Marine Life & Conservation
Giant manta rays found to be predators of the deep ocean
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
“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.
The Ocean Cleanup, the global non-profit project, has removed a verified all-time total of ten million kilograms (22 million lbs.) of trash from oceans and rivers around the world – approximately the same weight as the Eiffel Tower.
To complete its mission of ridding the oceans of plastic, The Ocean Cleanup uses a dual strategy: cleaning up the Great Pacific Garbage Patch (GPGP) to remove the plastic already afloat in the oceans, while stopping the flow of plastic from the world’s most polluting rivers.
Through cleaning operations in the GPGP and in rivers in eight countries, the cumulative total of trash removed has now surpassed ten million kilograms. This milestone demonstrates the acceleration of The Ocean Cleanup’s impact, while underlining the astonishing scale of the plastic pollution problem and the need for continued support and action.
While encouraging for the mission, this milestone is only a staging point: millions more tons of plastic still pollute our oceans and The Ocean Cleanup intends to continue learning, improving and innovating to solve this global catastrophe.
This announcement comes as governments from around the world meet to continue negotiations to develop a new legally binding instrument to end plastic pollution at INC4 in Ottawa, Canada. Representatives of The Ocean Cleanup will be in attendance and the organization will be urging decision-makers to collaborate towards a comprehensive and ambitious global treaty which addresses plastic at all stages of its life cycle and in all marine environments worldwide, including in areas beyond national jurisdiction.
It is encouraging to see that the need for remediation is reflected in the various options for potential treaty provisions. It is essential that the final treaty contains clear targets for the remediation of legacy plastic pollution, and reduction of riverine plastic emissions.
Tackling plastic pollution requires innovative and impactful solutions. The treaty should therefore incentivize the innovation ecosystem by fostering innovations that make maximal use of data, technology and scientific knowledge – such as those designed and deployed by The Ocean Cleanup.
‘After many tough years of trial and error, it’s amazing to see our work is starting to pay off – and I am proud of the team who has brought us to this point.’ said Boyan Slat, Founder and CEO of The Ocean Cleanup. ‘While we still have a long way to go, our recent successes fill us with renewed confidence that the oceans can be cleaned.’
The Ocean Cleanup was founded in 2013 and captured its first plastic in 2019, with the first confirmed catch in the GPGP coming soon after the deployment of Interceptor 001 in Jakarta, Indonesia. After surpassing one million kilograms of trash removed in early 2022, the non-profit project has since progressed to the third iteration of its GPGP cleaning solution, known as System 03, and a network of Interceptors currently covering rivers in eight countries, with more deployments set for 2024.
About The Ocean Cleanup
The Ocean Cleanup is an international non-profit organization that develops and scales technologies to rid the world’s oceans of plastic. They aim to achieve this goal through a dual strategy: stemming the inflow via rivers and cleaning up the legacy plastic that has already accumulated in the ocean. For the latter, The Ocean Cleanup develops large-scale systems to efficiently concentrate the plastic for periodic removal. This plastic is tracked and traced through DNV’s chain of custody model to certify claims of origin when recycling it into new products. To curb the tide via rivers, The Ocean Cleanup has developed Interceptor™ solutions to halt and extract riverine plastic before it reaches the ocean. Founded in 2013 by Boyan Slat, The Ocean Cleanup now employs a broadly multi-disciplined team of approximately 140. The foundation is headquartered in Rotterdam, the Netherlands.
For more information, visit: theoceancleanup.com and follow @theoceancleanup on social media.
Marine Life & Conservation
Steve Backshall to headline Shark Trust’s flagship event: For the Love of Sharks
Join a host of amazing, shark loving, speakers including Steve Backshall and the Shark Trust team for an evening celebrating shark conservation at the Royal Geographical Society in London this November.
Date: 29th November 2024
Time: 6-10pm
Location: Royal Geographical Society, London
Tickets: https://www.sharktrust.org/Event/flos24
The event will be a celebration of all things shark. Those lucky enough to get hold of tickets will hear from engaging guest speakers with a passion for sharks.
The line-up includes (*subject to change if unforeseen circumstances arise)
Steve Backshall: One of television’s busiest presenters, BAFTA award-winning wildlife expert Steve has been passionate about the wild world ever since he was young.
Steve’s impressive TV career has taken him all around the world, investigating a wide array of species and environments. Steve has filmed over 100 hours of children’s wildlife programmes with the BAFTA award winning Deadly 60 franchise and recently, with Sky Nature, for his new series ‘Whale with Steve Backshall’. He has been a patron for the Shark Trust for 10 years.
Simon Rogerson: is a photojournalist specialising in natural history, diving and the sea.
He is editor of SCUBA magazine, the official journal of the British Sub-Aqua Club. Simon started his career as a crime reporter but gravitated towards his ‘less depressing’ interest in underwater exploration, joining the staff of DIVE magazine in 1999. In 2005 he was named ‘Editor of the Year’ in the PPA’s Independent Publishing Awards. Simon also works as a freelance writer, contributing frequently to the Sunday Times and Telegraph, in addition to BBC Wildlife, Esquire, and a host of international diving magazines. He is the author of a book, Dive Red Sea, published by Ultimate Sports. Now based in Berkshire, Simon has been a Patron of the Shark Trust for 20 years.
More speakers to be announced soon. Head to the Shark Trust website to learn more.
The evening will also allow guests the final chance to see the Oceanic 31, shark art exhibition. Some of the artwork will be auctioned/raffled at the event, while the rest will be auctioned online to raise money for the Shark Trust Oceanic Programme.
For the Love of Sharks is an evening with something for everyone who is interested and fascinated by sharks. Join the Shark Trust, their Patrons, Trustees and Staff, along with a host of supporters for this celebration of shark conservation.
For more information or to buy a ticket: https://www.sharktrust.org/Event/flos24
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