Save Our Seas Blogs

29 July 2010

The Ecological Role of Hawksbill Turtles on Coral Reefs

The ongoing research of Rainer von Brandis into the impacts of hawksbill turtle foraging behaviour in the Seychelles has been revealing the startling importance of their role in maintaining balanced coral reef ecosystems. With another season’s field work drawing to a close, it’s a good opportunity to reflect on Rainer’s discoveries thus far.

Hawksbill turtles have been severely depleted by humans in recent centuries and their absence from modern reefs has almost certainly influenced ecosystem dynamics. Prior to their depletion, hawksbill turtles had substantial influence on their marine habitats through their many roles as consumers, prey, and competitors; as hosts for parasites and pathogens; as substrates for epibionts; as nutrient transporters; and as modifiers of the landscape.

At D’Arros Island, Rainer’s underwater observations indicate that the roles of foraging hawksbills as both consumers and modifiers of the landscape are fundamental to the sustained functioning of the platform reef ecosystem.

Hawksbill turtle extracting a sponge from the reef. Photo by Rainer von Brandis.

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26 July 2010

Making History in Brazil!

Diving and Laje de Santos

They say good things come to those who are patient. I never really gave this saying too much thought until just recently…In the name of manta research I have spent six solid weeks (during the winter of 2009 and winter of 2010) diving a remote offshore rock called Laje de Santos in the south of Brazil looking for the elusive giant manta (Manta birostris). Until today, I have searched in vain. I was the one that actually chose this location for part of the worldwide study on this newly discovered species of ray, as this little spec of a rock is the largest documented aggregation site for this species in the southern Atlantic Ocean. But, to tell you the truth, despite my normal determined outlook when working in the field, I was really beginning to loose hope (and that’s pretty bad, since my current international research campaign is ironically named “Ray of Hope’).

Andrea in the field at Laje

But that’s the funny thing about marine field research and, I suppose, diving in general. It doesn’t matter what the ocean throws at you…countless hours of searching, dozens of dives in cold, green water, boat trip after boat trip on rough, windy seas…all of the excruciating effort and disappointment literally seems melt away the second the animal that you have been searching for appears. Your breath catches in your throat, time stands still and everything seems to make sense in the world. And this is why we divers torture ourselves by squeezing into unbearably uncomfortable wetsuits, why we swim around the sea covered in all kinds of tanks and hoses, and why we spend all of our money and time bobbing around in the middle of the ocean. It is precisely for this sensation and these encounters with special marine creatures. For the majority of us, the most precious encounters are with large, elusive megafauna like sharks, whales and dolphins. The object of my affection, of course, is the manta ray.
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23 July 2010

The little creatures

Posted by Juerg Brunnschweiler in Bull Sharks, Fiji Tags: ,

Diving in the Shark Reef Marine Reserve is different from most other places foremost because of the number of sharks. By sharks I mean especially bull sharks that can show up in packs of up to 50+ individuals on some days. Add the ocasional tiger shark and you will understand that their presence somewhat distracts from focussing on the smaller creatures that live on the reef. And there are plenty of them! For example, tiny little juvenile sharksuckers that are looking for a host or already found one. Very little is known about the behaviour and ecology of sharksuckers generally and even less about their juveniles. Have you ever noticed small juvenile sharksuckers of 5 cm lenght on larger host species? This size class can be regularly seen on, for example, giant trevallies or the fast moving rainbow runners in the Shark Reef Marine Reserve. Ivan and I have published a little piece of information about small juvenile sharksuckers in the journal Coral Reefs. Send me an email if you want a PDF copy of it.

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14 July 2010

Shark Truth at the Dragon Boat Festival

Posted by Vivian Kwong in Shark Truth Tags: ,

Dragon boating is an ancient Chinese water sport firmly rooted in myth and tradition. It started more than 2,000 years ago as a fertility rite in southern China that celebrated the coming solstice by awakening the slumbering Heavenly Dragon through the fury of their oars.

Harry's vulnerable side is irresistible.

Harry's vulnerable side is irresistible.

Vancouver celebrates and continues this rich tradition by hosting the annual Dragon Boat Festival which attracts competition from teams across the globe and more than 100,000 eager spectators every year.
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13 July 2010

Egyptian Flying Carpets

Posted by Andrea Marshall in Manta Rays, Mozambique Tags: , ,

When I closed my eyes I was flying out over the dramatic skyline of Cairo into the Egyptian desert… when I opened my eyes again, I was literally squinting into the blazing sun and I had to blink several times, unable to process what seemed to be an incredible mirage below me. The plane started to descend and I realized that this was not a figment of my imagination, this was Sharm El Sheikh, my destination, and we were fast approaching what could only be described as the Egyptian equivalent of Las Vegas.

Diving in the Red Sea

Sharm El Sheikh is the epitome of a scuba diver’s paradise. Its close proximity to many parts of Europe, Asia and Africa makes the prospect of a hassle-free, quick holiday within reach. The crystal clear waters are teeming with fish life.  Reefs drenched in soft coral of every conceivable colour and spectacular wrecks surrounded by clouds of game fish ensure that there is something for everyone.

Clear water and healthy coral reefs

The dives are easy, the water is always warm and the sun is forever shining. While some find the artificially created beaches, the all inclusive resorts, and the lack of culture a bit off-putting, surely divers agree that world class reefs like Shark & Yolanda and Jackson are well worth the trip, as are the rare glimpses of elusive marine life like oceanic white tips, hammerheads, and whale sharks.

But of course this is not what drew me to this destination…I was here for one animal and one animal alone…the elusive giant manta ray, Manta birostris.  Since our team differentiated it from its smaller cousin the reef manta, Manta alfredi, in 2009, we have had our eye on this species. With next to nothing known about this giant ocean wanderer it became clear to us early on that more intensive monitoring would be necessary to learn about its habits and ascertain its conservation status.

Dramatic fish schools

Science aside, the giant manta ray has always held a special place in my heart. The first manta that I ever encountered was a giant, barreling down at me across another sandy desert, albeit an underwater one, off Cocos Island (Costa Rica). Almost two decades and one love affair with manta rays later, I am still as mesmerized with this giant animal as the first day that I laid eyes on one. These days, however, my interests in them have evolved.

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