Wednesday, December 17, 2014

Coral Spawning

As the sun sinks beyond the horizon giving rise to a waning moon during the warmer months of the year, something amazing starts to happen on our reefs: The corals begin to spawn... and that's exactly what happened here at Gili Lankanfushi last week!

Tiny orange coral eggs dot the surface of
the water
If you’re a frequent visitor to our blog, you’ll know that corals are made up of hundreds of tiny animals we call polyps. These animals employ tiny algal cells to provide energy for them through photosynthesis, and they use this energy to secrete a calcium carbonate skeleton. The animals are all connected and can share energy- so we call them coral colonies.

The water lapping the beach appeared to be 
pinky brown- this is a mass of coral eggs!
Whilst these animals can reproduce asexually through fragmentation and budding (where the new polyps are genetic clones of the originals), they also possess the ability to sexually reproduce (where completely new genetic material is made). Each colony is a single sex: hundreds of males or hundreds of females. Because most corals are sessile organisms (fixed in one place and immobile), most employ a tactic called broadcast spawning, whereby eggs and sperm are released into the water column and mixed by natural currents. Female polyps produce egg bundles, and males eject sperm clouds into the water. Induced by a mixture of temperature, tidal movements and the lunar cycle, this is an event which occurs simultaneously throughout the reef, meaning every colony will spawn at the same time!

Last week, a guest discovered that the water close to the beach on the Eastern side of our island was a pinky brown colour and after taking one look at the moon, we decided the coral must have spawned! As all the corals spawn at the same time on the same night, they create spawning slicks on the water’s surface, which can be so large, they’re visible from planes!
Sadly, we did not see any spawning, but we did spot this
Banded Snake Eel!!

Sometimes, this amazing coral spawning event can go on for a couple of nights, and as coral spawning is on the bucket list of every  so I grabbed a torch and my snorkeling gear the following evening, and went for a night snorkel. Whilst we didn’t manage to see any more spawning, we did see a banded snake eel and a beautiful nudibranch! 

Better luck next year!! 

Saturday, November 22, 2014

Gili Goes Fishing

It's exciting for us here at Gili Lankanfushi to be launching a new set of fishing excursions run by Ocean Paradise Dive Centre! Our two choices: Big Game Fishing and Sunset Fishing are quickly becoming popular choices for our guests; with Big Game Fishing being more of a sporting and active excursion, and the Sunset option being much more relaxing for guests who want to try their hand at local hand-lining techniques as the sun goes down.
Me with my first crimson jobfish 
(Pristipomoides filamentosus)
The introduction of these excursions has meant Vaidas has been busy this past month creating new responsible fishing guidelines. Around the World, fish stocks are being depleted due to over fishing and unsustainable techniques. Here at Gili we work hard to make sure all our excursions have as little negative impact on the environment as possible. Based on the sizes different fish can attain and their minimum reproductive sizes, Vaidas has put together an info pack with minimum landing sizes of each type of fish, as well as implementing other rules such as a bag limit (number of fish guests can keep per trip) and species limits (number of fish per species guests can keep) that ensure we don't catch and keep more fish than we need to, and that most of our fish are released un-harmed.
This undulated moray eel 
(Gymnothorax undulatusis not 
on the menu and was released

The local Maldivians have used hand lines for hundreds of years

Saturday, November 8, 2014

Coral Lines: How are we doing so far ?

After nearly 2 months of hard work that involved unusually large amounts of staring at the computer screen; Debs making the base framework of this report, and amassing large amounts of data,  and me trying to summarize it and transform it into shiny graphs, we think we have finally made it! We will be posting updates monthly on our Coral Lines blog from now on. 

As of 8th of November, we have 33 coral lines in our nursery. We are experimenting with different growth forms of coral including Staghorn, Table, Bushy and Sub-massive (boulder-like) corals.

A total of 1674 fragments of coral were planted in our mid-water rope nursery to date, and 17 species of coral were used. Out of all the planted coral, 1572 fragments are still alive, with an average mortality of 11% per Coral Line (which is normal, and was due to planting/fragmentation related stress).

A very exciting set of data from coral growth measurements. During the first year (nursery stage) every single coral fragment on each coral line is measured (across the widest point of colony) every 3 months. This allows us to get an estimate of how fast the coral colony grows. So far the data should be treated with caution, since method is very basic, and we need to monitor for one year to get more accurate estimates. Nonetheless, you can see what we have found to-date. The fastest growing corals were staghorn (Acropora aspera & A. muricata), expanding more than 3 cm in just 3 months! The majority of other corals grew less than 1 cm in 3 months, just highlighting how slowly coral reefs form.

Since 75% of each Coral Line donation goes towards GILI SEAS (Social, Environmental Awareness and Sustainability) fund, we are also reporting on the financial side of the project. As far as donations go, you can see that we hit the record of 9 donations in October, and we are currently working toward a system whereby those who wish can donate online. We would like to thank all the guests who have donated so far!

We have also used some of our fund already with the two major spending areas being equipment and cloud storage. Equipment included a temperature logger, weighing scales and calipers. Since the early stages of project, cloud backup was necessary to ensure that all our precious data was backed up and therefore not lost!

What is the plan for the future?

We are constantly working hard to develop and improve our methods using current literature as well as trial and error in a bid to produce excellent scientific data which will be of publishable standard in a peer reviewed journal. As we learn, we are documenting our findings and we hope to create a user friendly manual that can be used to guide others in the field. We also plan on continuing our focus on raising awareness by planting more lines with guests, providing more information online, and sharing our findings where possible.

Friday, September 26, 2014

Black Tip Reef Shark Breeding

We have been observing some very odd behaviour from our adult Black Tip Reef Sharks (Carcharhinus melanopterus) recently in the shallow water between the Spa and Jetty 2. Groups of up to 32 individuals have been observed within a small area being very active; chasing each other, almost beaching themselves, and making a huge commotion in the shallows! These groups are actually breeding aggregations, and we have been lucky enough to get some video footage of this very under studied event, which we have posted below! Credit goes to Sophon, our Spa Manager.

This species has black tips to all fins, most obviously the dorsal and caudal fin
It's not uncommon to spot large Black Tips from the jetty!
A small shark attaining lengths of around 1.8m with characteristic black tips to each fin which give them their name, these Black Tip Reef Sharks are usually seen on the reef flat and near the drop off in shallow water where they feed on small boney fishes, squid, and crustaceans. Despite a conservation status allocated by the IUCN as “Near Threatened”, it is not uncommon to spot Black Tips here at Gili, whether you’re snorkeling or just strolling along the jetties. With 37 different species of shark recorded in Maldives, and no recorded shark attacks since records began, we are lucky enough to be in one of the safest places in the world for snorkeling and diving with these beautiful creatures!

The life history of the Black Tip is a little bit of a mystery, with lots of conflicting data, which mostly reflects geographical ranges. Here at Gili, we observe mating behaviour around twice per year. This year, however, I was lucky enough to witness one such event from start to finish first hand! The sharks began to aggregate in water only 1m deep at about 10am, moving very slowly between each other at first, and building in numbers over a period of about 45 minutes. After approximately 1 hour, I could clearly see males following females very closely, attracted by chemicals she releases. All the sharks began to swarm quickly into a smaller area, where I could count ~32 within about 20 square meters!! After this courting behaviour, the male sharks bite the females’ pectoral fins and push her head against the shallow sand and mating begins. It lasts a few minutes, and once complete, all the sharks disperse and continue with their usual daily behaviour: Patrolling the reef.
Black Tip pups congregate in the shallow lagoon at 
Gili Lankanfushi

Studies suggest Black Tip gestation period is somewhere between 9 and 16 months, at which point our females will give birth to 2-5 live pups.  Black Tip Reef Sharks have high site fidelity, meaning these individuals will remain on Gili’s reef for many years. We will have to check back from next June and see if we can find any small pups hiding in the shallows! In the mean time- watch out for big pregnant females!!