tests, such as stable isotope analysis, which work on the ‘you are what you eat’ paradigm. These tests can determine what animals have been eating by examining a piece of tissue from a muscle biopsy from a free-swimming animal,” she added.

Professor Anthony Richardson, a scientist with UQ’s School of Mathematics and Physics and the CSIRO’s Oceans and Atmosphere Flagship, said: “The research found an average 27 per cent of the giant manta rays’ diet comes from surface zooplankton and 73 per cent from mesopelagic sources including fish from 200m to 1,000m below the ocean surface.”

“The deep ocean is the next frontier for open ocean fisheries, and we are only just realizing the potential reliance on this zone by threatened marine megafauna,” he added.

Giant mantas are known to dive to depths of over 1,000 meters making it difficult to study their feeding ecology. To determine the diet of a fish, researchers normally examine its stomach contents. However, this is usually a distressing or lethal procedure and would not be appropriate considering global manta ray populations have been in drastic decline due to anthropogenic threats such as targeted fishing or bycatch, pollution and habitat destruction.

Both species of Manta – the giant manta ray (Manta birostris) and reef manta ray (Manta alfredi) – are listed as ‘vulnerable to extinction’ on the IUCN Red List of Threatened Species. To date, manta rays are formally protected in Ecuador, Peru, New Zealand, the USA (Florida, Hawaii and Flower Garden Banks), Guam, Maldives, Yap, Indonesia, the Philippines and Mexico only. Filling the knowledge gaps on manta ray feeding ecology is crucial for the identification of critical habitats and aggregation sites, which are vital for developing effective conservation measures for these species.

marinemegafauna.org

science.uq.edu.au

mantasecuador.org

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Introducing the all-new PADI Dive Guides: connecting divers worldwide with local expertise

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The new PADI Dive Guides™ make it easier than ever for divers to discover, explore and plan their next adventure by providing the tools needed to research and book dive experiences or training anywhere in the world. PADI Dive Guides are the go-to resource whether planning a local dive or seeking inspiration and information about far-off destinations.

“Dive destination information has been integral to padi.com for years,” says Lisa Nicklin, Vice President of Consumer Marketing for PADI Worldwide. “This next evolution provides more detailed guides that will continue to grow in global coverage and bring unprecedented value to PADI Members and divers alike. Leveraging new system capabilities, the guides combine PADI’s global expertise with the immense local knowledge of PADI Members around the world. PADI Dive Guides enable divers to plan and book adventures near home or wherever their future travels may take them – all through one convenient platform.” 

Image: Al Hornsby

Now available at padi.com/exploration, the collection of thousands of guides offers marine life calendars, seasonal weather data and travel information. Users can learn about dive opportunities by continent and country, or drill down to specific dive destinations and dive sites. They will find a mosaic of dive sites to explore in each location with insight provided by local experts, as well as dive site reviews from fellow explorers. Users can easily contact PADI operators and book dives, snorkel excursions, holidays and courses through the integrated PADI Adventures™ platform.

Start exploring and planning your next adventure at padi.com/exploration.

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Why Every Diver Should Be A Rescue Diver (Watch Video)

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Why Every Diver Should Be A Rescue Diver! I’ve got three reasons why every diver should take a Rescue Diver course. The world would be a better place!

Rescue Diver is mine – and a lot of my Instructor buddies’ – favorite course to teach. A well-run Rescue Diver course should be heavily practical and feature realistic scenarios. It expands your vision to include situational awareness and give you the knowledge and skills to react should an accident occur.

Think resuscitation is hard on land? Wait until you’re given rescue breaths in water whilst towing the victim! It’s a fantastic confidence booster, especially for divers who are more naturally anxious or nervous.

Thanks for watching! D.S.D.O James


Subscribe here: http://bit.ly/DiversReady

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Explore the amazing triangle of Red Sea Reefs - The Brothers, Daedalus and Elphinstone on board the brand new liveaboard Big Blue.  With an option to add on a week at Roots Red Sea before or after. 

Strong currents and deep blue water are the catalysts that bring the pelagic species flocking to these reefs. The reefs themselves provide exquisite homes for a multitude of marine life.  The wafting soft corals are adorned with thousands of colourful fish. The gorgonian fans and hard corals provide magnificent back drops, all being patrolled by the reef’s predatory species.

£1475 per person based on double occupancy.  Soft all inclusive board basis, buffet meals with snacks, tea and coffee always available.  Add a week on at Roots Red Sea Resort before or after the liveaboard for just £725pp.  Flights and transfers are included.  See our brochure linked above for the full itinerary.

This trip will be hosted by The Scuba Place.  Come Dive with Us!

Call 020 3515 9955 or email john@thescubaplace.co.uk

www.thescubaplace.co.uk

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