Stenella Coeruleoalba Research Articles

Evidence for Unknown Sarcocystis-Like Infection in Stranded Striped Dolphins (Stenella coeruleoalba) from the Ligurian Sea, Italy.

Simple SummaryTwo stranded striped dolphins presented meningoenchepalitic lesions associated with the presence of unknown protozoan tissue cysts. The present study aimed at fully characterizing these previously undescribed parasites. Light microscopy re-examination of affected CNS areas showed high numbers of tissue cysts with morphological features resembling those of Sarcocystis species. Tissue cyst bradyzoites positively stained when labeled with polyclonal antisera but cross-reactivity could not be precluded. Sarcocystis sp. sequences with high homology to species infecting livestock were amplified by means of PCR from myocardial and muscle tissues. This is the first report of Sarcocystis-like tissue cysts in the cerebral tissue of stranded cetaceans with muscular sarcocystosis in Mediterranean dolphins. The obtained results may suggest a land-to-sea cycling of Apicomplexan parasites in this region and the need for further investigations in order to foster marine mammal conservation.Two striped dolphins (SD1, SD2), stranded along the Ligurian coast of Italy, were diagnosed with a nonsuppurative meningoencephalitis associated with previously undescribed protozoan tissue cysts. As tissue cysts were morphologically different from those of Toxoplasma gondii, additional histopathological, immunohistochemical, ultrastructural, and biomolecular investigations were performed, aiming to fully characterize the organism. Histopathology revealed the presence of large Sarcocystis-like tissue cysts, associated with limited inflammatory lesions in all CNS areas studied. IHC was inconclusive, as positive staining with polyclonal antisera did not preclude cross-reaction with other Sarcocystidae coccidia. Applied to each animal, 11 different PCR protocols precluded a neural infection by Sarcocystis neurona, Sarcocystis falcatula, Hammondia hammondi, and Neospora caninum. T. gondii coinfection was confirmed only in dolphin SD2. Sarcocystis sp. sequences, showing the highest homology to species infecting the Bovidae family, were amplified from SD1 myocardium and SD2 skeletal muscle. The present study represents the first report of Sarcocystis-like tissue cysts in the brain of stranded cetaceans along with the first description of Sarcocystis sp. infection in muscle tissue of dolphins from the Mediterranean basin.

Cetacean mortality due to interactions with fisheries and marine litter ingestion in the Croatian part of the Adriatic Sea from 1990 to 2019

Various anthropogenic threats negatively influence the survival of cetaceans in all world seas. Thanks to a long-running marine mammal surveillance program, we are able to report the results of a detailed analysis of the influence of cetacean-fisheries interactions and marine litter ingestion on cetacean mortality in the Croatian part of the Adriatic Sea over the last three decades. The total number of dead cetaceans was 459, and included 334 bottlenose dolphins (Tursiops truncatus), 40 striped dolphins (Stenella coeruleoalba), ten Risso’s dolphins (Grampus griseus), six Cuvier’s beaked whales (Ziphius cavirostris) and four fin whales (Balaenoptera physalus). Three hundred of them were examined postmortally. Cetacean-fisheries interaction occurred frequently in the Adriatic Sea, being detected in 96 (20.9%) of the recorded cases. Bycatch was the most abundant cetacean-fisheries interaction, with 66 (14.4%) cases recorded. Good nutritional condition and evidence of recent feeding were the most common findings recorded in bycatch cases, followed by persistent froth in the airways, edematous lungs, bruises and an amputated fluke or tail. Cetacean-fisheries interactions other than bycatch affected 30 animals and included larynx strangulations, long-term tail entanglement and fishing gear in the stomach. Ingestion of marine litter that was not related to fisheries was recorded in four animals. This study reveals the considerable negative anthropogenic influence on cetaceans in the Adriatic Sea, especially the bottlenose dolphin that is considered to be the most numerous cetacean species therein, and demonstrates the need for the urgent development of a cetacean bycatch reduction program. Finally, it also shows the importance of sustaining national surveillance programs to gain scientifically based knowledge important for cetacean protection and prospects for their long-term survival.

Cetacean Strandings and Museum Collections: A Focus on Sicily Island Crossroads for Mediterranean Species

The study examined the extent of the cetacean strandings in Italy, with a particular focus on Sicily Island. The paper aimed to contribute to the description of a pattern that contemplates the “regular and rare” cetacean species passage along the Sicilian coast. The estimate of marine cetacean strandings was extrapolated from the National Strandings Data Bank (BDS—Banca Dati Spiaggiamenti) and evaluated according to a subdivision in three coastal subregions: the Tyrrhenian sub-basin (northern Sicilian coast), the Ionian sub-basin (eastern Sicilian coast), and the Channel of Sicily (southern Sicilian coast). Along the Italian coast, more than 4880 stranding events have been counted in the period 1990–2019. Most of these were recorded in five Italian regions: Apulia, Sicily, Sardinia, Tuscany, and Calabria. Approximately 15% of the recorded strandings in Italy occurred on the Sicilian coast. In Sicily Island, 725 stranded cetaceans were recorded in 709 stranding events, resulting in approximately 20 carcasses every year; the total number of specimens identified to species level was 539. The distribution along the Sicilian coast was the following: 312 recorded in the Tyrrhenian sub-basin, 193 in the Ionian sub-basin, and 220 in the Channel of Sicily. Stenella coeruleoalba was the species that can be considered as the stable record along the time-lapse investigated, and some rare species have been recorded as well. The role of Sicily Island as a sentinel territory of the cetacean distribution for the central Mediterranean Sea and as a region receiving a marine resource suitable for the scientific research and cetological museum collections is discussed herein.

Integrating morphology and DNA barcoding to assess cetacean diversity in Brazil

Stranded cetaceans (whales, dolphins, and porpoises) are frequently used to obtain data on species occurrence and demographic trends. Accurate species-level identification of these individuals is crucial, but often challenging or impossible when relying solely on morphological features (e.g., for highly decayed specimens). To aid in the development of a reliable molecular assay for cetacean DNA-based identification, we tested the efficacy of the standardized DNA barcode segment of the coxI gene in identifying cetaceans occurring off the Brazilian coast and in its continental waters. We generated coxI sequences from 150 specimens (collected by 16 Brazilian institutions), most of which included voucher material (skulls, skeletons and/or images) deposited in scientific collections. This allowed a direct comparison between their morphological and molecular identification. CoxI sequences correctly identified ~93% of the samples, comprising 33 species (70% of the 47 cetaceans reported for Brazilian waters). Two species (Berardius arnuxii and Phocoena dioptrica) were sequenced for coxI for the first time. For only two dolphins (Stenella coeruleoalba and S. clymene) and a right whale (Eubalaena australis), coxI failed to identify the species due to overlapping distributions of intra- vs. interspecific divergences. Only one right whale species occurs in the southern hemisphere, facilitating identification in this case. Stenella dolphins present extensive sympatry and potential inter-species hybridization, suggesting that nuclear markers may be required for their reliable identification. These results indicate that DNA barcoding can reliably identify most stranded cetaceans and highlight the importance of voucher materials to validate the construction of a reliable DNA-based identification system.

Myoglobin Concentration and Oxygen Stores in Different Functional Muscle Groups from Three Small Cetacean Species.

Simple SummaryMarine mammals display several physiological adaptations to their marine environment. Higher myoglobin concentrations in their muscles compared to terrestrial mammals allow them to increase their onboard oxygen stores, enhancing the time available to dive. Most previous studies have calculated cetaceans’ onboard oxygen stores by assuming the myoglobin concentration of a single muscle to be representative of all the muscles in the body. In this study, we analyzed this assumption by comparing it to a more precise method that weighs all body muscles and measures myoglobin concentration in different functional groups.Compared with terrestrial mammals, marine mammals possess increased muscle myoglobin concentrations (Mb concentration, g Mb · 100g−1 muscle), enhancing their onboard oxygen (O2) stores and their aerobic dive limit. Although myoglobin is not homogeneously distributed, cetacean muscle O2 stores have been often determined by measuring Mb concentration from a single muscle sample (longissimus dorsi) and multiplying that value by the animal’s locomotor muscle or total muscle mass. This study serves to determine the accuracy of previous cetacean muscle O2 stores calculations. For that, body muscles from three delphinid species: Delphinus delphis, Stenella coeruleoalba, and Stenella frontalis, were dissected and weighed. Mb concentration was calculated from six muscles/muscle groups (epaxial, hypaxial and rectus abdominis; mastohumeralis; sternohyoideus; and dorsal scalenus), each representative of different functional groups (locomotion powering swimming, pectoral fin movement, feeding and respiration, respectively). Results demonstrated that the Mb concentration was heterogeneously distributed, being significantly higher in locomotor muscles. Locomotor muscles were the major contributors to total muscle O2 stores (mean 92.8%) due to their high Mb concentration and large muscle masses. Compared to this method, previous studies assuming homogenous Mb concentration distribution likely underestimated total muscle O2 stores by 10% when only considering locomotor muscles and overestimated them by 13% when total muscle mass was considered.

Stranding patterns and feeding ecology of striped dolphins, Stenella coeruleoalba, in Western Iberia (1981–2014)

The striped dolphin, Stenella coeruleoalba, is one of the most abundant cetacean species off the Western Iberian coast, however, studies on the species regarding biology, ecology, threats or conservation efforts are lacking. This study investigates stranding patterns (years 1981–2014) and diet (2002–2014) of striped dolphins (Stenella coeruleoalba) off the Portuguese mainland coast. Stranded animals were sampled along the whole coast (n = 252). Most stranded striped dolphins were recorded in the first half of the year and strandings increased over time. Analysis of stomach contents (n = 36) showed that striped dolphins in the area are mostly piscivorous (80% by number and weight of the diet), taking pelagic, meso-pelagic and demersal species. In terms of reconstructed biomass prey, sardine (Sardina pilchardus) and blue whiting (Micromesistius poutassou) were the most important. Prey items revealed that both sexes forage at a range of depths (pelagic and demersal systems) in both neritic and oceanic habitats, although females feed more often in coastal waters. Moreover, diet results also indicate that striped dolphins may co-occur with other neritic cetacean species, such as the common dolphin, Delphinus delphis, thus sharing some preferred prey species. The study revealed that striped dolphins on the Iberian coast interact with coastal fisheries sharing the same target species. Management measures for fisheries will need to be consistent with an ecosystem-based approach.

Age estimation and growth of striped dolphins Stenella coeruleoalba stranded along the coasts of south-western Italy

The knowledge of demographic traits such as longevity, growth rates and age at sexual maturity is crucial for understanding the structure of a population in its natural environment and implementing appropriate strategies for its management and conservation. Based on counts of growth layer groups in sections of decalcified teeth using the paraffin technique, we estimated the age and growth of 25 individuals of striped dolphin (Stenella coeruleoalba) found dead stranded along the coast of Campania and Calabria (south Italy, central-western Mediterranean) from 2013 to 2018. Seven individuals, with TL of 100–110 cm, were calves under 1 year old. The oldest male and female individuals were 19 and 14 years old, respectively. Growth curve estimated using the Gompertz growth model (GGM) showed that in S. coeruleoalba male growth trajectories are partly in accordance with those reported in other studies on the same species from different Mediterranean areas. The high frequency (28%) of calves strongly suggests that females of this species use the marine area all around the south-western Italian coasts to give birth to their offspring. Furthermore, a comparison with the estimated age of striped dolphins from other Mediterranean marine areas shows that the longevity of the individuals examined in this study is much lower. Our study provides information toward understanding the demographic traits of S. coeruleoalba from Mediterranean Sea. The results reported here can be useful for future research aimed at understanding population structure, mortality patterns and the effects of anthropogenic activity on the survival of this species in this marine area.

Diet of Mass-Stranded Striped Dolphins (Stenella coeruleoalba) in Southern Japan (East China Sea)

Striped dolphins (Stenella coeruleoalba) mass-stranded on 26 April 2013 at Minamisatsuma, Kagoshima Prefecture, in southern Japan (East China Sea). The diet of the mass-stranded striped dolphins was investigated to reveal their foraging pattern through analyses of the stomach contents and stable isotopes in muscle. Of 26 stomachs sampled, 25 contained hard parts of prey animals; no fleshy remains were found in any of the stomachs. The identified prey species represented four cephalopod families: Loliginidae, Onychoteuthidae, Histioteuthidae, and Ommastrephidae. Among these, ommastrephids had the highest abundance (42.4%) and frequency of occurrence (69.2%). A chi-square test revealed that the prey species consumed did not significantly differ between male and female dolphins, although deeper-water squids (Onychoteuthidae and Histioteuthidae) appeared only in the stomachs of females. The values of δ13C ranged from –20.4 to –17.0‰ (mean ± SD: –18.2 ± 0.9‰), and values of δ15N ranged from 10.2 to 12.5‰ (10.8 ± 0.5‰), with a significant difference in δ15N between sexes (P < 0.05).

Microscopic anatomical, immunohistochemical, and morphometric characterization of the terminal airways of the lung in cetaceans.

The lungs of cetaceans undergo anatomical and physiological adaptations that facilitate extended breath-holding during dives. Here, we present new insights on the ontogeny of the microscopic anatomy of the terminal portion of the airways of the lungs in five cetacean species: the fin whale (Balaenoptera physalus); the sperm whale (Physeter macrocephalus), the Cuvier's beaked whale (Ziphius cavirostris); the bottlenose dolphin (Tursiops truncatus); and the striped dolphin (Stenella coeruleoalba). We (a) studied the histology of the terminal portion of the airways; (b) used immunohistochemistry (IHC) to characterize the muscle fibers with antibodies against smooth muscle (sm-) actin, sm-myosin, and desmin; (c) the innervation of myoelastic sphincters (MESs) with an antibody against neurofilament protein; and (d) defined the diameter of the terminal bronchioles, the diameter and length of the alveoli, the thickness of the septa, the major and minor axis, perimeter and section area of the cartilaginous rings by quantitative morphometric analyses in partially inflated lung tissue. As already reported in the literature, in bottlenose and striped dolphins, a system of MESs was observed in the terminal bronchioles. Immunohistochemistry confirmed the presence of smooth muscle in the terminal bronchioles, alveolar ducts, and alveolar septa in all the examined species. Some neurofilaments were observed close to the MESs in both bottlenose and striped dolphins. In fin, sperm, and Cuvier's beaked whales, we noted a layer of longitudinal smooth muscle going from the terminal bronchioles to the alveolar sacs. The morphometric analysis allowed to quantify the structural differences among cetacean species by ranking them into groups according to the adjusted mean values of the morphometric parameters measured. Our results contribute to the current understanding of the anatomy of the terminal airways of the cetacean lung and the role of the smooth muscle in the alveolar collapse reflex, crucial for prolonged breath-holding diving.

Neurobrucellosis due to Brucella ceti ST26 in Three Sowerby's Beaked Whales (Mesoplodon bidens)

Fatal meningoencephalitis due to Brucella ceti infection has been described in striped dolphins (Stenella coeruleoalba), Atlantic white-sided dolphins (Lagenorhynchus acutus), short-beaked common dolphins (Delphinus delphis) and long-finned pilot whales (Globicephala melas), which are all within the family Delphinidae. We report B. ceti-associated neurobrucellosis in three juvenile male Sowerby's beaked whales (Mesoplodon bidens) that all had typical lesions of lymphocytic meningoencephalitis, which increased in severity from rostral to caudal regions of the brain. In two cases there was loss of ependymal cells lining the cerebral ventricular system, with large numbers of lymphocytes in the underlying neuropil. This finding suggests that B. ceti gains access to, and multiplies in, the cerebrospinal fluid, and confirms that this is the sample of choice for bacteriological recovery of the causative organism. These findings expand the increasing range of cetaceans susceptible to neurobrucellosis to members of the family Ziphiidae.

Occurrence of Brucella ceti in striped dolphins from Italian Seas.

Brucella ceti infections have been increasingly reported in cetaceans, although a very limited characterization of Mediterranean Brucella spp. isolates has been previously reported and relatively few data exist about brucellosis among cetaceans in Italy. To address this gap, we studied 8 cases of B. ceti infection in striped dolphins (Stenella coeruleoalba) stranded along the Italian coastline from 2012 to 2018, investigated thanks to the Italian surveillance activity on stranded cetaceans. We focused on cases of stranding in eastern and western Italian seas, occurred along the Apulia (N = 6), Liguria (N = 1) and Calabria (N = 1) coastlines, through the analysis of gross and microscopic findings, the results of microbiological, biomolecular and serological investigations, as well as the detection of other relevant pathogens. The comparative genomic analysis used whole genome sequences of B. ceti from Italy paired with the publicly available complete genomes. Pathological changes consistent with B. ceti infection were detected in the central nervous system of 7 animals, showing non-suppurative meningoencephalitis. In 4 cases severe coinfections were detected, mostly involving Dolphin Morbillivirus (DMV). The severity of B. ceti-associated lesions supports the role of this microbial agent as a primary neurotropic pathogen for striped dolphins. We classified the 8 isolates into the common sequence type 26 (ST-26). Whole genome SNP analysis showed that the strains from Italy clustered into two genetically distinct clades. The first clade comprised exclusively the isolates from Ionian and Adriatic Seas, while the second one included the strain from the Ligurian Sea and those from the Catalonian coast. Plotting these clades onto the geographic map suggests a link between their phylogeny and topographical distribution. These results represent the first extensive characterization of B. ceti isolated from Italian waters reported to date and show the usefulness of WGS for understanding of the evolution of this emerging pathogen.

Evaluating the presence of microplastics in striped dolphins (Stenella coeruleoalba) stranded in the Western Mediterranean Sea

Litter is a well-known problem for marine species; however, we still know little about the extent to which they're affected by microplastics. In this study, we analyse the presence of this type of debris in Western Mediterranean striped dolphins' intestinal contents over three decades. Results indicated that frequency was high, as 90.5% of dolphins contained microplastics. Of these microplastics, 73.6% were fibres, 23.87% were fragments and 2.53% were primary pellets. In spite of the high frequency of occurrence, microplastic amount per dolphin was relatively low and highly variable (mean ± SD = 14.9 ± 22.3; 95% CI: 9.58–23.4). Through FT-IR spectrometry, we found that polyacrylamide, typically found in synthetic clothes, was the most common plastic polymer. Here, we establish a starting point for further research on how microplastics affect this species' health and discuss the use of striped dolphins as indicators of microplastics at sea.

Temporal trends of halogenated and organophosphate contaminants in striped dolphins from the Mediterranean Sea

PBDEs, HBCD, novel DBDPE, PBEB and HBB, dechloranes, OPFRs and natural MeO-PBDEs were monitored in muscle of striped dolphins (Stenella coeruleoalba) from the Mediterranean Sea collected in three time periods (1990, 2004–2009 and 2014–2018). PBDEs levels decreased about 60% in under three decades, from 5067 ± 2210 to 2068 ± 2642ngg−1 lw, evidencing the success of their ban. Most PBDEs were found in all the samples, with BDE-47, -99, -154, -100 and -153 as the main contributors. Found in 71.4% of the samples, α-HBCD was stable through time and usually <LOQ. DBDPE concentrations decreased by 89% from 1990 to 2004–2009 and have remained stable since. HBB occurred rarely and decreased by 94% to a current few ngg−1 lw. Dec 602 was the main dechlorane with stable concentrations around 1200 ngg−1 lw, but a declining trend might have started in the last years. OPFRs concentrations were stable and showed the highest concentrations of all FRs in 2014–2018: 6253 ± 11,293ngg−1 lw. TBOEP and TNBP contributed to most of the OPFR concentration, the former with decreasing levels by 96%. MeO-PBDEs showed mean concentrations between 600 and 700ngg−1 lw in all periods. Non-targeted analysis allowed the identification and semi-quantification of additional chlorinated pollutants, such as polychlorinated terphenyls (PCTs) (levels decreasing by 81% to a current 770 ngg−1 lw mean) and polychlorinated diphenyl ethers (PCDEs) (decreasing by 83% to a current 3200ngg−1 lw) in Mediterranean marine mammals for the first time.

Alpha- and gammaherpesviruses in stranded striped dolphins (Stenella coeruleoalba) from Spain: first molecular detection of gammaherpesvirus infection in central nervous system of odontocetes

BackgroundHerpesvirus infections in cetaceans have always been attributed to the Alphaherpesvirinae and Gammaherpesvirinae subfamilies. To date, gammaherpesviruses have not been reported in the central nervous system of odontocetes.Case presentationA mass stranding of 14 striped dolphins (Stenella coeruleoalba) occurred in Cantabria (Spain) on 18th May 2019. Tissue samples were collected and tested for herpesvirus using nested polymerase chain reaction (PCR), and for cetacean morbillivirus using reverse transcription-PCR. Cetacean morbillivirus was not detected in any of the animals, while gammaherpesvirus was detected in nine male and one female dolphins. Three of these males were coinfected by alphaherpesviruses. Alphaherpesvirus sequences were detected in the cerebrum, spinal cord and tracheobronchial lymph node, while gammaherpesvirus sequences were detected in the cerebrum, cerebellum, spinal cord, pharyngeal tonsils, mesenteric lymph node, tracheobronchial lymph node, lung, skin and penile mucosa. Macroscopic and histopathological post-mortem examinations did not unveil the potential cause of the mass stranding event or any evidence of severe infectious disease in the dolphins. The only observed lesions that may be associated with herpesvirus were three cases of balanitis and one penile papilloma.ConclusionsTo the authors’ knowledge, this is the first report of gammaherpesvirus infection in the central nervous system of odontocete cetaceans. This raises new questions for future studies about how gammaherpesviruses reach the central nervous system and how infection manifests clinically.

Dolphins Stranded along the Tuscan Coastline (Central Italy) of the "Pelagos Sanctuary": A Parasitological Investigation.

Parasite monitoring is considered a necessary step for cetacean management and conservation. Between February 2013 and July 2015, 26 dolphins (15 Stenella coeruleoalba, 10 Tursiops truncatus, and one Grampus griseus) stranded along the Tuscan coastline of the protected marine area “Pelagos Sanctuary”, were examined. Organs, tissues, and faecal and blood samples taken from all animals were analysed by parasitological, immunological, and molecular techniques. Twenty-one out of 26 dolphins (80.77%) tested positive for at least one parasite species, and 13/15 (86.7%) S. coeruleoalba, 7/10 (70%) T. truncatus, and the single G. griseus were found positive. Identified parasites included the nematodes Skrjabinalius guevarai (7.69%, 2/26), Halocercus lagenorhynchi (3.85%, 1/26), Halocercus delphini (7.69%, 2/26), Stenurus ovatus (7.69%, 2/26), Crassicauda spp. (7.69%, 2/26); the trematodes Pholeter gastrophilus (26.92%, 7/26), Campula palliata (3.85%, 1/26); the cestodes Phyllobothrium delphini (42.31%, 11/26), Monorygma grimaldii (23.08%, 6/26), Tetrabothrium forsteri (7.69%, 2/26), Strobilocephalus triangularis (7.69%, 2/26), and the acanthocephalan Bolbosoma vasculosum (7.69%, 2/26). Moreover, 6/26 (23%) animals scored positive to Toxoplasma gondii at serology, but PCR confirmed the infection (T. gondii Type II genotype) in a single animal. In examined dolphins, obtained results showed a high prevalence of endoparasites, which included species considered as a cause of severe debilitation or death.

Mercury and cadmium in striped dolphins (Stenella coeruleoalba) stranded along the Southern Tyrrhenian and Western Ionian coasts

Pollution from heavy metals is becoming a serious and widespread problem due to their persistent and bioaccumulative nature, moreover in the Mediterranean Sea, threatening food safety and the health of humans and marine animals. Cadmium and mercury in particular, are considered two of the most toxic metals to living organisms. Their presence is associated with the contribution of human activity, implying an increased level in the different environmental compartments and the inevitable bioaccumulation in the food chain.In this study, levels of cadmium and mercury were determined in liver, kidney, and muscle tissue of dolphinid specimens of Stenella coeruleoalba stranded in different locations along the coastal areas of the Tyrrhenian and Ionian Sea in Southern Italy, during the period 2015–2018 by Atomic Absorption Spectrophotometry. Data were compared with those reported for other locations along the Mediterranean sea. The correlations between biometric data (body length, weight and gender) and cadmium and mercury concentrations in samples of cetaceans were statistically analysed in order to investigate the risk these contaminants may pose to the delphinids health.Examination of the pattern of contaminants revealed a significantly high distribution for mercury in all the matrices analyzed (liver, kidney and muscle tissue). On the contrary, elevated concentrations of cadmium were found only in liver (range: 0.005 - 8.95 mg/kg w.w.) and kidney (range: 0.005 - 34.1 mg/kg w.w.) due to accumulator role of these organs in long-term exposures.

Assessment of PCDD/Fs, dioxin-like PCBs and PBDEs in Mediterranean striped dolphins

Bio-accumulation of high levels of persistent organic pollutants represent a serious conservation concern for Mediterranean marine odontocetes. In this study, blubber samples from 10 striped dolphins (Stenella coeruleoalba) stranded along the Italian coasts during 2015–2016 were analyzed. All specimens showed dl-PCBs > PBDEs ≫ PCDD/Fs. Median concentrations were 1820 ng/g l.w., 456 ng/g l.w. and 23.9 pg/g l.w., respectively. dl-PCBs accounted for 93.3% of total TEQs. PBDE concentrations suggest that the Mediterranean basin may be considered a hotspot for organobromine compounds. OCDD did not represent the greatest contributor to PCDD/Fs profile, most likely due to a change in dioxin environmental sources in the last two-three decades. Despite international regulations, the present study emphasized that POP exposure levels in Mediterranean striped dolphins have not declined significantly in recent years. Toxicological and risk assessment studies on this sentinel species may provide an early indication of potential adverse health effects on Mediterranean ecosystems.

Spatial distribution and aggregation of Xenobalanus globicipitis on the flukes of striped dolphins, Stenella coeruleoalba: An indicator of host hydrodynamics?

AbstractWe analyzed patterns of aggregation and spatial distribution of the epizoic barnacle Xenobalanus globicipitis on the flukes of Mediterranean striped dolphins, Stenella coeruleoalba, assessing its potential use as an indicator of the host's hydrodynamics based on data from 55 dolphins. Barnacles occurred along the trailing edge with the cirri oriented towards the oncoming flow. Nearest neighbor analyses suggested that new recruits actively seek placement next to already settled barnacles, forming aggregations possibly to facilitate copulation. The probability of spanwise settlement strongly increased with fluke width (presumably enabling prolonged leading‐edge vorticity), and with chordwise length where pressure is predicted to be positive. Consequently, clustering tended to increase nonlinearly towards the fluke notch. Furthermore, it was three times more likely for barnacles to occur on the dorsal vs. ventral side of flukes, at an average abundance ca. 12 times higher. This difference could result from a host's asymmetric oscillation of the tail, which would alter leading‐edge vorticity, and/or an interaction between the wake produced by the dorsal fin and the flow associated with flukes. Both processes could primarily enhance cyprid contact and/or attachment on the dorsal side. This study offers a starting point for future comparison with other cetaceans.

Seafloor geomorphic features as an alternative approach into modelling the distribution of cetaceans

Bathymetric proxies tend to indicate the relationships between the distribution of cetaceans and the seafloor in species distribution models (SDMs). Usually, seafloor features are described arbitrary to explain these relationships. Currently, a global seafloor geomorphic features dataset is available, with an objective identification and full representation for each seafloor geomorphic feature. Models based on common bathymetric proxies were compared with models with seafloor predictors, by a standardized ensemble SDM framework. Occurrences of two species with different foraging strategies and relationships with the seabed were selected: the sperm whale (Physeter macrocephalus) and the striped dolphin (Stenella coeruleoalba).. For sperm whales, GLM models had a significant better performance with seageomorphic features than with the common bathymetric proxies. In GAM and MARS models, the performance was similar for both seabed features and bathymetric proxies' models. In relation to striped dolphins, all models obtained had a significant better performance with seafloor features than with bathymetric proxies, regardless the modelling technique. The models showed preference of sperm whales for areas distant from the continental shelf and continental rise areas which consists of submarine canyons with adjacent submarine fans. Striped dolphins showed a clear preference for continental slope areas. The modelling based on seafloor geomorphic features support the hypothesis that the use of this type of predictors can improve the modelling performance and provide a complementary understanding of the relationship between cetaceans and the seafloor.

Injuries, Malformations, and Epidermal Conditions in Cetaceans of the Strait of Gibraltar

The Strait of Gibraltar is a heavily used marine area, with intense fishing operations and one of the busiest shipping lanes worldwide. Concurrently, the Strait of Gibraltar is home to eight regularly occurring species of cetaceans. Thus, the potential for conflict between man and cetaceans is high. Injuries and external anomalies may serve as indicators for anthropogenic impacts and exposure to human activities. To explore potential impacts to cetacean populations inhabiting the Strait of Gibraltar, we analysed photographs taken opportunistically during whale-watching operations from 2001 to 2015. Externally visible conspicuous features and anomalies were detected in all of the eight regularly occurring cetacean species: long beaked common dolphin (Delphinus delphis), striped dolphin (Stenella coeruleoalba), common bottlenose dolphin (Tursiops truncatus), long-finned pilot whale (Globicephala melas), killer whale (Orcinus orca), sperm whale (Physeter macrocephalus), fin whale (Balaenoptera physalus), and minke whale (Balaenoptera acutorostrata). Altogether, 502 anomalies were documented in 494 cases of affected cetaceans, including injuries, skin anomalies, emaciation, and neoplasia. Highest prevalence was noted for injuries (245 incidences) of which a minimum of 44 (17%) were consistent with anthropogenic injuries. Our results suggest that human activities in the Strait of Gibraltar, especially fishing activities, pose a threat, particularly to small and medium-sized cetaceans. We, therefore, recommend stricter management enforcement of existing guidelines and laws, as well as the implementation of an area-wide management plan.