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Study of ultrasound effects on biofouling in artificial substrates in the aquatic environments

Grant number: 14/23981-0
Support type:Regular Research Grants
Duration: February 01, 2016 - July 31, 2018
Field of knowledge:Interdisciplinary Subjects
Principal researcher:Julio Cezar Adamowski
Grantee:Julio Cezar Adamowski
Home Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Assoc. researchers:Marco Aurélio Brizzotti Andrade ; Nilson Noris Franceschetti ; Rubens Mendes Lopes

Abstract

This project will study the effects of ultrasound treatment on fouling organisms, as a first initiative to provide information for the development of acoustic-based prevention and control instrumentation. The study will focus on two biological groups of interest for biofouling research: (i) the sun coral (Tubastraea spp.), which is a non-hermatypic exotic coral genus found in large abundances on oil platforms and other structures in south- and northeast Brazil; and (ii), barnacles, which are common and persistent fouling organisms on boats and marine platforms. Field trials will be conducted to assess the influence of varying ultrasound levels on fouling organisms, by using test plates as substrates. The operating frequency, sound pressure, average power applied and modeled distance from the ultrasound source to the test surface will be investigated. These evaluations will be conducted by mapping the acoustic field to evaluate the impact on substrate colonization, which will be assessed by image analysis tools. In field experiments, ultrasonic waves will be produced by customized battery powered ultrasound equipments. In addition, laboratory experiments will evaluate the effect of ultrasound, including acoustic cavitation, on larval settlement and survival. The acoustic pressure distribution within the experimental tank will be measured by a calibrated hydrophone. The acoustic pressure in the control volume will be monitored by using customized hydrophones that will be developed and fabricated. With preliminary experiments carried out at the IOUSP laboratory in Ubatuba, it was possible to set a basic experimental setup, with a control volume of approximately 50 mL. In the larval settlement and survival experiments, periodic images will be acquired with a digital camera. To evaluate the influence of ultrasonic irradiation on larvae settlement, high-frequency images will be obtained with two cameras orthogonally positioned to each other to provide tridimensional coordinates of larval swimming trajectories in the presence and absence of ultrasound. The larvae will be collected from spawning adult populations kept in the laboratory for the duration of the experiments. (AU)