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Microplastics on the menu of Manta Rays and Whale Sharks

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Plastics pollute Indonesian feeding grounds of plankton-feeding ocean giants…

Plastic pollution has a tremendous impact on marine life – and reef manta rays and whale sharks are not spared from it. These large filter-feeders swallow hundreds to thousands of cubic meters of plankton-filled water every day, and with it, tiny plastic pieces from broken down carrier bags and single-use packaging, a new study has found.

Marine biologists from the Marine Megafauna Foundation, Murdoch University (Australia) and Udayana University (Indonesia), estimated the amount of plastic particles present in the waters off Nusa Penida (Bali), Komodo National Park and East Java in Indonesia and, based on that, calculated how many pieces reef manta rays and whale sharks might be ingesting. These shark species sieve nutrient-rich water through their gills as they swim.

As manta rays and whale sharks spend a lot of time feeding in inshore surface waters where trash commonly aggregates, the researchers used a plankton net to trawl for plastics in the top 50 cm of the water column. They also counted any debris visible at the surface from the boat.

Elitza Germanov on boat – Marine Megafauna Foundation

Lead author Elitza Germanov, a researcher at the Marine Megafauna Foundation and PhD candidate at Murdoch University, said: “With time, plastics break down into smaller pieces called microplastics that large marine filter feeders might accidentally scoop up because they float among their prey.”

“Manta rays and whale sharks can ingest microplastics directly from polluted water or indirectly through the contaminated plankton they feed on,” she adds.

Plankton microplastics sampling – Marine Megafauna Foundation

The collaborative study, which is published today in the journal Frontiers in Marine Science, found that reef manta rays may ingest up to 63 pieces of plastic per hour of feeding in Nusa Penida and Komodo National Park. Whale sharks, which seasonally aggregate in Java, could be ingesting up to 137 pieces per hour.

Thin and bendable films from single-use bags and wrappers as well as hard fragments were the most prevalent plastics (over 50% combined). Of all plastic recorded, around 80% were small pieces of less than 5mm, so-called microplastics.

Manta ray poo and vomit also tested positive for plastics, which means that plastics are easily ingested when filter feeding and likely expose the animals to toxic chemicals and pollutants found in plastics while in their digestive system. These toxic substances can accumulate over decades and alter the hormones that regulate an animal’s metabolism, growth and development, and reproductive functions. Larger plastic particles can block nutrient absorption and cause damage to the digestive tract of animals.

Microplastics in manta poo (c) Elitza Germanov et al 2019

Neil Loneragan, Professor of Marine Ecology and Conservation at Murdoch University said: “It is difficult to assess how much plastic manta rays and whale sharks actually ingest because conventional methods used to study animal diets, such as stomach analysis, are unsuitable for threatened species like these.”

Manta rays and whale sharks are globally threatened species facing extreme pressures from overfishing. They are often caught incidentally in nets or become entangled in fishing lines.

Manta with plastic in Indonesia – Elitza Germanov, Marine Megafauna Foundation

Indonesia is currently ranked as the second worst plastic polluter in the world and many neighbouring countries within the Coral Triangle are among the top 10. This study found that plastic abundance was up to 44 times higher during the rainy season, with the largest seasonal effect observed in Nusa Penida.

Dr. I. Gede Hedrawan, an Indonesian plastics researcher from Bali’s Udayana University and an author on this study, said: “The seasonal variability in plastic pollution shows what a difference it would make to clean up river beds before the rainy season begins.” Local authorities could also prohibit any waste disposal in areas around water sources.

“We welcome Bali’s recent ban on single-use plastic bags, straws and take away containers, although the law is yet to reach its full effect and spread to smaller businesses,” he says.

Trash on beach Indonesia – Elitza Germanov, Marine Megafauna Foundation

It is vital to understand the effects of microplastic pollution on ocean giants since nearly half of the mobulid rays, two thirds of filter-feeding sharks and over one quarter of baleen whales are listed by the IUCN as globally threatened species and are prioritized for conservation. Previous studies found that baleen whales may swallow microplastic particles in the thousands every day.

“We now know that, through exposure to toxic substances, plastic contamination has the potential to further reduce the population numbers of these threatened animals because they reproduce slowly and have few offspring throughout their lives,” Germanov concluded.

As plastic production is projected to increase globally, future research should focus on coastal regions where pollution overlaps with the critical feeding and breeding grounds of these ocean giants. Many areas such as the Nusa Penida Marine Protected Area and Komodo National Park are biodiversity hotspots with significant marine tourism.

Trawling microplastic – Marine Megafauna Foundation

The field research was supported by the Ocean Park Conservation Foundation, PADI Foundation, Foundation FortUna, Mantahari Oceancare, Arenui Boutique Liveaboard, Current Junkies Liveaboard, Happy Days yacht, Scuba Junkie Komodo, and Wunderpus Liveaboard, and was carried out under a RisTek-Dikti (Indonesian Ministry of Research) permit. 

The study by Elitza Germanov et al., titled ‘Microplastics on the menu: Plastics pollute Indonesian manta ray and whale shark feeding grounds’ is published in the journal Frontiers in Marine Science on 19 November 2019 and is available here:  https://www.frontiersin.org/articles/10.3389/fmars.2019.00679/full


For further details, please see www.marinemegafauna.org or follow them on Twitter, Facebook and Instagram. For information about regional projects, follow the Marine Megafauna Foundation’s Southeast Asia Facebook page.

Marine Life & Conservation

Shark Trust launches Oceanic 31 Shark Art Auction

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After a two-year tour of UK art galleries, community spaces and aquariums, the Shark Trust’s acclaimed Oceanic31 exhibition takes its final bow at the Royal Geographical Society later this month. And the unique collection of artwork, depicting 31 species of oceanic sharks and rays, donated by 31 artists, is now open for bids from art lovers and shark enthusiasts. The online auction, launched today, will close on the 7th December at 8pm (BST). The money raised will support the Shark Trust Oceanics Programme.

People can now bid on 27 of the artworks by visiting this website:

https://superstars-auctions.com/sharktrustauction

It is a chance to own a beautiful piece of original art and to support the Shark Trust. The timing of the auction also means that these would make a very special Christmas gift for any shark-lover.

The diversity of pieces mirrors that of the sharks and rays they represent. You can bid on paintings, digital creations, sculptures, mixed media and more. You can pick your favourite artist or species of shark. Or you can select the perfect artwork to make a statement in your home or office. Whichever you choose, you will be supporting the work to protect these amazing animals.

One of the pieces of art has been selected to be auctioned live by Steve Backshall at the For the Love of Sharks event at the Royal Geographical Society in London on the 29th November. In addition to this, two further pieces will be raffled at this event, giving people a chance to win an incredible piece of shark art. For the Love of Sharks is the Shark Trust’s flagship evening. A night to celebrate sharks. Steve Backshall is the headline speaker at this event that will see other prominent shark advocates join him on stage.

Tickets for the event can be snapped up here:

https://thesharktrust.org.uk/Event/flos24

Those that would like to see the Oceanic 31 exhibition have one final chance. It is being displayed at the Pavilion at the Royal Geographic Society from 26th November until the 7th December. Entry is free.

Find out more here:

https://www.rgs.org/events/upcoming-events/oceanic-31

 Paul Cox, Shark Trust CEO, Said “This exhibition has given us the opportunity to reach out to a new audience. And inspire more people with the wonderful sharks and rays on which our Big Shark Pledge campaign is based. We are immensely grateful to the 31 artists who have worked so hard to create these works.”

Bid for your favourite Oceanic 31 artwork here:
https://superstars-auctions.com/sharktrustauction


Banner Image: Smooth Hammerhead by Alicia Hayden

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Gear News

Introducing the RS Series Drysuit from DYNAMICNORD

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drysuit

Cozy and warm in cold water.

It’s drysuit season all year round. With the new RS series premium drysuits from DYNAMICNORD, divers are perfectly equipped for all cold waters.

The sophisticated cut of the RS drysuits allows complete freedom of movement, providing maximum comfort. The high-quality 350 g/m² ripstop material with double ripstop zones on the elbows, knees, and crotch protect ensures extreme robustness as well as long life.

drysuit drysuit

The suit’s features leave nothing to be desired: A high-quality TiZip zipper, easily adjustable inlet and outlet valves, upgradeable with electrically heated underwear, HP bottleneck cuffs made of high-strength latex on the wrists, a 3mm neoprene neck cuff for maximum comfort, a 7mm hood with air outlet and 3mm boots made of double-sided, cross-layered neoprene with ankle straps and fin strap stoppers and a protective but very flexible sole.

drysuit

Noteworthy is the Molle fastening system, which can be used in a variable and compatible manner. This way, the two detachable leg pockets can be attached easily, safely and comfortably.

Alterations of boots to a different shoe size or adjustments to neck or wrist cuffs are done free of charge at the own DYNAMICNORD service centre in Germany in only a couple of days.

The matching Dynaskins made with high-quality Polartec® technology are available in various designs. As an undersuit under the drysuit, as a single suit in warm waters or as a two-piece suit. Polartec® technology’s main features are neutral buoyancy, breathablilty and quick-drying.

drysuit

Dynaskins are made largely from recycled plastic bottles.

The drysuit RS-351 for men and RS-352 for women are now available at your DYNAMICNORD dealer and in the online store.

Colors men and women: Black-Blue and Black-Burgundy

Sizes men: XS-4XL incl. intermediate sizes MS, MT, MLS, MLT, LS, LT, XLS, XLT, 2XLS, 3XLS, 4XLS

Sizes Women: XS-XL incl. intermediate sizes MS, MT, LS, XLS

DYNAMICNORD – Your Outdoor Companion.

www.dynamicnord.com

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