Embed Size (px)
Citation preview
ARION: a tool for real time bottlenose dolphin monitoring in the Portofino MPA LIFE 09/Nat/IT/190
Alessi J.(2), Bianchi C.N.(2), Bozzini G.(1) *, Brunoldi M.(1), Cappanera V.(3), Casale A.(1) *, Corvisiero P.(1), Fanciulli G.(3), Grosso D.(1), Magnoli N.(1), Melchiorre C.(4), Morri C.(2), Povero P.(2), Stasi N.(5), Taiuti M.(1), Viano G.(4), Wurtz M.(2)
(1) University of Genova, Physics, Genova, Italy, (2) University of Genova, Distav, Genova, Italy, (3) Portofino MPA, Genova, Italy, (4) Softeco Sismat, Genova, Italy, (5) Direzione Marittima di Genova, Italy * corresponding authors [email protected] ; [email protected]
The bottlenose dolphin (Tursiops truncatus, Montagu 1821) is a Mediterranean cetacean listed as “vulnerable” in IUCN Red List. The Ligurian Sea and the Portofino coastal area are subject to intensive boat traffic. This kind of impact represents a serious threat, especially for cetaceans, as they communicate with sounds and orient by underwater sonar-waves. The main objective of the project is the improvement of the conservation status of the bottlenose dolphin in the MPA of Portofino. To facilitate management and conservation policies, to support scientific projects and promote public dissemination, we aim to: create a controlled area, make people aware of the presence of the dolphins, disseminate the appropriate code of conduct among tourists in the Ligurian sea (in accordance with ACCOBAMS and Pelagos Sanctuary guidelines), verify that the given rules are respected .
INTRODUCTION
FIGURE 5. ARION data flow
SEA SURFACE BUOY
TOP VIEW
H2
H3 H4
H1
90m
20m
SEA BOTTOM
6m
5m
FIGURE 4. Detection unit structure FIGURE 1. Location and action range of the detection units FIGURE 2. The detection units
The detection units are composed by a network of hydrophones installed on two elastic beacons (FIG.2) in front of the Portofino MPA (FIG.1). The acquisition system communicates using a wi-fi bridge with an on-shore computer center housed inside Portofino’s lighthouse (FIG.3) to localize and track dolphins and boats in real time.
ITALY
THE ARION SYSTEM
SEMINARIO SULLA BIOLOGIA E LA CONSERVAZIONE DEI MAMMIFERI MARINI – University of Pavia CIBRA, Italy - October 30-31 2014
www.arionlife.eu FIGURE 7. Spectrograms of some observed whistle types
GENERAL FUNCTIONING (Figures 4 - 5): • 4 hydrophones on each buoy collect underwater sounds • Different sensors collect environmental data • Raw data are filtered and transmitted on shore using a wireless bridge • Dolphin's whistles and other sound sources are identified in real time • The position of a sound source (triangulated) is used to generate a track representing the route of the “target” (dolphins or boats) • Raw data are stored for research purposes • Information resulting from data analysis is transmitted to a web server and made available to the end users
FIGURE 3. Portofino’s lighthouse
FIGURE 6. Spectrogram of a hydrophone signal
• If each buoy detects the same acoustic source, we will find the position of the sound source by triangulation (FIG.8)
spectrogram
click whistle
• Whistle identification is realized by a proper detection function applied to the spectrogram (FIG.6).
• TDOA (Time Difference Of Arrival) is calculated by cross-correlating the hydrophone signals: 6 configurations for 4 hydrophones to check for good events in plane-wave approximation. From TDOAs calculation it is possible to determine the direction of arrival of the sound emitted by an acoustic source (azimuth and elevation angle) corrected by nautical angles (roll-pitch-compass). FIG.7 shows some observed whistle
types. FIGURE 8. Left: both buoys detect the same whistle in the spectrograms. Right: the position of the dolphin is calculated by crossing the directions obtained from the two detection units and the hyperbole corresponding to the time delay between the buoys.
DOLPHIN TRACKING ALARM GENERATION FIRST RESULTS
O
P
M
N
F
E A C
D
I
L
G
Q B
H
• Encounter rate (E.R.)
𝐸𝐸.𝑅𝑅. = 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃_𝐷𝐷𝐷𝐷𝐷𝐷𝑃𝑃𝑇𝑇𝑇𝑇𝑇𝑇_𝐷𝐷𝐷𝐷𝐷𝐷𝑃𝑃
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Encounter Rate
ER 2013 ER 2014
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Primavera '13(APR-GIU)
Estate '13 (LUG-SET)
Autunno '13 (OTT-DIC)
Inverno '13-14(GEN-MAR)
Primavera '14(APR-GIU)
Det
ectio
n ra
te
Detection rate
00:00-05:59 06:00-11:59 12:00-17:59 18:00-23:59
• Detection rates: day (Dd) and night (Dn)
𝐷𝐷𝐷𝐷 = 𝐷𝐷𝑃𝑃𝐷𝐷𝐷𝐷𝑇𝑇𝐷𝐷
𝐷𝐷𝐷𝐷 = 𝐷𝐷𝑃𝑃𝐷𝐷𝐷𝐷𝑇𝑇𝐷𝐷
DPM: total minutes of whistle registrations T: total functioning hours of detection units
FIGURE 9. Dissemination tools (web portal and mobile app)
FIGURE 10. Protocol of conduct
