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Subsidient: Thijs van Wuijckhuijse/Wageningen University
Subsidie: S163.S3

My name is Thijs van Wuijckhuijse, and I have been doing my internship here on Bonaire to continue with the already running project in Lac Bay regarding cage experiments and cafeteria experiments. My fieldwork started on November 1st, 2016 and ended on February 1st, 2017. February will be the time to write a report of my findings. My main research question is: To what extend does grazing impact the growth and reproduction of the native seagrass Thalassia testudinum and the exotic seagrass Halophila stipulacea? First, I wanted to know what seagrass species is preferable by the green sea turtle. The cafeteria experiment, where I offer three different grass species to sea turtles, show they eat all three species. During the cage experiments, where I studied the two most important seagrass species, I looked at the growth and reproduction of the native and exotic seagrass with no grazing present by sea turtles, where in a couple of cages I mimicked grazing by clipping the grass as a control. I also measured the ratio native/exotic. Once a month I took samples (above- and belowground) to study the difference in above- and belowground biomass. My results showed that the exotic seagrass is spreading, and the native seagrass is declining, especially close to the mangrove border in the northwestern part of the bay