Marine Ecology Research

Category: Fieldwork

  • Experiment finalized

    Experiment finalized

    The last fieldwork of my Phd is finished! While writing this blog post in Dubai on the way back to the Netherlands the dried seagrass samples patiently wait on the seat next of me, together with the other 70kg of equipment where I travel with. The first unofficial results are promising. On the aerial pictures we clearly see different patterns of gaps on the 3 different stations that lie on increasing distance from the beach.

    The grazing effect on the seagrass is enormous, which is clear if you remove the cages that kept away the grazing turtles. Seagrass regrows quicker into gaps behind wave barriers. And the effect of waves and grazing seem to differ between the stations, so now it is time to spend some hours analyzing the huge amount of data that we have collected and write the results up.

    In these last months we had quite a lot visitors. Research (photo) journalist Hans Wolkers visited a few weeks to write an article about our research here. With his too infected he could not photograph the turtles during his last days so he ended up helping to sort out numerous seagrass samples 🙂 . And we also had family/boy/girlfriends of Iris and Peter and my sister around. it was a lot of fun having him here. Hans, Sara, Sabine, Jelco, Ger thanx a lot for the help!

     

  • And it flies!

    And it flies!

    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 Berau and we could fly. And the footage is really cool: here are some first sneak peaks from the air.

    You can see a lot of turtles and my experimental set up. The wave barriers I’ve set up are clearly visible.

     

    Obstacles

    High palm trees/ phone tower are not the only obstacles to fly on Derawan.

    Obstacle 2: While looking at the flight track suddenly the plane flew 180 degrees the other way than planned, the plane was out of sight so we wondered what the disturbance  could have been. The plane corrected itself and safely landed but part of the frame was missing! We repaired it with syrofoam and during our test flight it became clear what did this: Sea eagles! A 1.5m wingspan sea eagle flew 100m above the plane and pulled in his wings in to rocket down on the plane, so after some quick steering I manage to make quick turns and with some shouting the plane escaped from the bird. Every next flight I gave 2 children the task to report any fish eagle and called the plane to the ground until the coast was clear of eagles.

    Obstacle 3: Children: The only place to land the airplane is on the “Lapangan” the soccer field right in the middle of the schools. Everytime that I come walking around the corner with the interesting suitcase the teachers don’t manage to keep the children in there classroom and it would be handy to have 8 hands extra to keep the hands of the plane, get the field cleared & stop the kids from running over the plane.

     

  • Green turtle foraging in Raja Ampat

    Green turtle foraging in Raja Ampat

    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 – Sayang. We planned our route using the aerial pictures of Max Ammer and the tips of his friendly staff. During the first trip we saw a dugong feeding at dusk on Enhalus leaves in front of the mangroves. The majority of the seagrass meadows were strips of multispecies (incl Enhalus) meadows in front of mangrove lined islands. Because we were the first foreigners to overnight in the village people did not know what to with us and we ended up sleeping in a empty information house on the jetty. In this area the fisherman are mostly Biak people that migrated here some decades ago. The Biak people explained us that green turtles are still hunted because of the tasty meat, in contrast to dugong meat that they did not like too much. Hence not too many foraging turtles, but a very nice trip. Here is a map of our trip and below it, you can see images of the trip.

    [simpleviewer gallery_id=”4″]

  • Green turtle Foraging areas in Wakatobi

    Green turtle Foraging areas in Wakatobi

    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 time we spend searching for foraging grounds. The local Bajau people spend all their time at sea and were the most helpful in pointing us in the right direction. The Bajau is the same “tribe” that settled in Derawan but in contrast to Derawan they do hunt adult turtles. So the further away from the villages the most likely to find foraging grounds. In Wakatobi, green turtles graze in highest densities on the South reefs; Karang Kapota, Karang Tomia, Karang Koko and Karang Kaledupa, and around the outer Islands were they also nest. Pulau Runduma, Pulau Anono, Maramoho.

    Overall we spend our most time looking for the turtles instead of finding them. We did several surveys of seagrass meadows to look for grazing evidence and suitability for grazing. The turtles we found most were Hawksbills and not the Greens we were looking for. But there is some evidence that on the South reefs the densities are far bigger. Time to go back some day. An impression of the conditions can be seen below.

    [simpleviewer gallery_id=”2″]

  • The latest experiment on Derawan

    The latest experiment on Derawan

    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 of the plots we used an unmanned aerial photo plane. A small disaster happened and the plane crashed in the telephone tower, and the plane is now in Switserland for repair. See below for a photo-report of the last month:

     

  • Checklist week 1 fieldwork Indonesia

    Checklist week 1 fieldwork Indonesia

    And were back! To give you an idea of what we did before travelling to our remote fieldwork site, here’s a (simplified) checklist:

    • Arrange research & travel permit, KITAS, letters for governors, certificate of good conduct police (10 trips, at least 3 days)
    • Give presentation at World Delta Summit & follow EcoDynamic Design workshop
    • Buy all research equipment (60 kg) from small shops all around Jakarta,
    • transport this on the back of Arifins’ motorcycle and busway to avoid being stuck for ours in Jakarta’s traffic jams
    • Book 25 domestic flight tickets
    • Get essential soto-ayam & es jeruk nipis,
    • Prepare 30 under-water cages at Wawans house
    • Introduce Iris & Peter to Indonesia
    • Visit the wedding of Arifin’s son that follows Indonesia’s principle: SMP (sesudah makan pulang; finished your food? go home)
    • Go to Open Science meeting (Jakarta) and give OSM workshop (Makassar)
    • This all with laryngitis under 33 degrees celsius in formal dress.

    This time Iris and Peter will join me for their MSc. intership during this last fieldwork period of my Phd. Here they are presenting our new penyu-team merchandise. You can follow Peters’ stories here, and Iris’ on facebook

  • Week 2 Shark Bay

    Week 2 Shark Bay

    Beautiful seagrass patterns of Sharkbay: Let the fieldwork begin!

    The team: Laura, me, Leon, Fons & Tjisse above the seagrass patterns

    The seagrass leaves of Amphibolis are still full of red pigment after the winter period and make a really beautiful underwater panorama..We were very lucky with the weather and could work in extremely calm waters. In September the water temperature is between 18 and 20 C and a 5mm wetsuit is still quit cold.

    Tjisse and Fons are analyzing the photosynthetic efficiency of our seagrass samples until 5 in the morning

    Thanx Leon & Laura for additional pictures!

  • First Week Sharkbay

    First Week Sharkbay

    Before starting the real work we spend a week preparing the field expedition. This included a medical test, x-rays, discussing our plans with John and Di from UWA (University of Western Australia), arranging a camper, the necessary permits etc. Jennifer Verduin was so kind to host Laura and me in Perth. And we also had a nice evening with Paul and his family.

     

    We surprised the hardware store assistant with a list of the strangest combination of fieldwork equipement, from osmocote to bamboo-sticks, to plaster etc. And bought 800 dollars of food to survive the next 4 weeks in Shark bay.

    After arriving in Denham, Sharkbay (a 10 hr drive from Perth), it was time to take a first glimps of the seagrasses:

     

    And the local fauna! Including loads of Dugongs, Sharks, Turtles, Emu’s walking inside mangroves, Kangaroos, and sea snakes later on.

     

    At the look out at Eagle Bluff we saw sharks swimming around the seagrass patches.

    Thanx Laura for additional pics!

  • 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.

  • 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.