[Coral-List] caging experiments on the reef flat

Christian Jessen fidelfisch at gmx.de
Wed Oct 21 10:03:35 EDT 2009

Dear coral-list members,
my name is Christian and I'm studying biology at the Free University of Berlin. At present I'm writing my diploma thesis about the impact of herbivorous fish on the reef flat of the fringing reef of the Red Sea. To get my data I constructed some cages (50 cm in diameter) to exclude fish. The cages contain tiles, which function as settling plates for algae that should grow in the absence of herbivorous fish. Every 4 weeks I remove one tile to check weight and species.
Now my problem. The horizontal positioned cages were put on the reef flat at ~1,5 m depth. Unfortunately the sedimentation rate exeeds the growth rate of algae, therefore I'm collecting only sediment with my tiles, whereas the cages (which are made of plastic) seem to be an ideal settling place for algae and need to be cleaned every few days. I've heard from a colleage of me that tiles don't appear as a appropriate settling ground. Has somebody some experience with this kind of settling substratum? Or might it be, that the horizontal position of the tiles is unsuitable for such experiments?

I would be really thankful for any comment / input / help.


Christian Jessen


Christian Jessen
RSEC - Red Sea Environmental Centre

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