Author(s): V. Stratigaki; E. Manca; P. Prinos; I. Losada; J. Lara; M. Sclavo; I. Caceres; A. Sanchez-Arcilla
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Abstract: Posidonia oceanica, the most abundant seagrass species in the Mediterranean, supports a highly bio diverse habitat and is crucial in protection against coastal erosion. The effects of marine/estuarine submerged vegetation on unidirectional flows has been studied at a variety of scales in the field and in laboratory flumes, while much less is known about the interaction between seagrass and waves. In this work large scale experiments have been conducted in the CIEM wave flume (Canal d'Investigacio i Experimentacio Maritima) in Barcelona (UPC/LIM), for the measurement of wave attenuation, transmission and energy dissipation over artificial Posidonia oceanica during low and high energy events in intermediate and shallow waters. The effects of submergence ratio hs/D (hs=height of seagrass, D=water depth) and seagrass density (number of shoots per squared meter) on the above characteristics are investigated. Measurements of mean velocities above and within the simulated P. oceanica field indicate the wave induced flow within the meadow, which influences processes such as nutrient uptake, waste removal and larval dispersion. Measurements of wave height at different locations along the meadow (seaward, front, middle, end and shoreward of P. oceanica field) indicate the wave attenuation along the patch for regular waves, three different submergence ratios hs/D (0.500,0. 416 and 0.322) and two seagrass densities (360 and 180 stems/m2). Results are also analysed with regard to the wave induced flow within the field and the effects of submergence ratio and seagrass density on mean flow characteristics are investigated based on measurements of mean velocities taken at three locations within the seagrass field (front, middle and end of P. oceanica field).
Year: 2009