Cambridge University based The Naked Scientists have just launched Naked Oceans, a great new podcast devoted to marine science sponsored by Save Our Seas. They’re off to a strong start, with episodes focusing on climate change and oil spills already available for free online and through iTunes:

The problem of oil spills
To launch this brand new podcast series, Naked Oceans ventures beneath the waves to investigate the impacts of oil spills on the marine environment. We hunt down the hidden world of microbes in Louisiana wetlands, trace the fingerprint of oil in the open oceans, and discuss the likely fallout from the Deepwater Horizon oil spill in the Gulf of Mexico. And 14 years on, we meet some of the survivors of the Sea Empress Oil Spill in the Welsh coast. And we invite Carl Safina to choose our first Critter of the Month. Listen now

Climate change and the Oceans
Join us as we dive into the science of climate change in the oceans. What changes are we already seeing, what affects are they having on marine life, and what are the prospects for the future? We call in on the Arctic and the Antarctic to find out what’s going on in some of the most vulnerable parts of the oceans, and we meet some extraordinary critters from the bottom of the sea at the bottom of the world. Listen now

You can easily stay up to date with the latest episodes by subscribing (for free!) here. Click here to learn more about Naked Oceans, or download the full press release.

Image credit: Cedric Guigand, University of Miami RSMAS Marine Photobank

Filming sevengill sharks at Millers Point, False Bay

Last year saw the initialization of the Save Our Seas Sevengill Research Project, looking into the population demography and behavioural ecology of the broadnose sevengill shark, Notorynchus cepedianus. The study aims to investigate aspects of the biology of the sevengill shark using in-water observations made by SCUBA divers. The project will form the basis of my MSc thesis, and is being supervised by Prof. Charles Griffiths (UCT) and Alison Kock (SOSSC). The project is being made possible through support and funding of SOSSC and Shark Explorers, and supported by diving companies Animal Ocean and Pisces Divers.

A major aspect of this project is the use of photographic identification (photo-ID) as an alternative to tagging, for the identification of individuals. Photo-ID allows for individual animals to be identified using natural spot patterns, without the need for invasive artificial tagging. This also allows us to record, on an individual level, almost every shark that we encounter on a dive; something that is not generally possible using conventional tagging practices. The viability of photo-ID as a reliable means of identification was validated last year, and is now being used as the basic means of individual identification for the project.

The black and white spots on the dorsal fin are used to identify individual sharks

This year we are furthering this study, looking at the demographics and behavior of a population of sevengill sharks around an aggregation site in False Bay, South Africa. So many questions about these animals remain unanswered, land we’ll be investigating population size and sex structure, as well as determining how these sharks are using the habitat, where and when are they feeding and aspects of reproduction, in particular where and when are they breeding and giving birth.

A large female sevengill with fresh bites, possibly indicating recent mating behaviour

Recent discussions within the SOSSC team have yielded some interesting ideas and some exciting developments to the project, which we will be sure to share with you as they progress. For now the team is continuing to dive with these ancient creatures on a regular basis, observing, studying and recording every detail we can. Any person can contribute by sending their photo-ID to: research.shark@gmail.com. Visit our Facebook page for all the details at http://www.facebook.com/#!/group.php?gid=131021003605004&ref=ts

Until next time, keep caring for our oceans,

Robert Raw

MSc student, University of Cape Town

On behalf of the Save Our Seas Shark Centre Team

Leslie Iwerks, Eugenie Clarke, Dan Beecham, Alison Kock in Kalk Bay

I was fortunate to be able to present some of our white shark research results in Hawaii and Australia earlier this year, while renovations were made to the SOSSC. We had to suspend most educational lessons at the centre during the renovations, but we were still able to host legendary shark research pioneer Dr. Eugenie Clarke and her daughter Aya in June. It was Dr. Clarke’s first visit to South Africa and during their stay we conducted white shark fieldwork and went sevengill shark diving. Diving with sevengills was another first for Dr. Clarke and even though the water was surgy and cold, Dr. Clarke enjoyed the experience of seeing sevengills up close. We also partnered with academy nominated film director, Leslie Iwerks, on a project, which we will be working on for the next few months. In July we welcomed Dr. Charlie Huveneers from the South Australian Research and Development Institute for the start of a specialized project on sharks and safety, but we’ll have more information for you soon as things progress on that front.

Robert Raw is conducting a MSc project on sevengill sharks

Adrian Hewitt will be completing his degree on reproductive biology of white sharks and assisting me with the ongoing genetic, tagging and photo-ID aspects of the project, while Robert Raw will be working on population demographics and habitat preferences of sevengill sharks (Notorynchus cepedianus). Adrian, Rob and myself will be keeping you updated on our shark research projects from the field, while Paul, Kevin, Meg and Sam will be updating you on exciting education and awareness campaigns. Other exciting projects lined up include more manual tracking of sharks in False Bay, attaching improved HD Crittercams to white sharks, beach clean-ups and participation in surfing and filming events.

Warm regards from all of us at the SOSSC

Adrian Hewitt is conducting a MSc on white shark reproductive biology

There are paradises on this planet? Indeed, and Fiji is one of them. Arte has produced a docu that also highlights some aspects of the Bull Shark Tagging Programme. You can watch it online here.

Holbox is the manta ray and whale shark capital of the Gulf

As I write this, I am sitting at the airport in Cancun, Mexico. I have this surreal feeling that something huge just happened to me, but I still cannot overcome the feeling that I am in a dream. Everything just seems a little too bizarre, a little too out of the ordinary.

A little over a week ago, I touched down in Mexico and was given a warm welcome by a fabulous team of Mexican biologists and conservationists. Considering the rural location, I was impressed at both the size of their strong and dedicated team and what they have been able to accomplish out here with respect to their marine protected areas. My heart swelled with hope as I thought about the future possibilities in Mozambique.

Almost immediately, I headed out to the tiny island of Holbox, a world-renowned aggregation site for whale sharks, to meet up with Silvia Hinojosa, the manta research team leader. It was early and I was battered, bruised and a little deflated from the Brazilian leg of my journey, not to mention a week behind schedule. While the scenery surrounding me was breathtaking, I have to admit that my fatigue was starting to get the better of me. But then she uttered four little magic words and my determination was instantly restored, “The mantas are here.”

The next three days passed in a whirlwind. There were mantas, there were tags, there was joy and there was guacamole.  What was this place and why had I never been here before? It seemed like utopia.

Getting up early does have its advantages!

After literally months of travel and struggle I had reached payday. Day 1, Mexico, probably the single best day I have spent in the field in two years. If I tell you about it, it will probably seem like fiction, but I will give it a go anyway…

Research kicks off early in the morning in Holbox. The team likes to get out on the water early to avoid competition with tourist boats, which suited me just fine. As we approached the dock at dawn, we were greeted by one of the most spectacular sunrises in recent memory. We may have the best sunsets in Africa…but surly Mexico has the best sunrises. The ocean that day was dam flat. Dam flat. I cannot reiterate this point enough. It was one of the most unusual things I have ever seen, and not because I have never seen the ocean like that before, but because as we started to drive out to sea, the water became flatter and flatter until there was not so much as a ripple on the surface (and we were a good hour offshore at this point). Incredible stuff. I looked at my watch, it was only 7:45 am and I was already overcome with a sense of good fortune.

The water was just full of zooplankton!

And sure enough, it continued… A few minutes later, like we were in some kind or zoo or game park, Silvia drove straight up to a massive group of feeding mantas, parking the boat a few meters off to the side of them. Imagine that! All over the world I’m diving at specific reefs or offshore rocks, waiting and waiting for mantas to arrive or spending countless hours searching, and we just zoom straight out to sea, with zero reference points, and just park next to 20 feeding mantas. I am still in disbelief.

Fearing my luck would fade, I quickly jumped in. The water was warm and inviting and I felt weightless after diving for weeks in heavy suits and diving equipment in Brazil. Invigorated by the freedom, I swiftly swam over to the pack of feeding mantas. At a distance, my first observation was of the water itself. While crystal clear, the water was swarming with endless varieties of zooplankton (from chaetognaths to copepods) making it slightly difficult to see properly. However, even from a distance, I could see the determination of the mantas trying to siphon up all of the wriggling and zooming animals into their enormous mouths.

Manta rays feeding...a thing of grace!

I am always awe-struck when I see manta rays feed. It seems so effortless, their technique so efficient, their bodies so well designed. Today the sea was so calm that the plankton reflected off the surface like glass, doubling the appearance of food particles in the water. I could almost hear the manta’s stomachs grumbling. Interestingly enough, much of the plankton was concentrated at the surface and the split vision of my dive mask allowed me to watch the tiny copepods jump clear into the air whenever the water was disturbed (an obvious technique to avoid predators).

While dramatically arching their backs, the mantas propelled themselves forward skimming the upper edge of their elongated mouths across the surface of the water. Their cephalic fins, held wide like enormous paddles on either side of their face, blocked the escape routes of the fleeing plankton. For hours I watched as these manta rays literally gorged themselves on this plankton feast.

And there were whale sharks too! True to Holbox’s reputation, dozens of whale sharks were spotted slowly patrolling beneath the surface of the ocean, their enormous dorsal fins weaving trails in the still surface water.

Note the prop marks down the side of the shark!

Amazingly the tourist only appeared interested in the sharks. Dozens and dozens of tourist boats dotted the horizon, each patiently awaiting their turn. Marine park law prohibits more than three people in the water at a time, which helps to reduce the stress on these massive animals while they are feeding in the park. Although most of the boats adhered to this and many of the other rules and regulation for swimming with these animals, I still saw several whale sharks and manta rays with fresh propeller marks, suggesting that, despite their best efforts to protect these gentle giants, there are still a fair amount of boat strikes occurring in the area.

But as amazing as all of this action was, it did not compare to the elation that overcame me as I swam into that first pack of feeding manta rays. For those of you that have been following our work, you may distinctly remember the discovery of a second species of Manta in 2009. If you have heard my lectures or have read our Manta taxonomy paper, you may also recall my proposal of a third species of Manta in the Atlantic.

Typical whale shark tourist boat in Holbox

I initially made this suggestion after a dissection I preformed on an odd looking specimen in a museum archive. This suspicion continued to strengthen after sourcing many photos from Caribbean and North American waters. Something was just not adding up; what I was seeing was neither Manta birostris (the giant manta) or Manta alfredi (the reef manta), it was something else. It was hard to put my finger on the differences at the time, but something was definitely different. I was sure of it.

As I swam into that cloud of feeding mantas on Day 1 in Holbox all of my doubts melted away. I was looking smack into the face of the mystery ray. I had not imagined it, I was not grasping at straws, it was real, it was alive, and it was coming right towards me. It is not often in the life of a scientist that you get a Eureka moment. I have been fortunate enough to have had a few so far in my short career. It is an amazing feeling, a totally indescribable moment (kind of a feeling of peace washing over you mixed with smug contentment, as the elated screams of your internal self claims its righteous victory).

Mantas feeding at the surface off Holbox

When I finally snapped out of it, I realized I was laughing with delight into my snorkel and the mantas were well behind me. Although I wanted to savour the moment, the scientist in me immediately kicked into gear and I knew that I had to get to work. I had a job to do…and with this newest bit of information I now had a lot more to do than I had initially bargained for…

Despite knowing that I was only meant to satellite tag giant mantas (Manta birostris) on my current worldwide expedition, I could not resist the temptation to put a few tags on this mysterious new ray as well. So, I made a snap decision, and in what felt like an instant, two tags went on. The two rays that I tagged could not have looked more unlike Manta birostris if they tried, both epitomizing the visual appearance of this foreign looking Manta.

I tagged one mature female and one mature male. As with the other mantas in the study, I named them after famous ocean explorers, Streeter (after Tanya Streeter-the no limits free diving champion) and Columbus. Columbus was feisty and did not hang around for long, but Streeter was very tolerant and allowed me to additionally take a genetics sample as well as many photos of her newly attached scientific jewelry!

Meet Streeter!

As I inspected her, I marveled at how unusual these mantas were and started to pick up on some of the subtle differences, like their soft skin and their atypical colouration. After spending almost a decade of my life working on these amazing creatures all over the world, it was such a shock, as well as a very pleasant surprise, to be in the water with such a different looking manta. It was a strange feeling, like looking at an old and new friend at the same time.

While it will be still be awhile before we can confirm the presence of a third species of Manta, we are definitely dealing with something unique along the western side of the Atlantic and into the Caribbean. To me this is where the real science and the real fun begin. Are we looking a new species? A new sub-species? A hybrid? Only time and a lot of investigation will tell and I look forward to getting started.

Holbox's black manta or 'Boca Negra' locally!

As the days passed in Mexico, I only got more excited about this location and these unusual mantas. They really were very different than any other manta rays that I have ever encountered, both behaviourally and physically. During my time in Holbox, we even came across a few melanistic mantas (the black colour form), which at this location were more charcoal grey than black. Rather than looking like the sleek stealth fighters that I was used to, these black mantas looked more like they had fallen down a chimney than anything else! Even the parasites on the mantas in Holbox were unusual. Instead of the normal clear to white caligid copepods that I was familiar with, they were often riddled with blood red or dark grey parasites. Their skin was literally crawling with hundreds and hundreds of these parasites and with no proper reef systems or cleaning stations in sight, it appeared (due to the scratches all over their skin) as if the manta rays were forced to scrape themselves on the sand itself to remove these annoying stowaways.

Manta breaching in the distance!

But there were some similarities too. I enjoyed watching the Holbox mantas breaching during their feeding bouts just like both Manta alfredi and Manta birostris. No matter how many times I witness manta rays breaching, I never get over how impressive this feat of acrobatics really is… At this location, the mantas seem to always breach twice in a row, usually landing on their backs. The reason for this is unclear, but the resulting splash could be heard from quite a distance and I was reminded of how this behaviour could really be a form of communication between the rays. Again, something else to investigate further in the future.

Amazingly, a few days after my arrival, the manta rays all but disappeared from Holbox. I imagine that both Columbus and Streeter left with the group and are on their way to exploit another plankton bloom down the coast. For the secrets of their journey, we will have to wait patiently for the tags to detach. I, for one, can hardly wait.

What a stunning location to encounter these rays!

My entire experience in Mexico was so interesting and overwhelming. As always, I am grateful for the opportunity to have come out to this location and thank the entire team on the ground in Holbox for their invaluable assistance. Once again, I am reminded how important it is to keep an open mind in the field. Anything, I mean anything, is possible and with manta rays I have gotten use to expecting the unexpected!

Shark week students and program manager, Edd Brooks, prepare to release a 100cm juvenile lemon shark.

In response to the barrage of scientific half truths and shark bite specials loosely disguised as “educational programming” annually aired on the Discovery Channel about this time of year, the CEI Shark Research and Conservation Program decided to start shark week of its own based on a revolutionary new idea.  We were going to use science, and hands on field experience to educate and inspire high-school children.  Crazy I know – but it might just work….

Shark week students return from setting the survey line in a local mangrove creek.

Amazingly, or not, the program was a total success! From 27 July through 3 August 2010 ten high school students from across the United States, the Bahamas, and Europe visited the Cape Eleuthera Institute for a week of shark research. The daily activities focused on student participation in field research during the day, while activities and classes on shark biology and ecology in the evenings. Students participated in two ongoing research projects, one focusing on the nursery habitat of the juvenile lemon shark found in local mangrove creeks, and the second focusing on the 2009/2010 SOSF funded project looking at the variation in abundance of various demographics within the annual Caribbean reef shark aggregation seen off cape Eleuthera.

Students were involved in every aspect of the research process, from cutting bait and setting the survey lines, to working up a shark after it was captured which included taking length measurements, identifying sex, taking a DNA sample and applying tags.  While not in the field, the students had the opportunity to listen and learn from SRCP staff presentations about shark science, local shark species, fisheries and fisheries management, shark conservation, shark reproduction, and shark anatomy. The week concluded with the students giving their own group presentations about each project for an audience of over thirty visiting teachers and CEI researchers!

Shark week student Colleen Cahill holds a Caribbean reef shark in tonic imobility next to the boat just prior to its release.

Shark week students also experienced a taste of life off-campus. The first event was the  Tarpum Bay Homecoming Festival, where students enjoyed traditional Bahamian food, culture, and music. Conch fritters, conch salad, and guava duff were some of the favorite snacks of choice. Probably not the most healthy, but definitely the most delicious! The other off-campus trip was on the last full day of shark week at the Cape Eleuthera Institute and the students traveled to Lighthouse Beach on the southernmost tip of Eleuthera. On the way to the beach there was a short stop at underground caves where the students were able to climb around the rocks and explore. There was even a community of bats! When we arrived at the beach it was quite a sight. Lighthouse Beach is by far one of the most beautiful beaches on Eleuthera with crystal clear water of various shades of blue flowing between a reef and pink sand bottom surface, and seemingly perfect layered cliffs overlooking the beach. Students went snorkeling and many saw a Caribbean reef shark swim by and some giant Tarpon!

All around the first CEI shark week was a huge success and a far more effective educational tool than the television version – although we perhaps didn’t reach quite as households.  Roll on 2011 for a bigger and better CEI shark week.

Written by Stephanie Liss.

2010 American Elasmobranch Society Meeting, Providence Rhode Island.

The field of elasmobranch stress physiology has grown to such an extent that the subject warranted a special symposia at the 2010 American Elasmobranch Society Meeting held in Providence, Rhode Island.  The stress physiology symposium entitled “The Physiological Stress Response in Elasmobranch Fishes”,  was hosted and run by Dr Greg Skomal, and Dr John Mandelman, and was was kindly sponsored by The Fisheries Conservation Foundation, and the long time supporters of the CEI Shark Research and Conservation Program, the Save Our Seas Foundation.

Edd Brooks presenting on the the 2008 SOSF funded project, "The Physiological Consequences of Longline Capture in the Caribbean Reef Shark (Carcharhinus perezi)."

The Cape Eleuthera Institute was represented by the manager of the Shark Research and Conservation Program, Edd Brooks, who presented the findings of last year’s SOSF funded study into the effects of longline capture on the Caribbean reef shark (Carcharhinus perezi).  This ground breaking study used field based blood chemistry diagnostic equipment to look at the sub lethal effects of capture, combined with new acoustic tracking equipment to correspond the magnitude of the physiological disruption to any variation in post release behaviour.  A copy of the AES presentation can be downloaded here, and the complete findings of the project will be published along with the rest of the presentations from the stress symposium in the Journal of Comparative Biochemistry and Physiology – Part A later this year.

In addition to the SOSF sponsored stress physiology work conducted at CEI, another SOSF funded scientist, Dr Cynthia Awruch, presented on her research on elasmobranch stress hormones.  In fact she presented twice, ensuring that a full 25% of the stress symposium presentations were by SOSF funded scientists!  Thank you SOSF!

The elasmobranch stress physiology symposium participants

Thank you SOSF!

Laje de Santos

As I left Brazil, after spending nearly a month in the field, I was informed of the passing of one of my friends in a diving accident in South Africa. He was a great man and he will be deeply missed, but his passing reminded me what a curiously unforgiving place the ocean can be. I find that the ocean’s wild beauty often belies its fierce nature. In reality our oceans are vast, their waters often relentlessly rough and turbulent.

Diving at Laje de Santos

Many parts of these great expanses of water are distinctly inhospitable, however, scattered within this liquid eternity are tiny oases of hope, life and refuge. Laje de Santos is precisely one of those places. This little barren rock juts out from a largely desolate seafloor like a proud sentinel in what I often found to be a stormy and chaotic Brazilian sea. As you approach you cannot shake the uncomfortable feeling that this rock is really out in the middle of nowhere. Once moored and looking down into its surrounding cold, green water, your apt to think, “what am I doing out here?”

Hairy carangid fish

But one giant leap into the chilly waters of the Atlantic reveals a very different reality. This rock is actually home to an incredible amount of life. While it is only approximately 300 meters or so long, Laje de Santos is an amazing refuge to at least 196 species of fish including some magically rare animals such as hairy carangid fish (Alectis ciliaris), Halichoeres sazimai, and an endemic species of tube dwelling Cerianthos anenome.

Sand Tiger Shark at Laje

Laje is also rich in elasmobranch fauna (particularly rays) and during my short time there I was fortunate enough to dive with a couple of friendly sand tiger sharks as well as many eagle rays, butterfly rays, thorny stingrays and of course the elusive giant manta ray! While all of these animals are relatively frequent visitors or inhabitants to this small island, Laje also provides sanctuary, on occasion, to animals passing through on ocean voyages such as Bryde’s whales, Mola mola, penguins and whale sharks. And yes, I did say penguins and whale sharks in the same sentence! Oddly enough these two animals have actually been seen on the same day at this location before (one of the most unbelievable things I have ever seen by the way!).

Laje has an amazing array of small life as well

But this island has really drawn its fame from the giant manta rays that pass though every year during the winter months. Divers are regularly treated to VERY close encounters with what may be some of the friendliest manta rays I have ever seen in my life. The experience is miraculous! So, religiously, these brave Brazilian divers make the one and a half hour boat ride out to the island, diving in rain or shine, to observe these rays and the rest of the marine life at this small island refuge.

Thorny Stingrays

Born out of their fierce love for this destination and its animal inhabitants, some of the more devoted divers formed a small research institute, which is dedicated to both scientific study and the monitoring of the park itself. Founded by one of the most passionate animals lovers I have ever met, Ana-Paula Balboni, this group of naturalist, scientists and divers have produced many international scientific papers and have various projects underway including their flagship project, “Mantas do Brazil”.

Laje is a haven for massive schools of fish

I have been working with the Laje Viva Institute on the ‘Mantas do Brazil’ project since 2009. This project, headed up by Guilherme Kodja, monitors the population visiting Laje each year in addition to gathering information on any sightings of these giant rays along the Brazilian coastline. This winter, our mission was to attach satellite tags to individual rays to determine where they travel on their clear seasonal migrations along the coast. In addition to being a part of my worldwide study on the movements and behaviour of the newly described giant manta, this project has clear local conservation objectives as well. It has become relatively clear to our team thus far that the population of giant manta rays in southern Brazil may be very small, with only 69 individuals identified since 2006.

Gauntlet of shipping boats surrounding Laje

With very little basic knowledge about how these animals live their lives (e.g. where these manta rays spend most of their time, where their major feeding grounds are, where they mate and give birth, etc.), it is very difficult to regulate or protect them effectively. But because of their annual visitation to this tiny offshore island, Laje is quickly becoming one of the best places in the world, especially in the Atlantic, where these questions can be asked and answered effectively.

Unfortunately, as it is located off the mouth of one of the largest natural marine ports in Brazil, the positioning of this remote island couldn’t be worse for manta rays or other large pelagics like whales, turtles and whale sharks. Hundreds of massive transport vessels and fishing boats pass this tiny marine protected area on a weekly basis, forming a gauntlet of danger for any animal that is obliged to come to the surface.

Divers cutting a manta out of a net at Laje

Plastics and pollution from these large boats are seen strewn across the sea on a daily basis, as are large off-cuts of fishing nets, hooks and buoys. It is just a disaster area, and it is not uncommon for divers to cut manta rays out of nets and fishing line. But despite this, life at Laje de Santos continues to flourish, aided considerably by the degree of protection it is afforded by its protected area status, which was awarded in 1993. If nothing else, Laje de Santos is a mighty testament to the effectiveness of these types of marine sanctuaries, which allow natural fauna to thrive without most of the pressures or influences of man. But clearly these small reserves do not afford larger, migratory or pelagic species the protection they desperately need.

One of the many illegal fishing boats in the area

So with a goal of safeguarding this population throughout their wider home range, we headed out to Laje to try and shed some light on the mysterious question of where they go when they leave this tiny island and how they spend most of their time. Armed with the coolest technology in the business, ranging from satellite tags to mini underwater ROVs, we began to try and tackle these questions. Luckily the conditions this year were far more favorable than last year, and despite having an accident mid-way through my trip that put me out of action for a week, we managed to spend many wonderful days out at the island observing mantas and contemplating their future along this coastline.

Out team was successful in placing on two satellite tags before I left (with another 2 planned for later in the season) and the Brazilian manta ray sighting database steadily grew through our ‘citizen science’ program, generating range extensions both to the north and south of Laje. What once seemed like a lone aggregation site for manta rays now appears to be a wider range of habitats (from shallow estuaries to offshore islands) strung together along a massive expanse of coastline.

Mini ROV used to investigate Laje and search for mantas

It is likely that these giant manta rays are exploiting different planktonic resources in these habitats at different times of the year in order to feed their insatiable diets.

But, with some of the tags programmed to come off in only 6 months time, we will now have to sit back and patiently await the results to determine if this theory is correct. If true, it will give us remarkable new evidence of their exceptionally large home ranges, while at the same time highlighting the critical need for habitat protection, as many of these areas face threats from pollution, coastal development, shipping traffic, and fishing pressure.

What is immediately clear to me though, and it is a strong call to action for the rest of us out there, is that the passion and commitment of a few individuals can be more powerful that we could ever imagine. In my few weeks here, I have seen

Green Turtle encounter at Laje

enraged divers single handedly apprehend illegal fishing boats in marine protected waters, I have seen the determination of a community banding together to protect a small sanctuary for these magnificent creatures, I have seen naturalists (not scientists) pushing the boundaries of what we know about these animals out of sheer curiosity and concern, and I have seen ordinary citizens rise up and take on the monumental challenge of conservation with out a hint of apprehension or fear. I have seen it happen with my own eyes and I am seeing them succeed. What will you do for your favorite ocean oasis?

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.

Hawksbills as consumers of sponges: Sponges are competitively superior in space acquisition to hard and soft corals and, such that when unchallenged by spongivores, are known to overgrow and kill corals. Consequently, at reefs where sponges are ubiquitous and space is limited, spongivores play an important role in maintaining biodiversity by reducing their competitive edge to the point where coral colonies can successfully establish.

On average, an immature hawksbill at D’Arros consumes 110-215 grams of sponge material each day. Considering that approximately 50 turtles regularly forage on coral reefs around the island, this means between two and four tonnes of sponge biomass is consumed each year by hawksbills alone! In the absence of predation, these fast growing sponges would probably dominate the surface of reef.

Thus, in the absence of hawksbills, hard corals and other benthos might be choked out by sponges resulting in a decrease in reef biodiversity. Given recent coral bleaching events, in which typically 50-90% of corals perished locally, the role of hawksbills in controlling sponges has become even more important.

Hawksbill turtle exposing food for reef fish. Photo by Rainer von Brandis.

Hawksbills as modifiers of the reef landscape: Hawksbills at D’Arros typically move between several feeding sites whilst foraging. Food hidden within the consolidated rubble is located by smell and then extracted by means of physical excavation techniques that result in structural alterations to the reef. Since food items are diminutive and evenly distributed, the average weight of food extracted per feeding site is a meagre 10.9 grams. Considering that approximately two to four tonnes of food are consumed annually, in excess of 183,000 feeding sites are exploited every year.

Turtles are able to displace considerable portions of reef substrate (biotic and abiotic) when gouging out food at feeding sites. Despite occasional damage to reef benthos, the ecological benefits of this foraging behaviour are considerable:

i) otherwise cryptic food is exposed for fish to eat;

ii) perforations and crevices created in the reef substrate provide microhabitats and shelter for juvenile fish and other vulnerable organisms;

iii) a diverse and patchy habitat mosaic is created, and

iv) increased topographical relief provides shelter for a variety of larger species.

Despite having submitted his Doctoral thesis, Rainer aims to continue working with hawksbill turtles in the Seychelles, expanding into the realm of acoustic and satellite tags to help determine both their local and large scale movements.