Marine Ecology Research

Category: Green Turtle

  • 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.

  • 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!

  • 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.

  • Monitoring river input on seagrass

    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 same sites from the river to the open see we saw a lot of variation in species composition, algea cover, morphology. At the moment that I write this article Leon Lamers is travelling back to Nijmegen with +/- 10kg of dried seagras, sea water, and syringes with gas. Sjoerd will analyse the samples when he is back in february, we are looking forward to the results of the plant-nutrient analysis.

    Check the photos to get an impression! And leave a comment, so that we also get some information back 🙂

    We can also receive old fashioned post. Here is the adress:

    Nama: Sekni AS
    Untuk Ibu Marjolijn tinggal di Ibu Heldi Wisma Aditya Di Derawan
    JL H.ISA III 66 Mardatillah No. 16 Rt / Rw 10
    Kode pos 77311
    Tanjung Redeb, Kab. Berau
    Propinsi Kalimantan Timur, Indonesia

  • NAEM Posterprize 2009

    NAEM Posterprize 2009

    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 inspired from foodweb interations compared between seagrass, Serengeti-Mara, Hluhluwe (S.A.), and Barro Colorado (Panama) ecosystems.

    The second day it was time for Madelon and me to present our poster “Overgrazing by Green Turtles?” (PDF) together with 45 others. The poster were evaluated on scientific quality, clarity and attractiveness. Not without succes, like you will see below we won the NERN and NECOV 2009 posterprize, and 300 euros! We are very happy with this result, now its time to write an article from it to apply for the PhD paper award next year ☺

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    The only critics on the poster: increase fontsize of the author names

  • New Year : New URL

    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 of my fieldwork in Kalimantan? For 3 months I was hiding behind high piles of samples in the laboratory of my University back in the Nijmegen, together with Laura. We analyzed soil and surface water for Ammonium, Phospate, Potassium, Sodium, Cloride, in the autoanalyser. And also we analysed Nitrate, which required a specific set-up with a Cadmium column as a reductor, which we first had to build ourselves. Furthermore we analysed Carbon:Nitrate ratios including stabile isotope ratio’s of dryed seagrass plants, to do this we had to shred the seperate plant parts into fine powder and fold 1500 samples into thin cups to balls of 1-1mm. We weighed biomass of all samples and made extracted elements from the dryed seagrass material by threating them with acid in the microwaveoven. Later we analyzed in the ICP spectometer what elements (including phosphate) were present in this extraction to check what the plants (-parts) took up from the water and soil. So combining this analysis we can now also compare C:N:P ratio’s. Many thank to Jelle Eygensteyn (Technician on the G.I.) for all the help with the analysis! Besides this, Madelon and I are also trying to calculate how many Green turtles the seagrass field could feed. First results look very promissing!

    The last week of December I also followed a course in Basic Statistics (highly recommended) in Wageningen. So this year I can start with the analysis of all the data that I gathered in 2008 during my first fieldperiod. And now it is time to test the hypothesis, see if my experiments worked, and to make new plans for next fieldvisit coming August.

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  • Research projects available 2009-2010

    *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
    • Highly motivated & enjoys working in field and lab?
    • Interested in being a co-author on a scientific paper?

    Then please send a 1-2 page CV and a letter with your motivation to me: m.christianen@science.ru.nl

    Background
    The objective of our project:

    • We wish to address the possible shifting states of seagrass in relation to eutrophication and turtle grazing, using field experiments in the Derawan Archipelago, Kalimantan, Indonesia.
    • In parallel, we wish to obtain insight in the variation in production and community composition of seagrass assemblages between sites at diffent distance to the river and relate this variation to spatial and environmental variables.

    Most field experiments will be carried out in the coastal zones of the Berau and Mahakam rivers, East-Kalimantan, Indonesia. Ecosystems states (e.g. eutrofication, turtle grazing) and possible shifts between them will be provoked in a series of experiments involving turtle exclosures, turtle grazing mimicking and nutrient enrichments, both in the field and in the lab. The research will be carried by Radboud University Nijmegen (The Netherlands) in close cooperation with the Indonesian Institute of Science (LIPI, Indonesia) and the Netherlands Institute of Ecology in Yerseke.

    What you will do:
    Participate in fieldwork and exclosure-experiments. Participate in lab-work, collecting toxicity and biogeochemical data. We can discuss the details of the internship to create an exciting project that encompasses both your research interests and the goals of our project.
    Your project could start in the middle of 2009, with fieldwork (3-6 months) starting from beginning of August 2009. Due to application deadlines of funding (and visa preparations) It is advised to start early < 6 month before the start of your project with the preparations.

    In Dutch:
    Studenten gezocht: Stage Mariene Ecologie Indonesie,
    Als je op zoek bent naar een buitenlandse stage voor je master in Mariene Ecologie / Biologie lees dan bovenstaande beschrijving even door. Ik ben op zoek naar studenten die bereid zijn om voor hun master project ook veldwerk uit te voeren in het buitenland. Indonesie op het eiland Kalimantan voor verschillende maanden. Heb je interesse, neem dan contact met me op.