Acoustic detection of bubbles in a pond covered by the seagrass Cymodocea nodosa

摘要

This paper describes two experiments conducted in a pond covered by the seagrass Cymodocea nodosa at the Aquaculture Research Station of the Portuguese Institute for the Sea and Atmosphere in Olhao, Portugal, aiming at developing acoustic methods to assess oxygen production of seagrasses. The first experiment was carried out in July covering two days, when warm water and high photosynthetic rates give a high probability of oxygen supersaturation in water. The second experiment was carried out in late October, covering a period of 10 days, when seagrass productivity was expected to be lower than in July given the low irradiance and photoperiod. In the July experiment the high attenuation of low frequency pulses and broadband water pump noise (收起