1. T-PODS, an effective management tool to determine the use of habitat by
bottlenose dolphins in Medes Island Marine Protected Area
(North eastern Spain) A22
Carla A. Chicote1, Manel Gazo1 and Manuel Castellote2
carlachicote@submon.org
1 SUBMON Conservation, study and awareness of marine environment- Rabassa, 49-51 – 08024 Barcelona, Spain
2 Research Department, L'Oceanogràfic - City of the Arts and Sciences, Junta de Murs i Valls s/n - 46013 Valencia Spain.
The establishment of Marine Protected Areas (MPA) is one of the most effective strategies
for preserving habitats and species (Hooker & Gerber 2004) as it is considered a
fundamental tool for biodiversity conservation.
This study investigates the use of a MPA by bottlenose dolphins using passive acoustic
monitoring (Train Porpoise Detector(T-POD), Chelonia Ltd.). Although sporadic and
opportunistic sightings of bottlenose dolphins have been reported in the area, no
ZONE B
information on the use of the area by the species has been collected yet in order to (Buoy 6)
improve the management of the MPA.
Materials and methods
ZONE A
An acoustic monitoring program was established in order to obtain daily and seasonal patterns (Buoy 2)
during one year study period (January 2009 - January 2010). Two T-PODs (version 5) were moored at
18 and 25 m depth respectively attached to two of the border buoys of the MPA (bottom depth
60m). T-PODs were located at 0,2 nm and 0,5 nm from the outer islet and distance between both
was 0,5nm. The detection range was assumed to be 500 m based on Philpott et al. (2006). Data was Study area
recovered monthly. Each time that dolphins were detected after an absence period of 7 days it was The study was carried out at the Medes
considered as a new visiting period. Island, a group of 7 islets, located off the
northeast coast of Catalonia (north
The T-POD is an acoustic detector that logs the time and duration of eastern Spain) established as Marine
clicks resembled during the echo-localization, produced by Protected Area since 1990. Buoys
odontocetes, with a resolution of microseconds. In order to avoid indicated the location of the moored T-
false detections (invertebrates, fishes or boats), the information PODs.
registered by the T-POD was further analysed with a software
(TPOD.EXE V8.24). T-POD scanning settings were based on results
from Esteban & Castellote (2008) to minimize the effect of snapping
shrimp noise in the echolocation detection efficiency.
% positive days %
25
Results
20
Table 1 summarizes the sampling period for each of the two T-PODs. Results describe an important
35,3 Buoy 2
15
percentage of positive days of detection (Fig. 1) in both zones, but no significant differences were found in
10 the number of detections (U Mann-Whitney p=0,8) between buoys.
Buoy 6
42,5 5
Total clicks
0
Total sampling days Total positive days
Buoy 2 Buoy 6
Figure 1. Percentage of positive days of detected trains of clicks Figure 2. Percentage of fast clicks trains (>100 clicks/sec)
ZONE A (BUOY 2) 153 65 4539
%
80
N clicks ZONE B (BUOY 6) 114 54 4482
Buoy 6
70
60 200
180
Table 1. Summarizes the sampling period for both T-PODs.
50 160
Percentage of fast click trains (Pulse repetition frequency (PRF)>100 with terminal buzzes), associated to
140
40 Daytime 120
100
30
Nightime 80
20
10
60
40
20
feeding activity (Au. 1993, Johnson et al. 2008), reached 20% with strong preference to the outer buoy 2
(Fig. 2).
0
0
01/02/2009
08/02/2009
15/02/2009
22/02/2009
01/03/2009
08/03/2009
15/03/2009
22/03/2009
29/03/2009
05/04/2009
12/04/2009
19/04/2009
26/04/2009
03/05/2009
10/05/2009
17/05/2009
24/05/2009
31/05/2009
07/06/2009
14/06/2009
21/06/2009
28/06/2009
05/07/2009
12/07/2009
19/07/2009
26/07/2009
02/08/2009
09/08/2009
16/08/2009
23/08/2009
30/08/2009
06/09/2009
13/09/2009
20/09/2009
27/09/2009
04/10/2009
11/10/2009
18/10/2009
25/10/2009
01/11/2009
08/11/2009
15/11/2009
22/11/2009
29/11/2009
06/12/2009
Buoy 2
Buoy6
N of clicks
Bottlenose dolphins visited the area 11 times along the year (Fig. 3) with an average permanency of 25
Figure 4. Percentage of positive days during the daily periods Buoy 2 days for winter time and 3 days for summer time.
% 350
300
90
80
250
200 Different patterns in the use of the area have been found, showing preferences (71,9% of presence) for
night period (7:01 pm-7 am) (Fig. 4) with peaks after dusk (23pm -2am) (Fig. 5). Seasonal pattern shows a
70 150
100
60
clear preference (67,8% of presence) for winter months (October-May), decreasing the presence toward
50
50 Winter 0
40
30/01/2009
06/02/2009
13/02/2009
20/02/2009
27/02/2009
06/03/2009
13/03/2009
20/03/2009
27/03/2009
03/04/2009
10/04/2009
17/04/2009
24/04/2009
01/05/2009
08/05/2009
15/05/2009
22/05/2009
29/05/2009
05/06/2009
12/06/2009
19/06/2009
26/06/2009
03/07/2009
10/07/2009
17/07/2009
24/07/2009
31/07/2009
07/08/2009
14/08/2009
21/08/2009
28/08/2009
04/09/2009
11/09/2009
18/09/2009
25/09/2009
02/10/2009
09/10/2009
16/10/2009
23/10/2009
30/10/2009
06/11/2009
13/11/2009
30
20
Summer
summer period (Fig. 6).
10
Conclusions
0
Figure 3. Detected clicks per day in both areas
Buoy 2
Buoy 6
Figure 6. Percentage of positive days during the seasonal periods
N clicks N clicks
Dolphins spend some time feeding in this MPA, with a strong seasonal preference for winter months
and a strong diel preference for night time.
Buoy 6 Buoy 2
600 800
700
500
600
400
Passive acoustic monitoring using T-PODs successfully described habitat use in this MPA and proved
500
n clicks
n clicks
300 400
300
200
to be a good tool for the conservation management of the bottlenose dolphin in the area.
200
100
100
0 0
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:00
11:00
12:00
13:00
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15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
local time local time
Bibliography
Figure 5. Distribution of the clicks detection during the day in both areas • Au, W.W.L. 1993. The sonar of dolphins. Springer; New York.
• Esteban J.A. and M. Castellote. 2008. Snapping shrimp's pulses effect in the Bottlenose dolphin (Tursiops truncatus) acoustic detection in the Columbretes Islands
Marine reserve. European Research on Cetaceans 22:99-101.
• Johnson, M.; Hickmott, L. S.; Aguilar Soto, N. and P. T. Madsen. 2008. Echolocation behaviour adapted to prey in foraging Blainville’s beaked whales (Mesoplodon
Acknowledgements densirostris). Proceedings of the Royal Society B 275: 133-139.
• Philpott, E.; Englund, P. E.; Rogan, A. E. and Ingram, S. 2006 Detection distance estimate for the TPOD using bottlenose dolphins. Proceedings de 20th Annual
Conference of the European Cetacean Society, Gdynia, Poland, 2-7th April 2006.
This study would have not been possible without the collaboration of all the • Hooker S.K and .Gerber L.R. 2004. Marine Reserves as a Tool for Ecosystem-Based Management: The Potential Importance of Megafauna. Bioscience: Vol. 54, No.
team of the Area Protegida de les Illes Medes, specially without the support of 1, Pages 27–39
Alex Lorente, manager of the MPA, and the guards, Salva and Quim. We are
also grateful to all the members of SUBMON’s fieldwork team that participated
in the collection of data, especially to J. Sanchez, A. Bartolí, M. Romagosa and J.
Zorilla. Special thanks are due to J.A. Esteban from L’Oceanogràfic of the City of
the Arts and Sciences and to Jordi Prats and his team from Rei del Mar diving
center. The MUSEU de la MEDITERRÀNIA also contributed to the study funding
the data collection and analysis, and batteries were provided by Cegasa S.L.