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Blasi M.F.,Filicudi WildLife Conservation | Giuliani A.,Istituto Superiore di Sanita | Boitani L.,University of Rome La Sapienza
Aquatic Mammals | Year: 2015

We studied the influence of trammel nets on the behaviour and spatial distribution of bottlenose dolphin in the Aeolian Archipelago, Southern Italy. Ninety-six dolphin groups were followed for 98.75 h from 2005 to 2011 during 400 boat sur-veys. Thirty-three dolphins were photo-identified, and their age and sex were estimated. The encoun-ter rates, residency times, and group sizes were used to model the spatial distribution of dolphins with trammel nets and physiographic variables. Principal Component Analyses were applied to find the habitats selected for different behavioural activ-ities. Encounter rates were significantly higher in early summer when trammel nets were more abun-dant. Residency times were spatially correlated to the mean number of trammel nets. Group sizes increased with distance from coast but decreased with abundance of trammel nets. Males preferred smaller groups than females, and groups with calves were larger than the other groups. Resting, socializ-ing, and playing groups were larger than groups of dolphins engaged in travelling, foraging, and feed-ing. Spatial segregation between groups of dolphins with different sizes was observed. Although dol-phins benefit from taking fish in trammel nets, this interaction can be dangerous because the fishermen can use harmful methods to deter dolphins from the net. Herein, we proposed that males prefer habitats where they have a higher probability of locating/capturing a desirable prey such as coastal areas with a greater amount of trammel nets; while for other activities, they may move into safer areas. On the contrary, females prefer habitats for reasons not associated with prey such as social behaviours, rest-ing, or calf care/learning; and they may spend more time in the safest areas, at a distance from the coast, simply feeding when the opportunity presents itself. This study showed that group size/composition data are of critical importance for modeling dolphin- habitat relationships with significant consequences in terms of conservation strategies. Source

Blasi M.F.,Filicudi WildLife Conservation | Boitani L.,University of Rome La Sapienza
Endangered Species Research | Year: 2012

Modelling cetacean distributions is crucial to understanding their ecology and to relating use patterns to environmental changes. In the present study, a combination of statistical methods was applied to model the distribution of bottlenose dolphin Tursiops truncatus with 18 physiographic variables around the Island of Filicudi, southern Italy. Principal components and clustering analyses were used to describe the habitat structure derived from mutually correlated predictor variables. Multivariate regression and canonical correlation analyses were used to find critical habitats and core use areas by combining the contribution of 2 response variables: the encounter rate and an index of use calculated according to the spatial behaviour of the dolphin groups. Three critical habitats were identified as distinct combinations of physiographic variables at a 1 km2 spatial scale. Two of these were associated with opportunistic and natural feeding activities. A third, a highly variable topographic habitat located in shallow waters at greater distance from the coastline, appears to serve as a resting/calving habitat by providing defence from anthropogenic pressures. The analysis also estimated an 80% shift from feeding to resting habitats associated with physiographic changes. Since the bottlenose dolphin encounter rate has decreased in recent years, the identification of core areas is useful in the preparation of local marine protected areas for the Aeolian archipelago. This analytical approach to studying dolphin-habitat relationships is relevant for conservation planning as it shows how environmental variability can modify dolphin distribution on a local scale according to the response variables relevant to the species. © Inter-Research 2012. Source

D'ilio S.,Italian National Institute for Health | Mattei D.,Italian National Institute for Health | Blasi M.F.,Filicudi WildLife Conservation | Alimonti A.,Italian National Institute for Health | Bogialli S.,University of Padua
Marine Pollution Bulletin | Year: 2011

Chemical elements and persistent organic pollutants (POPs) are globally present in aquatic systems and their potential transfer to loggerhead marine turtles (Caretta caretta) has become a serious threat for their health status. The environmental fate of these xenobiotics may be traced by the analysis of turtles' tissues and blood. Generally, loggerhead turtles exhibited a higher metal load than other turtle species, this could be explained by differences in diet habits being food the main source of exposure. Literature shows that muscle, liver and kidney are most considered for the quantification of chemical elements, while, organic compounds are typically investigated in liver and fat.This paper is an overview of the international studies carried out on the quantification of chemical elements, polychlorinated biphenyls (PCBs), organochlorines (OCs) and perfluorinated compounds (PFCs), in tissues, organs and fluids of C. caretta from the Mediterranean Sea, the Atlantic and the Pacific Oceans. © 2011 Elsevier Ltd. Source

Blasi M.F.,Filicudi WildLife Conservation | Boitani L.,University of Rome La Sapienza
PLoS ONE | Year: 2014

We investigated social structure and association patterns for a small population of Mediterranean bottlenose dolphins, Tursiops truncatus, inhabiting the Aeolian Archipelago (southern Italy). Specifically we evaluate the role of sex and age composition, residency patterns and interaction with trammel nets on this social organization. Association data for 23 regularly sighted individuals were obtained from summer photoidentification surveys collected from 2005-2012. Using a combined cluster and social network analysis approach, we found associations between dolphins were hierarchically structured, where two mixed-sex social units were subdivided into smaller temporarily dynamic groups. We found non-random and long-term preferred associations in the population; however, the degree of social cohesion, residence pattern and interaction with trammel nets differed considerably between the two social units. Six of eight females occurred in the more resident social unit-1; in addition, social unit-1 individuals had significantly stronger associations, higher preferred associates, lived in larger groups and occurred less frequently with trammel nets. Nine of eleven males were clustered in social unit-2 and five of these males, interacting with trammel nets, formed small groups and preferred associations. We propose that female and male groups associate in the study area during the breeding season and that some males choose to interact with reproductive females forming a distinct but interrelated social unit. Other males may be associating in a larger fission-fusion network, which consists of dolphins that appear to temporarily join the network from the coastal population. We cannot exclude that some males specialized in trammel net foraging, suggesting that this foraging technique may favor a solitary lifestyle. Large group sizes and high degree of social cohesion for females could be an indication of greater protection and more efficiency in detecting, deterring or repelling anthropogenic pressures. Most likely dolphins' social organization depends on a combination of socio-ecological, demographic and anthropogenic factors. © 2014 Blasi, Boitani. Source

Mattei D.,Istituto Superiore di Sanita | Veschetti E.,Istituto Superiore di Sanita | D'Ilio S.,Istituto Superiore di Sanita | Blasi M.F.,Filicudi WildLife Conservation
Marine Pollution Bulletin | Year: 2015

This study analyzed the carapace distribution of Ca, Cd, Cr, Cu, Mg, Mn, Pb, Sb, U, V and Zn by GF-AAS and ICP-AES in one specimen of Caretta caretta from Mediterranean Sea. Calcium, Mg, Mn, Pb, U, Zn were mainly distributed in the central area while Cd, Cr, Cu, Sb, V in lateral areas. Cadmium, Cr, Mg, Mn, Sb, U and V were different between lateral areas. The different distribution may be related to several exposures during lifetime and/or the shell ossification during growth. Carapace may be a suitable matrix for metal biomonitoring, however, further studies are required to confirm these findings. © 2015 Elsevier Ltd. Source

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