Marine Ecology Research

Category: Fieldwork

  • 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

  • Dutch Seagrass Excursion

    Last year Laura was working together with me in Indonesia for her MSc. Now she already harvested a mega-seagrass-experiment for her own Phd. research. After receiving al lot of positive sms from Laura, when I was in Indonesia, I was looking forward visiting her experiment in Viane. Wouter also showed us his research on seagrass transplantation in Roelshoek. Eric Visser, Eelke Jongejans (both from RU’s Plant Ecology Department), Marieke and Leon were also invited to brainstorm over the driving forces behind succesful recolonisation after seagrass transplantation. The growth-season is very short from spring to early autumn but Zostera noltii growth rates are almost comparable, nevertheless seagrasses are still declining in the Netherlands. It is a pity that on the sites were seagrass grows most successful, dikes have to be enforced and seagrass have to give way.

  • Fieldwork with Wawan Derawan 2009

    Fieldwork with Wawan Derawan 2009

    Derawan did not changed a lot since I left 10 months ago. This time Wawan and me came for only a few weeks to do 3 experiments on Derawan Island and to go to the other important Green turtle foraging grounds on Maratua (40km from Derawan) and Pulau Panjang (8 km from D).  What did we do?

     

    Terimah kasih Wawan for some of the pictures!

    In short: At Derawan island the turtles were still grazing the seagrass by digging out complete (more…)

  • About infections and Stingrays

    And now a horror story about infections and dangerous animals, which combination was still lacking on this blog. Halfway my experiments I got stung by a stingray when I walked to the experimental site (knee-deep water). I felt something very sharp and hard stinging 5 cm into my feet, 3 cm under my ankle, resulting in a lot of blood. I wore booties but it stung right through the neoprene and rubber. At first I kept thinking it was a sharp shell or glass and not a stingray because I did not notice any pain from poison at first and I expected to feel something moving if it was a stingray.

     

    I had some visions about me unable to come back to the field so we continued and harvested the experiment for 2 hours. Already halfway I got some suspicion that I maybe was a stingray, I was in a lot of pain and an hour later I was experiencing the most pain ever. Looking at the 400m distance that I have to walk back to the shore made me feel hopeless. The pain was up to my knee. Off course I know that the stingrays are there and I always walk with sliding movements, which scarred them away 300 times before when I walked in the same area but I was just unlucky this time.

    And know the worst part….. (more…)

  • Fieldwork on Pulau Tikus near Jakarta

    Fieldwork on Pulau Tikus near Jakarta

    This time I will be here for 6 weeks only, visiting seagrass meadows of Pulau Tikus (Pulau Seribu, in front of Java) and Derawan (Kalimantan) again. I am working together with Wawan Kiswara (the Indonesian seagrass expert from Jakarta) who is very helpful and has a never-ending hospitality surge. Together with his daughter Nina we had our first long fieldwork day in Pulau Tikus. In Pulau Tikus we could find mono-species meadows of Halodule uninervis like we have in Derawan Island, but the big difference is that here they are still ungrazed.

    After 3 weeks we went back. Arriving in Jakarta from Derawan we left already the next day for the last fieldwork on Pulau Pari and Pulau Tikus. My planning was very tight, maybe a little bit to tight because Wawan and I already also worked for weeks without weekends and making long working days (7-22) every day but there is so much to do,! Based on the field station of LIPI on Pulau Pari (=stingray island without stingrays) we could reach Pulau Tikus in 30 minutes. I added some more pictures of the end of experiment on Pulau Tikus. The gaps in the ungrazed seagrass recolonized the sandy gaps (created 20 days ago by us) very fast. So the experiment was a success, now we compare it with the seagrass regrowth in gaps of in the grazed area of Derawan.

  • 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.

  • NH4 toxicity experiment

    After performing the same experiment with transported Thalassia hemprichii last year I wanted to test the same treatments in the field. So after some creative thinking I came up with this set-up (click for more pics):

    I’m (amongs others) testing if high ammonia concentrations could cause troubles to seagrass.

  • More Fieldwork at Derawan

    Time is flying. The enclosure experiment is finished and Laura and Madelon left for their holidays. Time for me to visit the civilized world and put some pictures on the internet. It isn’t very structured but that is because only emailing this pictures costed me 1 1/2 a small discription can be found next to the pictures. The last 3 weeks will be spend on performing an NH4 toxicity experiment and a comparison of seagrass productivity at an island close to the river compared to an island far from the river.

  • Turtles @ Derawan

    In the first week at Derawan I saw so many turtles, therefore a post about the “production of new turtles”. Yesterday night I saw 4 turtles (Chelonia mydas) crawling on the beach to search for a suitable site to lay their eggs above the high tide line.

    She digged out a large hole in the surface of the beach using a swimming movement of her front flippers, creating the “body pit”. After ten minutes or more, actively throwing sand behind her, she beginned digging with her hind limbs, excavating the egg chamber of about 60 cm deep. Without pausing she continued laying 90 ‘ping-pong-sized-eggs’ (While the eggs are being deposited into the egg chamber, they can tolerate bouncing, rolling, tumbling or handling, but about two hours after being laid, the embryo will resume development, and may be killed by a simple roll of the egg.) Ferry from the WWF digged up the eggs to protect them from poachers. Now we have to wait 45-70 days for the small Tukik (turtle hatchling in Bahasa Indonesia) to hatch. Higher temperatures produce more females and result in shorter incubation periods. At Derawan Ferry will check development of the nests so that he can digg the eggs out and release the small flippering friends before poachers or predators find them.
    After nesting, the female went back to the coral reef to rest and complete the next clutch of eggs. They are known to mainly rely on their stored fat reserved while resting and completing the next clutch of eggs. She can lay several clutches of eggs at approximately two-week intervals before finally migrating back to her feeding ground. We are still in doubt if the mother turtles are the same ones grazing on the seagrass fields in front of Derawan at daytime, or if they only visit this Island to lay their eggs and travel back to their feeding ground.


  • My first cage

    Before my supervisors arrive and the experiment will be started I’m first testing my cage set-up. The cages are build out of concrete-iron with fishing nets on the sides and on top of the cage, attached by cable ties. The net is 5cm in diameter to prevent the turtles from getting stuck into the net. Within the cage I’ve tested the best way to sample, harvest and count the seagrass shoots. And also tested how long it takes for the seagrass leaves to grow back. The locals are very interested in the strange things that I’m doing underwater so it’s never boring. I’m leaving to Balikpapan know to pick up my supervisors and check the seagrass in Balikpapan bay and after that the experiment can start. Finally! Click on the photo for more pictures.