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Poster European Cetacean Society (ECS) 2010
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Poster European Cetacean Society (ECS) 2010 Document Transcript

  • 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 14:00 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.