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Marine Life & Conservation

Underwater ultrasound & first ever blood sampling on adult Whale Sharks

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Innovative techniques used on whale sharks in the Galapagos to find out more about their reproduction

Researchers in the Galapagos have successfully completed ultrasounds on free-swimming whale sharks, and taken blood samples from adult whale sharks for the first time ever in the wild. The incredible results allowed them to see and identify reproductive organs, such as the ovaries, and even developing follicles. These technologies hold promise for finally unlocking the mystery of breeding in the world’s largest sharks.

Photo Credit: GWSP (www.galapagoswhaleshark.org/) / Simon J Pierce’s (www.simonjpierce.com).

A team of global whale shark experts, comprised of scientists and conservationists from the Galapagos Whale Shark Project (Ecuador), Galapagos National Park (Ecuador), Okinawa Churashima Foundation (Japan), University of San Francisco/Galapagos Science Center (Ecuador) and the Marine Megafauna Foundation (USA), has just returned from a two-week expedition to Darwin Island, in the far north of the Galapagos Archipelago.

This remote volcanic island is one of the few places where huge adult female whale sharks, up to 14 m (45 ft) in length, are commonly seen each year. The main aim of the expedition was to assess the sharks’ reproductive state.

Photo Credit: GWSP (www.galapagoswhaleshark.org/) / Simon J Pierce’s (www.simonjpierce.com).

Jonathan R. Green, the expedition leader and founder of the Galapagos Whale Shark Project, notes: “Almost nothing is known about the reproduction of these giant sharks. After I first saw these huge female whale sharks in the far north Galapagos, I realised that this was a great opportunity to learn more. We’ve been able to put together an experienced team to research sharks in this remote area, one of the world’s most isolated dive sites.”

Dr Simon Pierce, an expedition member from the Marine Megafauna Foundation, explains further: “Whale shark breeding is a mystery. Only one pregnant shark has been physically examined so far, back in 1995 in Taiwan. That ‘megamamma’ shark had 304 little whale shark eggs and pups inside, all less than 60 cm in length.”

The team conducted scans using a 17 kg ultrasound system in a waterproofed case. Whale sharks have tough protective skin, more than 20 cm thick on some individuals, so the 30 cm penetration of the ultrasound waves proved a challenge – not to mention the difficulty of carefully checking the whole belly area of a gigantic shark while it is swimming. Dr Matsumoto had to use a propellor system mounted on his air-tank to keep up with the sharks.

Photo Credit: GWSP (www.galapagoswhaleshark.org/) / Simon J Pierce’s (www.simonjpierce.com).

We use some interesting technology anyway, but working with the Okinawa team was something else”, commented Dr Pierce. “I felt cool by association. We saw dive groups a couple of times at the site, and I can only imagine what they thought – why is that guy diving with a briefcase? And a jetpack?

Dr Matsumoto reports that the initial results were promising: “We confirmed the presence of follicles in the ovaries but none of the images captured embryos or egg capsules inside the uterus. These adult female sharks we saw at Darwin Island might be on their way to mate further offshore. I am confident that we can judge the sexual maturity, and probably also determine the pregnancy of whale sharks in the field, using the underwater ultrasound”.

The researchers attached satellite-linked tags to the sharks to track their onwards movements. Professor Alex Hearn from the University of San Francisco/Galapagos Science Center explains: “We’ve tagged whale sharks in Galapagos before, but there are lots of predatory sharks at Darwin and they often try to eat the tags, which can rip them out of the whale sharks almost immediately. To reduce early tag loss, we tried a different method on this trip, clamping the tags to the tip of the dorsal fins. All tags are transmitting well, so we should get great information on where these sharks swim over the months to come.”

Project member Dr Alistair Dove, from Georgia Aquarium, notes that these tags could document some amazing behaviours: “Whale sharks are already known to be the deepest-diving of all fish. The current depth record is 1,928 m – well over a mile – set by a juvenile whale shark. Larger, older animals can generally dive deeper than young smaller ones, so perhaps we will challenge that record.”

Kiyomi Murakumo, from Okinawa Churashima Foundation, successfully collected blood samples from six adult sharks – no easy job. Her colleague, Dr Ryo Nozu, analyzed the results immediately following the trip: “Sex steroid hormone levels in the blood are an excellent way to monitor reproduction in individual sharks. This study measured levels of estradiol, progesterone and testosterone of wild, adult female whale sharks for the first time in the world. Estradiol could be associated with follicular development, and progesterone could be involved in ovulation and pregnancy. Over time, as we sample more whale sharks, we can build up a complete picture of their reproductive cycle by combining the blood sampling with the ultrasonography.”

Jonathan R. Green added: “These big female sharks are not going to give up their secrets easily. One thing is clear: there’s a lot of work still to do to understand the reproductive processes of this endangered species. However, this trip proved that it is possible to research their breeding in the wild. We’ll continue to hone our techniques and build upon this knowledge, as we need to understand these enigmatic sharks and protect them through their life cycle.”

This project was supported by Galapagos Conservation Trust, Planeterra Foundation and Temperatio.

Photo Credit: GWSP page www.galapagoswhaleshark.org – and Simon J Pierce’s site – www.simonjpierce.com.

For more information about the Marine Megafauna Foundation please visit their website by clicking here.

Marine Life & Conservation

New report shows simple measures needed to cut beach plastic pollution

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The Marine Conservation Society has launched its annual State of our Beaches 2023 report, highlighting the need for less single-use plastic items and more refillable options.

The charity’s beach cleaning programme, now in its 30th year, asks volunteers to record all litter that they find within a 100-metre stretch of beach. By gathering vital data from across the UK and Channel Islands, the charity creates change for cleaner seas and a healthier planet through policy and industry change. Last year, over 148 kilometres of beach were surveyed by volunteers, who removed 17,208kgs of litter from our coast.

Using data collected by over 14,000 volunteers, the State of our Beaches 2023 report shows that half of all litter collected came from public sources – either dumped, blown or washed onto our beaches.

Drinks-related litter, such as plastic bottles, caps and cans were one of the most found items, with an average of 16 found per 100 metres of beach surveyed. This figure is up 14% compared to the charity’s 2022 report.

Plastics caps and lids were recorded on 89% of surveys, with over 30,000 found in total. Plastic bottles were also commonly collected, with 73% of surveys finding this single-use item – a 4% increase compared to 2022. The charity’s inland litter pick survey, Source to Sea, also reported finding plastic bottles on 92% of cleans.

However, the charity’s State of Our Beaches 2023 report also indicates that some types of litter are on a downward trend. Although still in the top 10 litter items, disposable plastic cutlery, trays and straws were found on 5% fewer beaches across the UK, showing that bans on these plastic items between 2022 – 2023 could be working. The presence of plastic cotton bud sticks also dropped by 14%.

Lizzie Price, Beachwatch Manager at the Marine Conservation Society, said, “Half of the litter found on our beaches originates from public sources, underscoring the pressing issue of single-use plastic. Evidence shows that refillable alternatives and litter return schemes effectively reduce rubbish, as demonstrated by the decline our data has shown in items like plastic bags and disposable cutlery.

“Urgent and decisive action from UK governments is needed to accelerate our shift towards a circular economy, where we reuse, repair and recycle. The public needs greater access to refillable products and systems need to be implemented in which manufacturers are responsible for their waste.”

Governments across the UK have committed to delivering deposit return schemes from October 2025. However, the proposed scheme in England does not include glass items, despite glass being found on 52% of beaches in 2023. The charity is calling for governments across the UK to introduce compatible all inclusive deposit return schemes as soon as possible. This would see aluminium cans, and plastic and glass bottles have a 20p deposit which would be returned when recycled which would reduce drinks-related pollution.

Businesses are, however, starting to take refillable and reusable options into their own hands. Supermarket chain, Aldi, the largest corporate funder of the charity’s 2024 Beachwatch programme, is already leading the charge in refillable items by trialling refillable options for cereals and porridge oats in their stores over the past 5 months.

Plastics and Packaging Director, Luke Emery, from Aldi, who are running 4 beach cleans for staff and volunteers in 2024, said, We are continually working to reduce single-use plastics and packaging, and making unpackaged product options more commonplace for our customers is a key part of this. We are really pleased with the uptake of our refillable range so far by customers. Not only are we making sustainable shopping more accessible, but we also offer refill products for a better price than the packaged alternative, helping our customers save money.”

Marine litter is one of the biggest threats to our seas, with plastic breaking down over time into microplastics and threatening marine life which can ingest or become entangled in them. The Marine Conservation Society is urging the UK Government to move faster on its policies to cut down plastic waste and prevent items from reaching our seas.

To find out more about the charity’s beach cleans and how to get involved, please visit mcsuk.org/beach-cleans

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Guarding Against Coral Invaders

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Protecting (Dutch) Caribbean Reefs from Unomia stolonifera

Recent reports highlight the concerning spread of the invasive soft coral, Unomia stolonifera, currently devastating Venezuela’s marine ecosystems and detected in Cuba. With the potential threat of its expansion to the (Dutch) Caribbean islands, urgent action and awareness are essential to safeguard marine biodiversity and local economies from possible catastrophic consequences.

Invasive species are animals or plants from another region of the world that don’t belong in their new environment. These species can have major ecological effects by decimating native flora or fauna. They can also cause large economic losses and impact human health. Invasive species also pose a significant threat to marine ecosystems worldwide, including the Dutch Caribbean. Among these invaders is the octocoral species Unomia stolonifera or “Pulsing Xenia”, originally from the Indo-Pacific. With its rapid growth and lack of natural predators, this species can outcompete native species and disrupt fragile marine habitats such as seagrass beds and coral reefs.

Background

The invasive soft coral U. stolonifera was first identified in 2014, off the coast of Venezuela. It is believed to have been introduced via the illegal aquarium trade.  Since this species can reproduce sexually and asexually (or fragment), even small pieces can regenerate to spread.  Once introduced it quickly took over shallow reefs and hard substrate at depths of 0-50 meters, outcompeting local corals and seagrass for space.  Follow on surveys found that this coral species exhibited average percentage cover as high as 80%, vastly outcompeting native corals. In highly colonized areas, fish are disappearing due to loss of habitats.

In 2022, during a survey conducted in Cuba by the University of Havana, an unknown octocoral was discovered which was later identified as the invasive Unomia stolonifera. It is suspected that the coral larvae arrived in ballast water from fossil fuel ships originating from Venezuela, as nearby sites adjacent to Venezuelan ports have been heavily affected by the invasion.

How to help

Prevention through continuous monitoring, particularly in high-risk areas such as marine harbors and oil facilities, is paramount. Early detection plays a pivotal role in mitigating the threat posed by Unomia stolonifera.

The public’s involvement and awareness are also vital. Local communities, recreational divers, tourists, and all stakeholders are urged to participate in early detection efforts by reporting sightings (photo, location and date) of this invasive coral to their respective Protected Area Management Organization (PMO’s)- the Fundacion Parke Nacional Aruba (FPNA)STINAPA BonaireCARMABI Curaçao Saba Conservation Foundation (SCF)Nature Foundation St. Maarten (NFSXM) and St. Eustatius National Parks (STENAPA). If an invaded area is confirmed, follow the recommendations by the local PMO’s.

Keys to Success

Despite the challenges, early detection is key to mitigating the threat posed by Unomia stolonifera. With continued vigilance, research, and community engagement, there is hope for containing this potential issue before it becomes a major threat.

About the DCNA

The Dutch Caribbean Nature Alliance (DCNA) supports (science) communication and outreach in the Dutch Caribbean region by making nature related (scientific) information more widely available through amongst others the Dutch Caribbean Biodiversity Database, DCNA’s news platform BioNews and through the press. This article contains the results from several scientific studies but the studies themselves are not DCNA studies. No rights can be derived from the content. DCNA is not liable for the content and the in(direct) impacts resulting from publishing this article.

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