Spatio-temporal patterns of genetic diversity in the Mediterranean striped dolphin (Stenella coeruleoalba)

Comparing the genetic composition of wild animals between geographic regions with distinct environments is common in evolutionary studies. However, genetic composition can also change through time in response to environmental changes but studies examining this are carried out less often. In this study, we characterise striped dolphin genetic composition in the Mediterranean Sea across both geography and time. We provide genotype data for 15 microsatellite loci and 919 bp of mtDNA control region, collected over 21 years across all main Mediterranean Sea basins. We investigated spatial genetic structure using both classical and Bayesian population structure methods, and compared it with temporal patterns of genetic change using time series statistics. We integrated the temporal datasets with known environmental pressures and data on social structure, to infer potential drivers of observed changes. Geographic analyses suggest weak differentiation for striped dolphin in the Mediterranean Sea, with evidence for a recent expansion. Temporal analyses show significant cyclical fluctuations in genetic composition over 21 years, which correspond well with recurrent morbillivirus epizootics. Similarly, social group composition shows changes in the relative number of juveniles and adults per group, and an overall increase in the number of adults per group relative to juveniles over the time period. We suggest that the observed changes in genetic and group composition could relate to specific dynamics of morbillivirus resistance. Overall, our study highlights the importance of tracking long term genetic variation, and the potential for this species as a model in studying genetic adaptation to environmental stress

Trumpet sounds emitted by male sperm whales in the Mediterranean Sea

Sperm whale trumpets are sounds only occasionally documented, with a well recognisable and stereotyped acoustic arrangement. This study investigated the acoustic features of the trumpets and the context in which these sounds were recorded, using acoustic data collected over 22 years, in the Pelagos Sanctuary area (North-Western Mediterranean Sea). Analysed trumpets (n = 230), recorded at the beginning of a dive after the whale fluke-up, comprised a series of acoustic units organized in short sequences. Acoustic parameters were derived for the entire trumpet and for each distinguishable unit in a trumpet. Overall, trumpet durations and their initial frequencies were higher in recordings collected when multiple whales were visually or acoustically detected in the observation area. The identity of 68 whales was assessed through photo-identification, with 29 individuals producing trumpets within and between years. The variability of the acoustic parameters appeared to be higher within the same individuals rather than between different individuals, suggesting an individual plasticity in composing and arranging units in a trumpet. Different click patterns were observed before and after the trumpets, with more complex sequences when (1) other whales were visually/acoustically detected, and (2) individuals were in suitable foraging sites (i.e., canyon areas). Trumpets were commonly followed or preceded by click patterns suited for communication, such as codas and/or slow clicks. Significant relations between the trumpet emission and the male-only long-range communication click pattern (i.e. slow clicks) emerged, supporting the hypothesis that a trumpet is a sound emitted by maturing/mature males in feeding grounds. This study provides the first evidence that trumpets were conserved in the sperm whale acoustic repertoire at the decadal timescale, persisting across years and individuals in the same area. This persistence may be functionally specific to foraging activities performed by males in a well-established feeding area

The Seabed Makes the Dolphins: Physiographic Features Shape the Size and Structure of the Bottlenose Dolphin Geographical Units

The common bottlenose dolphin (Tursiops truncatus) is a cosmopolitan delphinid, regularly present in the Mediterranean Sea. According to previous studies, this dolphin tends to form resident geographical units scattered on the continental shelf. We investigated how the physiographic characteristics of the area of residence, with special reference to the size and shape of the continental shelf, affect the home range and the group size of the local units. We analysed and compared data collected between 2004-2016 by 15 research groups operating in different study areas of the Mediterranean Sea: the Alboran Sea, in the South-Western Mediterranean, the Gulf of Lion and the Pelagos Sanctuary for the marine mammals, in the North-Western Mediterranean, and the Gulf of Ambracia, in the North-Central Mediterranean Sea. We have found that in areas characterised by a wide continental platform, dolphins have wider home ranges and aggregate into larger groups. In areas characterized by a narrow continental platform, dolphins show much smaller home ranges and aggregate into smaller groups. The results obtained from this collective research effort highlight the importance of data sharing to improve our scientific knowledge in the field of cetaceans and beyond

Microenvironmental regulation of the IL-23R/IL-23 axis overrides chronic lymphocytic leukemia indolence

Although the progression of chronic lymphocytic leukemia (CLL) requires the cooperation of the microenvironment, the exact cellular and molecular mechanisms involved are still unclear. We investigated the interleukin (IL)-23 receptor (IL-23R)/IL-23 axis and found that circulating cells from early-stage CLL patients with shorter time-to-treatment, but not of those with a more benign course, expressed a defective form of the IL-23R complex lacking the IL-12R beta 1 chain. However, cells from both patient groups expressed the complete IL-23R complex in tissue infiltrates and could be induced to express the IL-12R. 1 chain when cocultured with activated T cells or CD40L(+) cells. CLL cells activated in vitro in this context produced IL-23, a finding that, together with the presence of IL-23 in CLL lymphoid tissues, suggests the existence of an autocrine/paracrine loop inducing CLL cell proliferation. Interference with the IL-23R/IL-23 axis using an anti-IL-23p19 antibody proved effective in controlling disease onset and expansion in xenografted mice, suggesting potential therapeutic strategies

Sometimes Sperm Whales (Physeter macrocephalus) Cannot Find Their Way Back to the High Seas: A Multidisciplinary Study on a Mass Stranding

BACKGROUND: Mass strandings of sperm whales (Physeter macrocephalus) remain peculiar and rather unexplained events, which rarely occur in the Mediterranean Sea. Solar cycles and related changes in the geomagnetic field, variations in water temperature and weather conditions, coast geographical features and human activities have been proposed as possible causes. In December 2009, a pod of seven male sperm whales stranded along the Adriatic coast of Southern Italy. This is the sixth instance from 1555 in this basin. METHODOLOGY/PRINCIPAL FINDINGS: Complete necropsies were performed on three whales whose bodies were in good condition, carrying out on sampled tissues histopathology, virology, bacteriology, parasitology, and screening of veins looking for gas emboli. Furthermore, samples for age determination, genetic studies, gastric content evaluation, stable isotopes and toxicology were taken from all the seven specimens. The animals were part of the same group and determined by genetic and photo-identification to be part of the Mediterranean population. Causes of death did not include biological agents, or the "gas and fat embolic syndrome", associated with direct sonar exposure. Environmental pollutant tissue concentrations were relatively high, in particular organochlorinated xenobiotics. Gastric content and morphologic tissue examinations showed a prolonged starvation, which likely caused, at its turn, the mobilization of lipophilic contaminants from the adipose tissue. Chemical compounds subsequently entered the blood circulation and may have impaired immune and nervous functions. CONCLUSIONS/SIGNIFICANCE: A multi-factorial cause underlying this sperm whales' mass stranding is proposed herein based upon the results of postmortem investigations as well as of the detailed analyses of the geographical and historical background. The seven sperm whales took the same "wrong way" into the Adriatic Sea, a potentially dangerous trap for Mediterranean sperm whales. Seismic surveys should be also regarded as potential co-factors, even if no evidence of direct impact has been detected

Wild whale faecal samples as a proxy of anthropogenic impact

The occurrence of protozoan parasite, bacterial communities, organic pollutants and heavy metals was investigated in free-ranging species of fin (Balaenoptera physalus, n. 2) and sperm (Physeter macrocephalus, n. 2) whales from the Pelagos Sanctuary, Corsican-Ligurian Provencal Basin (Northern-Western Mediterranean Sea). Out of four faecal samples investigated, two from fin whales and one from sperm whale were found positive to Blastocystis sp. A higher number of sequences related to Synergistetes and Spirochaetae were found in sperm whales if compared with fin whales. Moreover, As, Co and Hg were found exclusively in sperm whale faecal samples, while Pb was found only in fin whale faecal samples. The concentration of both PAH and PCB was always below the limit of detection. This is the first report in which the presence of these opportunistic pathogens, bacteria and chemical pollutants have been investigated in faecal samples of free-rangingwhale species and the first record of Blastocystis in fin and sperm whales. Thus, this study may provide baseline data on new anthropozoonotic parasite, bacterial records and heavy metals in free-ranging fin and sperm whales, probably as a result of an increasing anthropogenic activity. This survey calls for more integrated research to perform regular monitoring programs supported by national and/or international authorities responsible for preservation of these still vulnerable and threatened whale species in the Mediterranean Sea

Cetacean response to environmental and anthropogenic drivers of change: Results of a 25-year distribution study in the northwestern Mediterranean Sea

reserved5Marine mammals are in many situations one of the most studied component of marine ecosystems. Their habitat requirements may be used to detect and describe the impacts of changes in the environmental conditions or in the human-induced pressures affecting the area where they live. The aim of this study is to investigate the distribution patterns of the most frequent cetacean species occurring in the area of the Pelagos Sanctuary (Northwestern Mediterranean Sea) and their potential correlations with both environmental and anthropogenic drivers of changes. Two different types of data were used: sighting data from ship-board surveys and strandings data collected along the Ligurian coast by the Italian Stranding Network, spanning from 1986 to 2014. Sighting data were collected during summer surveys conducted from June to September, between 1990 and 2014 in an area of approximately 29,000km2, within the Pelagos Sanctuary for over 115,000km surveyed under favorable conditions. A total of 4,683 sightings of the five most common cetacean species were collected: 3,305 (70.5%) striped dolphins, 814 (17.3%) fin whales, 169 (3.6%) Risso's dolphins, 347 (7.4%) sperm whales and 48 (1.02%) Cuvier's beaked whales. The species time series of both encounter and stranding rates have been investigated in the light of potential drivers of changes. The results suggest that the area may be suffering from some ecosystem change which is causing the observed changes in the distribution pattern of the five species. Potential disturbance from human activities, namely fishery and maritime traffic, could not be excluded.mixedAzzellino, A.; Airoldi, S.; Lanfredi, C.; Podestà, M.; Zanardelli, M.Azzellino, Arianna; Airoldi, S.; Lanfredi, Caterina; Podestà, M.; Zanardelli, M

Long-term trend analysis of deep diving cetacean species occurring in the Pelagos Sanctuary (Northwestern Mediterranean Sea).

Several threats are known to affect cetacean species and their habitats in the Mediterranean sea, most of them being related to human activities. To enforce effective mitigation actions, extensive knowledge of cetacean ecology is required. In this study a 23-year sighting series (1990-2012) of sperm whale (Physeter macrocephalus), Risso’s dolphin (Grampus griseus) and Cuvier’s beaked whale (Ziphius cavirostris) was analysed to assess temporal patterns or trends in their presence in the Pelagos Sanctuary area. Sighting data were collected by Tethys Research Institute (n= 434) and CIMA research Foundation (n= 142) during shipboard surveys conducted between 1990-2012 and 2004-2012, respectively. This effort yielded a total of 576 sightings: 289 sperm whales, 164 Risso’s dolphins and 123 Cuvier’s beaked whales. For the purpose of the analysis a grid of 6.8 x 9.3 km cell units was created and used for the spatial analysis. The species’ encounter rate variability in time was analysed through a General Linear Model approach, which revealed the existence of a significant increasing trend (P<0.05) for sperm whales and Cuvier’s beaked whales presence in the area. Contrarily, no trend was found for Risso’s dolphin. This study provides evidence that the animal distribution in the Pelagos Sanctuary is affected by some drivers of change. Changes may be due to a wide range of causes (i.e. prey availabilities, climate change, noise). The correlation of the results obtained with this long term trend analysis with the available time series of environmental variables (i.e. Sea Surface Temperature from remote sensing) and anthropogenic pressure affecting the area (i.e. maritime traffic, fishing activities) will provide essential information to evaluate the implications of the different factors of variability and their possible interactions in order to support appropriate management and conservation strategies

Long‐term photo‐identification study of fin whales in the Pelagos Sanctuary (NW Mediterranean) as a baseline for targeted conservation and mitigation measures.

1. Historical abundance estimates are important for establishing baselines fromwhich trends can be determined using more recent data. Long-term studies basedon photo-identification were merged and used to estimate population size,survival rate and sex ratio (biopsy sampling) of fin whales in the North-westernMediterranean.2. Merging four existing photo-id catalogues yielded a Mediterranean cataloguewith 507 individually identified fin whales. Ninety-five (18.7%) individuals wereresighted at least once during the study period (1990–2007): 71 whales wereresighted in different years, 24 within the same season and 13 both in the sameseason and in different years. The number of resightings within-season rangedfrom one to four, over periods from 1 to 90 days.3. Capture histories from these individuals were used in the capture–recaptureanalyses. Estimates of the animals present in the area each year between 1991and 1995 through different modelling approaches were consistent: 900–1,000from a POPAN open population model; 1,200 from a multi-sample closedpopulation model; and 900–1,100 from simple two-sample closed populationmodels for pairs of consecutive years, all with heavily overlapping 95%confidence intervals.4. The estimated apparent survival rate of 0.916 (95% CI=0.773–0.972) was lowerthan expected, which may be linked to temporary or permanent emigration, ormortality possibly owing to ship strikes.5. Conservation and mitigation measures such as Important Marine Mammal Areasand Particularly Sensitive Sea Areas are presented and discussed