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Lymphoid and haematopoietic neoplasms are rare in cetaceans. This report describes intravascular lymphoma in an adult common dolphin that presented with neurological signs prior to stranding. Intravascular lymphoma is a rare neoplasm previously recorded in humans, dogs, a cat and a horse. The condition is characterized by intravascular neoplastic lymphocytic proliferation, the sequelae of which are dependent on the organ affected. Key pathological findings in this case included multifocal cerebrocortical malacia secondary to vascular occlusion associated with intravascular neoplastic lymphocytic proliferation. Immunohistochemistry supported a T-cell phenotype similar to that observed in dogs. The neurological presentation was consistent with that seen in other species in which the central nervous system is involved. The aetiology and pathogenesis have not been established in other species and although no further investigations were made in this common dolphin, this report adds to the short list of species affected by this rare neoplasm. [ABSTRACT FROM AUTHOR]

Ocean noise generated by human activities at sea has been increasing over the decades, affecting marine ecosystems. Ship traffic flow between the Mediterranean or South Atlantic and northern Europe makes the coast of Portugal one of the most intense shipping highways on a global scale. Among the cetaceans of the coast of Portugal, the common dolphin (Delphinus delphis) was selected as a target species. Based on 15 years of observations, the common dolphins' habitat suitability was estimated, together with the shipping noise maps for the year 2019, to produce seasonal risk maps for the same year. A large number of areas with a high noise risk index (≥ 0.85) were found in Portugal's southern and southwestern coasts, especially during the summer and fall seasons. Comparably, the 0.50 risk index exceeds 7 % and 3.5 % of the total area in summer and fall, respectively. These percentages decrease to 1 % in spring and winter. • We estimated common dolphin's habitat suitability and shipping noise on the Portuguese coast, region of intense ship traffic • We combined the habitat suitability maps and noise maps in order to obtain a risk map for each season of the year • The final maps showed a higher risk of exposure in summer and in shallow waters • These results are just a first step towards understanding the risk from shipping noise exposure on the common dolphin [ABSTRACT FROM AUTHOR]

Marine pollution is considered a current driver of change in the oceans and despite the urgency to develop more studies, there is limited information in the southern hemisphere. This study aimed to analyze the levels and profiles of natural (MeO-PBDEs) and anthropogenic (BFRs: PBDEs, HBB, PBEB) organic brominated compounds in adipose tissue of two species of dolphins with different distribution and trophic requirements from the Southwestern Atlantic Ocean; the short-beaked common dolphin (Delphinus delphis) and the Fraser's dolphin (Lagenodelphis hosei). In addition, we aim to investigate maternal transfer and biological pattern relationship (sex, age, sexual maturity) in short-beaked common dolphin bioaccumulation. The levels of both groups of contaminants were in the same order of magnitude as those reported for other marine mammals on both a regional and global scale. BFRs profiles were dominated by BDE 28 and BDE 47 in short-beaked common dolphin and Fraser's dolphin, respectively, whereas 2-MeO-BDE 68 was the most abundant natural compound in both species. Evidence of maternal transfer, temporary increase in BDE 154 levels and no influence of sex, age, or sexual maturity on brominated compound concentration was observed in short-beaked common dolphin. This study fills a gap in the knowledge of the Southwestern Atlantic Ocean providing new information on emerging organic pollutants bioavailability for dolphins and, therefore, for the different trophic webs. In addition, it serves as a baseline for further contamination assessments. [Display omitted] • Organobromine compounds are available in the trophic webs of D. delphis and L. hosei. • Evidence of maternal transfer on brominated compounds was found in D. delphis. • BFRs profiles were dominated by BDE 28 (D. delphis) and BDE 47 (L. hosei). • Both trophic webs, represented by dolphin's species, were dominated by 2-MeO-BDE 68. [ABSTRACT FROM AUTHOR]

Abstract Plastic debris is currently recognised as one of the major global threats to marine life. However, few data exist on the presence and abundance of microplastics (plastics < 5 mm in size) in marine mammals. This is the first record of the presence of microplastics in the digestive tracts of marine mammals from the Iberian Peninsula. This study made use of 35 samples of common dolphin stomach contents. Microplastics were identified in all the samples analysed, an average of 12 items per stomach although abundance varied widely from one stomach to another. Most plastic items were small fibres although some fragments and a bead were also found. Excluding the smallest fibres as possible airborne contamination, the estimated occurrence of microplastics could drop to as low as 94%. Although factors affecting accumulation of microplastics and their effect on common dolphins are unknown, the fact that all stomachs analysed contained microplastics is a cause for concern. [ABSTRACT FROM AUTHOR]

Monitoring and assessment of the status of marine mammal populations is a requirement of the European Marine Strategy Framework Directive (MSFD). Due to the difficulty of collecting data in the marine environment and because many populations of these highly mobile species inhabit waters of several Member States, monitoring of marine mammals is particularly challenging. In the present work we have used a 10-year time-series of data collected from multidisciplinary research surveys to estimate common dolphin ( Delphinus delphis ) abundance and trends in continental shelf waters of the northwest Spanish sub-region. We argue that this approach provides a valuable addition to large-scale dedicated surveys, offering a shorter interval between surveys and hence offering the possibility to track abundance changes at a regional scale. Trends in the number of dolphins present in the study area over the last 10 years show a mean increase of about 9.6% per year, which results in an evaluation of Good Environmental Status for the species in the area using the abundance indicator adopted in the framework of the MSFD. Data obtained from dedicated dual-platform surveys have been used to correct the detection bias in our data collected using single-platforms (attraction toward the observation platform and animals missed on the track-line), to obtain absolute abundance estimates for calculating bycatch limits. The average abundance over the study period was 12,831 dolphins [CI 95%; 9025, 18,242] calculated with the conventional distance sampling methodology, 4747 [3307, 6816] corrected for attraction and missed animals on the track-line, and 22,510 [15,776, 32,120] corrected only for missed animals on the track-line. The estimated safe bycatch limit for this area calculated from these abundance values were 218 [153, 310], 81 [56, 115] and 383 [268, 546] per year, respectively. Comparing these figures with estimates based on different sources, the percentage of dolphins that die in this study area is higher than the maximum limit allowable under the OSPAR criteria for population mortality adopted as an indicator for the MSFD. [ABSTRACT FROM AUTHOR]

From the Habitat Directive to the recent Marine Strategy Framework Directive, the conservation status of cetaceans in European water has been of concern for over two decades. In this study, a seasonal comparison of the abundance and distribution of cetaceans was carried out in two contrasted regions of the Eastern North Atlantic, the Bay of Biscay and the English Channel. Estimates were obtained in the two sub-regions (375,000 km²) from large aerial surveys conducted in the winter (November 2011 to February 2012) and in the summer (May to August 2012). The most abundant species encountered in the Channel, the harbour porpoise, displayed strong seasonal variations in its distribution but a stable abundance (18,000 individuals, CV=30%). In the Bay of Biscay, abundance and distribution patterns of common / striped dolphins varied from 285,000 individuals (95% CI: 174,000–481,000) in the winter, preferentially distributed close to the shelf break, to 494,000 individuals (95% CI: 342,000−719,000) distributed beyond the shelf break in summer. Baleen whales also exhibited an increase of their density in summer. Seasonal abundances of bottlenose dolphins were quite stable, with a large number of ‘pelagic’ encounters offshore in winter. No significant seasonal difference was estimated for pilot whales and sperm whale. These surveys provided baseline estimates to inform policies to be developed, or for existing conservation instruments such as the Habitats Directive. In addition, our results supported the hypothesis of a shift in the summer distributions of some species such as harbour porpoise and minke whale in European waters. [ABSTRACT FROM AUTHOR]

Throughout their range, marine mammals are vulnerable to incidental capture in fishing gear. Bycatch is a particularly important issue for cetaceans, which generally have lower potential rates of population growth and are thus more susceptible to the effects of bycatch mortality than other marine mammals. Spatial and temporal gaps in our knowledge of cetacean distributions can make it difficult to mitigate and manage bycatch. Here, we modelled the spatial and temporal distribution of two species of cetacean for which bycatch is known to occur; the common dolphin ( Delphinus delphis ) and the harbour porpoise ( Phocoena phocoena ) and the spatial and temporal distribution of six different gear types. The models were integrated into a Productivity Susceptibility Analysis (PSA) to calculate risk in both spatial and temporal dimensions. Models showed temporal variation in spatial distribution for both species but particularly for harbour porpoise, whilst common dolphins were distributed in association with areas of high primary productivity where pelagic fish are likely to shoal. The risk assessment indicated two areas in the study region where risk from bycatch is likely to be particularly high, with gillnets being assessed as the highest risk gear type. Results should be used to guide fisheries and bycatch management through an integrated ecosystem approach, and could be used as a guide to where further observer effort should be focused. Results also provide valuable information for the designation of Marine Protected Areas for marine mammals. [ABSTRACT FROM AUTHOR]

Organic compounds, in particular organochlorines, are highly persistent compounds which accumulate in biotic and abiotic substrates. Marine mammals bioaccumulate and biomagnify persistent organic pollutants (POPs) through diet. ∑ PCB (26 PCB congeners), ∑ DDT (pp-DDT, pp-DDD, pp-DDE), ∑ HCH (α-HCH, β-HCH, γ-HCH, δ-HCH), HCB and mirex were analyzed from samples of subcutaneous adipose tissue of common dolphins, Delphinus delphis , and Fraser's dolphins, Lagenodelphis hosei , obtained in 1999 and 2012. The aim of this study was to determine the concentrations of POPs to get baseline information on the current state of pollution by these compounds in these two species in South Atlantic. At the same time, to assess concentrations of POPs in relation to age, the total length and sexual maturity in common dolphins . Organochlorine pesticides dominated Fraser's dolphins, DDT being the most abundant, while PCBs were mostly present in common dolphins. In both species, the distributions of isomers or metabolites followed the order: β-HCH > δ-HCH > γ-HCH > α-HCH and pp-DDE > pp-DDD > pp-DDT. As for ∑ PCB, the largest contribution was given by congeners of high molecular weight, particularly by hexa and hepta - CBs. Common dolphins did not show effects on sexual maturity, age and standard length in the concentration of organochlorines. The mean concentrations found in this study are lower compared to those reported in other studies performed in dolphins elsewhere. This study provides new information regarding levels of organochlorines in common dolphins for the Southwestern Atlantic. [ABSTRACT FROM AUTHOR]

Bycatch of marine mammals in fishing gear is a global problem, and considered a significant threat to cetaceans in the East Sea. The characteristics of cetacean bycatches in this area between 2013 and 2014 were investigated. The Korea Coast Guard reported a total of 717 cetacean bycatches involving 10 species. Four species, spinner dolphins ( Stenella longirostris ), long-beaked common dolphins ( Delphinus capensis ), minke whales ( Balaenoptera acutorostrata ), and finless porpoises ( Neophocaena asiaeorientalis ) accounted for 95.6% of the bycaught cetaceans. More bycatches occurred in the spring (49.8%) than in other seasons, with a peak in April (22.0%). Most bycatches involved three types of fishing gear: set nets, pots and gill nets (n = 706; 98.5%). The remaining bycatches were associated with trawl nets (n = 4; 0.6%). Most bycatches took place within 5 M of land (n = 504; 79.5%). [ABSTRACT FROM AUTHOR]

Construction of ecosystem models requires detailed information on trophic interactions which may not be readily available, especially for top predators such as cetaceans. Such information can also be useful to estimate natural mortality ( M ) for fish stock assessments and to evaluate the potential for competition between cetaceans and fisheries. In the present paper we provide estimates and confidence limits, taking into account sampling error, for consumption of fish by the four most common cetaceans along the Atlantic coast of the Iberian Peninsula, while highlighting the uncertainties and biases inherent in the information presently available on energy requirements, diet and population size. We estimated that common dolphins ( Delphinus delphis ) consume around 6800 (95% CI, 4871–9476) tons of sardine ( Sardina pilchardus ), 8800 (6195–12,647) tons of gadids, 1100 (721–1662) tons of hake ( Merluccius merluccius ) and 1900 (1222–2752) tons of scads ( Trachurus sp.) annually. For striped dolphins ( Stenella coeruleoalba ), prey consumed were 900 (196–2661) tons of sardine, 6200 (3448–11,129) tons of gadids, 200 (11–504) tons of hake and 1600 (0–5318) tons of scads. Estimated amounts taken by harbour porpoises ( Phocoena phocoena ) and bottlenose dolphins ( Tursiops truncatus ) are much lower, reflecting their low abundance in the area. Cetacean predation on sardine represents 2–8% of the current M value, indicating that cetaceans probably have little influence on sardine population dynamics. For the southern hake stock, estimated average removal by cetaceans often exceeds M . While this may indicate that both M and the consumption estimates for hake require revision it also suggests that cetaceans could have a more significant impact on hake populations. Different approaches to estimation of energy requirements of cetaceans can result in figures that differ by at least a factor of 2. The lack of good estimates of field metabolic rate for most species probably represents the most serious barrier to reliably quantifying the role of cetaceans in the ecosystem. [ABSTRACT FROM AUTHOR]

The ubiquitous protozoan parasites Giardia and Cryptosporidium have been detected from many species of captive and free-living wildlife, representing most mammalian orders. Twenty species of marine mammals have been reported to inhabit Galician waters and the region has one of the highest rates of stranding in Europe. Evidence from stranding, reported by-catches and sightings, suggests that the common dolphin (Delphinus delphis) is the most abundant cetacean on the Galician coast (Northwest Spain). The objective of this study was to detect and molecularly characterize isolates of Giardia and Cryptosporidium obtained from common dolphins stranded in this area. Between 2005 and 2012, sections of large intestine from 133 common dolphins stranded along the Galician coast were collected by the personnel of the Galician Stranding Network (Coordinadora para o Estudo dos Mamíferos Mariños, CEMMA). Using direct immunofluorescence antibody test (IFAT) and PCR amplification and sequencing of the SSU-rDNA, β-giardin genes and the ITS1-5.8S-ITS2 region, Giardia and Cryptosporidium were detected in 8 (6.0%) and 12 samples (9.0%), respectively. In two samples, co-infection by both parasites was observed. The molecular characterization revealed the presence of Giardia duodenalis assemblages A (genotypes A1 and A2) and B and Cryptosporidium parvum in these samples. This constitutes the first study in which the presence of Giardia and Cryptosporidium has been investigated in common dolphins on the European Atlantic coast, and it is also the first report of C. parvum in this host. Our findings indicate that these animals could act as reservoir of these waterborne parasites or could be victims of the contamination originated by anthropogenic activities. [ABSTRACT FROM AUTHOR]

Abstract: Cetacean strandings are an important source of information on cetacean population status and of biological samples. Nevertheless, collecting stranding data remains opportunistic and their representativity must be improved. The aim of this study was to improve the ecological significance of strandings, through the determination of stranded common dolphin origin found along the coasts of the Channel and the Bay of Biscay, by using the drift prediction model MOTHY. In order to map inferred distribution of dead dolphins, origin of strandings were weighted by the probability that cetaceans dying at sea become stranded. The difference between observed stranding origin and origin of expected strandings under the hypothesis of spatial and temporal uniformity of dead cetaceans, constituted the anomaly in stranding origin. Between 1990 and 2009, 6182 common dolphin strandings were reported by the UK and French stranding networks. Distribution inferred from strandings suggested that common dolphins died mostly in the neritic Bay of Biscay. The anomaly in stranding origin was maximal in the southern Bay of Biscay, highlighted as an area of high relative abundance or strong mortality for common dolphin. The monthly decomposition of this anomaly showed that positive anomaly was located in the southern Bay of Biscay in winter and expanded northward over the whole Bay of Biscay and western Channel in spring and summer. These results were consistent with current knowledge on common dolphin distribution and provide new insight on strandings as cetacean population indicators. These parameters are essential components for assessing the conservation status of vulnerable populations. [Copyright &y& Elsevier]

Summary: This report describes the pathological findings in an adult female short-beaked common dolphin (Delphinus delphis) stranded alive in the Canary Islands. Necropsy examination revealed the presence of a nodular neoplastic growth in the central nervous system (CNS) at the level of the thalamus. Microscopical examination revealed the mass to be a lymphoma and immunohistochemical labelling demonstrated a T-cell origin. No significant lesions were observed in other organs, including lymphoid organs. This is the first report of a primary T-cell lymphoma in the CNS in cetaceans. [ABSTRACT FROM AUTHOR]

This paper describes the immunophenotype of cellular inflammatory infiltrates in chronic cholangitis in six common dolphins (Delphinus delphis), four striped dolphins (Stenella coeruleoalba), three Atlantic spotted dolphins (Stenella frontalis) and one pygmy sperm whale (Kogia Breviceps) found stranded along the coasts of the Canary Islands (Spain). A panel of 5 antibodies previously tested in dolphins (anti-CD3, -IgG, -MHC class II, -S100 protein and -lysozyme) were used. The present work also reports cross reactivity with dolphin antigens of two antibodies not used to date in dolphins (anti-mouse iNOS and anti-mouse Foxp3). The most common type of cholangitis found was chronic granulomatous cholangitis, associated with the presence of the parasite Campula spp., or its eggs in bile ducts. The cellular composition of the hepatic inflammatory infiltrate associated to chronic parasitic cholangitis was closely similar to that found in the cortex of control lymph nodes, including the presence of S100+ and MHC class II+ dendritic- like cells in lymphoid follicles and interfollicular areas. Only occasional macrophages expressed iNOS, whereas Foxp3+ lymphocytes were not found in any of the lesions described in the different types of cholangitis. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge of species' ecological niches can be used to assess ecological interactions between different taxa. Sixteen species of cetaceans have been recorded in Galician waters and niche partitioning is expected to occur among these species in order to allow them to co-exist. In this study, the niches occupied by five of the most commonly encountered odontocete species off Galicia (NW Iberia) were compared, based on seven ecogeographic variables, using a PCA-based methodology and Classification trees. Significant differences in niche centres and niche widths were found among all the species. During the summer, the harbour porpoise occupied the narrowest and most differentiated niche when compared to the rest of the species. Three species could be compared during the winter, when long-finned pilot whales preferred colder and less variable water temperatures than did common dolphins. Seasonal differences in habitat preferences were found for bottlenose dolphins. A higher degree of specialisation was found during the summer, resulting in stronger differences in habitat use in this season, which may be related to an increment in resource availability during the upwelling period (April–September). The PCA-based methodology used in this study provides an effective multivariate approach to explore niche partitioning between co-existing species. [Copyright &y& Elsevier]

Highlights: [•] Robust abundance estimates for five cetacean species in EU Atlantic shelf waters. [•] No evidence for large-scale change in abundance between 1994 and 2005 in 3 species. [•] Large shift in harbour porpoise distribution demonstrated by spatial modelling. [•] Results allow assessment of conservation status at large spatial scale. [Copyright &y& Elsevier]

Abstract: We report concentrations of organochlorine pesticides (HCB, HCHs, DDTs, dieldrin) and PCBs in the blubber of 43 common dolphins bycaught in fisheries operating off the SW coast of the UK from 1992 to 2006. Concentrations of ΣDDT (summed p,p′-DDT and its metabolites, p,p′-DDE and p,p′-TDE) and of 25 summed CB congeners ranged from 0.2 to 16.1 and 2.1 to 62.4mgkg−1 lipid weight, respectively. Concentrations of sum HCH, HCB and dieldrin were lower, ranging from not detected to 0.14, 0.01 to 0.27 and 0.01 to 0.73mgkg−1 lipid weight, respectively. All contaminants studied showed a downward time trend but only that for HCHs was statistically significant. Overall, 72% of the dolphins analysed had blubber PCB concentrations above an established toxicity threshold value. [Copyright &y& Elsevier]

Abstract: Cetaceans are difficult to observe in the wild, and demand complex logistics for dedicated collection of biological data. As such, the distribution of most cetacean species is still poorly understood. Ecological niche models are useful in studying species distributions and their ecological determinants, and platforms of opportunity (e.g. commercial nautical operators) can provide an alternative source for that data in cetaceans. In this study, we modelled common dolphin (Delphinus delphis) habitat preferences using ecological niche modelling and presence data obtained from distinct platforms of opportunity in two different areas in the Portuguese coast (west and south mainland Portugal) for the period 2005–2007. Models from southern Portugal were projected to western Portugal and vice-versa, to check for robustness in predicting the species ecological niche. Our results show that data from platforms of opportunity can result in robust ecological models and provide extremely useful information on cetacean ecology. We found that common dolphins exhibit a patchy distribution pattern over the Portuguese coastline, and identified key habitats for their occurrence. The most important variable associated with this species'' distribution was chlorophyll concentration which, given the results from previous research, we hypothesise reflects an ecological specialisation on pelagic schooling fish. Given that the most abundant schooling fish species in Portugal is increasingly overexploited and in constant decline, more attention should be given to the conservation of common dolphin in Portuguese waters. [Copyright &y& Elsevier]

Abstract: Although overfishing has been recognized as responsible for the decline of major fish stocks, it has been less easy to demonstrate its indirect and detrimental effects on marine mammals, particularly dolphins. Competition with fisheries for the same food resources has been hypothesized to have led to the decline of several species of dolphins, including the endangered Mediterranean short-beaked common dolphin. Based on an ecosystem model for the Inner Ionian Sea Archipelago, a former hotspot for common dolphins in the Mediterranean Sea, we investigated the effect of increasing fishing effort on common dolphins, its prey and on marine biodiversity and we evaluated the outcomes of different fisheries closures (1 – closure of the purse seine fishery, 2 – closure of purse seine, trawl and beach seine fisheries, 3 – entire area closed to fisheries) ran between the years 2011 and 2030. Our results showed that local fisheries have negatively impacted the marine biodiversity of the ecosystem causing sharp declines of common dolphins and major fish stocks and weakening the robustness of the marine food web. The implementation of fisheries closures would gradually recover fish stocks, while common dolphins would increase more pronouncedly only if the study area was to be closed to all fisheries. As shown in this study, common dolphins have reflected ecosystem changes and degradation over time. Ensuring the survival of dolphin populations is thereby essential to enhance marine ecosystems and ensure sustainable fishing. [Copyright &y& Elsevier]

Abstract: Data on the occurrence and accumulation profiles of butyltins (BTs), including tributyltin (TBT), in marine mammals are scarce. This is the first study to investigate residue levels and accumulation patterns of BTs in cetaceans from Korean coastal waters. The total concentrations of BTs (sum of mono- to tri-butyltins) in minke whales (Balaenoptera acutorostrata) and long-beaked common dolphins (Delphinus capensis) ranged from 15.7 to 297ng/g wet weight (mean: 100ng/g wet weight) and from 59.0 to 412ng/g wet weight (mean: 228ng/g wet weight), respectively. Dibutyltin (DBT) accounted for 63% of the total BTs in all cetacean samples. Significant species-specific differences in BT concentrations, possibly due to the differences in their habitat and diet, were found between the two cetacean species. The concentrations of DBT and TBT in most cetacean samples exceeded the threshold value for cytotoxic effects in cetaceans, implying potentially adverse health risks from exposure to BTs. [Copyright &y& Elsevier]

Summary: An immature unilateral hermaphrodite common dolphin (Delphinus delphis) was found stranded on the southwest coast of the UK. The external phenotype was that of a female, but internally there was one ovotestis, containing both ovarian follicles and testicular tubular elements, and a contralateral ovary. Ovarian portions of the ovotestis appeared normal and demonstrated follicular development, whereas the testicular tissue exhibited hypoplasia and degeneration. This is the first reported case of an ovotestis in a cetacean species. [ABSTRACT FROM AUTHOR]

Abstract: One of the most challenging applications of time–frequency representations deals with the analysis of the signal issued from natural environment. Recently, the interest for passive underwater context increased, basically due to the rich information carried out by the natural signals. Taken into account the non-linear multi-component time–frequency behaviour of such signals, their analysis is a challenging problem. In this context, the analysis of underwater mammal’s whistles is aimed to extract, accurately and adaptively, their main time–frequency components. In this paper, we define a time–frequency-phase tracker which is composed of three steps. The first one consists of modelling the short-time segments of the vocalization by a set of third order polynomial phase modulations. The second step consists in the fusion of local polynomial phase modulations according to a local phase continuity criterion. Finally, in the third step, the detected time–frequency track is used to design the time–frequency filter, in charge of extracting the samples corresponding to the detected track. This procedure is then iterated until all component of interest are extracted. Tests provided for realistic scenarios and real data taken in Bay of Biscay at September 2009 containing whistles of common dolphin Delphinus delphis illustrate the potential and the benefits of the proposed approach. [ABSTRACT FROM AUTHOR]

Which characteristics define the prey species constituting the diet of a given predator? Answering this question would help predict a predator's diet and improve our understanding of how an ecosystem functions. The aim of this study was to test if the diet of common dolphins, Delphinus delphis , in the oceanic Bay of Biscay reflected prey availability or a selection shaped by prey energy densities (ED). To do this, the community of potential prey species, described both in terms of relative abundance and energy densities, was compared to the common dolphin diet in this area. This analysis of a predator's diet and its prey field revealed that the common dolphin selected its diet on the basis of prey energy densities (significant values of Chesson's index for ED > 5 kJ g− 1). High-energy prey were positively selected in the diet [ e.g. Notoscopelus kroeyeri , ED = 7.9 kJ g− 1, 9% of relative abundance in the environment (%Ne); 62% of relative abundance in the diet (%Nd)] and low-energy prey disregarded (Xenodermichthys copei , ED = 2.1 kJ g−1, 20%Ne, 0%Nd). These results supported the hypothesis that common dolphins selected high energy density prey species to meet their energetically expensive life style and disregard prey organisms of poor energy content even when abundant in the environment. [ABSTRACT FROM AUTHOR]

Abstract: Despite several studies that report accumulation of polychlorinated biphenyls (PCBs) and DDT in marine mammals worldwide, very few have examined polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like PCBs. In particular, no earlier studies have reported concentrations and accumulation profiles of persistent organic pollutants (POPs) in marine mammals from Korea. In this study, concentrations and accumulation features of PCDD/Fs and dioxin-like PCBs were measured in liver and blubber of minke whales and long-beaked common dolphins collected from Korean coastal waters. The concentrations of PCDFs and dioxin-like PCBs in blubber were 3–10 times higher than the concentrations measured in liver, but PCDDs were higher in liver than blubber. Total toxic equivalent (TEQ) concentrations in blubber of minke whales and common dolphins from Korean coastal waters were similar to, or higher than those reported for cetaceans and seals from other countries. Homologue and congener profiles of PCDD/Fs were different between livers and blubbers, while the profiles of dioxin-like PCBs were similar between the tissues. Concentrations of PCDD/Fs and dioxin-like PCBs in liver and blubber of dolphins were significantly higher than those measured in whales, due to differences in habitat and diet. The relative contribution of individual chemical groups to total TEQs was different between the two cetacean species, suggesting different exposures and metabolic activity. The TEQ levels in minke whales did not exceed the threshold level suggested for immunomodulation, while TEQs in all dolphin samples exceeded the suggested threshold level, implying potential adverse health effects from exposure to PCDD/Fs and PCBs. [Copyright &y& Elsevier]

Concentrations of several congeners and classes of organohalogen contaminants (OHCs) and/or their metabolites, namely organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), hydroxylated-PCBs (OH-PCBs), methylsulfonyl-PCBs (MeSO2-PCBs), polybrominated diphenyl ether (PBDE) flame retardants, and OH-PBDEs, were measured in cerebrospinal fluid (CSF) of short-beaked common dolphins (n = 2), Atlantic white-sided dolphins (n = 8), and gray seal (n = 1) from the western North Atlantic. In three Atlantic white-sided dolphins, cerebellum gray matter (GM) was also analyzed. The levels of OCs, PCBs, MeSO2-PCBs, PBDEs, and OH-PBDEs in cerebellum GM were higher than the concentrations in CSF. 4-OH-2,3,3′,4′,5-pentachlorobiphenyl (4-OH-CB107) was the only detectable OH-PCB congener present in CSF. The sum (Σ) OH-PCBs/Σ PCB concentration ratio in CSF was approximately two to three orders of magnitude greater than the ratio in cerebellum GM for dolphins. [Copyright &y& Elsevier]

Cetaceans have been naturally exposed to toxic trace elements (TEs) on an evolutionary time scale. Hence, they have developed mechanisms to control and/or mitigate their toxic effects. These long-lived species located at high trophic positions and bioaccumulating toxic elements are assumed to be good biomonitoring organisms. However, anthropogenic emissions have strongly increased environmental levels of toxic TEs in the last decades, questioning the efficiency of the detoxication mechanisms in cetaceans. In this context, temporal trends of mercury (Hg), cadmium (Cd) and lead (Pb) concentrations were studied through the analysis of 264 individuals from two cetacean species the common dolphin (Delphinus delphis) and the harbour porpoise (Phocoena phocoena) and belonging to two different Management Units (MUs) for the latter. These individuals stranded along the French Atlantic coasts from 2000s to 2017. All the trends presented were age- and sex-corrected and stable isotope ratios of carbon (δ 13C) and nitrogen (δ 15N) were measured as proxies of their feeding ecology. Results showed that Pb concentrations clearly decreased over time in both species and MUs. This decrease agrees with the lead petrol regulation after 2000s, supporting the use of these species as valuable bioindicators of changes for TE levels in the marine environment. A significant long-term increase of total Hg concentrations was only observed in common dolphins. Cadmium concentrations also revealed different trends over the period in both species. The different Hg and Cd trends observed in the two species, probably reflected a contrasted contamination of habitat and prey species than a global increase of the contamination in the environment. These results highlight the necessity and gain of using different species to monitor changes in marine environments, each of them informing on the contamination of its own ecological niche. Lastly, the Se:Hg molar ratios of species suggested a low risk for Hg toxicity over time. [Display omitted] • Temporal trends of Pb, Hg and Cd in two cetacean species and management units. • Eco-biological factors were included in models to assess temporal trends. • Pb showed the same trend for both species with few effects of ecological factors. • Hg and Cd showed different trends for both species and porpoise management units. • The Se:Hg molar ratios evolution over time suggested low risk for Hg toxicity. [ABSTRACT FROM AUTHOR]

This study arose from recommendations given in response to a legislated ecological assessment of the South Australian Sardine Fishery in 2004, urging it to: (i) attempt to mitigate operational interactions with marine mammals if excessive levels were detected; and (ii) improve the accuracy of their reporting of these events. An initial observer program revealed high rates of encirclement and mortality (1.78 and 0.39 dolphins per net-set, respectively) of short-beaked common dolphins (Delphinus delphis). This equated to an estimate of 1728 encirclements and 377 mortalities across the entire fleet over the same period. The average time taken for fishers to respond to encirclements was 135.93±3.72min and 21.3% of encircled animals subsequently died. During that time, fishers only reported 3.6% of encirclements and 1.9% of mortalities recorded by observers. A code of practice (CoP) was subsequently introduced aimed at mitigating operational interactions. A second observer program revealed a significant reductions in the observed rates of dolphin encirclement (0.22; down 87.3%) and mortality (0.01; down 97.1%) with an estimate of 169 and eight, respectively. The average time taken for fishers to respond to dolphin encirclements also reduced to 16.33±4.67min (down 76.9%) and the proportion of encircled animals that subsequently died reduced to 5.0%. Agreement between industry reports and observer records improved, with the fishery reporting 57.9% and 58.9% of the rate of encirclements and mortalities, respectively, recorded by observers. A number of avoidance and release strategies in the CoP may have been responsible for these improvements. In particular, fishers were required to delay or relocate their activities if dolphins were observed prior to fishing and to release encircled dolphins immediately or abort the fishing event if release procedures were unsuccessful. Future improvements to the CoP include: (i) improved response times when an encircled dolphin is detected; (ii) better use of behavioural cues for deciding when to abort a net-set; (iii) ceasing fishing during rough weather; and (iv) continuing to increase reporting accuracy by fishers. It is also recommended that the abundance, movements and boundaries of the common dolphin population in the region be determined, so that the impact of fishing activities on their status can be established. [Copyright &y& Elsevier]

Abstract: Halogenated 1′methyl-1,2′-bipyrroles (MBPs) have been identified worldwide in marine mammals. Here we present the tentative identification of previously undetected MBP congeners in Delpinus delphis blubber using gas chromatography/electron capture negative ion mass spectrometry (GC/ECNI-MS) and comprehensive two-dimensional gas chromatography/time of flight mass spectrometry (GC×GC/TOF-MS). This is the first report of 26 congeners. The presence of numerous partially halogenated congeners suggests that they are either biosynthesized concomitantly with their perhalogenated counterparts or that their dehalogenation products can also bioaccumulate. The newly found compounds fit the geographic trend that has been previously noted. That is, samples from the Atlantic Ocean are dominated by the more brominated congeners while those from the Pacific are dominated by the more chlorinated congeners. [Copyright &y& Elsevier]

Trace elements, polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticide levels were determined in tissues collected from stranded and bycaught common dolphins (Delphinus sp.) from New Zealand waters between 1999 and 2005. The concentrations of mercury (Hg), selenium (Se), chromium (Cr), zinc (Zn), nickel (Ni), cadmium (Cd), cobalt (Co), manganese (Mn), iron (Fe), copper (Cu), tin (Sn), lead (Pb), arsenic (As) and silver (Ag) were determined in blubber, liver and kidney tissue. PCBs (45 congeners) and a range of OC pesticides including dieldrin, hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) and its metabolites DDE and DDD were determined in blubber samples. Cr and Ni were not detected in any of the samples and concentrations of Co, Sn and Pb were generally low. Concentrations of Hg ranged from 0.17 to 110 mg/kg wet weight. Organochlorine pesticides dieldrin, HCB, o,p′-DDT and p,p′-DDE were present at the highest concentrations. Sum DDT concentrations in the blubber ranged from 17 to 337 and 654 to 4430 μg/kg wet weight in females and males, respectively. Similarly, Σ45CB concentrations ranged from 49 to 386 and 268 to 1634 μg/kg wet weight in females and males, respectively. The mean transmission of ΣDDTs and ICES7CBs between a genetically determined mother–offspring pair was calculated at 46% and 42%, respectively. Concentrations of organochlorine pesticides determined in the present study are within similar range to those reported for Hector''s dolphins (Cephalorhyncus hectori) from inshore New Zealand waters. [Copyright &y& Elsevier]

Abstract: In this study, results from an observer programme on a drift net fishery in the eastern North Atlantic are presented. Observers recorded all fish, marine mammals, seabirds and turtles caught and discarded and coverage ranged from 47.8% of the fleet (n =7 vessels) in 1996, to 2.2% (n =21 vessels) in 1998. A minimum of seven fish species were caught and landed during the fishing period; albacore tuna (Thunnus alalunga) comprised approximately 99% of the total landings (by number) in both years. Eleven fish species were discarded, of which blue shark (Prionace glauca) was the most frequently recorded representing 68% of all fish discarded by number. At least four species of seabird (Northern Gannet Morus basanus, Northern Fulmar Fulmarus glacialis, Manx shearwater Puffinus puffinus, Atlantic Puffin Fratercula arctica) and two species of turtle, including the leatherback turtle (Dermochelys coriacea), were also entangled. Eight species of Cetacea were recorded as bycatch during these fishing operations, including common dolphins Delphinus delphis and striped dolphins Stenella coeruleoalba. Length–frequency distributions for both these dolphin species suggest that age segregation occurs. Using landings of albacore tuna as an indicator of effort, the extrapolated decadal scale data from Irish and other driftnet fleets operating in this area suggest that during the period 1990–2000, a minimum (95% confidence intervals) of 778,452 (622,520–934,384) blue sharks were caught, with a substantial proportion discarded. An estimated 24,358 dolphins were killed during these years by these fleets, of which 11,723 (7670–15,776) were common dolphins and 12,635 (10,009–15,261) were striped dolphins. Although this type of fishing was effective at catching the target species, it removed a large biomass of megafauna and likely accelerated the decline of blue sharks in this area. [Copyright &y& Elsevier]

Summary: A wild common dolphin was found stranded on the French Atlantic coast. At necropsy, an intracranial grey- to tan-coloured mass (7 × 5 × 4cm) was found at the right cerebellopontine angle, compressing the right cerebellar hemisphere, the brainstem and the occipital lobe of the right cerebral hemisphere. Microscopically, the tumour was composed of small lobules of polygonal to elongated neoplastic cells with multifocal areas of stellate and vacuolated cells. Neoplastic cells strongly expressed vimentin, S-100 protein and neuron-specific enolase. They were rarely positive for cytokeratin. Ultrastructurally, the neoplastic cells displayed all the diagnostic features of meningiomas and in some areas showed long cytoplasmic processes delimiting extracellular spaces. The immunohistochemical and ultrastructural features were consistent with the histopathological diagnosis of a microcystic meningioma. This is the first report of a meningioma in dolphins or in any other cetacean species. [Copyright &y& Elsevier]

Abstract: Sixty-five fatty acids were quantified in the blubber of common dolphins (Delphinus delphis, D. capensis) incidentally caught off the coast of southern California. Dolphins were grouped by sex, reproductive status and species, and a blubber sample was collected at a mid-lateral site located caudal to the trailing edge of the dorsal fin. Samples were divided horizontally into inner, middle and outer layers and gradients in fatty acid content (mass percent) were observed across the depth of the blubber. Levels of monounsaturated fatty acids were greatest in the outer layer, whereas levels of saturated and polyunsaturated fatty acids were greatest in the inner layer. Degree of stratification was greatest in sexually mature dolphins. Blubber of sexually immature, but physically mature, male dolphins was also highly stratified, suggesting that this difference may be attributed to differences in diet. Classification and regression tree analysis resulted in the fewest misclassifications when dolphins were grouped by species, possibly indicating that these closely related animals forage on different prey species. Dietary-derived fatty acids were typically selected as splitting criteria in classification and regression tree analyses, suggesting that the observed differences in fatty acid composition between the various groups of dolphins may be attributed to differences in diet. [Copyright &y& Elsevier]

Abstract: The effect of age, sex, nutritive condition and organochlorine concentration on blubber retinoid concentrations was examined in 74 common dolphins incidentally caught off northwestern Spain. Age and blubber lipid content were strong determinants of the retinoid concentrations in males, while these variables did not account for the variation found in females. Retinoids were positively correlated with organochlorines in males and negatively in females. However, pollution levels were moderate and likely to be below threshold levels above that a toxicological response is to be expected. Thus, a cause–effect relationship between organochlorine and retinoid concentrations could not be properly established, and the observed correlation may be the result of an independent association of the two variables with age. Further research on the influence of the best predictor variables on retinoid dynamics is required to implement the use of retinoids as biomarkers of pollutant exposure in cetaceans. [Copyright &y& Elsevier]

We determined retinoid concentrations in various body positions of the blubber of 25 common dolphins (Delphinus delphis) to study topographical variation in concentrations. Specimens were obtained from incidental catches and were apparently healthy. We found concentrations to be high and therefore conclude that blubber represents a significant contribution to total retinoid body load. Consequently, blubber is proposed as a tissue of choice for monitoring retinoid status in this species. Anterior-ventral blubber had the highest vitamin A concentration and posterior-dorsal the lowest. Therefore, when assessing retinoid status, topographical variation should be taken into account to ensure consistent sampling. This pattern appeared to be explained by a parallel variation in lipid content. Thus, the dynamics and body distribution of retinoids appear to be basically governed by the lipophilicity of the molecules. The highest lipid richness found in the anterior-ventral region might indicate that this region is comparatively more important for insulation and lipid storage than the dorsal posterior region. Retinoid levels did not appear to vary according to sex, but they did vary with lipid content. This should be taken into account when designing sampling protocols; for monitoring purposes, biopsies from healthy, free-ranging individuals should be preferred to samples from stranded animals. [Copyright &y& Elsevier]

We monitored the effects of a ‘Swim-with-Dolphin’ (SWD) programme on the behaviour of three female common dolphins. They were studied from January 1999 to July 1999 at Marineland, Napier, New Zealand. Before, during and after SWD sessions we recorded: (1) the use of a refuge area, (2) the frequencies and location of surfacing and (3) the behaviour changes of the dolphins. Refuge use increased significantly during SWD sessions and within 15 min after the sessions ended returned to pre-SWD levels. During SWD sessions the dolphins surfaced more often and the percentage of surfacings in the refuge area increased. SWD sessions had little effect on the general behaviour of the dolphins. There was a slight increase in Touch and Other behaviours but contrary to expectation there was a decrease in Aggressive, Submissive, Abrupt and Play behaviour during SWD sessions. The three dolphins had similar reactions to swimmers. The SWD sessions did not appear to have a detrimental effect on the dolphins. [Copyright &y& Elsevier]

From the aerial parts of four Delphinium species 11 known and 3 new norditerpenoid alkaloids have been isolated: from D. dissectum Huth: delavaine A/B, deoxylycoctonine, methyllycaconitine; new: 10-hydroxymethyllycaconitine; from D. excelsum Reichenb.: delcaroline, delectinine, delterine, methyllycaconitine; new: 10-hydroxymethyllycaconitine, 18-O-methyldelterine and 10-hydroxynudicaulidine; from D. grandiflorum L.: delcosine, deltatsine, grandiflorine, methyllycaconitine; from D. triste Fisch.: delcosine, macrocentridine, 14-dehydrodelcosine. The structures of the new alkaloids were established on the basis of MS, 1H, 13C, DEPT, homonuclear COSY, HMQC and HMBC NMR spectroscopic techniques. [Copyright &y& Elsevier]

Human noise can be harmful to sound-centric marine mammals. Significant research has focused on characterizing behavioral responses of protected cetacean species to navy mid-frequency active sonar (MFAS). Controlled exposure experiments (CEE) using animal-borne tags have proved valuable, but smaller dolphins are not amenable to tagging and groups of interacting individuals are more relevant behavioral units for these social species. To fill key data gaps on group responses of social delphinids that are exposed to navy MFAS in large numbers, we describe novel approaches for the coordinated collection and integrated analysis of multiple remotely-sensed datasets during CEEs. This involves real-time coordination of a sonar source, shore-based group tracking, aerial photogrammetry to measure fine-scale movements and passive acoustics to quantify vocal activity. Using an example CEE involving long-beaked common dolphins (Delphinus delphis bairdii), we demonstrate how resultant quantitative metrics can be used to estimate behavioral changes and noise exposure-response relationships. • Mid-frequency navy sonar can be harmful to sound-centric marine mammals. • Exposure experiments with tags can measure behavioral responses of larger cetaceans. • Abundant dolphins are too small to tag and likely respond as social groups. • We collect remotely-sensed data during experiments to quantify dolphin group responses. • Models estimate behavioral state changes and exposure-response relationships. [ABSTRACT FROM AUTHOR]

Blubber of free-ranging common dolphins (Delphinus delphis) from thenorthwestern coast of Spain (Atlantic), sampled in 1984 and 1996, and of common dolphins entangled in fishing nets in the southwestern Mediterranean, sampled during 1992/1994, was analysed for organochlorine pollutants. In the Atlantic, concentration of all pollutants was significantly higher in males than in females. The overall tPCB/tDDT ratio in this area was 3.35, which indicates a predominance of industrial inputs over those associated with agriculture. Individuals sampledin 1996 showed significantly lower DDT concentrations but a higher ppDDE/tDDT ratio than those sampled in 1984, which reflects the aging of the environmental load. In the same period, tPCB concentration remained constant and, as a consequence, the tPCB/tDDT ratio more than doubled. In the Mediterranean, the reduced sample size of adult individuals precluded proper statistical investigation of sex-related variation. The overall tPCB/tDDT ratio was 1.12, suggesting a higher contribution of pollutants of agricultural origin. Individuals had significantly higher levels of all DDT forms and a higher ppDDE/tDDT ratio than their counterparts from the Atlantic, but similar PCB concentrations. However, the relative frequency of the different congeners in relation to the total PCB load was different in the two areas. This indicates that the two populations do not mix, at least in the short- ormedium-term. Organochlorine levels in both areas are at the mid to low end of the range of concentrations detected in other common dolphin populations and in that of other Delphinidae species from the same region. Although the impact of the organochlorine concentrations on the common dolphin populations surveyed cannot be assessed, it is considered unlikely that they have played a significant role in the decline that the species has suffered in recent decades in the western Mediterranean. [ABSTRACT FROM AUTHOR]