Tuesday, April 26, 2016

Coral Bleaching Basics & the 2016 El Nino

We have noticed the usual colours draining from our beautiful corals over the last few weeks. This phenomenon is known as Coral Bleaching, and is caused by excessive stressful conditions in the seawater. We have been collecting data to document this event, but before we share our findings, we wanted to help our readers to understand coral bleaching and why it is happening. To do this we must first understand what coral really is…

Tiny coral animals live together in colonies
Coral is made up of hundreds of tiny jelly-like creatures, all stuck together. Like a jellyfish, they have stinging tentacles that are used to catch plankton in the water for food. Their skin is see-through, but living within are thousands of plant or algal cells called zooxanthellae. Not only do these algal cells give the corals their colours (browns, greens and yellows), but they also provide the coral animals with lots of energy. In fact, about 90% of the energy that coral needs to survive is taken from these algal cells as they convert sunlight into sugars through photosynthesis. With this energy, the coral animals are able to build a hard, limestone skeleton by accumulating naturally occurring calcium and carbonate ions from the seawater. This skeleton is white, and this is what we see during coral bleaching events.

Some resistant or shaded corals evade bleaching...
...Others bleach bright white
The current bleaching is happening because of an increase in water temperature. We have all noticed the hot, calm weather recently. This is caused by El Nino- a weather phenomenon affecting the Pacific Ocean which is so influential that the whole world can feel the effects. Here in the Indian Ocean, we experience a rise in temperature. Since 1900, the world has endured 26 El Nino events, and this year’s El Nino is set to be the strongest in recorded history, with sea surface temperatures already rivaling that of the 1997/1998 El Nino, with an average increase of 2.3°C!

Acropora nasuta is almost fluorescent in a bleached state
The beautiful greens and purples are natural pigments usually
hidden by the zooxanthellae
These unusually high water temperatures are damaging the delicate relationship between the coral animal and algae, which live together symbiotically. The animal respires by taking in oxygen and releasing carbon dioxide as a waste product (just like humans), whereas the algae respires in the opposite fashion; by taking that carbon dioxide ‘waste’ and releasing oxygen. Thereby, the coral and algae use each other’s waste and live in a perfect balance. When the temperature increases, the algae start to release oxygen radicals, or bad oxygen molecules, which can damage animal tissues. Because of this, the animal must spit out what has become harmful algae. As the algal cells are ejected, the coral loses its colour. This coral is not dead, rather it is surviving in a stressed state, where it must try to gain all of its energy by capturing plankton. In this bleached state, without those energy making algal cells, coral can only survive for about 3 weeks, by which time the coral starts to metabolise its own tissues and, in effect, it starves. If the normal temperatures return, the corals can capture new algal cells for storage, recovering its colour and its vitality.

In 1998, the previous El Nino event was responsible for the loss of an estimated 80% of the coral in the Maldives! This current event is expected to be worse, where this hot weather will likely continue through until May. If this happens it could take between 10-15 years for many reefs to make any kind of recovery. El Nino events are increasing in severity and frequency- this is a direct cause of anthropogenic Climate Change. If the Maldives loses its reefs, it will lose its fisheries, its tourism and eventually its islands. These reefs are intrinsically linked to Maldivian survival- don't sit by and watch. Do your bit to help the planet. it is so important for us to try and reduce our carbon footprint, both as individuals and within our businesses! Help the planet and our coral reefs (and also your wallet) by saving energy, streaming for renewables, and reducing emissions!

Saturday, April 2, 2016

Mantas of Rasfari

The Manta rays are so shallow, it's perfect for snorkeling!
Even though the water is crystal clear, and we can see a huge array of marine life on our doorstep, myself and Josie have been receiving requests to see Manta rays over Easter. Whilst it isn't our Manta season, it's the perfect time of year to take a smooth 30 minute speedboat ride to the West of the atoll where we can spot the Mantas at a site called Rasfari! What is special about this cleaning station is how shallow it is! At 2m deep, you have to lie flat on the surface to make sure the Mantas can pass beneath you untouched! 
With the biggest brain of any fish, we wonder what this girl was thinking!

So many cleaner fish made getting a belly spot ID impossible!!
We were lucky enough to swim with three of these gentle giants on our last trip! They hover over the seabed, which acts as a spa for the huge rays, where tiny cleaner fishes nip away blood sucking parasites and old bits of food from the Mantas gill rakers. With so many cleaner fishes, it was almost impossible to take clear belly photographs to identify the individuals by their unique spot patterns! Seemingly oblivious to the snorkelers on the surface, we had to actively swim out of their way as they wheeled about to find the best cleaning spot! 

Sites like the one at Rasfari are of vast ecological importance- a special place for the Manta rays to come to ensure healthy skin, and possibly to engage in courtship activities. Whilst it is an exciting experience for snorkelers, and a great opportunity to get up close and personal with these harmless sea creatures, it is always important to ensure we do not disturb them or their natural behaviour. To do this, we always brief our guests before entering the water, and we ask our readers to ensure they never touch, chase, or alter the swimming direction or behaviour of Manta rays during snorkeling and diving activities. Remember that many snorkelers will come to these sites, and if we do not give the Mantas space and respect, they will no longer come to these amazing cleaning stations, which is not only a huge shame for tourism, but may also impact upon the welfare of the Mantas in the area! Always listen to the guides in the water, who are trying to ensure everyone has an incredible experience in a way that will sustain the site as it is for years to come! 

Anyone on their way to Gili over the next month? A trip to Rasfari to see these shallow water giants is a must! On the way back, we can even squeeze in a spot of turtle snorkeling! 

Wednesday, March 23, 2016

Visiting scientists collect valuable data on COTS plague

We have had a busy week here in the Marine Biology section as we welcomed more international researchers to our little slice of paradise! 

The most beautiful pest in the World?
Starfish devour the only piece of living coral left on this reef
Following the recent Crown of Thorns Starfish (COTS) outbreak on reefs in the Maldives, many reef managers, including ourselves, were concerned for the reef's health. As such, we have collectively reached out to all corners of the globe for help, so that we might better understand and control this plague. Our call was answered this week by a research team from James Cook University in Australia. 

You may remember that with the help of the Living Oceans Foundation in October, Gili Lankanfushi removed 1000 individuals over a 2km reef tract during a 4 day period. With each starfish capable of eating a dinner plate sized amount of coral per day, you can see why these creatures are recognised as a pest. When the population density is high enough, they can decimate entire reefs in a matter of weeks! Removing them from the ecosystem during outbreaks is the only way we can hope to control numbers and save our reef!
Not a bad office: Prof. Pratchett dissects 
one specimen to  determine fecundity

Whilst these outbreaks are detrimental for the reef systems, they also provide an opportunity for us to study these infamous creatures, in the hope to understand more about their ecology and biology. Without this knowledge, we cannot hope to develop successful control techniques. At Gili Lankanfushi, we were lucky enough to host one of the World's leading authorities on COTS ecology; Professor Morgan Pratchett from James Cook University in Townsville, Australia.

The majority of Morgan's experience with COTS has been from the Great Barrier Reef, and having never visited the Maldives before, he was keen to jump in the water and study our beautiful purple colourmorph populations. We had just 4 days to remove starfish from the reef and process them for genetic study and to assess their fecundity (their capacity to produce offspring). Over the course of the field trip, we removed 100 starfish and were able to collect samples from them all for further study. Some whole specimens of this understudied North Indian Ocean morph have even gone to various museums to be compared to other starfish in the same family!
Debs gets involved with the removal effort in an attempt to save our reef!
Using the data, we hope to understand more about the population dynamics of this particular outbreak, and once armed with more knowledge, we might be able to prepare more effectively for future invasions!

The Marine Biology team are really grateful to the management of Gili Lankanfushi Resort for supporting such important research studies, and we look forward to making more great connections with the international scientific community.

Thursday, February 18, 2016

A Surprise Encounter!

The beauty of diving in the Maldives is that a wonderful surprise can occur at any time. Today’s bolt from the blue (no pun intended) was a juvenile whale shark! An extremely rare sighting in North Male Atoll, whale sharks are much more commonly found in South Ari, some 120km further south than Gili Lankanfushi. It was during Dive 4 of the Open Water diving certification course, that a family of 4 got up close and personal with the world’s largest fish! Often confused for a whale because of the name, the whale shark (Rhincodon typus) is in fact a filter feeding cartilaginous fish that is completely harmless, unless you were to get in the way of its huge tail. The largest whale shark on record is 12.65m, however our particular gentle giant was only 3-4m in size, making it a young juvenile estimated to be about 4 years old. Like most little ones, he/she was very curious and swum within an arm’s length of the group. A true spectacle of nature!
Unfortunately on this occasion, nobody had a camera with them to get a shot of the juvenile. The above photograph was taken on Debs' last trip to South Ari where this 5.5m individual crept up on them during a snorkel.
Very little is actually known about these elusive giants, and to discover more about them, a group of Marine Biologists founded the Maldives Whale Shark Research Programme (MWSRP) in 2006. The research-based conservation charity based here in the Maldives is dedicated to studying the whale shark to find out more about their numbers, behaviour and movements in Maldives, as well as setting up community based conservation initiatives. In 2009 their work highlighting important whale shark habitats in the Maldives was crucial to the establishment of SAMPA; a large marine protected area in South Ari atoll. In addition, the codes of conduct MWSRP have developed make it possible for visitors to enjoy the whale sharks in a sustainable way, without disturbing these vulnerable animals.

 Here at Gili Lankanfushi, we have recently added a 'Whale Shark Adventure' to the list of excursions that we have on offer. This full day trip would include travelling down to the famous South Ari Marine Protected Area on our luxury yacht 'Gili Goes Voyaging'. Not only does the area offer a great chance to snorkel with the beautiful whale sharks, but it is also an amazing place to spot Manta rays, dolphins and turtles along the same reef! To fully appreciate the day, we can even stop at a deserted sandbank for a gourmet picnic, or cruise for a spot of big game fishing on the return journey! - whatever your heart desires, really!

The spots behind the gill slits are unique to each individual
and are used for photographic ID.
We can't wait to get down to SAMPA again, and hopefully, with the help our guests, get some ID photographs that can contribute to the great work that the MWSRP are doing. Similar to the Manta rays, the sharks have spot patterns unique to each individual. If you see your own whale sharks in Maldives, and especially if you have photographs of the sides of the fish, you should head to the Big Fish Network; an App you can download on your mobile to document your sightings.

With dry season in full swing, the sea is flat as a pancake and the visibility is fantastic. As for the dive team, we can’t wait to jump back in the water in the morning to see what tomorrows surprise will be. 

Jon, Debs & Josie