Marjolijn Christianen

In total now we captured and measured more than 800 green turtles around Derawan and tagged 500 of them. The WWF guys (Udin, Darjon), some locals (Jeffrey, Tiar) and we catched them using the rodeo technique. This year we recaptured some individuals that we tagged previously in 2009 on Derawan Island. These turtles grew 3-6 [...]

To get an idea of green turtle densities on foraging grounds around the Derawan Archipelago I hopped over the border to Malaysia to visit the islands around Semporna (Mabul, Sipadan, Pom Pom, & Pandanan). Steve Oakley and Celebes Beach resort were so kind to host me on Pom Pom Island. Read the blog post by [...]

After crashing my aerial photography plane directly after the first flight, we retrieved the bits and pieces (the plane from the top of a 70m telephone tower & the catapulted-rest by logging a 20m perimeter of bushes), and shipped the plane around the world to get repaired. But 1.5 months later DHL delivered it in [...]

Our second destination in our quest to find the green turtle foraging grounds was Raja Ampat. Some of the tracks of the GPS tagged turtles show foraging greens that travel all the way from Raja Ampat to Kalimantan. We were based at Kri with papua diving and did 2 short expeditions; 1 to Batanta & 1 to Wayag [...]

After spending so much time on Derawan where green turtles are so abundant we wanted to compare Derawan with other foraging grounds in Indonesia. Wakatobi was our first destination. In contrast to nesting sites of which a lot is known. It is unclear where the green turtles forage in Indonesia, so the majority of the [...]

Just got back on the mainland. Last month we succesfully set-up a large experiment on Derawan to look at interactive effects of hydrodynamics & turtle grazing on seagrasses. This involved building 30 cages and 15 large underwater wave-bunkers for which we almost used al the sand from the nearby sand spit. To determine the location [...]

After some long days in the field we took in the camp kitchen. Fons and Tjisse worked all night to measure the photosynthetic efficiency of the seagrasses, which resulted in this cool picture:   Check the slide show for a report of our last week of research in Shark Bay. Tjisse, Fons and Leon left [...]

Last year I met Teresa Alcoverro and Rohan Arthur at the Turtle Symposium in India were we discovered that our research had a hudge overlap; we were both doing comparable work on ecosystems with very high densities of green turtles and declining seagrasses, and we only found this out just then. My lastest MS about habitat [...]

Although this animal is already been found in 1996, this giant Archelon ischyros Turtle fossil of 70 million years old keeps impressing me.                       Its “flipper-span” reaches 4.9 meters and its shell 4 meters across. Imagine snorkeling next to this this turtle. Did these ancient already [...]

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 [...]

In January, National Geographic Indonesia published a very nice map about the important habitats for the green turtles in the Derawan Archipelago. See low resolution map below. The Editor in chief visited Derawan and interviewed all goverment NGO’s and researchers (me) having something to do with the green turtles in November and he made a good [...]

Finally, the Article that Arie and me published, is online: “Abundance, edge effect, and seasonality of fauna in mixed-species seagrass meadows in southwest Sulawesi, Indonesia” in Marine Biology research (fieldwork from my master-thesis in 2005). In addition Kiki Dethmers received her “Dr.” titel after her defence last week in Nijmegen, here is her thesis. So 2 [...]

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 [...]

Udayana University (Denpasar, Indonesia) and the joint program WWF Berau, was so kind to provide one of their fastlock gps systems (Sirtrack) to track a green turtle from Derawan to study the movement on its foraging ground. Jaya Rata came all the way from Denpasar to Derawan to attach the Sirtrack transmitter. He has tagged a lot [...]

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 [...]

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 [...]

10 February Judith Sarneel and me found our way back (was it a Levy walk?) to Conference centre “De Werelt” for 2 days of total saturation by Ecological research during the Netherlands Annual Ecology Meeting in Lunteren: At daytime listen to “Allee effects”, early warning signals by spatial patterns, plantquality-herbivore interactions and at nighttime getting [...]

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 [...]

*Next fieldwork period from Augustus 2009* Are you looking for a research project for your MSc specialisation? AND: Interested in Marine Ecology and Ecosystem wide processes? Would like to participate in fieldwork in the Derawan Archipelago, East Kalimantan, Indonesia Would like to gain experience in fieldwork in an experimental setting and in chemical laboratory technique [...]

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 [...]