Variability of the low-frequency acoustic response along leaf blades and between species of seagrass (Posidonia oceanica and Cymodocea nodosa)

An acoustic resonator was used to measure the low-frequency (1-5kHz) effective acoustic properties of the leaf blades of two Mediterranean seagrass species (Posidonia oceanica and Cymodocea nodosa). Variability along blades was assessed by measuring the effective change in sound speed per gram blade biomass of the basal and apical halves of P. oceanica leaves separately (-11 and -1.5ms(-1)g(-1), respectively). Large differences in the effective sound speed per unit biomass between P. oceanica and C. nodosa (43-52ms(-1)g(-1) larger for C. nodosa) are discussed using microscopic imagery of blade cross-sections.