Development of a Measurement System for Assessment of Bubble Production of Seagrass

Abstract

The main objective of this work is to develop and to test an acquisition system for measuring bubbles on the water column, based on its effect on acoustic propagation. Bubbles in the water increase the acoustic signal attenuation and decrease the effective water sound speed, noticeable at frequencies below the resonance frequency. Acoustic propagation over seagrass meadows is strongly affected by the occurrence of oxygen bubbles under oversaturation conditions during the photosynthesis. The amount of oxygen released as bubbles is difficult to measure by conventional methods. The proposed system is controlled by a low cost Red Pitaya board and includes signal generation, acquisition and basic data analysis. The system was designed and tested, based on previous experiments conducted on the interest area, a pond covered by the Cymodocea nodosa seagrass. The practical aspects of the experimental setup taking into account the constraints imposed by the very shallow water marine environment will be addressed. Preliminary results of systems testing will be discussed. This work is a contribution to the development of an acoustic system to measure the oxygen produced by marine plants in the form of bubbles. Therefore, it represents a contribution to a more accurate estimation of primary production of marine plants and understanding of their photosynthesis, acoustic measurement systems, underwater bubbles, acoustic oceanography.