Echolocation clicks of free-ranging Cuvier's beaked whales (Ziphius cavirostris)

Author Posting. © Acoustical Society of America, 2005. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 117 (2005): 3919-3927, doi:10.1121/1.1910225.Strandings of beaked whales of the genera Ziphius and Mesoplodon have been reported to occur in conjunction with naval sonar use. Detection of the sounds from these elusive whales could reduce the risk of exposure, but descriptions of their vocalizations are at best incomplete. This paper reports quantitative characteristics of clicks from deep-diving Cuvier's beaked whales (Ziphius cavirostris) using a unique data set. Two whales in the Ligurian Sea were simultaneously tagged with sound and orientation recording tags, and the dive tracks were reconstructed allowing for derivation of the range and relative aspect between the clicking whales. At depth, the whales produced trains of regular echolocation clicks with mean interclick intervals of 0.43 s (±0.09) and 0.40 s (±0.07). The clicks are frequency modulated pulses with durations of ~200 µs and center frequencies around 42 kHz, –10 dB bandwidths of 22 kHz, and Q3 dB of 4. The sound beam is narrow with an estimated directionality index of more than 25 dB, source levels up to 214 dBpp re: 1 µPa at 1 m, and energy flux density of 164 dB re: 1 µPa2 s. As the spectral and temporal properties are different from those of nonziphiid odontocetes the potential for passive detection is enhanced.Tag was funded in part by a Cecil H. and Ida M. Green Award and the US Office of Naval Research. WHOI fieldwork and tag development was funded by the National Oceanographic Partnership Program (NOPP), the Strategic Environmental Research and Development Program (SERDP) under Program No. CS-1188, and the Packard Foundation, and was supported by BluWest and the NATO Undersea Research Center

Multiple Processes Regulate Long-Term Population Dynamics of Sea Urchins on Mediterranean Rocky Reefs

We annually monitored the abundance and size structure of herbivorous sea urchin populations (Paracentrotus lividus and Arbacia lixula) inside and outside a marine reserve in the Northwestern Mediterranean on two distinct habitats (boulders and vertical walls) over a period of 20 years, with the aim of analyzing changes at different temporal scales in relation to biotic and abiotic drivers. P. lividus exhibited significant variability in density over time on boulder bottoms but not on vertical walls, and temporal trends were not significantly different between the protection levels. Differences in densities were caused primarily by variance in recruitment, which was less pronounced inside the MPA and was correlated with adult density, indicating density-dependent recruitment under high predation pressure, as well as some positive feedback mechanisms that may facilitate higher urchin abundances despite higher predator abundance. Populations within the reserve were less variable in abundance and did not exhibit the hyper-abundances observed outside the reserve, suggesting that predation effects maybe more subtle than simply lowering the numbers of urchins in reserves. A. lixula densities were an order of magnitude lower than P. lividus densities and varied within sites and over time on boulder bottoms but did not differ between protection levels. In December 2008, an exceptionally violent storm reduced sea urchin densities drastically (by 50% to 80%) on boulder substrates, resulting in the lowest values observed over the entire study period, which remained at that level for at least two years (up to the present). Our results also showed great variability in the biological and physical processes acting at different temporal scales. This study highlights the need for appropriate temporal scales for studies to fully understand ecosystem functioning, the concepts of which are fundamental to successful conservation and management

The challenge of habitat modelling for threatened low density species using heterogeneous data : the case of Cuvier’s beaked whales in the Mediterranean

We are grateful to the ACCOBAMS Secretariat for their support in this work, including a small grant for the analysis.The Mediterranean population of Cuvieŕs beaked whale (Ziphius cavirostris), a deep-diving cetacean, is genetically distinct from the Atlantic, and subject to a number of conservation threats, in particular underwater noise. It is also cryptic at the surface and relatively rare, so obtain robust knowledge on distribution and abundance presents unique challenges. Here we use multiplatform and multiyear survey data to analyse the distribution and abundance of this species across the Mediterranean Sea. We use a novel approach combining heterogeneous data gathered with different methods to obtain a single density index for the region. A total of 594,996 km of survey effort and 507 sightings of Cuvier’s beaked whales, from 1990 to 2016, were pooled together from 24 different sources. Data were divided into twelve major groups according to platform height, speed and sea state. Both availability bias and effective strip width were calculated from the sightings with available perpendicular distance data. This was extrapolated to the rest of the sightings for each of the twelve groups. Habitat preference models were fitted into a GAM framework using counts of groups as a response variable with the effective searched area as an offset. Depth, coefficient of variation of depth, longitude and marine regions (as defined by the International Hydrographic Organization) were identified as important predictors. Predicted abundance of groups per grid cell were multiplied by mean group size to obtain a prediction of the abundance of animals. A total abundance of 5799 (CV = 24.0%) animals was estimated for the whole Mediterranean basin. The Alborán Sea, Ligurian Sea, Hellenic Trench, southern Adriatic Sea and eastern Ionian Sea were identified as being the main hot spots in the region. It is important to urge that the relevant stakeholders incorporate this information in the planning and execution of high risk activities in these high-risk areas.PostprintPeer reviewe

The European VLF/LF Radio Network: Advances and Recent Results

Since 2009 a network of VLF (20-60 kHz) and LF (150-300 kHz) radio receivers has been put into operation in Europe in order to study earthquakes precursors. At the moment the network consists of ten receivers three of which are located in Italy, two in Greece and one in Portugal, Romania, Malta, Cyprus and Turkey. The data (sampling rate of 1min) are downloaded automatically at the end of each day and are collected at the Department of Physics of the University of Bari (Italy) that is the central node of the network. A detailed study of the radio data collected in the radio network from July 2009 to September 2011 was performed, using different methods of analysis. In total 27 cases suitable for analyzing were found and successes, i.e. radio anomalies preceding the subsequent earthquake (Mw 5.0) and clearly related to the event, were obtained in 70% of the cases; but increasing the value of the Mw threshold for the earthquakes this percentage seems to increase. Among the different methods of analysis the Wavelet spectra appear to be the most sensitive ones. At the moment a system able to apply on the radio data the Wavelet analysis automatically at the end of each day is being developed. On May 20, 2012 an earthquake with Mw=6.1 occurred in north Italy (Emilia region); the epicenter is located inside the “sensitive” area of the network. The results obtained in such occasion are presented

The European VLF/LF Radio Network: Advances and Recent Results. Geophysical

Since 2009 a network of VLF (20-60 kHz) and LF (150-300 kHz) radio receivers has been put into operation in Europe in order to study earthquakes precursors. At the moment the network consists of ten receivers three of which are located in Italy, two in Greece and one in Portugal, Romania, Malta, Cyprus and Turkey. The data (sampling rate of 1min) are downloaded automatically at the end of each day and are collected at the Department of Physics of the University of Bari (Italy) that is the central node of the network. A detailed study of the radio data collected in the radio network from July 2009 to September 2011 was performed, using different methods of analysis. In total 27 cases suitable for analyzing were found and successes, i.e. radio anomalies preceding the subsequent earthquake (Mw ≥ 5.0) and clearly related to the event, were obtained in 70% of the cases; but increasing the value of the Mw threshold for the earthquakes this percentage seems to increase. Among the different methods of analysis the Wavelet spectra appear to be the most sensitive ones. At the moment a system able to apply on the radio data the Wavelet analysis automatically at the end of each day is being developed. On May 20, 2012 an earthquake with Mw=6.1 occurred in north Italy (Emilia region); the epicenter is located inside the “sensitive” area of the network. The results obtained in such occasion are presented

The European VLF/LF Radio Network: the current status

Since 2009 a network of VLF (20-60 kHz) and LF (150-300 kHz) radio receivers has been put into operation in Europe in order to study earthquakes precursors. At the moment the network consists of eleven receivers four of which are located in Italy, two in Greece and one in Portugal, Romania, Malta, Cyprus and Turkey. The data (sampling rate of 1min) are downloaded automatically at the end of each day and they are stored in the server located at the Department of Physics of the University of Bari (Italy), that is the central node of the network. Still, in some case, problems of connection exist. The different trends are open and visible on the web site: http://beta.fisica.uniba.it/infrep/Home.aspx. The data files can be downloaded by the same web site but they are protected by username and password. Among the different methods of data analysis the Wavelet spectra appear to be the most sensitive ones. The software able to apply this technique on the radio data automatically at the end of each day has been planned and realized. At the moment it operates on four signals collected by one of the Italian receivers; if an anomaly stands up and it is over a fixed threshold a warning advise appears. In the web site, this activity is protected by a specific username and password

Recent developments in the Gavdos calibration site

Μη διαθέσιμη περίληψηNot available summarizationΠαρουσιάστηκε στο: Cryosat-2 and ICESAT Meetin