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Marine Life & Conservation

The Yucatan Cenotes – A paradise under threat from tourism

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An interview with Sam Meacham by Jeff Goodman

A few years ago I made a film for the BBC called ‘Secrets of the Maya Underworld’ and was about the Cenotes and forests of the Yucatan Peninsula, Mexico. Previously I had always promised myself not to ever cave dive as I had a fear of being lost or trapped far underground with no escape route. Then a few very good friends told me of the Cenotes and the incredible wildlife that was associated with them. I had to see for myself.

Yucatan-Cenotes-2It was then I met Sam Meacham, an American living near Cancun. He had been exploring the caves and passageways of the Yucatan Peninsula for the previous 18 years and now to date has discovered with other divers 252 known caves and cave systems in that region with a total of 1,103.3 km or 685.5 miles of surveyed passageway between them.  Two of the five longest caves on the planet Sistema Sac Actun and Sistema Ox Bel Ha are found close to the town of Tulum.

The Yucatán Peninsula was once a shallow coral reef and now over a few million years has become a porous limestone shelf covered with forest and wildlife. There are no visible rivers; all the fresh water rivers are underground. Being porous, caverns and caves formed where the fresh water collects – hence the Cenotes or water sinkholes.

Recently, the Cenotes have become a great dive destination and the eastern Yucatan coastline an ever developing tourist area for sun worshipers and beach goers. The seemingly uncontrolled developments are taking their toll on this unique ecosystem.

I recently got back in touch with Sam to see if things were improving.

Jeff:  Can you just tell us exactly what the Cenotes are and what is so special about them?

Sam: Cenotes are karst sinkholes that occur in Mexico’s Yucatan Peninsula.  The Cenotes are windows into the freshwater aquifer of the region and the entrances to the very complex flooded solution cave systems along the Caribbean coastline.

Yucatan-Cenotes-3Jeff:  The underground water systems give life to the forests above where wildlife is obvious to find, but is there life in the caves as well?

Sam: Most people think of the cave environment as a very sterile place.  In fact, there are over 40 life forms so far identified that live in the dark recesses of these caves.  The majority are crustaceans and they are all considered extremeophiles because of the conditions they live in.  The Cenotes themselves are also magnets for life; this includes a number of freshwater tropical fish species, crocodiles, turtles in the water and birds and mammals (including jaguars) at the surface.

Jeff: How long has man know about the Cenotes?

Sam: There is growing evidence that the caves and Cenotes were accessed by humans during the last ice age, which was 8000-10000 years ago.

Jeff: Did the Maya have any idea about the complexity of the underground waterways?

Sam:  It is hard to say if the Maya realized that some of the Cenotes were connected by the intricate and complex cave systems. Many of the underground rivers flow out to the sea in very impressive upwellings; perhaps they put two and two together when they observed this.  It was not until the 1980’s that cave divers really began to probe the depths of the Cenotes and really revealed just how complex and extensive they were.

Jeff: Are the Cenotes and reliant ecosystems in any threat now due to the commercial tourist developments?Yucatan-Cenotes-4

Sam: There is a very real and continuing threat from the development of the tourism industry along the coastline.  Karst landscapes like the Yucatan are very susceptible to contaminants that leach through the porous limestone and into the aquifer.

Jeff:  What are the main issues?

Sam: The main issues we face are contamination from solid waste (garbage) and sewage.  Once contaminants hit the aquifer there is the high potential for them to be transported through cave conduits and out to the Caribbean Sea.  High concentrations of contaminants cause algal blooms that cover the Mesoamerican Reef and kills the corals.  If we lose the reef, we lose the protection to the beaches.  If the beaches erode, where will the tourists go?  Effectively, we risk killing the goose that lays the golden egg.

Jeff:  Is anyone listening to the conservation needs of the area or is commercialism taking its full toll?Yucatan-Cenotes-5

Sam: Well, I think worldwide conservation efforts are always facing an uphill battle and this area is no exception.  But I do think there is a great deal more awareness about the existence and importance of the flooded caves.  My personal belief is that the outreach and education about the caves is the only way we can engage the public and effect change.

Jeff:  As Divers, how can we help preserve this unique ecosystem?

Sam: If you dive in the Cenotes, it is a great opportunity to perfect your skills particularly your buoyancy and trim.  Really, any time you go diving you should be perfecting your skills.  We, as divers, are privileged visitors to the underwater environment and must make every effort to protect it.

Jeff:  If readers want to learn more where can they get further information?

Sam:  Here are a few websites:

www.mcep.org.mx

www.cindaq.org

http://newswatch.nationalgeographic.com/2011/02/18/skull_in_mexico_cave_may_be_oldest_american_found/

http://www.caves.org/project/qrss/qrss.htm

Jeff is a multiple award winning, freelance TV cameraman/film maker and author. Having made both terrestrial and marine films, it is the world's oceans and their conservation that hold his passion with over 10.000 dives in his career. Having filmed for international television companies around the world and author of two books on underwater filming, Jeff is Author/Programme Specialist for the 'Underwater Action Camera' course for the RAID training agency. Jeff has experienced the rapid advances in technology for diving as well as camera equipment and has also experienced much of our planet’s marine life, witnessing, first hand, many of the changes that have occurred to the wildlife and environment during that time. Jeff runs bespoke underwater video and editing workshops for the complete beginner up to the budding professional.

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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.
Follow on Facebook and Instagram.
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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