Mega Turtle

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 graze on seagrasses? Probably not, it had a leathery carapace, and therefore this turtle seems more related to the present carnivorous leatherback turtle. The original fossile was found in Dakota by  the South Dakota School of Mines and Technology . Thanks to Euroturtle for the link!

Students internships 2011-2012

Update 1-6-2011: STUDENT RECRUITMENT CLOSED: both internship positions taken

I have 2 MSc. student internship opportunities available with fieldwork in Indonesia from end of November 2011 till February 2012. Students should already have finished 1 other internship. Contact me this month if you are interested.

Check for here for more info, or at the site of my University (in Dutch).

Deep Seagrass

During our divetrip to the Similan and Surin island in the Andaman sea I found some seagrass (a Halophyla sp. >8 cross veins) growing very deep, between burrows of the shy spotted garden eels. While I know that some species are found much deeper, e.g. 50m deep (Beer et al. 1982) I was quite happy finding it as a variation to the depressing coral reef. This reef consisted of 90% dead coral probably as a result of the 2004 Tsunami, 2010 Bleaching event (after some months with 34C water temperature, in contrast to the normal 29C), and some local dynamite fishing.

Seagrass workshop Thailand

I just had a great time in Phuket and Trang in Thailand were the seagrass scientists of the world gathered for 11 days for the World Seagrass Conference and the International Seagrass Biology Workshop.

Here a group picture of al the people joining the ISBW inside the Emerald Cave after surviving the 80 meters of darkness to enter the cave in snake-formation:

Part of our Workshop was a fieldtrip were we spotted the dugong feeding trails (pic middle) of the 40 dugongs that live in the area around Trang. Further searches of Dominik Kneer and me after the workshop only resulted in a observation of 3 vage brown silhouettes underwater which we lost in the waves after a boat passed by.

On our first night we released our floating flowers at the Loy Kratong festival (every full moon in November, pic right)

I presented my first exclosure experiment (seagrass with nutrient addition and mimicked turtle grazing) at the conference and received a 2nd prize in the student presentation competition, yeah.

East Kalimantan Programme Conference Samarinda

After our first meeting in Texel in 2009 our second meeting was in Samarinda, Indonesia. The university of Samarinda (UNMUL) hosted the meeting and in 2 days we were updated of the outcomes the 15 WOTRO/ KNAW Phd projects that are now running in the Mahakam and Berau river Delta, including my project. The projects within the East Kalimantan program are very diverse ranging from geological, GIS, physical geography, to ecology, social and law. Many local NGO’ and scientists joined the meeting making it an interactive meeting. And the end of the second day Irfan Cibaj (Total) took us to a very interesting outcrop were he showed us the history of the previous delta in 70 meters of delta deposits. We even learned that there were once hard corals in the Mahakam delta, and that this delta is one in a series of ±30 delta’s that are situated on top of eachother. That puts a the human lifespan into perspective. On the 3rd day a big boat was arranged to travel downstream to show us the apex of the Mahakam rivers and the fluvial and tidal channels that transport the water out and into the delta respectivily. Duddy demonstrated and collected some sediment samples. We closed with a delicious Indonesian diner at Mesra Hotel and I travelled to Derawan Island for 2 days of fieldwork (heavy rain see pic). It was my shortest trip to Indonesia ever. Thanx Retno Wulandari for the picture above!


My First ISTS Sea Turtle Symposium

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!

Berau’s Green Turtles in National Geographic Indonesia

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 review about the most important turtle issues. Below the map you can find the text were I was quoted.

Unfortunately just after NG left, another big threat to the turtles in the area became clear. Over 100 turtles got stuck in a >1000m net in front of Maratua Island, clearly set out to catch turtles specifically.  You can read more in the article of Frank Zindel. The last 4 years a turtle net (big mesh sized) was found on 4 occasions in this area and killed a hudge number of turtles: ±150 dead turtles in 2005, ±400 in 2007, ±100 november 2009, ±15 December 2009 and the Chinese illegal poaching can still continue until the local authorities have enough resources to patrol regularly in the area.

Translated (thanks google translate) from the text of NG Januari.…”Marjolijn christianen, a Dutch researcher who pursues seagrass in waters off the island, conveys her worries about many sea turtles that are run over by fast speedboats in the shallow water area were the banana boat attracks a lot of tourists. Turtle carapaces are scratched when they are hit by the engine propeller of the fast speed boat. This propellor also damaged seagrass beds. Another threat, which is huge but more subtle, is pollution from the mainland and from the island Derawan itself. “I study the interaction of nutrients from river pollution and household waste on seagrass beds and the feeding relationship with the green turtle” Marjolijn explaines. Pollutants bring nutrients that feed algae. The more algae that grow in shallow water prevent sunlight to reach the seagrass, so its growth is reduced. Seagrass is a staple food of sea turtles and may decline as a result of the pollution, seagrass and thus turtles are estimated to continue decreasing.”…..

Turtle Cake

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 times cake time. A special turtle cake 🙂 I love this one, the details are very precise.

With Google+ plugin by Geoff Janes