Marjolijn Christianen

Based on the monitoring data on nesting turtles that Jessica Berkel and her team at STENAPA are collecting we were able to predict the turtle’s return to the beaches. For this we used the inter-nesting durations of the first green turtles tracks that were reported for Zeelandia beach, St. Eustatius. Equipped with a turtle box, satellite transmitters, our red [...]

Two weeks ago we arrived on Bonaire. Since then we worked non-stop and we made great progress! The first thing we did was to set up a turtle exclosure experiment on the seagrass beds in Lac Bay, after Funchi (STCB) and Sabine Engel (STINAPA) kindly showed us all the suitable seagrass areas. The native dominant [...]

The Wadden Natuur kaart (Wadden Sea Nature Map) is now online: this is one of the publications of the Waddensleutels project on which I worked in the last 2+years. You should definitively explore and test it. For example; activate the benthos hotspot layer (upper left) and see which areas are most interesting as foraging areas for [...]

I had the opportunity to go back to Derawan for 3 more weeks of fieldwork, thanks to the Schure Beijerink Popping foundation. I gathered samples for food web analysis, checked the current turtle density and seagrass biomass, recaptured green turtles and made a new series of aerial photographs with a kite (with super assistant Sipke [...]

This summer we (the Waddensleutels team) visited all dutch Wadden Islands to collect samples for food web comparisons between mussel beds and surrounding habitats. It was a very successful operation. We collected around 1800 samples of organism that are now going to be analyzed for stable isotopes at the NIOZ, Texel. Sampling involved fishing with [...]

The Bank d’Arguin is a magnificent place: Not only to see loads of beautiful birds, some marked with colourfull rings as a souvenir from the Netherlands, but also to do seagrass research. Together with Jim de Fouw (our expedition leader), Laura Govers, Tjisse van der Heide en Karin van de Reijden we traveled through the [...]

After all those weeks behind the computer I am already longing back to my view from my research base in Derawan, enjoy my time lapse video. Do you see the tide rising? 2 last hours of sun on a typical fieldwork day.

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 [...]

One of the cool things of seagrass meadows is that at first sight it might not seem too rich in animal life. But when working for hours on the seagrass around our cages and sandbags you find cool new animals that you might miss normally. In the last weeks I went out to make the [...]

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 [...]

The last fieldwork of my Phd is finished! While writing this blog post in Dubai on the way back to the Netherlands the dried seagrass samples patiently wait on the seat next of me, together with the other 70kg of equipment where I travel with. The first unofficial results are promising. On the aerial pictures [...]

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 [...]

And were back! To give you an idea of what we did before travelling to our remote fieldwork site, here’s a (simplified) checklist: Arrange research & travel permit, KITAS, letters for governors, certificate of good conduct police (10 trips, at least 3 days) Give presentation at World Delta Summit & follow EcoDynamic Design workshop Buy [...]

Beautiful seagrass patterns of Sharkbay: Let the fieldwork begin! The team: Laura, me, Leon, Fons & Tjisse above the seagrass patterns     The seagrass leaves of Amphibolis are still full of red pigment after the winter period and make a really beautiful underwater panorama..We were very lucky with the weather and could work in [...]

Before starting the real work we spend a week preparing the field expedition. This included a medical test, x-rays, discussing our plans with John and Di from UWA (University of Western Australia), arranging a camper, the necessary permits etc. Jennifer Verduin was so kind to host Laura and me in Perth. And we also had [...]

From Christmas there wasn’t time to travel to the internetcafe on the mainland to update this blog because we preferred to do some extra experiments J instead of spending 2 day travelling. Now, I just arrived back home and I will give you a comprehensive update of the work of Sjoerd, Sarah and me the [...]

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 [...]