Marine Ecology Research

Author: Marjolijn

  • East Kalimantan Programme Conference Samarinda

    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!


  • Writing, Writing, Writing

    Writing, Writing, Writing

    From May onwards it was finally time for data analysis and writing! My data folders look like these:

    And know its time to revise (ms 2), email the editor (ms 1), and wait for comments (ms 3).
    Thanx Phd comic for recognizable stories.

  • My First ISTS Sea Turtle Symposium

    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

    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.

  • Gap regrowth, Macrofauna & Turtle-kiting

    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 last 2,5 months.

    Gap-regrowth: We measured the regrowth of the seagrass into the empty sand area (mimicking the situation after turtle grazing) every 2 weeks. High waves caused a lot of sand dunes to walk through the area but they luckily had a minor effect on the regrowth. Though these waves caused the cage to crash critically just 2 weeks before the end of the experiment. Our Derawanese friends helped us out by pulling the cage up with ropes behind their speedboats!

    Macrofauna: Dominik Kneer and Arie Vonk visited to sample the fauna on, and in- between the roots of the seagrasses on Derawan. Because the seagrasses here are so different; small plants and dominance of 1 species (Halodule uninervis) instead of a multispecies meadow with large plants, we expect a lot of differences with Dominik’s research site Barang Lompo, Spermonde Archipelo, Sulawesi. It was good fun accompanied by some nice stinky samples!

    Turtle kiting: After 2,5 months of light breezes we almost forgot about our kite. But then halfway January there was enough wind for our kite and I photographed (time-lapsed) turtles in a grid on the seagrass while grazing. Now I have to develop a script to automatically process these 1000’s of pictures. So now it is time for a year in the office to analyse this gigantic amount of data into articles!

    Left: Sarah ready to harvest seagrasses from our cage. Right; our hosts and great cooks on Derawan Islands.

  • Strange turtle sightings

    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.

    In the rainy season and the rest of the northeastern monsoon the number of females per night laying eggs is less but on the islands we visited it wasn’t difficult to spot them (there were still 7 that night) and in the afternoon we also encountered mysterious spots of moving sand after which more than 100 tukik per nest emerged. It is like Kill Bill 100-fold!

    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!

  • Happy Holidays!

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    Tropical underwater Christmas (tree) worms are greeting you to wish you happy holidays from East-Kalimantan. Unlike in The Netherlands, here is no snow, no party but we celibrate the fact that we reached our goal of catching 300 turtles, with some rice, fish and onde-onde (sticky sweet green things)!

     Cheers Marjolijn

  • Mayo tagged with Fastlock GPS

    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 of turtles in Indonesia. 

    The route of Mayo the green turtle can be followed here: http://www.seaturtle.org/tracking/?tag_id=53005  Have a look! Will she stay around Derawan or travel to greener meadows?

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    From left to right Turtle guards Darjon & Dody, Jaya (Udayana Univ./WWF), Sjoerd, Me, and Rusli (WWF-TNC Berau)

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    Turtle “Mayo” is sunbasking and waiting for the epoxy to dry before she is released again.She is 78,5 cm (CCLmin) and 70,9 cm (CCW). Her weight was 58.4 kg.

  • Tankap Bokok

    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. 

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    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.

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    Transport of the turtle from the net – boat by kano.

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    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.