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Jepson P.D.,UK Institute of Zoology | Deaville R.,UK Institute of Zoology | Barber J.L.,Center for Environment | Aguilar A.,University of Barcelona | And 29 more authors.
Scientific Reports | Year: 2016

Organochlorine (OC) pesticides and the more persistent polychlorinated biphenyls (PCBs) have well-established dose-dependent toxicities to birds, fish and mammals in experimental studies, but the actual impact of OC pollutants on European marine top predators remains unknown. Here we show that several cetacean species have very high mean blubber PCB concentrations likely to cause population declines and suppress population recovery. In a large pan-European meta-analysis of stranded (n = 929) or biopsied (n = 152) cetaceans, three out of four species:- striped dolphins (SDs), bottlenose dolphins (BNDs) and killer whales (KWs) had mean PCB levels that markedly exceeded all known marine mammal PCB toxicity thresholds. Some locations (e.g. western Mediterranean Sea, south-west Iberian Peninsula) are global PCB "hotspots" for marine mammals. Blubber PCB concentrations initially declined following a mid-1980s EU ban, but have since stabilised in UK harbour porpoises and SDs in the western Mediterranean Sea. Some small or declining populations of BNDs and KWs in the NE Atlantic were associated with low recruitment, consistent with PCB-induced reproductive toxicity. Despite regulations and mitigation measures to reduce PCB pollution, their biomagnification in marine food webs continues to cause severe impacts among cetacean top predators in European seas. © 2016, Nature Publishing Group. All rights reserved.

Gaspari S.,University of Florence | Holcer D.,Croatian Natural History Museum | Holcer D.,Marine Conservation Institute | Mackelworth P.,Marine Conservation Institute | And 9 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2015

Habitat diversity plays a significant role in shaping the genetic structure of cetacean populations. However, the processes involved in defining the genetic differentiation of these highly mobile marine mammals are still largely unknown. Levels of genetic differentiation and dispersal patterns of common bottlenose dolphins (Tursiops truncatus) were assessed in the north-eastern Mediterranean Sea, with a focus on the Adriatic Sea. This is a region characterized by diverse marine ecosystems and high levels of human-induced habitat degradation. Although this species seems almost uniformly distributed throughout the Adriatic Basin, genetic evidence rejected the hypothesis of a single stock. Pairwise estimates of genetic differentiation at 12 microsatellite loci, and mitochondrial DNA (entire control region, 920bp), revealed diverse levels of genetic differentiation among five putative populations from the Tyrrhenian Sea to the Aegean Sea. A fine-scale genetic structure was recorded within the Adriatic Sea, where females appear to be the principal gene flow mediators. The assessment of recent migration rates indicates a relatively high level of gene flow from the North Adriatic towards adjacent areas. Indication of a fine-scale population structure across the Adriatic Sea is a factor to be carefully considered in the emerging marine management scenario set by the implementation of the EU Marine Strategy Framework Directive (2008/56/CE), particularly when it comes to assessing and managing direct mortality caused by human activities (e.g. fisheries or maritime traffic). A good knowledge of population structure at the basin level is also fundamental for the identification of potential Adriatic Special Areas of Conservation for the bottlenose dolphin under the Habitats Directive (Council Directive 92/43/EEC). © 2013 John Wiley & Sons, Ltd.

Genov T.,University of Primorska | Angelini V.,Fondazione Cetacea ONLUS | Hace A.,Morigenos Slovenian Marine Mammal Society | Palmisano G.,University of Padua | And 4 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2015

Understanding animal movement patterns is not only important for providing insight into their biology, but is also relevant to conservation planning. However, in aquatic and wide-ranging species such as cetaceans, this is often difficult. The common bottlenose dolphin (Tursiops truncatus) is the most common cetacean in the northern and central Adriatic Sea and has been the focus of long-term studies in some areas. All of the studied local populations show a relatively high degree of site fidelity, but their movements, ranging patterns or connectivity are not well understood. On 24 and 26 April 2014 a single adult bottlenose dolphin was observed and photographed alive off the Slovenian coast. The same individual was found dead on the shores of Goro, Italy, on 5 May 2014, about 130 km from the two sighting locations. The well-marked dorsal fin made the identification straightforward. The dolphin was found freshly dead, suggesting it had died very recently prior to being found. This indicates that the reported movement was a real one, rather than an artefact of currents. Although single cases cannot provide the basis for making population-level inferences, our observation shows that northern Adriatic bottlenose dolphins can make substantial movements in short periods of time and suggests that such movements could be more common than currently documented. Comparisons among photo-ID catalogues and stranding events can be highly informative, as they can provide useful information with implications for the cross-border conservation of mobile marine predators. Copyright © Marine Biological Association of the United Kingdom 2015

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