Aviad Scheinin

Gray whale ( Eschrichtius robustus ) in the Mediterranean Sea: anomalous event or early sign of climate-driven distribution change?

On 8 May 2010, a gray whale was sighted off the Israeli Mediterranean shore and twenty-two days later, the same individual was sighted in Spanish Mediterranean waters. Since gray whales were last recorded in the North Atlantic in the 1700s, these sightings prompted much speculation about this whales population origin. Here, we consider three hypotheses for the origin of this individual: (1) it represents a vagrant individual from the larger extant population of gray whales found in the eastern North Pacific; (2) it represents a vagrant individual from the smaller extant population found in the western North Pacific; or (3) it represents an individual from the previously thought extinct North Atlantic population. We believe that the first is the most likely, based on current population sizes, on known summer distributions, on the extent of cetacean monitoring in the North Atlantic and on the results of a performed route analysis. While it is difficult to draw conclusions from such singular events, the occurrence of this individual in the Mediterranean coincides with a shrinking of Arctic Sea ice due to climate change and suggests that climate change may allow gray whales to re-colonize the North Atlantic as ice and temperature barriers to mixing between northern North Atlantic and North Pacific biomes are reduced. Such mixing, if it were to become widespread, would have implications for many aspects of the marine conservation and ecology of these two regions.

Persistent organochlorine pollutants and heavy metals in tissues of common bottlenose dolphin (Tursiops truncatus) from the Levantine Basin of the Eastern Mediterranean.

DDTs, PCBs and heavy metals (HM) were measured in tissues of common bottlenose dolphins, collected along the Israeli Mediterranean coast during 2004-2006. SigmaDDT and PCBs concentrations were highest in the blubber, with a wide concentration range of 0.92-142 and 0.05-7.9 mg kg(-1) wet weight, respectively. Blubber PCBs values were an order of magnitude lower than in tissues of this and other delphinid species in the Western Mediterranea. We found relatively high DDE/SigmaDDT percentage (85-96%); a common indicator of DDT degradation, which fitted the general trend of increase in the last 20 years in the Mediterranean Sea, indicating the progressive degradation of the remnant DDT and the absence of new inputs. Concentrations of HM ranged as follows: 0.01-123 mg kg(-1) wet weight for Hg, <0.04-1.3 for Cd, 1-30 for Cu, 0.3-4 for Mn, 19-517 for Fe, 4.3-68 for Zn and 2.4-48 for Ni. These concentrations were similar to those found in specimens collected during previous years in the region, suggesting stability over time in the HM levels of the basins food-web.

Drivers of Population Structure of the Bottlenose Dolphin ( Tursiops truncatus ) in the Eastern Mediterranean Sea

The drivers of population differentiation in oceanic high dispersal organisms, have been crucial for research in evolutionary biology. Adaptation to different environments is commonly invoked as a driver of differentiation in the oceans, in alternative to geographic isolation. In this study, we investigate the population structure and phylogeography of the bottlenose dolphin (Tursiops truncatus) in the Mediterranean Sea, using microsatellite loci and the entire mtDNA control region. By further comparing the Mediterranean populations with the well described Atlantic populations, we addressed the following hypotheses: (1) bottlenose dolphins show population structure within the environmentally complex Eastern Mediterranean Sea; (2) population structure was gained locally or otherwise results from chance distribution of pre-existing genetic structure; (3) strong demographic variations within the Mediterranean basin have affected genetic variation sufficiently to bias detected patterns of population structure. Our results suggest that bottlenose dolphin exhibits population structures that correspond well to the main Mediterranean oceanographic basins. Furthermore, we found evidence for fine scale population division within the Adriatic and the Levantine seas. We further describe for the first time, a distinction between populations inhabiting pelagic and coastal regions within the Mediterranean. Phylogeographic analysis suggests that current genetic structure, results mostly from stochastic distribution of Atlantic genetic variation, during a recent post-glacial expansion. Comparison with Atlantic mtDNA haplotypes, further suggest the existence of a metapopulation across North Atlantic/Mediterranean, with pelagic regions acting as source for coastal environments.

Laryngeal Snaring by Ingested Fishing Net in a Common Bottlenose Dolphin (Tursiops truncatus) Off the Israeli Shoreline

We report an unusual snaring of the larynx in an adult, female common bottlenose dolphin (Tursiops truncatus). The dolphin was observed swimming and diving in Haifa Port, Israel, but was found dead the next day, 60 km south, on the coast. Postmortem examination revealed stranded-cordage, nylon filaments wrapped around the larynx, cutting through the soft tissue, and extending down into the forestomach, where a large mass of netting was found. The cachectic state of the dolphin and the subacute to chronic, hyper-plastic response of soft tissue surrounding the filaments lodged around the larynx, suggest a prolonged period of starvation, which led to the final weakness and wasting of the dolphin.

Pulmonary fungal infection caused by Neoscytalidium dimidiatum in a Risso's dolphin (Grampus griseus)

Neoscytalidium dimidiatum was isolated from two 12-18 cm abscesses in the lung and the mediastinal lymph nodes of a stranded Rissos dolphin (Grampus griseus). Histopathologic examination of samples of these organs revealed the presence of hyphae and sclerotic body-like fungal elements. Photobacterium damselae subsp. damselae was recovered from the dolphins organs which also were found to contain numerous Monorygma grimaldii cysts. No histopathological signs of morbillivirus infection were seen. To the best of our knowledge, this is the first report of N. dimidiatum infection in a sea mammal.

The Rough-Toothed Dolphin, Steno bredanensis, in the Eastern Mediterranean Sea: A Relict Population?

Only recently included among the cetacean species thought to regularly occur in the Mediterranean, the rough-toothed dolphin (Steno bredanensis) is an obscure and enigmatic member of this ensemble. Preliminary genetic evidence strongly indicates an Atlantic origin, yet the Mediterranean distribution for this species is conspicuously detached from the Atlantic, with all authenticated records during the last three decades being east of the Sicilian Channel and most within the bounds of the Levantine Basin. These dolphins are apparently a small, relict population, probably the remnant of a larger one, contiguous with that in the Atlantic and nowadays entrapped in the easternmost and warmest province. Abundance data are lacking for the species in the Mediterranean. Configuring acoustic detection software to recognise the apparently idiosyncratic vocalisations of rough-toothed dolphins in past and future acoustic recordings may prove useful for potential acoustic monitoring. Evidence accumulated so far, though scant, points to seasonal occupation of shallow coastal waters. Vulnerability to entanglement in gill-nets, contaminants in the region, and the occurrence of mass strandings (possibly in response to anthropogenic noise), are major conservation concerns for the population in the Mediterranean Sea.

Detection of Toxoplasma gondii in three common bottlenose dolphins (Tursiops truncatus); A first description from the Eastern Mediterranean Sea

Toxoplasma gondii has been described in several marine mammals around the world including numerous species of cetaceans, yet infection and transmission mechanisms in the marine environment are not clearly defined. The Israel Marine Mammal Research and Assistance Center has been collating a database of all marine mammal stranding events along the countrys national coastlines since 1993. In this study, we describe the molecular detection and characterisation of T. gondii in three common bottlenose dolphins (Tursiops truncatus) including one case of coinfection with herpesvirus. The animals were found stranded on the Mediterranean coast of Israel in May and November 2013. In one of the three cases, the dolphin was found alive and admitted to intensive care. To our knowledge, this is the first report of T. gondii infection of marine mammals in the Eastern Mediterranean Sea. As this parasite acts as an indicator for marine pollution and marine mammal health, we believe these findings add important information regarding the state of the environment in this region.