A methodology for analyzing data from long-term passive acoustic monitoring.

• Ano de defesa: 2017
• Autor(a) principal: Sánchez Gendriz, Ignacio
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Big Data; Data processing; Digital son processing; Mares; Oceanos; Passive acoustic monitoring; Processamento de dados; Processamento digital de som; Soundscape
• Link de acesso: http://www.teses.usp.br/teses/disponiveis/3/3152/tde-26062017-145831/

Despite the extensive Brazilian coast areas, little is known on underwater acoustic environments in Brazil. Acoustic environments (or soundscape) are composed by biological, geological and man-made sound sources. Soundscapes are strongly linked to ecosystems dynamics, and follow temporal patters that can vary at daily and seasonal scales. Thus, for soundscape characterization, it is necessary to undertake sound recordings for long periods, which demands innovative analyzing methods. Accordingly, the present research focuses in two principal objectives: (1) to develop methods for analyzing long-term acoustic recordings and, (2) to characterize marine soundscapes of selected points in São Paulo State. Four deployment sites were selected for the underwater acoustic monitoring: a point located at the channel entrance of the Santos Harbor, and three marine Protected Areas (PAs) in Sao Paulo state. As a result, the largest underwater acoustic database from Brazilian seas was acquired. The present work used Power Spectral Density (PSD), Sound Pressure Level (SPL) and Spectrograms to develop an innovative methodology for analyzing long-term acoustic data. In addition, a new visualization tool and a method for automatic detection of dawn and dusk choruses are presented. The achieved results validated the proposed methodology as an effective tool for analyzing long-term acoustic data. The area close to the first site, the vicinity of Santos Harbor, was dominated by ship noise, which values reach levels that can affect some species of fish and marine mammals. The soundscapes of the other three remaining measurement sites were dominated by fish and crustacean choruses, with daily and seasonal patterns (related to sunrise and sunset). For the monitored regions, the present work signifies the first contribution for cataloguing fish choruses, and establishes a baseline for the study of their underwater acoustic environment. Although the proposed methodology has used long-term undersea acoustic datasets as case-study, it can also be extended for monitoring other aquatic or terrestrial ecosystems. Finally, the research indicates to Brazilian environmental agencies and to the related scientific community that passive acoustic monitoring is a noninvasive and cost-effective tool that can be used for the management of PAs and points of economic relevance.