Turbulence and waves inside flexible-wall systems designed for biological studies

Simultaneous flow measurements were performed by hot-wire anemometry inside and outside (a) a closed bag, and (b) a flow-through system designed for metabolic experiments of Fucus vesiculosus communities. Since water movement is considered an important parameter in such biological studies, the walls of the systems were flexible in order to establish flow conditions within the enclosed water body comparable to those in the natural environment. In situ experiments in the Baltic Sea at a water depth of 2 m showed that energy spectra inside the systems were comparable to those outside for a variety of flow and wave conditions. Thus, biological data from glexible wall systems, carefully designed to meet specific natural flow requirements, can be taken as reliable input data for natural ecosystem modeling.Contribution No. 147 of the Joint Research Programme 95 Interaction Sea-Sea Bottom, Kiel University, Kiel (FRG), and Hawaii Institute of Geophysics Contribution No. 803.