A novel mesocosm setup for benthic‐pelagic coupling experiments

A new mesocosm setup containing both water column and sediment suitable for benthic‐pelagic coupling experiments is described. The presence of a large volume of water (>1.5 m3) with sufficient depth (4 m) on the top of the sediment, combined with a large volume of sediment on the bottom (30 cm height, 80 L volume) offers new opportunities for benthic‐pelagic experiments on the mesocosm scale. The experimental setup includes a mesocosm bag, a securing ring with a cap on the top, a sediment container on the bottom, sediment traps, an autonomous water sampling system at specific depths, and a newly developed sediment sampler for collecting samples without disturbing the system. The mesocosm setup was successfully deployed in the context of a benthic‐pelagic coupling eutrophication experiment in the CRETACOSMOS mesocosm facilities of the Hellenic Centre for Marine Research in Crete. A number of variables related to the technical aspects and proper ecosystem functions of the mesocosm setup were monitored throughout the duration of the experiment (58 d), which proved that the proposed setup is suitable for benthic‐pelagic coupling experiments, providing an intermediate experimental tool between small‐scale micro/benthocosm experiments and large scale in situ sea experiments.