Category: Seagrass

  • Megaherbivores may impact expansion of invasive seagrass in the Caribbean: our paper in Journal of Ecology

    Megaherbivores may impact expansion of invasive seagrass in the Caribbean: our paper in Journal of Ecology

    Green sea turtle digging its own watery grave due to invasion of non-native seagrass….

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  • Paper out: estimating the exposure to river plumes for coastal ecosystems

    Paper out: estimating the exposure to river plumes for coastal ecosystems

    Can we estimate the exposure to river plumes for coastal ecosystems? During my PhD fieldwork I had the opportunity to collaborate with a multidisciplinairy team of hydrologists, physical geologists, modelers, coral reef biologists to study this in East Kalimantan, Indonesia.

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  • Personal research NWO-VENI grant received!

    Personal research NWO-VENI grant received!

    Happy news! I received a personal VENI (research) grant today, from the Netherlands Organization for Scientific Research (NWO)! To work for 3-4 yrs on “Global defaunation and plant invasion: cascading effects on seagrass ecosystem services”. It will involve … (more…)

  • Experiment on (invasive) seagrass & turtle grazing, Bonaire

    Experiment on (invasive) seagrass & turtle grazing, Bonaire

    Two weeks ago we arrived on Bonaire. Since then we worked non-stop and we made great progress! The first thing we did was to set up a turtle exclosure experiment on the seagrass beds in Lac Bay, after Funchi (STCB) and Sabine Engel (STINAPA) kindly showed us all the suitable seagrass areas. The native dominant seagrass species here are Thalassia testudinum (or turtle grass) and Syringodium filiforme. However after a quick snorkel survey across the bay the cover of invasive seagrass species Halophila stipulacea seems almost higher.

    That is impressive since the species was reported only in 2010 for the first time in Lac Bay. NGO Sea Turtle Conservation Bonaire that works since 1991 on turtles here estimates the sea turtle population (green and hawksbill) between 1000-2000 turtles (more…)

  • Green turtles threaten their own food source in MPAs: New paper Proceedings B

    Green turtles threaten their own food source in MPAs: New paper Proceedings B

    Our new paper is out in Proceedings of the Royal Society B! Green turtle populations have expanded so much in Indonesia’s east coast islands marine protected areas that they are adopting new feeding habits, degrading the ecosystem and threatening their own conservation. Read more about  “Habitat collapse due to overgrazing threatens turtle conservation in marine protected areas” and download the paper here.

    After press coverage of the Associated Press the news has gone viral! see Washington Post, Time and others

    rspb_christianen

  • Research cruise SIBES 2013 on the Navicula

    Research cruise SIBES 2013 on the Navicula

    This week I am joining the SIBES 2013 crew on the Navicula. They are sampling benthos at ± 4500 points spread througout the Wadden Sea, a program that is already running for 6 years. (more…)

  • PhD thesis in the pocket!

    PhD thesis in the pocket!

    The 22th of March was the Big Day, I had to defend my PhD thesis. After a 10 minute summary about my research I had one hour to answer the questions of 8 (associate) Professors. 1.5 hours later this happy photo was taken. (more…)

  • My research in the (Dutch) media

    My research in the (Dutch) media

    After sending out the press release about my upcoming PhD defense, my research on seaturtles destroying their own habitat did receive some attention in Trouw newspaper and a science-radio program. Check these links here.

  • 10th ISBW Buzios, Brasil (& sea hares)

    10th ISBW Buzios, Brasil (& sea hares)

    The 10th international seagrass biology workshop was a success! Together with seagrass specialists from around the globe we enjoyed 3 days packed with talks & workshops in a resort town of Buzios in Brasil. See WSA’s blog by Sity for a nice overview of the highlights and of the speakers (gallery seagrass watch)

    It also included a field trip to the seagrass (Halodole wrightii) meadows of  Ilha do Japonês, Cabo Frio. Here Dominik and I found some small green turtles above the seagrass bed and loads of sea hares swimming and mating.

    Together with the other young seagrass punks we had a great conference! See then here in their natural habitat:

    Many thanks to Tjeerd & Leon to provide funding for this great opportunity

  • Seagrass expedition Bank d’Arguin, Mauretania

    Seagrass expedition Bank d’Arguin, Mauretania

    The Bank d’Arguin is a magnificent place: Not only to see loads of beautiful birds, some marked with colourfull rings as a souvenir from the Netherlands, but also to do seagrass research. Together with Jim de Fouw (our expedition leader), Laura Govers, Tjisse van der Heide en Karin van de Reijden we traveled through the Mauritanian desert to the Bank d’Arguin research station.



    This station has been used for decades by many researchers, which can be noticed by the strange collections of research equipement: fake birds, umbrella’s, cages, nets, loads of rain meters (desert??) and snow rackets. These snow rackets were used the next day (don’t worry: no climate change-induced snow storm in the desert) to walk on the mudflats to reach our seagrass plots, to prevent to sink knee deep in the mud, which did occur to Laura due to a broken racket. The tidal flats are dominated by seagrass: in the intertidal Zostera noltii and a bit of Halodule whrightii and subtidal Cymodocea nodosa. Contrasting to the tropical reeftop seagrass meadows where I usually work, here, the seagrasses build up a hudge amount of organic matter and trap a lot of suspended particles so that the mudflat is raised by a couple of centimeters per year. In an experiment we test the effect of this phenomena and bivalves on seagrasses. Another series of experiment and observations focussed on the seagrass foodweb. Unfortunately snorkeling is not really a lot of fun here because of the poor visibility. Above the seagrass we encountered a lot of bottlenose dolphins (twice the size of the Indo-Pacific ones), fidler crabs, shoavelnose-, torpedo-, and sting-rays, jumping yellow mullets, borrowing crabs, Cymbium shells, and in the ground under the seagrass off course loads of the world-famous Loripes lacteus and Anadara (“Shell”-) shells.

    A very dramatic sight was the enormous amount of dead green turtle carapaces that were washed up the beach and eaten by jackals in the previous month; approximately 1 dead turtle every 20 meter at a stretch of 3km beach. There was no sign of poaching (cuts in the carpace) or hunger, the carapace lenght (CCL) ranged from 40 cm till 90 cm, and the local rangers and researchers also don’t have a clue what happened here, leave a comment if you know more! Some random photos: