Before attending the symposium there were 2 obstacles to take: Waiting before it was safe again to fly from north-europe after the gigantic ash clouds following the eruption of Eyajallajokull. And secondly, getting my businessvisa (3 days at the visa office) from the Indian Ambassy in The Hague. But the day before departure I finally received the visa and planes were flying again, so Goa, India, here I come!
After 2 days of pre-symposium workshops on stabile isotopes, south (-east) asia, and opportunities to include dugongs in turtle research, the main symposium began. After a very interesting talk of Teresa Alcoverro on Turtle Grazing, it was time for my first presentation for the 700 seaturtle people in the ecosystem functioning session (invitation only). Based on a lot of positive feedback afterwards the talk was very succesfull. Attending the symposium, its many interesting presentations and meeting so many seaturtle people from around the world motivated me a lot. Thank you all!
We explored the southern islands of the Berau Archipelago, Bilangbilangan, Blambangan and Mataha in search of more foraging areas for the green turtle. In January 2010 National geographic Indonesia published a map + article on the green turtle in Berau. Turtle foundation is conserving the nesting beaches on these Islands and has posts on Bilangbilangan and Mataha were some very commited staff guards the turtle eggs. And you directly see the effect: On the Island without conservation posts eggs are stolen. A boat with poachers was directly fleeing when we arrived at Blambangan with our speedboat. This is the picture of a fresh egg forgotten by poachers that dug out the rest of the nest.
While egg harvesting is forbidden for some years in Indonesia local government creates their own rules and along the roadside of Samarinda and even on the local market of Berau you can still buy the ping-pong-ball-shaped green turtle eggs. Eggs are most likely from the few islands without conservation posts like Blambangan.
Like all organisms turtles development of hatchlings also sometimes fails. Here the TF guards showed us a tukik (Indonesian for hatchling) without legs and a hatchling with 2 heads.
When we arrived back we want to measure the population size of the green turtles in the area so we recaptured a lot of green turtles by rodeo method to check for tags.
All with help of Dodi, Jeffrey, Tiar and Darjon, who normally also help WWF/TNC. We used waterproof marker to prevent recapturing the same turtle. 1 of the turtles missed part of his front flipper (@pic right below). We also encountered a lot of turtles with cuts in their carapace (below-left), presumably caused by speeding speedboats around the island. If you see a turtle with tagnr 2722.. – 2725.. email me!
The special thing about this research area (Derawan, Indonesia) is the high density of Green turtles (Bokok in bahasa Bajau, the local language). Last year we found 1 turtle per 30 square meters of seagrass. However on the different feeding grounds densities differ, possibly regulated by the availability of food, seagrass. In the last 2 weeks we visited 3 islands Derawan, Maratua and Pulau Panjang (east-Kalimantan, Indonesia) and we catched, measured, painted and tagged 300 turtles.
The sizes (of the carapace) ranged from 40 to 112 cm, the weight from 8 to 116 kg’s. The most of them were catched in nets by a team of us; Sarah, Sjoerd and me, and 4 enthusiastic Derawanese locals in a fishermen’s boat. For 3 days the local assistants of Pak Rusli from the WWF-TNC joint program Berau catched extra turtles with the rodeo method by jumping from a speedboat. The coming month we will try to spot our tagged/painted turtles back, so that we can learn about their movement and the population size. In addition we are also cooperating with Udayana University to study the population genetics of these turtles.
Transport of the turtle from the net – boat by kano.
Even in heavy rain the crew is searching for turtles. See here the net of 100 meters in front of the village of Payung Payung, Maratua.
After 1 week of preparation the penyu team arrived at Derawan. Here Ibu Heldi invested my last payments in improving her place. Now it feels even more like home and our own research station even!
In the week that my supervisors are here we revisited the seagrass meadows that they sampled in 2003. Sampling the same sites from the river to the open see we saw a lot of variation in species composition, algea cover, morphology. At the moment that I write this article Leon Lamers is travelling back to Nijmegen with +/- 10kg of dried seagras, sea water, and syringes with gas. Sjoerd will analyse the samples when he is back in february, we are looking forward to the results of the plant-nutrient analysis.
Check the photos to get an impression! And leave a comment, so that we also get some information back
We can also receive old fashioned post. Here is the adress:
Nama: Sekni AS
Untuk Ibu Marjolijn tinggal di Ibu Heldi Wisma Aditya Di Derawan
JL H.ISA III 66 Mardatillah No. 16 Rt / Rw 10
Kode pos 77311
Tanjung Redeb, Kab. Berau
Propinsi Kalimantan Timur, Indonesia
The second day it was time for Madelon and me to present our poster “Overgrazing by Green Turtles?” (PDF) together with 45 others. The poster were evaluated on scientific quality, clarity and attractiveness. Not without succes, like you will see below we won the NERN and NECOV 2009 posterprize, and 300 euros! We are very happy with this result, now its time to write an article from it to apply for the PhD paper award next year ☺
The only critics on the poster: increase fontsize of the author names
Like you must have noticed, I’ve moved the Blog of my Phd project to Penyu.nl! “Penyu” is off course ‘Sea Turtle’ in Bahasa Indonesia and I’m more flexible to do things with the weblog. Please change it in your Favourites or RSS subscriptions.
So what happened after my last blogs where I showed you pictures of my fieldwork in Kalimantan? For 3 months I was hiding behind high piles of samples in the laboratory of my University back in the Nijmegen, together with Laura. We analyzed soil and surface water for Ammonium, Phospate, Potassium, Sodium, Cloride, in the autoanalyser. And also we analysed Nitrate, which required a specific set-up with a Cadmium column as a reductor, which we first had to build ourselves. Furthermore we analysed Carbon:Nitrate ratios including stabile isotope ratio’s of dryed seagrass plants, to do this we had to shred the seperate plant parts into fine powder and fold 1500 samples into thin cups to balls of 1-1mm. We weighed biomass of all samples and made extracted elements from the dryed seagrass material by threating them with acid in the microwaveoven. Later we analyzed in the ICP spectometer what elements (including phosphate) were present in this extraction to check what the plants (-parts) took up from the water and soil. So combining this analysis we can now also compare C:N:P ratio’s. Many thank to Jelle Eygensteyn (Technician on the G.I.) for all the help with the analysis! Besides this, Madelon and I are also trying to calculate how many Green turtles the seagrass field could feed. First results look very promissing!
The last week of December I also followed a course in Basic Statistics (highly recommended) in Wageningen. So this year I can start with the analysis of all the data that I gathered in 2008 during my first fieldperiod. And now it is time to test the hypothesis, see if my experiments worked, and to make new plans for next fieldvisit coming August.
We wish to address the possible shifting states of seagrass in relation to eutrophication and turtle grazing, using field experiments in the Derawan Archipelago, Kalimantan, Indonesia.
In parallel, we wish to obtain insight in the variation in production and community composition of seagrass assemblages between sites at diffent distance to the river and relate this variation to spatial and environmental variables.
Most field experiments will be carried out in the coastal zones of the Berau and Mahakam rivers, East-Kalimantan, Indonesia. Ecosystems states (e.g. eutrofication, turtle grazing) and possible shifts between them will be provoked in a series of experiments involving turtle exclosures, turtle grazing mimicking and nutrient enrichments, both in the field and in the lab. The research will be carried by Radboud University Nijmegen (The Netherlands) in close cooperation with the Indonesian Institute of Science (LIPI, Indonesia) and the Netherlands Institute of Ecology in Yerseke.
What you will do:
Participate in fieldwork and exclosure-experiments. Participate in lab-work, collecting toxicity and biogeochemical data. We can discuss the details of the internship to create an exciting project that encompasses both your research interests and the goals of our project.
Your project could start in the middle of 2009, with fieldwork (3-6 months) starting from beginning of August 2009. Due to application deadlines of funding (and visa preparations) It is advised to start early < 6 month before the start of your project with the preparations.
In Dutch:
Studenten gezocht: Stage Mariene Ecologie Indonesie,
Als je op zoek bent naar een buitenlandse stage voor je master in Mariene Ecologie / Biologie lees dan bovenstaande beschrijving even door. Ik ben op zoek naar studenten die bereid zijn om voor hun master project ook veldwerk uit te voeren in het buitenland. Indonesie op het eiland Kalimantan voor verschillende maanden. Heb je interesse, neem dan contact met me op.
Time is flying. The enclosure experiment is finished and Laura and Madelon left for their holidays. Time for me to visit the civilized world and put some pictures on the internet. It isn’t very structured but that is because only emailing this pictures costed me 1 1/2 a small discription can be found next to the pictures. The last 3 weeks will be spend on performing an NH4 toxicity experiment and a comparison of seagrass productivity at an island close to the river compared to an island far from the river.
Two months into my first research period I would like to update you on my progress. Because it’s almost impossible to post from my research location on Derawan I will show a compilation of photo’s. When I will be back in the Netherlands I will elaborate some more on the specific experiments. Click on the photo for all the research photo’s.
In the first week at Derawan I saw so many turtles, therefore a post about the “production of new turtles”. Yesterday night I saw 4 turtles (Chelonia mydas) crawling on the beach to search for a suitable site to lay their eggs above the high tide line.
She digged out a large hole in the surface of the beach using a swimming movement of her front flippers, creating the “body pit”. After ten minutes or more, actively throwing sand behind her, she beginned digging with her hind limbs, excavating the egg chamber of about 60 cm deep. Without pausing she continued laying 90 ‘ping-pong-sized-eggs’ (While the eggs are being deposited into the egg chamber, they can tolerate bouncing, rolling, tumbling or handling, but about two hours after being laid, the embryo will resume development, and may be killed by a simple roll of the egg.) Ferry from the WWF digged up the eggs to protect them from poachers. Now we have to wait 45-70 days for the small Tukik (turtle hatchling in Bahasa Indonesia) to hatch. Higher temperatures produce more females and result in shorter incubation periods. At Derawan Ferry will check development of the nests so that he can digg the eggs out and release the small flippering friends before poachers or predators find them.
After nesting, the female went back to the coral reef to rest and complete the next clutch of eggs. They are known to mainly rely on their stored fat reserved while resting and completing the next clutch of eggs. She can lay several clutches of eggs at approximately two-week intervals before finally migrating back to her feeding ground. We are still in doubt if the mother turtles are the same ones grazing on the seagrass fields in front of Derawan at daytime, or if they only visit this Island to lay their eggs and travel back to their feeding ground.
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