Bioacustica
1. Tipi di suoni prodotti
2. Funzione dei suoni
3. Passive Acoustic per gli studi di popolazione
4. Identificazione acustica degli odontoceti del Mediterraneo
Tipi di suoni
Misticeti
“There is no standard nomenclature for baleen whale sounds.
Similar sounds are oftn given different names by differents
authors. (…). It is difficult to study context and functions of
baleen whale sounds. Unlike others marine mammals, baleen
whale are rarely held in captivity. It has rarely been possible to
associate specific whale sounds with specific animals activities
where under observation”.
(Marine mammals and noise, 1995)
Tipi di suoni
Odontoceti
“Odontocete sounds can be classified into three general
categories: tonal whistle, pulsed sounds (echolocation), and
less distincte pulsed sounds such as cries, grunts, and barks”.
(Marine mammals and noise, 1995)
Whistle: maggior parte dell’energia <20 KHz. Grande variabilità
(single wh, loop, multi)
Clicks e pulsed sounds: 1-90 al secondo, 0.1-200 KHz (P.
macrocephalus: 0.1-30KHz)
Tipi di suoni
Odontoceti - Dd
Tipi di suoni
Odontoceti
Tipi di suoni
Odontoceti - Dd
Tipi di suoni
Odontoceti - Dd
Tipi di suoni
Odontoceti - Gm
Tipi di suoni
Odontoceti - Gm
Tipi di suoni
Odontoceti - Sc
Tipi di suoni
Odontoceti - Sc
Tipi di suoni
Odontoceti - Pc
Tipi di suoni
Odontoceti - Pc
Tipi di suoni
Odontoceti - Pc
Tipi di suoni
Odontoceti - Pc
Tipi di suoni
Funzione dei suoni
The vocalizations of dolphins are assumed to have
communication, navigation, and food location functions. Some
researchers have advanced a "signature whistle" hypothesis,
that states that certain vocalizations that are emitted by
preference by individuals in a pod represent an acoustic
"signature" for that individual.
“Stock assessment” e “habitat use”
con metodi acustici
NOOA workshop, la Jolla (CA), 20-22 novembre 2002
Survey acustici attuali:
• incremento della capacità di avvistamento visivo.
Survey acustici futuri:
• analisi della struttura di popolazione
determinare
relazione tra la struttura di popolazione determinata con
l’acustica e quella determinata con la genetica
• analisi di abbondanza e densità
necessarie ulteriori
ricerche per l’identificazione acustica delle specie, soprattutto
dei piccoli cetacei (già utilizzato per capodoglio e alcuni
misticeti)
• disturbo da rumore naturale
• densità relativa, distribuzione stagionale, trends.
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
Sperm whales are deep diving animals. They regularly make
dives to depths of around 1000m lasting over 45 minutes. For
this reason, traditional survey methods, which involve
searching for them by eye, are less effective than acoustic
surveys.
Fortunately for us, while they are submerged, sperm whales
make loud clicks, which can be heard several miles away.
By listening to the clicks it is possible to track its movement
underwater without even setting eyes on it.
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
Counting acoustically has the following other advantages
over traditional survey methods:
•
Acoustic surveys can continue 24 hours a day, therefore
using boat time more efficiently.
•
Acoustic surveys can be automated, as we have done for
sperm whales, making them more objective and less prone
to variations in the efficiency of individual observers.
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
• Automatic acoustic surveys do not require a large observer
team, so they can be carried out from smaller vessels and
platforms of opportunity.
•
Acoustic surveys are less affected by changes in sea
state than visual surveys, again making them more
efficient.
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
Sperm Whale Survey in the Mediterranean Sea
IFAW – ACCOBAMS 2003-2004
Necessarie ulteriori ricerche per l’identificazione
acustica degli altri odontoceti,
per il loro monitoraggio acustico passivo
Sound propagate long distances in the ocean (Medwin and Clay 1998)
and many cetaceans are extremely vocal (Richardson et al. 1995).
Steiner (1981) correctly classified the whistle of five western North
Atlantic odontocete species 70% of the time. Wang et al. (1995)
correctly classified the whistle 65% of seven odontocete species from
diverse geographic locations. Rendell et al. (1999) correctly classified
55% of the whistle of five odontocete species form diverse geographic
locations. Oswald et al. (2003) correctly classified the whistle 41,5% of
nine odontocete species in the ETP.
Correct classification scores obtained in most whistle
classification studies have been significantly greater than would
be expected by chance alone, suggesting that differences in
whistle structures can be used to identify species.
Mancavano studi per il Mediterraneo
Oswald et al. 2003: acoustic identification of
nine delphinid species in the ETP