06 Dec

Together with Nicole Esteban we have a nice paper out on #oceanoptimism: Climate change impacts clearly threaten many species. Sea turtles are a flagship conservation group and one major threat of climate warming is the feminisation of populations which may occur since all species have temperature dependent sex determination with female hatchlings being produced at warmer [...]

17 Jul

Green sea turtle digging its own watery grave due to invasion of non-native seagrass press release written by Jac Niessen and Lonneke Dortmans (Wageningen University) about our new paper that came out today in Journal of Ecology  (pdf) “Megaherbivores may impact expansion of invasive seagrass in the Caribbean” A seagrass species from the Red Sea [...]

17 May

A new paper by lead author Alan Rees and collegues reviews how we can use drones and other UAVs in sea turtle research and conservation. Here we review the diverse ways in which incorporating inexpensive UAVs may reduce costs and field time while improving safety and data quality and quantity over existing methods for studies [...]

22 Sep

Last week we* successfully placed a satellite transmitter on a big green turtle female after she nested at Little Curacao’s turtle beach. The signals of the ARGOS satellite are updated hourly and I am very happy to report that this female is swimming very fast in the direction of Nicaragua 1050km in the first 10 [...]

15 Aug

4 sub-adult green turtles that we caught in Lac Bay are now equipped with satellite transmitters to study their movements and use of the seagrass meadows, (see more photos below). The greens that forage in the shallow Lac Bay area are typically sub-adults. We selected some of the biggest turtles that forage here, to not [...]

30 Jul

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 [...]

10 Jul

I am very excited to finally start our fieldwork on sea turtles and seagrass in the Bonaire, Aruba and Curacao! What started as a proposal (initiated by Lisa Becking and me) in August 2013, finally resulted in a research project May 2015 entitled  “Ecology and conservation of Green and Hawksbill turtles in the Dutch Caribbean”. [...]

31 Jan

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 [...]

18 Jan

Our new paper is out in Proceedings of the Royal Society B! Green turtle populations have expanded so much in Indonesia’s east coast islands marine protected areas that they are adopting new feeding habits, degrading the ecosystem and threatening their own conservation. Read more about  “Habitat collapse due to overgrazing threatens turtle conservation in marine protected [...]

22 Mar

The 22th of March was the Big Day, I had to defend my PhD thesis. After a 10 minute summary about my research I had one hour to answer the questions of 8 (associate) Professors. 1.5 hours later this happy photo was taken. Standing with my Phd between my (co-) promoteres; Tjeerd, Marieke, Peter, Leon, [...]

20 Mar

After sending out the press release about my upcoming PhD defense, my research on seaturtles destroying their own habitat did receive some attention in Trouw newspaper and a science-radio program. Check these links here.

28 Mar

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 [...]

23 Mar

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 [...]

19 Mar

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 [...]

25 Feb

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 [...]

18 Feb

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 [...]

25 Dec

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 [...]

04 Oct

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 [...]

11 Aug

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 [...]

18 May

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 [...]