The Heat Is On: Sea Turtles Are Becoming Mostly Female Due To The Earth’s Warming Climate

Some of the more charismatic inhabitants of the reef here at Gili Lankanfushi are the Turtles, and we do our best to help them thrive.

In fact, our resident Hawksbill Turtle, the aptly named ‘Gili’, was initially found here in critical condition, but was rescued by our marine biology team who sent her straight to the Four Seasons Rehabilitation Centre for recovery. Of all the threats posed to these animals; poaching, entanglement in fishing gear, plastic and other marine debris, and ocean pollution – There is one issue you may not be aware of: Climate change is turning Sea Turtles female.

As reported by Sarah Kaplan for The Washington post, scientists in the 1980s accidently discovered that temperature can determine the sex of Turtles. The team were attempting to aid a population of sea Turtles by rescuing eggs from vulnerable beaches and keeping them warm in incubators until they were ready to hatch. To their surprise almost all the hatchlings were male. What these scientists observed was “Temperature-dependent sex determination (TSD)”, a phenomenon that occurs only in reptiles (and some fish).

At what biologists call the ‘pivot temperature’ (roughly 29oC for Green Turtles), nests will produce equal amounts of males and females. A little warmer and embryos develop as females, but keep the eggs just a few degrees cooler (like the scientists did with their incubators) and they’ll come out mostly male.

Turtles tend to target their breeding periods to times when the sand is slightly warmer than their pivot temperatures, resulting in populations moderately skewed towards female, but a recent study conducted around Australia’s Great Barrier Reef found that the populations are becoming more than moderately skewed. On the warmer nesting sites 99.1% of juvenile Green Turtles were female, as were 86.8% of adults, suggesting that there has been a shift in gender ratios over the last few decades.

Scientific evidence for warming of the climate system is unequivocal
-Intergovernmental Panel on Climate Change

Global warming is rapidly emerging as a universal threat to ecological integrity and function, say scientists studying coral reef assemblages. In species with temperature-dependent sex determination the impacts of rising temperature are particularly pertinent. At the key breeding grounds of many Sea Turtle populations the sand has warmed significantly since the 1990’s and researchers say that this almost certainly accounts for the dramatic decrease in the number of males. Since turtles will often return to the same beaches where they were born to lay their own eggs, this cycle will likely continue; and with global temperatures continuing to rise, many Sea Turtle populations are in danger of high egg mortality and female-only offspring production.

“Finding that there are next to no males among young Northern Green Turtles should ring alarm bells, but all is not lost for this important population.”
– WWF Australia CEO Dermot O’Gorman

The good news is that management strategies are possible. Options include shading beaches or using artificial rain to cool the beach. Protecting some of the big breeding males from threats such as poaching and entanglement is also going to be of particular importance.

Of the seven species of sea Turtles in the world, five species have been recorded in the Maldives and some species are known to nest here: The Green Turtle (Chelonia mydas), Hawksbill Turtle (Eretmochelys imbricata), Olive Ridley Turtle (Lepidochelys olivacea), Loggerhead Turtle (Caretta caretta) and Leatherback Turtle (Dermachelys coriacea). The Maldivian archipelago clearly serves as an important habitat for Sea Turtles, and here at Gili Lankanfushi we strive to help maintain that habitat by educating our guests about the negative effects of global warming; reducing the amount of harmful marine debris entering the ocean and growing our seagrass beds that act as a carbon sink and produce food for our sea turtle population.

So, what can you do to help mitigate climate change? Start by finding ways to reduce your carbon footprint; embrace a minimalist lifestyle, walk instead of drive, [a comprehensive list of ways to reduce your carbon footprint can be found here and here] and support only the large companies that are reducing theirs too.

Acknowledgements:

Guarino, Ben. 2018. Climate change is turning 99 percent of these baby sea turtles female’. Washington Post.

Hogge, Katie. 2018. Not Cool: Climate Change Turning 99% of These Sea Turtles Female. Ocean Conservancy.

Jensen, M.P., Allen, C.D., Eguchi, T., Bell, I.P., LaCasella, E.L., Hilton, W.A., Hof, C.A. and Dutton, P.H., 2018. Environmental warming and feminization of one of the largest sea turtle populations in the world. Current Biology, 28(1), pp.154-159.

Kaplan, Sarah. 2016. Some like it hot: Scientists figure out why female turtles are born at higher temperatures. Washington Post.

WWF. 2018. How climate change is turning Green Turtle populations female in the Northern Great Barrier Reef. WorldWildLife.org.

PADI guest blogger Jon Fry introduces himself:

After receiving my degree in Marine Biology & Coastal Ecology from Plymouth University I worked in Madagascar where I gained experience in reef restoration and tropical biology. I believe awareness is the most important tool we have in conservation, and I am pleased to be here at Gili Lankanfushi where I can educate the curious about marine life and sustainability.

Green Sea Turtle Nesting on Earth Day 2018

In the early hours of Earth Day, 22nd April 2018, a female green sea turtle was coming to an end of her journey as she finished laying the last of her 150 ping pong ball sized eggs in the sand close to the tree line at Gili Lankanfushi.

The adult turtle was around one meter in size with her carapace (shell) measuring around 80cm. After arriving on the beach just before high tide (at 4:30am) she searched for a safe spot to lay her eggs in an area where the sand was soft enough to dig a hole around 50 cm deep.

She succeeded on her second attempt and went into a trance to deliver her clutch. We did not want to disturb her but used this opportunity to assess her size and check the hole was deep enough for her eggs.

After a two-hour process, she began to make her way back to the ocean. Her energy levels were high and her timing impeccable as she re-entered the water at 6:15am, just before first light.

The nest is in an area that could be disturbed by hosts or guests walking, so we constructed a make shift boundary to protect the eggs from the pressure of human feet above.

After a 60 day incubation period we hope to witness the emergence of the hatchlings as they make their way down to the ocean. Turtle hatchlings follow the light of the moon to reach the ocean so we will be sure to turn off external lights during this time as any light pollution could cause the hatchlings to make a wrong turn and reduce their chance of survival.

Female green sea turtles nest three to five times per season and they lay their eggs on beaches within a 100kilometre radius of where they hatched. We hope she is planning to nest again on Gili’s shores in the next few months. We noticed a unique marking on her carapace and we will try to use this white mark to identify her in the future. However, we were not able to get clear photographic identification as we did not want to disturb her behaviour by shining a light on her.

As she entered the water, we became acutely aware of the responsibility we had been given – to keep these eggs safe from disturbance and predators for around two months until they emerge as hatchlings.

As only one in 1000 turtle hatchlings make it to adulthood we can safely say that Gili is carrying precious cargo into the months ahead.

PADI’s guest blogger Clare Baranowski introduces herself:

I am a marine zoologist from the UK who has worked throughout the tropics researching mega fauna and reef ecosystems in the Caribbean and Indian Ocean. I have experience monitoring and restoring coral and surveying manta, turtle and dolphin populations. I began my career as a science communicator before moving into research and management roles, this is why I incorporate outreach and education into every project I work on and I hope to continue this at Gili Lankanfushi

Earth Day – Sunday 22nd April

On Sunday 22nd April, the Prodivers team and guests of Hurawalhi joined the largest civic-focused day of action in the world – Earth Day! The campaign for Earth Day 2018 was ‘End Plastic Pollution’, a movement dedicated to providing information and inspiration needed to fundamentally change human attitude and behaviour towards plastics.


Plastics are a substance the earth cannot digest. The very qualities that made plastics such an attractive material initially; durable, flexible, versatile and inexpensive, have ultimately generated rubbish with staying power – a huge environmental issue. Our voracious appetite for plastic goods, coupled with our tendency to discard, litter and thus pollute, has led to an estimated 8 million tonnes of plastic entering our oceans every year. Plastics not only threaten our wildlife through entanglement, ingestion and habitat disruption, but their ability to absorb chemicals and accumulate in the human food chain has also led to plastics negatively affecting human health.


So, instead of diving with sharks or snorkelling with manta rays, the 48th Earth Day saw Hurawalhi staff and guests dive and snorkel for debris instead! They were let loose to clean up as much plastic and rubbish they could find off a nearby reef. Whilst they may have made only the tiniest dent in removing some of the debris currently be in our oceans, every action counts. There are so many simple ways to reduce plastic consumption in our day-to-day lives, here are some of the tips our Marine Biologist, Kirsty, shared with all of our volunteers this Earth Day:

1. Refrain from using plastic straws, even in restaurants. If a straw is a must, purchase a reusable one.

2. Forget the plastic bag. Purchase a reusable produce bag and be sure to wash them often.

3. Give up gum. Chewing gum is made of a synthetic rubber, i.e. plastic.

4. Ditch bottles for boxes. Often, products like laundry detergent come in cardboard which is more easily recycled than plastic.

5. Leave the single-use plastic bottles on the shelf. Use a reusable bottle or mug for your beverages, even when ordering from a to-go shop.

6. Don’t buy foods in plastic containers e.g. berries, tomatoes etc. Ask your local grocer to take your plastic containers back.

7. Disregard the disposable nappy. Use cloth nappies to reduce your baby’s carbon footprint and save money.

8. Stop purchasing single serving products. Buy bulk items instead and pack your lunch in reusable containers and bags.

9. Refuse to buy disposable razors and toothbrushes. Purchase replaceable blades instead.

Abstain from buying frozen foods. Even though those that appear to be packaged in cardboard are coated in a thin layer of plastic, plus you’ll be eating fewer processed foods.

A great quote from Marine Biologist, Sylvia Earle, sums up perfectly the importance of looking after the ocean: ‘No water, no life. No blue, no green’

PADI’s guest blogger Kirsty introduces herself:

Growing up in Mallorca, surrounded by the riches of the Mediterranean Sea, Kirsty’s ambition to pursue a career in marine biology was ignited from a young age. Kirsty completed both her undergraduate and postgraduate degrees at Newcastle University in England. During her studies she had the opportunity to conduct fieldwork in the Bahamas, Bermuda and the Maldives. It is not surprising then that her research interests to date have focused on tropical reef ecology. More specifically, Kirsty is interested in studying the movement patterns and habitat use of sharks and rays. Kirsty is currently part of the Maldivian Manta Trust research team, collecting data around the country’s manta population, its movements, and how the environment and tourism / human interactions affect them.

 

 

Project AWARE® and how to introduce more to your Business

I have mentioned before about Project AWARE® and the benefits for your Business. But I have been moved by the recent uptake of PADI Centres and Instructors who have signed up as 100% AWARE Partners. If you don’t include myself there is now 9 Centre’s and 4 Instructors in the UK. Each one making a contribution to the cause with every Certification they are doing.

Thank you
Oxford Dive Centre
Vivian Dive Centre
Reef Scuba Ltd
Scuba Leeds
The Fifth Point Diving Centre
Wavecrest Scuba
Viewpoint North Diving
Gatwick Scuba
London Diving Centre
Instructor’s Daniel Chan, Ollie Powell, Geoffrey Creighton and Ian Edge

One of our goals at PADI is to mobilise  Divers to Be a Force for Good, which is critical to PADI’s Four Pillars of Change.

Project AWARE® plays a huge part in our Ocean Health Pillar.  Ocean Health is vital to us all on this Ocean Planet and we at PADI are forging partnerships with organisations that support the establishment of more marine protected areas (MPAs) and the reduction of human pressures that threaten the future of our blue planet like marine debris.

Please take time to mobilise your own divers and get engage through the Project AWARE® specialty courses. Why not include Dive Against Debris® as part of your Advanced Open Water or conduct it on every dive as it is so easy now to record your data using the Project AWARE® App.

Do you generally dive at the same spot, then why not Adopt a Dive Site™? Adopt a Dive Site is tailored to our most dedicated dive leaders: participants commit to carrying out monthly Dive Against Debris surveys, reporting types and quantities of marine debris found underwater each month from the same location. This picture was sent to me from The Fifth Point Diving Centre. What was really interesting was the fact that Tudor Crisps went out of business in 1993, so that bag which looks relatively intact has been around for some time.

I was watching with interest over Scuba Leeds’ quest to find a site to adopt. The social media interactions over this from people who were inquiring as to how to join in and to let them know next time they were doing a dive was phenomenal. Fantastic work everyone and please keep up the great work.

Why not have a look at the interactive map  and get your own clean up on there. It will certainly raise your profile when you share it.

Please speak to your Regional Manager to find out more about it.

 

Dive site topography in Lhaviyani Atoll – Part 1

The underwater topography of the Maldives is dramatic, varied and perfect for exploring. Scuba divers visiting the Lhaviyani Atoll in particular have a huge variety of reef formations awaiting them on the dive sites – the first glimpses of which can even be spotted from the seaplane window. In this, the first of a three part series, the underwater islands of giris and thilas are explored.

What is a giri?

Giris are shallow underwater islands with a top reefs lying at around 5 meters and appearing as blueish-green spots when viewed from the seaplane window. Typically found inside the atoll, they are perfect for beginner divers and macro lovers.

One of Hurawalhi’s favourite giris is Maa Giri. It means Flower Island and it is usually described as ‘fish soup’. On the front of the giri are thousands of lunar fusiliers catching food in the gentle currents that flow around the dive site. Once the divers descend a little deeper they can explore small overhangs and crevices where nurse sharks are sleeping or moray eels are getting cleaned. All around the giri are schools of yellow snappers, humpback snappers, and sweetlips. Occasionally, at the right time of the year, there is a glittering swarm of glass fish that divers can swim into the middle of – this is an enchanting experience that will be remembered for a very long time. Along the walls there are macro creatures like the mantis shrimp, whip coral shrimp and nudibranchs.

Picture by Ray van Eeden

On Tinga Giri, close to Hurawalhi, there is currently a large red frogfish that can often be seen fishing with the lure, which comes out from the top of its head.

What is a thila?

A thila is a deeper underwater island usually starting around 12-14 meters. Two of the Hurawalhi team’s favourite and most fascinating thilas are Anemone Thila and Fushivaru Thila.

Picture by Ray van Eeden

Anemone Thila gets its name from the incredible amount of anemones that have made themselves at home there. It is a very small thila and can be dived all they way round its circumference 2-3 times in one dive. This site is great for underwater photography and experimenting with macro photography. The most spectacular part of the dive is towards the end when divers arrive at the shallowest part of the thila and see the clownfish swimming above all the anemones along with bright blue and pink damselfish. For a good part of the year this site is also completely covered in ‘baitfish’ – so many that visibility can be reduced to 1-2 m with the fish parting to make way for the passing divers.

Picture by Ray van Eeden

Fushivaru Thila is a manta cleaning station and from November to January divers can witness the spectacular sight of the majestic mantas as they cruise in and hover over the station as small cleaner wrasse come and cleanse them of parasites. When the mantas are elsewhere, Fushivaru Thila is just as beautiful with huge schools of snappers and hunting grey reef sharks, nurse sharks sleeping under coral blocks, and large stingrays on the sand.

Picture by Ray van Eeden

There are many underwater island dive sites in Lhaviyani Atoll waiting to be explored. In Part 2 of the Dive Site Topography series all will be revealed about the differences between East and West sides of the Atoll.

 

PADI’s guest blogger Paige Bennett introduces herself:

I am an American Scuba diving instructor who has been living in the Maldives for the past 2 ½ years. I have been travelling and working for the past 6 years and have been to Koh Tao Thailand, Playa del Carmen Mexico, Marsa Alam Egypt and have now settled in the Lhaviyani Atoll working with Prodivers Diving center. I love the abundance of textures and patterns in the ocean and am very interested in underwater macro photography. I also have been involved with several conservation/restoration projects such as ReefCI in Belize, Eco Koh Tao in Thailand, and the coral transplantation project for the 5.8 undersea Restaurant on Hurawalhi Island Resort.

 

Earth Hour

Earth Hour is an annual worldwide movement to encourage individuals, communities, and businesses to conserve our resources. Celebrating it is a symbol of our commitment to our planet.

At Gili we celebrated Earth Hour on March 24th with the rest of the world, we hosted a Coral Conservation themed day with multiple events leading into each other. For each event, all guests and hosts were invited to attend and take part.

Our first event was a coral workshop hosted for Marine Biologists and enthusiasts. In attendance were three participants from our local island Himmafushi who have a keen interest in protecting their reef and inspiring locals. Additionally, Marine Biologists from Four Seasons Resort, Bandos Resort, Atoll Marine Centre and Hurawalhi Resort attended. Jinah, a journalist from Hotelier Maldives covered our event celebrations.

Our coral lines project launched in 2014 and currently has 190+ lines, each containing around 50 coral fragments. The aim of the project is to rehabilitate our degraded house reef through direct transplantation of mature corals and through indirect coral spawning from the nursery. The project was the first low-tech and high efficiency coral recovery project that involves rope in the Maldives.
Due to the optimal location and care that goes into the project we had 68% survival after the El Nino event and the crown of thorn starfish outbreak. Due to the success of our project, many Marine Biologists are interested in learning more as they want to launch their own projects or further their current projects in other locations. This is why we invited them to join us in celebration of Earth Hour.

 

We felt that hosting a coral conservation themed day would create a platform for a discussion on possible project improvements and new project ideas. Overtime the coral line nursery will contain heat tolerant coral species, fragmenting these species and planting lines could lead to natural spawning of more heat tolerant species which will increase survival rate in future warming events. This will lead to the creation of more healthy reefs decreasing the pressure of predation, providing a healthier habitat, refuge and nurseries for marine organisms like turtles, juvenile fish and other fish species as well as conserving a key ecological ecosystem.
On the day the visiting Marine Biologists arrived at 14:00pm and a land based presentation was carried out, topics included an in depth overview of the project, project creation, management, challenges and future plans. This was followed by a practical demonstration of making a coral line, monitoring the lines and general maintenance including cleaning and removal of invasive species. To view the coral line made by the Marine Biologists click here. To conclude there was a group discussion on possible project improvements and a question and answer session.

 

Following the success of the coral workshop together with guests, Marine Biologists and hosts we designed and created a coral shape in the sand on Library Beach. In celebration of the official Earth Hour which is between 20:30 – 21:30 we turned off none essential lights and filled the coral shape with sustainably sourced candles – coconuts and used cooking oil. During the official event our coral shape was beautifully illuminated by flickering candle lights and guests, Marine Biologists and hosts were able to enjoy this display whilst attending our Earth Hour cocktail evening.

 

To conclude our Earth Hour celebrations we hosted the documentary Chasing Coral in our Jungle cinema and Host Village. Chasing coral is a fantastic documentary about a group of divers, photographers and scientists who set out on an ocean adventure to discover why the reefs are disappearing and to reveal the underwater mystery to the world. They found that coral reefs around the world are vanishing at an unprecedented rate and documented their discoveries and explained them in a way that is accessible to everyone.
Overall the event was a huge success with all participants learning something new and being inspired to help conserve our resources. We hope that you will join us in celebrating Earth Hour next year!

PADI’s guest blogger Emma Bell introduces herself:

I am a marine biologist and scuba diver from England. I have had the privilege of working in Greece, Seychelles and Maldives. I have worked in an aquaculture research centre where I focused on hormonal manipulation of a pelagic fish species. In addition, I have experience with coral restoration projects including frames and ropes; habitat restoration – crown of thorns, drupella and invasive plant species removal; educational activities and social media updates including blogs. I have also monitored population dynamics of bird, turtle, shark and cetacean species to aid in their conservation. I started my career working in the Maldives and I have done a round trip via Greece, England and Seychelles, I hope to increase my skills set and knowledge further whilst I am at Gili Lankanfushi, Maldives.

Common crabs encountered in the Maldives: Part 2

Crabs are an underappreciated species. Whilst living in a harsh and arid environment they dedicate their lives to keeping the beach pristine.

Swift-Footed rock crab Laura Pola

Swift-Footed Rock Crab

The swift-footed rock crab can easily go unnoticed due to its elusive behaviour. It inhabits rocky shores at mid to high tide level and so can be found around beach rocks, boat ramps, rock walls and jetties. These crabs are fast moving and are generally only seen at night, unless disturbed. Then you may observe them jumping from rock to rock trying to find a new refuge.

Their colouration can be mesmerising with a multitude of blue, green, purple, orange, white and black. The crabs encountered on Gili are more blue, green and purple with white stripes. The shell (carapace) can be up to eight centimeters wide and is flattened, compared to other crabs which have shells that are more rounded.

Swift-Footed Rock Crab. Picture by Laura Pola

The crab feeds on algae, detritus, small vertebrates, barnacles, limpets and snails. They use their claws to break into the shells of other animals and to tear off pieces of their prey to be transferred into their mouth. This species is predated upon by a variety of animals including birds, octopus and fish, so it isn’t safe for them in the ocean or out of it!

Fiddler Crab. Picture by Carly Brooke

Fiddler crabs

Fiddler crabs are a small and short lived species of crab (up to two years) and are closely related to ghost crabs. They are found in mangroves, brackish water, mud flats, lagoons and swamps. The colouration of the crabs change in correlation with circadian rhythm – during the day they are dark and at night they are light.

Fiddler crabs are well known for their sexual dimorphism – the male’s major claw is much larger than the females. If the large claw has been lost the male will develop a new large claw on the opposite side, which will appear after molting. The female’s claws are the same size. The crabs use their claws in communication, courtship and combat. The male claw is used in waving displays which signals to the female that they are ready to mate. A more vigorous waving display indicates a healthier male and a larger claw indicates a wider burrow which will provide better temperatures for egg incubation. Females chose their partners based on claw size and the quality of waving. Once a female has been attracted she will reside in the male’s burrow whilst the eggs are being laid. The female will carry her eggs on the underside of her body for a two week gestation period. After this period the female will venture out of the burrow and release the larvae into a receding tide.

During feeding the crabs move their smaller claw from the ground to their mouth. This movement looks like the crab is playing the smaller claw like a fiddle – hence the name, fiddler crab. The smaller claw is used to pick up the sediment which is then sifted through in the crab’s mouth. Algae, microbes and fungus are the preferred diet of the crab. After the nutrients are extracted the sediment is placed back onto the ground in a ball. The feeding habits may play a vital role in preserving the ecosystem as they aerate the soil. The fiddler crab can be seen when visiting local islands, especially in the mangrove area at low tide

PADI’s guest blogger Emma Bell introduces herself:

I am a marine biologist and scuba diver from England. I have had the privilege of working in Greece, Seychelles and Maldives. I have worked in an aquaculture research centre where I focused on hormonal manipulation of a pelagic fish species. In addition, I have experience with coral restoration projects including frames and ropes; habitat restoration – crown of thorns, drupella and invasive plant species removal; educational activities and social media updates including blogs. I have also monitored population dynamics of bird, turtle, shark and cetacean species to aid in their conservation. I started my career working in the Maldives and I have done a round trip via Greece, England and Seychelles, I hope to increase my skills set and knowledge further whilst I am at Gili Lankanfushi, Maldives.

Whale sharks of the Maldives

‘What is it? A shark? A whale? Whatever it is it’s massive!’

The whale shark is the biggest fish in the ocean, and therefore is also the biggest shark. It is one of three species of filter feeding shark; also including the basking shark and the mega mouth shark. On the 7th January we were lucky enough to spot Pedro who is a juvenile male at six metres. It was a truly breath taking moment! The best time to look for a whale shark is three to five hours before high tide and a few days before the full moon. However, finding a whale shark cannot be a guaranteed experience.

For many, seeing a whale shark is a once in a lifetime experience, with a place at the top of numerous bucket lists. These enigmatic and gentle creatures can be seen year round in South Ari Atoll, only a short seaplane ride from Gili Lankanfushi. The whale sharks are attracted to South Ari Atoll due to the vicinity of the Chagos-Laccadive Plateau, which provides very deep and highly nutrient rich water. Whale sharks are a pelagic species, able to travel around 100 miles per day and dive to at least 1600m – probably deeper, but this cannot be officially recorded due to tracking tags breaking under the phenomenal pressure at great depth.

Whale sharks are fascinating animals that predate the dinosaurs by 220 million years. All sharks, including the whale shark are cartilaginous fish, which means that their skeletons are made from cartilage, not bone. As with all sharks the whale shark’s skin is covered by dermal denticles, a substance more like teeth than fish scales. The dermal denticles are a couple of millimetres thick and protect the shark’s skin from damage and parasites. They also provide better hydrodynamics. Under this layer of protective armour is a fatty layer, around 10 to 15 cm thick that is most likely used as an energy store and protection from injuries, together with insulation during deeper dives. Whale sharks have over 300 rows of tiny replaceable teeth which are made from a stronger version of dermal denticles. Scientists are still debating the use of these teeth as whale sharks are filter feeders so their teeth are not required for feeding. Another anatomical feature which perplexes scientists is that the whale shark has spiracles. These are a breathing aid for stationary sharks, but the whale shark is classified as a highly mobile shark so what is the use? It could be that the whale shark is very closely related to bottom dwelling sharks, and it is a feature that will eventually disappear through evolution, or it could be used on the rare occasions that the shark is stationary and not feeding.

Whale sharks are known to make seasonal feeding aggregations in 20 countries, including Australia, Gulf of Mexico, Belize, Gulf of California, Seychelles and Maldives. Whale sharks feed on microscopic plankton and small fish that they suck into their one and half metre wide mouths. Their throats are much smaller in comparison; around the size of a drain pipe. They have two known methods for feeding, ram filtration and suction feeding. Suction feeding allows whale sharks to feed on more mobile prey such as small fishes, which they actively suck into their mouths, together with volumes of water that are then expelled through their gills. By comparison ram feeding is passive; the shark swims through the water with their mouth open and plankton filters in. It has been suggested that whale sharks are more suited to suction filter feeding because the gaps between their five to seven gills are small. This small gap is more effective at filtering out plankton when the shark is suction feeding. Whale sharks have very weak eyesight, they can probably only see three meters away, and so rely on their nostrils to find prey. Their nostrils are very sensitive due to their well-developed olfactory capsules; they can detect chemicals in the water produced by their planktonic prey.

Plankton tend to shelter at depths between 100 – 200m. This is the oxygen minimum zone and is not a suitable habitat for many organisms which would prey on them. Whale sharks however are able to feed at these depths and will spend the majority of their time between 50 – 250m. They do venture to deeper depths where the temperature drops to 3 degrees Celsius but scientists believe that due to the infrequency of these dives this is related to parasite removal, not feeding. Whale sharks cannot internally control their body temperature and so return to the surface to warm up and reload oxygen. This is why they can be found in the shallow waters around South Ari Atoll. During this warming and reloading period the sharks can be impaired cognitively and physically which explains their sluggish and relaxed behaviour.

Due to the sluggish behaviour of whale sharks and the shallow depths they travel in they are under threats from boats. It is estimated that 67% of whale sharks have injuries ranging from scratches to amputations. The effects of pollution, poor waste management and increased sedimentation on the whale shark population have not yet been suitably evaluated. Another issue is disturbances to their habitat resulting from tourism – if the guidelines for whale shark encounters are not followed the sharks can negatively be affected. For example, if a large group of tourists are crowding a shark it can cause the shark to dive before it has properly warmed up and reloaded oxygen. Adult whale sharks can also be targeted by great white sharks and orcas, whilst babies have been found in the stomachs of blue sharks and swordfish. In some parts of the world whale sharks are hunted for their meat and fins. In 2010 the Maldives implemented a ban on all forms of shark fishing. However, due to the longevity of whale sharks it will take many years for the population to return to optimal levels.

It is estimated that whale sharks can live between 70 – 100 years, reaching sexual maturity after 25 years at a size of eight to nine metres. Although some people report sightings of whale sharks up to 18 metres in length the largest confirmed has been 12.65m. It is easy to identify a male whale shark because when it has reached sexual maturity their sexual organs have a ragged appearance called claspers which extend past their pelvic fin. The whale shark is classified as ovoviviparous which means that they produce eggs which hatch inside the body. A female whale shark can store sperm for many months and can have babies at different stages of development. For example a female was found with 300 embryos at numerous stages of development. Due to whale sharks storing sperm and having babies at different stages of development the gestation period is unknown. Upon birth the pups are around half a metre in size and weight one kilo.

Whilst whale sharks are regularly sighted, 98% of these sightings are juvenile males with a length of six metres. At any one point it is estimated that there are 200 whale sharks in the waters of the Maldives. The most common behaviour observed of these sharks is cruising, only 12% of encounters are feeding.

We can’t wait to show you these gentle giants next time you are at Gili Lankanfushi. Please ask your Mr/Ms Friday and we can book a trip for you.  When you see one be sure to snap a photo of the checkerboard pattern on their side by their pectoral fins. This can help us with identification and research.

For more information and to upload your whale shark encounters please visit: https://maldiveswhalesharkresearch.org/

PADI’s guest blogger Emma Bell introduces herself:

I am a marine biologist and scuba diver from England. I have had the privilege of working in Greece, Seychelles and Maldives. I have worked in an aquaculture research centre where I focused on hormonal manipulation of a pelagic fish species. In addition, I have experience with coral restoration projects including frames and ropes; habitat restoration – crown of thorns, drupella and invasive plant species removal; educational activities and social media updates including blogs. I have also monitored population dynamics of bird, turtle, shark and cetacean species to aid in their conservation. I started my career working in the Maldives and I have done a round trip via Greece, England and Seychelles, I hope to increase my skills set and knowledge further whilst I am at Gili Lankanfushi, Maldives.

Bioluminescence at Gili Lankanfushi

The sea never sleeps. Even at night it is bursting with a wonder that seems almost magical – flashes seeming to appear out of nowhere when the ocean is otherwise shrouded in darkness

When the lights go out nature doesn’t stop communicating. Similar to our adaptations to cope with the dark, by making light, many organisms have developed the ability to produce light. This is called bioluminescence and is created by a chemical reaction within the organism. It is not the same as fluorescence which results from the organism absorbing light at one wavelength and then re-emitting it at another wavelength. Bioluminescence is therefore an active form of communication, whereas fluorescence is passive communication. Whilst visual light is required to observe fluorescence, bioluminescence can be witnessed in pitch black environments. It is generally blue/green in color and this is due to the shorter blue/green light waves travelling further under water.

Bioluminescence can be found throughout the ocean
It can be found in many different groups such as jellyfish, sharks, fish, algae and worms to name a few. In each group the chemical reaction that produces the light varies, which is evidence that bioluminescence has evolved multiple times. Generally, bioluminescent animals contain the chemicals required to produce light, but occasionally an animal can take in bacteria or a different bioluminescent organism that has the ability to produce bioluminescence. For example, the Hawaiian bobtail squid takes in bioluminescent bacteria which are stored in a special light organ and at night they then work together to produce light. This light acts as a cloaking device preventing the squid from casting a shadow and hence camouflaging the squid from predators.

For light to be produced organisms must contain the molecule luciferin which when combined with oxygen produces light. Different organisms will contain different types of luciferin. Some organisms can contain a catalyst called luciferase which can speed up the chemical reaction. Additionally, luciferin and oxygen can be bundled together to make a photoprotein which can be activated instantaneously when a certain ion becomes present. The intensity and colour displayed can also vary and this is very important for communication.

 
Bioluminescent animals can be found on land and in the water column, from the surface to the deepest part of the ocean at challenger deep (10,994m), and in coastal and oceanic environments. In coastal environments around 2.5% of organisms are bioluminescent whereas in pelagic environments the number is significantly higher. Studies estimate that around 70% of fish and 97% of cnidarians (jellyfish, corals, anemones and hydroids) are bioluminescent. Due to the vastness of this form of communication it could be said that bioluminescence may be the most abundant form of communication on earth. Humans see only a small portion of bioluminescence – we generally observe bioluminescence resulting from physical turbulences of the surface water due to waves or boat hulls. The aggravation of the water triggers a bioluminescent response in surface dwelling bioluminescent organisms. One of the most common bioluminescent displays observed by humans is from planktonic surface dwellers. When blooming they form a dense surface layer, which by daylight is reddish-brown in colour but at night transforms into a light display. We can see bioluminescence at Gili Lankanfushi – turn your torch off on a night snorkel and wave your hands around to disturb the water. Bioluminescence is unpredictable but the best times to observe it are when the moon is waning. 
 
Animals can light up for a variety of reasons:
to defend themselves, to procure mates and to camouflage or hunt. The dark is an unforgiving place and finding food can be life or death. Some animals concentrate their bioluminescence in a lure and dangle it around their mouths. The deep-sea angler fish has this adaptation – its lure is lit by bioluminescent bacteria. Prey are attracted to the light and can be engulfed before they realise it. The Stauroteuthis octopus which lives below 700m has replaced some of its suckers with bioluminescent cells that direct their planktonic prey into their mouth. The production of light by the cookie-cutter shark tricks whales and squid into venturing closer and once close enough the shark takes a bite out of the animal before it escapes.

Long wavelengths like red light are absorbed quickly in the surface waters and it is due to this that many deep sea animals are red – they become invisible. Additionally many organisms have lost the ability to see red light. However, the dragonfish has evolved to emit and see red light. This allows it to see red coloured prey and also they can light up the surrounding water to hunt or look for a mate.

 
Finding a mate in the dark can be a major hardship.
Flashing bioluminescent displays can be used as a signal between males and females of the same species to signify the desire to reproduce. For example, a type of male Caribbean crustacean (ostracod) lights up its upper lips to attract females. 
 
Even though bioluminescence lights up the darkness it can be used for protection and camouflage. Many animals will produce a strong flash of light to confuse predators and swim off whilst the predator is blinded. Some squid can produce bioluminescent ink – upon ejection it can stick to the predator and light it up. This can lead to the predator becoming a meal for something even larger. If a predator manages to take a bite out of a bioluminescent organism the stomach of that predator will glow making it an easy target and giving the prey time to escape
Bioluminescence can also be used for counter illumination. This is where the animal can manipulate light to prevent itself producing a shadow and making it almost invisible. They can use bioluminescence to match the light coming from the surface. This makes it almost impossible for predators below to see their prey. The lantern shark is an example of this – it can make itself look invisible by producing blue/green light to blend in with the background.
It’s surprising how any organisms create light, even in an aquarium you may notice it.
Next time you are at Gili Lankanfushi try and see the bioluminescence yourself. You never know when the next flash of light will catch you by surprise!

PADI’s guest blogger Emma Bell introduces herself:

I am a marine biologist and scuba diver from England. I have had the privilege of working in Greece, Seychelles and Maldives. I have worked in an aquaculture research centre where I focused on hormonal manipulation of a pelagic fish species. In addition, I have experience with coral restoration projects including frames and ropes; habitat restoration – crown of thorns, drupella and invasive plant species removal; educational activities and social media updates including blogs. I have also monitored population dynamics of bird, turtle, shark and cetacean species to aid in their conservation. I started my career working in the Maldives and I have done a round trip via Greece, England and Seychelles, I hope to increase my skills set and knowledge further whilst I am at Gili Lankanfushi, Maldives.

Carpe Diem Maldives Introduces Coral Reef Awareness Campaign in Celebration of IYOR 2018

January 2018: Carpe Diem Maldives Pvt. Ltd. begins a 12-month social media campaign to celebrate International Year of Coral Reefs 2018.

Crystal clear waters teeming with colour and marine life surround The Maldives, making it one of the most appealing and diverse coral reef destinations in the world. The new digital campaign led by Carpe Diem Maldives promotes awareness towards the status of the destination’s coral reefs. Recreational and professional divers are invited to share their underwater images through Instagram and Facebook channels using hashtags #maldivesreefawareness #carpediemmaldives and #IYOR2018 stating information to three related Ds – dive, date and depth – on each image.

2018 was announced International Year of the Reef (IYOR – www.iyor2018.org) for the third time since 1997 by International Coral Reef Initiative (ICRI), an informal partnership between the Nations and organisations that strive to preserve coral reefs and related ecosystems around the world. IYOR is a global effort to increase awareness and understanding on the values and threats to coral reefs, as well as to support related conservation, research and management efforts.

Francis Staub, International Coordinator for the Year of the Reef for ICRI states, “We welcome this initiative embracing modern media and recognising public awareness as an essential element of coral reef conservation. Campaigns such as this ensure that the general public understands the value of, and the threats to coral reefs. Furthermore, the ongoing stream of images through #maldivesreefawareness on social media channels provides marine scientists and other stakeholders around the world access to real time data on coral reefs in The Maldives.”

Regularly visited dive sites across the Maldivian atolls will be captured to show the real time reef status amidst the effects of global warming, while also recording the ongoing recovery and conservation efforts being carried out by organisations such as Coral Reef CPR. At the same time, the digital campaign encourages public engagement and general awareness to the importance of coral reefs globally.

Haris Mohamed, Acting Managing Director for Maldives Marketing and Public Relations Corporation says, “Recently awarded World’s Leading Dive Destination at the 24th annual World Travel Awards, the Maldives attracts divers from around the world to experience the beauty of our underwater marine life and reefs. This initiative by Carpe Diem Maldives highlights the conservation efforts various organisations are carrying out to ensure our reefs remain resilient and healthy for generations to come. We strongly encourage all divers to the Maldives to share their images on social media with the hashtag #maldivesreefawareness.” 

Likewise, PADI Regional Manager for The Maldives, Matt Wenger, explains “Coral reefs are among the most beautiful ecosystems on the planet and PADI works with local communities around the world to ensure that residents understand the value of their local treasure. With close to 1.2 million tourist arrivals a year to The Maldives, initiatives like Carpe Diem’s #maldivesreefawareness are so important to get the message across about the beauty of the underwater world and why we need to do everything we can to protect it. We wholeheartedly encourage all divers to participate in this simple yet effective image sharing campaign.”

The digital campaign, which will run exclusively in The Maldives until December 31st, 2018, will be promoted to guests on Carpe Diem’s liveaboard dive cruises and at the upcoming resort in Raa Atoll. Carpe Diem Cruises welcome up to 60 divers weekly across all three of their luxury liveaboard cruises. Towards the end of 2018, campaign images posted throughout the year can be submitted to a panel of professional photographers, conservationists and IYOR officials, with a chance of winning a 4-night stay in 2019 at the new resort Carpe Diem Beach Resort & Spa.

 

For more information on Carpe Diem Maldives Pvt. Ltd., please visit www.carpediemmaldives.com