Bioacoustics represents a powerful tool to explore the marine environment, to obtain useful information on marine organisms as well to increase scientific knowledge and to plan conservation strategies in response to the impacts due to human activities (acoustic and chemical pollution, depletion of resources, habitat alteration, interactions with fishing and boating). In the last decades, several scientists have confirmed that sound is indispensable for the life of various marine animals. Among the marine organisms that emit sounds, mammals have exceptional acoustic capabilities, essential for their life (communication, echolocation, perception of the environment). Receiving and studying their sounds, a complete research about their ecological dynamics can be performed. In this thesis, various methods of analysis of the Sperm Whale sounds are shown, with great interest in the ability to acoustically measure the size of the animals recorded. It is also examined the scientific literature to outline a historical overview of bioacoustic research since 1985. A particular interest is reserved to the identification of the size of the animals recorded through the analysis of the acoustic signals. The body length is estimated by measuring the structure of sounds emitted for Echolocation. The signals emitted by the Sperm Whale are impulsive, called "click", consisting of two or more pulses generated by reflections inside the spermaceti organ, the delay between these pulses (IPI) provides the estimate of spermaceti size, and then, through specific mathematical equations (Gordon, Growcott and Tethys), the size of the sperm whale's body. The analysis was based on two large sets of data: the first is represented by historical data consisting of the recordings made in the Mediterranean sea by Bill Watkins, a pioneer of marine bioacoustic research, the second data set is current, collected from CIBRA with the research cruises SIREN 2011, occurred in summer (July), in autumn (October) and winter (December), in the Ligurian Sea. With SIREN 2011 has been carried out a study of the presence of the sperm whale in the Ligurian Sea in different seasons and it was demonstrated the presence in winter. In addition, an acoustic data sample acquired in the Ligurian sea during the collaboration between CIBRA and BOMBYX project of the University of Toulon has been taken into account. All the recordings have been analyzed by spectrographic analysis with SeaPro 2.0 software developed by CIBRA.
La ricerca bioacustica marina rappresenta uno strumento importante per ottenere informazioni sull’ambiente marino e gli organismi che lo abitano, per aumentare le conoscenze scientifiche e per pianificare le strategie di conservazione in risposta agli impatti dovuti alle attività umane (inquinamento acustico e chimico, depauperamento delle risorse, alterazione dell’habitat, interazioni con la pesca e la navigazione). Negli ultimi decenni numerosi studiosi hanno confermato che il suono è uno strumento indispensabile per la vita di molte specie marine. Tra queste, i mammiferi marini hanno sviluppato capacità acustiche molto evolute essenziali per la loro vita (comunicazione, ecolocalizzazione, percezione dell’ambiente). La ricezione e lo studio dei segnali acustici da loro emessi consente lo sviluppo di una ricerca approfondita riguardo le loro dinamiche ecologiche. In questo lavoro di tesi sono applicati metodi di analisi dei segnali acustici emessi dai Capodogli in Mediterraneo per valutare le dimensioni degli animali registrati. Viene inoltre esaminata la letteratura pertinente e delineato un quadro storico delle ricerche bioacustiche a partire dal 1985. Un particolare interesse è riservato alla possibilità di risalire, mediante l’analisi dei segnali acustici, alle dimensioni degli animali registrati. La lunghezza del corpo viene stimata misurando la struttura dei suoni emessi per ecolocalizzare. I segnali emessi dal capodoglio sono impulsivi, chiamati “click”, composti da due o più impulsi generati dai riflessi all'interno dell'organo dello spermaceti, il ritardo tra questi impulsi (IPI) fornisce la stima della dimensione dello spermaceti e quindi, attraverso specifiche equazioni matematiche (Gordon, Growcott e Tethys), della dimensione del corpo del capodoglio. L’analisi è stata effettuata su due grandi set di dati: il primo è rappresentato da dati storici costituito dalle registrazioni in Mediterraneo messe online della fonoteca di Bill Watkins, un pioniere della ricerca bioacustica marina, mentre il secondo è attuale, raccolto dal CIBRA con la crociere di ricerca SIRENA 2011, effettuate in estate (luglio), in autunno (ottobre) e in inverno (dicembre), in Mar Ligure. Con SIRENA 2011 si è realizzato uno studio della presenza del capodoglio in mar ligure nelle varie stagioni, dimostrandone anche la presenza invernale. Sono stati anche presi in considerazione campioni di dati acustici acquisiti in mar ligure nel corso della collaborazione del CIBRA con il progetto BOMBYX dell’Università di Tolone. Le registrazioni sono state analizzate tramite analisi spettrografica con il software SeaPro 2.0 sviluppato dal CIBRA.
Lo sviluppo della ricerca bioacustica sul Capodoglio in Mediterraneo: da Bill Watkins ai giorni nostri.
BOSCAGLIA, MARTINA
2015/2016
Abstract
Bioacoustics represents a powerful tool to explore the marine environment, to obtain useful information on marine organisms as well to increase scientific knowledge and to plan conservation strategies in response to the impacts due to human activities (acoustic and chemical pollution, depletion of resources, habitat alteration, interactions with fishing and boating). In the last decades, several scientists have confirmed that sound is indispensable for the life of various marine animals. Among the marine organisms that emit sounds, mammals have exceptional acoustic capabilities, essential for their life (communication, echolocation, perception of the environment). Receiving and studying their sounds, a complete research about their ecological dynamics can be performed. In this thesis, various methods of analysis of the Sperm Whale sounds are shown, with great interest in the ability to acoustically measure the size of the animals recorded. It is also examined the scientific literature to outline a historical overview of bioacoustic research since 1985. A particular interest is reserved to the identification of the size of the animals recorded through the analysis of the acoustic signals. The body length is estimated by measuring the structure of sounds emitted for Echolocation. The signals emitted by the Sperm Whale are impulsive, called "click", consisting of two or more pulses generated by reflections inside the spermaceti organ, the delay between these pulses (IPI) provides the estimate of spermaceti size, and then, through specific mathematical equations (Gordon, Growcott and Tethys), the size of the sperm whale's body. The analysis was based on two large sets of data: the first is represented by historical data consisting of the recordings made in the Mediterranean sea by Bill Watkins, a pioneer of marine bioacoustic research, the second data set is current, collected from CIBRA with the research cruises SIREN 2011, occurred in summer (July), in autumn (October) and winter (December), in the Ligurian Sea. With SIREN 2011 has been carried out a study of the presence of the sperm whale in the Ligurian Sea in different seasons and it was demonstrated the presence in winter. In addition, an acoustic data sample acquired in the Ligurian sea during the collaboration between CIBRA and BOMBYX project of the University of Toulon has been taken into account. All the recordings have been analyzed by spectrographic analysis with SeaPro 2.0 software developed by CIBRA.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/20762