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Marine Life & Conservation

Silent Reef Keepers: The Fight to Save the Caribbean Reef Shark

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Caribbean Reef Shark

The Kingdom of the Netherlands will ask for increased protection for the Caribbean reef shark during next month’s Conference of Parties for the Cartagena Convention (COPs) on Aruba.  Caribbean reef sharks play a critical role in maintaining a healthy reef ecosystem and building resilience within the oceans. This increased protection is critical for ensuring a sustainable future for this iconic species.

The Caribbean Sea is renowned for its crystal-clear waters, vibrant coral reefs, and a dazzling array of marine life. Among the charismatic inhabitants of this underwater paradise is the Caribbean Reef Shark (Carcharhinus perezii), a species that plays a crucial role in maintaining the health of coral reef ecosystems. In the Dutch Caribbean, these apex predators face mounting threats, but there is hope on the horizon. At the upcoming Conference of Parties for the Cartagena Convention (COPs), the Kingdom of the Netherlands will seek increased protection for these magnificent creatures by listing this species on Annex III of the SPAW Protocol.  Annex III includes plant and animal species which require additional protection to ensure this species is able to adequately recover their populations in the Wider Caribbean Region.

Importance

Caribbean reef sharks thrive in warm, tropical waters of the Caribbean region, with a distribution range that stretches from Florida to Brazil. This species is one of the most encountered reef shark species throughout the whole Caribbean Sea.  Growing up to 3m (9.8ft) in length, this shark is one of the largest apex predators in the reef ecosystem and is at the top of the marine food web, having only a few natural predators. 

In addition to being of great economic value, as shark diving is a major draw for divers from around the world, this species is also critical for maintaining balance within the reef ecosystem. Their presence helps regulate the population of smaller prey species, which in turn, prevents overgrazing on seagrass beds and coral reefs and eliminates sick or weak fish from the population. This balance is essential for maintaining the health and diversity of the entire coral reef.

Threats

Despite their ecological and economic significance, Caribbean reef sharks in the Caribbean face numerous threats that have led to a population reduction estimated to be between 50–79% over the past 29 years. In the (Dutch) Caribbean this is mainly caused by:

Habitat Degradation: The degradation of coral reefs and seagrass beds due to climate change, pollution, and coastal development has a direct impact on the availability of prey for these sharks. Loss of habitat reduces their ability to find food and shelter.

Overfishing: Overfishing poses one of the most immediate threats to Caribbean reef sharks. They are often caught incidentally in commercial fisheries, where fishermen are targeting other species, or intentionally, where they are sought after for their fins, used in shark fin soup.

A Call for Increased Protection

There are different organizations and individuals working to protect sharks and their habitats in the Dutch Caribbean. A significant milestone was the establishment of protected areas such as the Yarari Marine Mammal and Shark Sanctuary between Bonaire, Saba and St. Eustatius.  Another milestone was in 2019 when the Dutch government adopted an International Shark Strategy. The strategy sets out which protective and management actions for sharks and rays are to be taken by the government in all seas and oceans where the Netherlands has influence (including the Dutch Caribbean).  Additional efforts are still needed to create more marine protected areas, enhance enforcement, reduce pollution in the ocean, and promote sustainable fishing practices.  These species know no (political) boundaries and their protection requires broadscale conservation efforts within the Dutch Caribbean and beyond.

Conclusion

The Caribbean reef shark is a species of paramount importance to the (Dutch) Caribbean’s coral reefs. With the extra protection being requested during the next COPS meeting in Aruba, there is hope that this species will have a healthy future. By recognizing their ecological significance and the challenges they face, we can work together to ensure a brighter future for the Caribbean Reef Shark in the Dutch Caribbean and beyond.

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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 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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Photo + photo credit: Jim Abernethy-all rights reserved

For more information, please contact: research@DCNAnature.org

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Can reef conservation be both enjoyable and profitable?

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wakatobi

At Wakatobi Dive Resort, guests are always thanked for coming to enjoy this special place, as it is their presence that creates the magic making ongoing reef conservation efforts a reality. “The more you know, the more you notice,” says in-house marine biologist Julia Mellers. “And what better place to learn about reef biodiversity and custodianship than in Wakatobi.”

“My main project for the first year is to establish a way of monitoring the health of Wakatobi’s reef ecosystem,” Julia says. “This will allow us to provide hard scientific proof that Wakatobi’s conservation model measurably benefits reef health. Holding a finger to the pulse of the reef will also assist management decisions, such as identifying priority areas for increased protection.”

Modern methods for reef management

The Wakatobi Reef Health Assessment program utilizes a customized set of modern imaging and data analysis techniques that provide a comprehensive indication of the state of a reef ecosystem. “We use the latest ecological theory, technology, and artificial intelligence to develop a novel package to efficiently and robustly measure reef health,” Julia says. “This will enable us to monitor how Wakatobi’s reefs are faring throughout the protected area without significantly diverting resources from protecting the reefs.”

The process begins in the water, capturing the reef’s sights, sounds, and landscape. Above water, Julia is developing and implementing analysis methods and training machine learning models to extract measures of reef health from captured data. When not on the island, she will research new approaches and ideas for coral reef assessment and help spread the word about Wakatobi’s scientific initiative.

“It’s an absolute privilege to work within a system that benefits both the reefs and the local people,” says Julia. “It also gives us a unique opportunity to assess and document reef health and dynamics within an ecosystem that is actually getting healthier. In stark contrast to declines in coral health recorded elsewhere, our scientific data is already beginning to demonstrate Wakatobi’s astonishing biodiversity – which is evident to anyone who ventures underwater at the resort.”

The program focuses on three indicators of reef health: the diversity of the reef community, which measures the variety and abundance of living organisms colonizing the reef surface; structural complexity, describing the degree to which the reefs incorporate elaborate details; and reef soundscapes, recording the noise a reef’s inhabitants make, including the snapping of shrimp and the feeding sounds of fish. By measuring these elements, it is possible to estimate how much life the habitat supports.

“Luckily, we don’t have to work all that out manually,” Julia says. Artificial intelligence plays a vital role. “I train machine learning models to identify signals of reef functioning that would otherwise be undetectable. For example, a model can be trained to recognize the sounds that characterize a healthy reef. This allows us to monitor the reefs at a scale, and with a thoroughness that would otherwise be inconceivable.”

Julia and the dive team have also started an eDNA survey of the reefs. ”This involves taking seawater samples near the reef at different depths and filtering them to trap environmental DNA (eDNA) that organisms shed into the water,” Julia explains. “The samples are now in a lab, where the DNA is labeled using probes and sequenced to identify which species are around. Using this technique, we should be able to detect hundreds of species from just a single litre of seawater. It’s a very cool process!”

wakatobi

A Wakatobi welcome

Julia says the Wakatobi team has been exceptionally supportive and welcoming. “They are able to maintain a totally laid-back atmosphere while coordinating an exceptionally professional operation.” She adds that Wakatobi feels remote in the best ways, with pristine reefs, peace, and quiet, while also being an extremely comfortable and well-connected place to work.

“Working within a system that works for the reefs because it works for the people is an absolute privilege,” she says. “It also gives us a unique opportunity to unpick reef health and dynamics within an ecosystem that is actually getting healthier. In stark contrast to declines recorded elsewhere, our scientific data is already beginning to demonstrate the astonishing biodiversity evident to anyone who ventures underwater at Wakatobi.”

The Wakatobi team has also proven to be an invaluable source of knowledge about the local ecosystem,” Julia says. “Wakatobi makes the perfect scientific laboratory. Being able to go from library to laptop to reef, all in the space of a hundred meters, is the perfect recipe for generating new ideas and trying them out. It is so exciting to work with open-minded innovators keen to try novel approaches and look at things from different angles.”

“Having such a dynamic team has meant that we’ve made progress quickly,” Julia says. “So far, we have a highly accurate machine learning model that classifies the reef community, a method to analyze the sounds that reef critters make, and a fully automatic way of measuring fish abundance. We are also in a position to add to this repertoire, trialing different techniques to quantify the complex 3D structure that corals make. We have added DNA analysis to the arsenal, which enables us to detect biodiversity invisible to the naked eye.”

From frogs to frogfish

Julia acquired her love of nature and biology from her parents, whom she describes as eco-friendly before the concept became trendy. “Camping, compost heaps, and Attenborough documentaries were features of a nature-centric English childhood. I raised pond-dwelling critters, peered down microscopes, and became transfixed by cephalopods.” Biology was an inevitable choice, she says, and the sea came into her life at a young age. “Having long been a sailor, with a family of sailors, I am at home at sea,” she says. “I took my first sip of compressed air at the bottom of a swimming pool in London and have spent as much time as possible eye-to-eye with octopuses since.”

After completing an undergraduate degree in biology at Oxford University, Julia shifted her Master’s focus to marine biology. It was a move she describes as swapping frogs for frogfish. “I went into marine biology because I see marine biological research as a powerful tool to connect people with the planet,” she says. “Of course, nature should be worth more to us preserved than destroyed – but if you can’t put a price on it, no one pays. Wakatobi has created an economic engine that financially incentivizes reef custodianship. This leads to an ideal scientific setting – demonstrably vibrant reefs linked to genuine socio-economic fairness.“

Julia’s Master’s project was done in collaboration with the Australian Institute of Marine Science and investigated mysterious bare rings of sand that surround reef patches within algal meadows. “We think these ‘reef halos’ form because foraging fish will only venture a short way from the shelter of a coral patch if they are under threat from patrolling sharks,” she says. “Since you can spot these halos from satellite images, they could be a neat way of keeping an eye on shark populations from space… and a possible addition to Wakatobi’s monitoring program”!

As the Reef Health Assessment program progresses, Julia will create new learning and participation opportunities for guests to enhance the depth and enjoyment of their Wakatobi experience. Wakatobi Dive Resort will also continue to provide updates and insights on the important work Julia and the rest of the Wakatobi team are doing to understand and protect some of the world’s most pristine and spectacular coral reefs.

Many thanks go to Wakatobi’s guests, whose continued enjoyment of the marine preserve helps keep ongoing reef protection efforts a reality!

Contact the team at office@wakatobi.com or enquire >here.
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View Wakatobi videos on the YouTube Channel.

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Marine Life & Conservation

Book Review: Coral Triangle Cameos

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Coral Triangle Cameos. Biodiversity and the small majority by Alan J Powderham

This colourful coffee table style book wonderfully shows off the incredible and vibrant marine life of an area, roughly triangular, that spans the waters of Indonesia, Malaysia, the Philippines, Papua New Guinea, the Solomon Islands, and Timor-Leste. The biodiversity here is incredibly rich. And this book covers the wonders that those lucky enough to dive here can experience.

It is worked into chapters that cover the types of marine life found here from coral to worms and everything in-between. The chapter on corals features lovely wide angle scenes, as well as close up details. And all the following chapters contain stunning images and interesting descriptions of both common and rare animals that have divers flocking to this region to discover. I think the cephalopods are my favourite. But this book certainly offers plenty of other options to marvel at.

This is a book to dip in and out of. Enjoy the beautiful images within (of which there are many). Peruse the descriptions of your personal favourite species and learn about new behaviours and interactions that are part of every day life on these abundant reefs. It is the type of book that will keep you coming back over and over again. And will always bring a smile to your face as you explore this incredible underwater world and the marine life that calls it home.

What the Publisher Says:

Dive into the Hidden Wonders of the Coral Triangle, a kaleidoscope of marine life which boasts the greatest biodiversity in the oceans. While most focus on the giants of the deep, Coral Triangle Cameos celebrates the “small majority” — the tiny but vital creatures that power this underwater paradise.

Renowned underwater photographer Alan Powderham brings the unseen to life with stunning visuals and he divulges the fascinating science behind these diminutive wonders in an accessible, relatable way.

About the Author:

Alan J Powderham is a seasoned underwater photographer with over 40 years of experience capturing the magic of the ocean depths. His previous books include At the Heart of the Coral Triangle (2021).

Book Details

Publisher: Dived Up Publications

Hardcover

Price: £45

ISBN: 978-1-909455-57-3

Published: 17th September, 2024

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