Friday, December 23, 2016

Dry season brings some exciting sightings!

The monsoonal winds are starting to shift here at Gili Lankanfushi, with blustery days giving over to calm glass-like seas. Sadly this means the end of our epic Manta season is approaching, but on the plus side, the strong incoming currents of the Iruvai season bring with them some fantastic shark sightings!

Just last week we were lucky enough to spot two incredible Oceanic Blacktip Sharks (Carcharhinus limbatus) (Above)! This secretive species is rarely seen in Maldives, however we hear whispers of areas where they're more common than other sites.. Note the much larger size, sharp snout, elongated upper caudal lobe, and diminished black dorsal tip, distinguishing it from its reef counterpart, Carcharhinus melanopterus (Right).


Whilst Dive Instructor Nazeef came back from a dive last week claiming another Great Hammerhead sighting, I had exciting news of my own, having snorkeled with the elusive Guitarfish!
We have been lucky to have daily Giant Guitarfish (Rhychobatus djiddensis) (left) sightings this week! These fish, technically in the ray family, use their ventrally located mouth to dig small organisms out of the sand. This bold individual can be seen cruising under our arrival jetty each day at about 5pm, where she didn't seem phased by my presence at all!

All in all, a pretty cool few days under water! 

Monday, December 12, 2016

Researching entangled turtle populations with the Olive Ridley Project

Recently we have been teaming up with the folks over at the Olive Ridley Project to conduct several experiments in order to assist with Martin Stelfox (Founder and CEO)'s PhD thesis. With Martin's twice yearly visit looming, myself and Josie nipped over to see our friends at the Turtle Rehabilitation Centre at the Four Seasons at Kuda Huraa to collect some DNA samples from their turtle patients.

As entanglement often leads to flipper amputation,
researching this issue to find solutions is vital.

As you may know, the Olive Ridley Project is working towards eradicating ghost fishing gear in the Indian Ocean, and part of Martin's thesis is to discover where these nets may be coming from in order to inform fisheries. One way of finding this out is to work backwards, by finding out where the turtles, which become entangled in these nets, came from. Each turtle has it's own DNA signature which gives us clues as to which population it has come from. We can then start to piece together where the net was present in order to capture a particular turtle. Genius! 
Chilled out juvenile 'Winslow'

As Four Seasons is the central hub where victims of entanglement are sent for rehabilitation, we headed there to collect our samples.

Having a tissue sample taken is a little bit like having your ear pierced, so thankfully the turtles only feel a little pinch. The skin on their flippers is extremely tough; designed not to be damaged whilst they forage on sharp coral reefs, but we are still mindful to be quick and clean. We did everything possible to reduce stress to the turtles, who were very well behaved, and our results could unlock some interesting answers, making these turtles ambassadors for the protection of their species!

Our thanks go out to the Marine Savers of Kuda Huraa for their hospitality and help with the project!

Martin visited Gili Lankanfushi for a few days last week, where he was able to collect his all important samples and take them back to the lab in the UK! 
Martin has trained over 40 hosts at Gili Lankanfushi!
Whilst here, he helped train a new batch of hosts in case they come across a ghost net or entangled turtle. He also held an interesting presentation for our guests, and set up a pilot study with the ultimate aim of aging ghost gear based on bio-accumulation and UV radiation! 
Martin demonstrates how turtles can become
entangled to an interested group of guests.

To support the important work of the Olive Ridley Project, you can join their #FreeTheFlipper campaign and donate by clicking this link: https://www.generosity.com/animal-pet-fundraising/free-the-flipper . The money raised will help develop a system in Pakistan where ghost gear will be collected and reused by the community to generate an alternative income: basically turning trash into treasure, and eliminating discarded nets in the ocean! 

Friday, November 4, 2016

Drupella Removal Expedition: Gili Hosts Help Save our Coral!

Drupella aggregate on Montipora, leaving a white coral
skeleton behind
Spa Therapist, Esther, swaps jobs for the day! 
Drupella cornus are a coraliverous species of snail known to prey upon fast growing branching coral species. Following the recent El Nino of 2016 which killed of ~80% of corals on most reefs in the Maldives, we are seeing what appears to be an outbreak of these snails, with up to 20 individuals found preying upon one coral colony. We believe however, that the number of snails has not increased, merely their prey has drastically decreased, causing those existing snails to aggregate on the remaining coral and making it appear as if there are more than before. When the coral-snail ratio is thrown off balance following a major disturbance such as coral bleaching, it can be detrimental to the reef. In their usual small numbers, these snails do influence reef structure and biodiversity in a positive way, much like the Crown of Thorns Starfish (Acanthaster planci), but when there are too many snails in comparison to the amount of coral, reef managers are encouraged to step in to control the predator outbreak, much like we have been doing with the Crown of Thorns Starfish. At Gili Lankanfushi, we are lucky in that we have huge amounts of a coral known as Montipora digitata on our Eastern Reef Flat which was unaffected by the massive El Nino in April. It has recently become a favourite food of these pesky Drupella snails, and so myself and Josie decided to arrange a snorkel with our hosts to remove as many as possible in the hope of restoring some balance to the predator-prey relationships. 
Josie and Esther with their Catch of the Day! 

Within 30 minutes, 3 of us were able to remove more than 300 snails! We plan to go back over the coming weeks to make more of a dent in the population. It's important we don't remove them all though, as a great number of fish species naturally prey on these snails, and we don't want to steal their dinner! Triggerfish, porcupine fish, snapper and bream are just some of the fish groups known to eat Drupella, and we wonder if the fish are finding it easy to snap them up in their aggregated state, will we see a small increase in fish numbers in the near future? 

Wednesday, November 2, 2016

Unbelievable Manta Ray Sightings!

The Manta action is really heating up here at Gili Lankanfushi, as we are treated to some of the best Manta sightings at our local Manta Point in 15 years! As we step off the boat at our Manta Points these days, it's getting really hard not to have massive expectations, and so far, the Manta's have delivered! 
We had 30 positive IDs from this day at Lankan Manta Point! The activity is mind blowing! Credit: Deborah Burn
Normally between 5 and 10 Mantas on the cleaning station is a good day for us, with 16 being the maximum number of individuals we have sighted there during one dive over the last 4 years (Remember last September's Manta Mania post). This year however, is a different story with at least 30 individual Manta rays gracing our Manta Point at one time! The Manta Trust tells us they're receiving about 100 different individual IDs for the site over a one day period! The reason why? A super productive monsoon combined with breeding season! The Manta Trust are speculating that this years' plankton productivity has boosted our Manta's energy levels, causing record breaking breeding activity! 

Manta Courtship. video credit: Dean De Mouilpied.
We are seeing massive aggregations of males and females coming into the cleaning stations to find a mate, which means we are not only treated to the usual cleaning behaviour, but also to some spectacular breeding behaviour!! Statistically, female Mantas spend more time grooming at the cleaning stations than males do, but during breeding season these ratios shift, and we see higher numbers of males showing up at the stations looking to meet a mature female. Once the female is ready to mate, we believe she releases a pheromone signalling the males, who will start to follow her. She will then lead these males on a mad chase around the reef, testing their fitness, which we call a 'mating train'. This involves all manner of high speed twists and turns, and can even include breaches out of the water! At our local Manta Point we are even seeing the larger females, who are more used to seeing divers, using us and our bubbles as part of their obstacle course, trying to determine the fitness of her suitors by testing which of the males is brave enough to come close to the divers and swim through our bubbles! This can be a pretty spectacular sight- being dive bombed by around 10 mantas all in a train! Check out the video above which documents some fantastic courtship behaviour at Sunlight Thila. Video credit goes to Dean De Mouilpied, one of our lucky divers who was treated to not one, but several insane Manta dives last week! 
Josie has submitted over 100 Manta IDs this season alone! 

You may remember that taking a simple photograph of the unique spot patterns on Manta bellies helps us to track each individual Manta ray. Because of the unusually high number of males at our cleaning stations at the moment, which are usually more elusive, we have been treated to some brand new encounters where we have managed to identify 5 brand new male Mantas over the last week! This important data helps to give a more clear picture of Manta demographics in the Maldives. 
Working closely with the Manta Trust and Manta Ecology Project, we submit these ID's along with vital data about the dive including abiotic factors and behavioural notes. This information is helping researchers unravel the mysteries of Manta ray biology and ecology, and can help inform policy and protective strategies for these majestic animals, so if you have a beautiful belly shot, don't hesitate to send it to us, or to the above websites, where you can help our research! If you're really lucky, you may even get to name your very own Manta!!

Stay tuned to meet this months brand new Mantas, and discover how many Mantas we have seen so far this season! Spoiler alert: We have smashed last year's total of 233 already! 

See you soon,
Debs