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ABSTRACT The acoustic ecology of a previously unexamined dolphin population in the Mediterranean was assessed by investigating how sound emissions and acoustic features are influenced by concurrent conditions. Whistles and click‐trains emission rates were compared among different environmental, social and behavioural conditions. Structural variability of 3928 good/high‐quality vocalizations was analysed in relation to contexts through a two‐stage approach. First, two multivariate MANOVA‐models were fitted considering the entire set of acoustic parameters extracted from whistles and click trains, to investigate the effect of concomitant factors on the overall acoustic structure of each vocalization. Subsequently, GLMM models were applied to each acoustic feature individually to explore its response to different contextual factors. Emission rates increased significantly with calves and in larger groups, with also a positive effect of socialization on whistles and of muddy/sandy seabed and depth on impulsive sounds. The multivariate approach showed that all contextual factors influenced sounds’ structure, with whistles being strongly affected by behaviour and calves’ presence. The GLMM models highlighted that each acoustic parameter varied differently in response to specific factors, with (1) increasing trends in whistles’ duration and inflection points during interaction with fishery and decreasing ones during socializing, and (2) decreasing inter‐click‐intervals and increasing click‐repetition‐rates in larger groups and during interactions with fishery. These results provide new findings on the acoustic plasticity of bottlenose dolphins and a more comprehensive view of the magnitude of the social, environmental and behavioural influence, highlighting how the complexity of the species’ acoustic repertoire has yet to be unravelled at the local level. [ABSTRACT FROM AUTHOR]

Simple Summary: In recent decades, environmental changes consequent to human activities have become more important factors in the conservation of wild species. Despite the Ligurian sea being part of the Pelagos Sanctuary, which has been a Specially Protected Areas of Mediterranean Importance (SPAMI) and a Marine Protected Area (MPA) since 1999, several anthropogenic threats affecting the health of cetacean populations living in this area are known to be present. In particular, interaction with fishing activities, contamination with chemical compounds such as organochlorine compounds (OCs), interaction with marine debris (especially, plastic debris), and the emergence of infectious agents, many of which are of terrestrial origin as a result of contamination of the marine environment by agricultural, animal, and human waste, are just some of the threats. In this regard, cetaceans stranded along the Ligurian coast between 2020 and 2022 were evaluated by means of a comprehensive post mortem examination and thorough specific diagnostic investigations to assess the level of anthropic pressure in this area by the Italian National Reference Center for Diagnosis of stranded Marine Mammals (C. Re. Di. Ma). Data collected by C. Re. Di. Ma over a 3-year period (2020–2022) were considered to assess anthropic pressure on cetaceans living in the Ligurian sea. Out of a total of 37 stranded cetaceans, a complete post mortem examination was performed on 23 cases. Of these, 14 were further selected considering at least one of these conditions: (i) confirmed, probable, or suspected interaction with fishing activities through the application of a standardized diagnostic framework (7/14; 50%), (ii) toxicological stress through the evaluation of OCs hazardous levels (14/14; 100%), and (iii) terrestrial pathogen-associated disease (systemic infection and/or associated lesions) (7/14; 50%). For 9 animals out of a total of 14 selected, the cause of death was classified as natural (6/14; 42,8%), anthropic (3/14; 21,4%), or not determined (5/14; 35,7%) based on gross and histological pathology and ancillary testing. These findings extend our knowledge of the anthropic pressure to which cetaceans stranded along the Ligurian coastline are subjected from a multidisciplinary point of view. [ABSTRACT FROM AUTHOR]

Simple Summary: In this work, we documented the presence of two neurotrophins NGF (Nerve Growth Factor) and BDNF (Brain-Derived Neurotrophic Factor) in the pancreas of two species of marine mammals, Tursiops truncatus (common bottlenose dolphin) and Otaria flavescens (South American sea lion). Pancreas samples were provided by the Mediterranean Marine Mammal Tissue Bank of the Department of Comparative Biomedicine and Food Science of the University of Padua (Italy). These two growth factors are well-known mediators for maintaining the survival of neurons but also exert a metabotrophic effect. The localization in the pancreas of bottlenose dolphins and sea lions of these neurotrophins could help to better understand how these marine animals handle metabolic challenges in their adaptation to ocean life. In this study, we have investigated the immunolocalization of NGF (Nerve Growth Factor) and BDNF (Brain-Derived Neurotrophic Factor) in the pancreas of two species of marine mammals: Tursiops truncatus (common bottlenose dolphin), belonging to the order of the Artiodactyla, and Otaria flavescens (South American sea lion), belonging to the order of the Carnivora. Our results demonstrated a significant presence of NGF and BDNF in the pancreas of both species with a wide distribution pattern observed in the exocrine and endocrine components. We identified some differences that can be attributed to the different feeding habits of the two species, which possess a different morphological organization of the digestive system. Altogether, these preliminary observations open new perspectives on the function of neurotrophins and the adaptive mechanisms of marine mammals in the aquatic environment, suggesting potential parallels between the physiology of marine and terrestrial mammals. [ABSTRACT FROM AUTHOR]

In this study, we examined the usefulness of a simpler and more feasible method for determining the optimal timing of artificial insemination and the conditions for its success in six female common bottlenose dolphins. Pregnancy was successfully achieved in five dolphins by performing intrauterine insemination, using chilled semen stored for less than 3 days or frozen semen within 24 hr of exhibiting a peak serum estradiol (E2) level of 100 pg/mL or higher or on the day with a serum E2 level of approximately 100 pg/mL, measured with a simple measuring device. We concluded that the determining the optimal timing of intrauterine insemination by measuring serum E2 levels is a simpler and more useful method compared with the conventional approach. [ABSTRACT FROM AUTHOR]

Rhodococcus equi is a terrestrial bacterium and a common pathogen in foals (Equus caballus), in which causes pneumonia. This report describes for the first time the infection caused by R. equi in a common bottlenose dolphin (Tursiops truncatus) stranded in the Calabrian coast, Italy. The post mortem examination of the animal revealed lesions in lung and colon. The animal was also positive to dolphin morbillivirus. The histological study showed lesions attributable to R. equi infection, such as pyogranulomatous bacterial pneumonia and chronic granulomatous colitis. Whole genome sequencing of the isolated strain confirmed its identification as R. equi. [ABSTRACT FROM AUTHOR]

Data collected by C. Re. Di. Ma over a 3-year period (2020–2022) were considered to assess anthropic pressure on cetaceans living in the Ligurian sea. Out of a total of 37 stranded cetaceans, a complete post mortem examination was performed on 23 cases. Of these, 14 were further selected considering at least one of these conditions: (i) confirmed, probable, or suspected interaction with fishing activities through the application of a standardized diagnostic framework (7/14; 50%), (ii) toxicological stress through the evaluation of OCs hazardous levels (14/14; 100%), and (iii) terrestrial pathogen-associated disease (systemic infection and/or associated lesions) (7/14; 50%). For 9 animals out of a total of 14 selected, the cause of death was classified as natural (6/14; 42,8%), anthropic (3/14; 21,4%), or not determined (5/14; 35,7%) based on gross and histological pathology and ancillary testing. These findings extend our knowledge of the anthropic pressure to which cetaceans stranded along the Ligurian coastline are subjected from a multidisciplinary point of view.

Small, island-associated populations of cetaceans have evolved around numerous oceanic islands, likely due to habitat discontinuities between nearshore and offshore waters. However, little is known about the ecology and structure of cetacean populations around the Mariana Islands, a remote archipelago in the western Pacific Ocean. We present sighting, photo-identification, and genetic data collected during twelve years of surveys around these islands that reveal the existence of a small, island-associated population of bottlenose dolphins. Nearly half of the photo-identified individuals were encountered in more than one year. Both haplotypic and nuclear genetic diversity among sampled individuals was low (haplotypic diversity = 0.701, nuclear heterozygosity = 0.658), suggesting low abundance. We used mark-recapture analysis of photo-identification data to estimate yearly abundance in the southern portion of the population's range from 2011 to 2018. Each abundance estimate was less than 54 individuals, with each upper 95% confidence interval below 100. Additional survey effort is necessary to generate a full population abundance estimate. We found extensive introgression of Fraser's dolphin DNA into both the mitochondrial and nuclear genomes of the population, suggesting at least two hybridization events more than two generations in the past. The Mariana Islands are used extensively by the U.S. military for land and sea training operations. Thus, this unique bottlenose dolphin population likely faces high exposure to multiple threats. [ABSTRACT FROM AUTHOR]

Small, island-associated populations of cetaceans have evolved around numerous oceanic islands, likely due to habitat discontinuities between nearshore and offshore waters. However, little is known about the ecology and structure of cetacean populations around the Mariana Islands, a remote archipelago in the western Pacific Ocean. We present sighting, photo-identification, and genetic data collected during twelve years of surveys around these islands that reveal the existence of a small, island-associated population of bottlenose dolphins. Nearly half of the photo-identified individuals were encountered in more than one year. Both haplotypic and nuclear genetic diversity among sampled individuals was low (haplotypic diversity = 0.701, nuclear heterozygosity = 0.658), suggesting low abundance. We used mark-recapture analysis of photo-identification data to estimate yearly abundance in the southern portion of the population's range from 2011 to 2018. Each abundance estimate was less than 54 individuals, with each upper 95% confidence interval below 100. Additional survey effort is necessary to generate a full population abundance estimate. We found extensive introgression of Fraser's dolphin DNA into both the mitochondrial and nuclear genomes of the population, suggesting at least two hybridization events more than two generations in the past. The Mariana Islands are used extensively by the U.S. military for land and sea training operations. Thus, this unique bottlenose dolphin population likely faces high exposure to multiple threats. [ABSTRACT FROM AUTHOR]

In this study, we have investigated the immunolocalization of NGF (Nerve Growth Factor) and BDNF (Brain-Derived Neurotrophic Factor) in the pancreas of two species of marine mammals: Tursiops truncatus (common bottlenose dolphin), belonging to the order of the Artiodactyla, and Otaria flavescens (South American sea lion), belonging to the order of the Carnivora. Our results demonstrated a significant presence of NGF and BDNF in the pancreas of both species with a wide distribution pattern observed in the exocrine and endocrine components. We identified some differences that can be attributed to the different feeding habits of the two species, which possess a different morphological organization of the digestive system. Altogether, these preliminary observations open new perspectives on the function of neurotrophins and the adaptive mechanisms of marine mammals in the aquatic environment, suggesting potential parallels between the physiology of marine and terrestrial mammals.

Small, island-associated populations of cetaceans have evolved around numerous oceanic islands, likely due to habitat discontinuities between nearshore and offshore waters. However, little is known about the ecology and structure of cetacean populations around the Mariana Islands, a remote archipelago in the western Pacific Ocean. We present sighting, photo-identification, and genetic data collected during twelve years of surveys around these islands that reveal the existence of a small, island-associated population of bottlenose dolphins. Nearly half of the photo-identified individuals were encountered in more than one year. Both haplotypic and nuclear genetic diversity among sampled individuals was low (haplotypic diversity = 0.701, nuclear heterozygosity = 0.658), suggesting low abundance. We used mark-recapture analysis of photo-identification data to estimate yearly abundance in the southern portion of the population’s range from 2011 to 2018. Each abundance estimate was less than 54 individuals, with each upper 95% confidence interval below 100. Additional survey effort is necessary to generate a full population abundance estimate. We found extensive introgression of Fraser’s dolphin DNA into both the mitochondrial and nuclear genomes of the population, suggesting at least two hybridization events more than two generations in the past. The Mariana Islands are used extensively by the U.S. military for land and sea training operations. Thus, this unique bottlenose dolphin population likely faces high exposure to multiple threats.

As the first line of defense, the integumentary system is critical in comprehensively evaluating dolphin morbidity during stranding response. Most published studies on skin lesions in bottlenose dolphins (Tursiops truncatus) lack standardized gross descriptions and methodologies for evaluating lesions. The primary objective of this study was to evaluate the effectiveness of an assessment matrix designed to consistently describe skin lesions based on a set of standardized gross description characteristics. The matrix was implemented by reviewing necropsy reports, histopathology reports, and photographs collected from bottlenose dolphins stranded in Southwest Florida from 2015 through 2019. Of the 32 dolphins that met the inclusion criteria, 19 presented with skin lesions and five reviewers described each of the 46 lesions according to a novel, standardized assessment matrix. The most common descriptor selected, in each of the respective matrix categories, were, by anatomic location, head; distribution, multifocal to coalescing; quantity, moderate (10-30); size, <2 cm; shape, punctate; margin, rounded; color modifier, hyperpigmentation; texture, smooth; and texture modifier, flat. These prevalent descriptors coincided with the frequent occurrence of histologically described hydropic degeneration (n=7, 15.2%) and were confirmed poxviral lesions in 6.52% (n=3). Identifying lesion patterns using standardized descriptors capitalizes on the unique pathogen tissue tropism and the implementation of certain disease mechanisms in the integumentary system. Therefore, it can facilitate differential disease diagnoses and guide ancillary diagnostics testing. The use of standardized descriptors will aid in etiologic identification and monitoring of skin lesions and associated diseases, advancing our understanding of dolphin morbidity and mortality. [ABSTRACT FROM AUTHOR]

As the first line of defense, the integumentary system is critical in comprehensively evaluating dolphin morbidity during stranding response. Most published studies on skin lesions in bottlenose dolphins (Tursiops truncatus) lack standardized gross descriptions and methodologies for evaluating lesions. The primary objective of this study was to evaluate the effectiveness of an assessment matrix designed to consistently describe skin lesions based on a set of standardized gross description characteristics. The matrix was implemented by reviewing necropsy reports, histopathology reports, and photographs collected from bottlenose dolphins stranded in Southwest Florida from 2015 through 2019. Of the 32 dolphins that met the inclusion criteria, 19 presented with skin lesions and five reviewers described each of the 46 lesions according to a novel, standardized assessment matrix. The most common descriptor selected, in each of the respective matrix categories, were, by anatomic location, head; distribution, multifocal to coalescing; quantity, moderate (10–30); size,

Due to anthropogenic pressures, estuarine systems are among the most broadly impacted areas for marine top predator species. Given this, it is crucial to study the interaction between the vulnerable marine species that inhabit these regions with environmental and anthropogenic variables. This study aims to determine whether nutrient pollution is related to the presence of bottlenose dolphins in a coastal environment. Using a multi-year dataset and GAMs, we studied the relationship between marine pollutants and the presence of bottlenose dolphins in this highly impacted coastal marine environment. We observed that urban fertilizers were linked to the spatial distribution of bottlenose dolphins. There was a higher presence of bottlenose dolphins in areas with high levels of phosphoric acid. In contrast, at higher concentrations of nitrate, the presence of bottlenose dolphins decreased. [ABSTRACT FROM AUTHOR]

Affiliative behavior in social animals may have several functions such as maintaining social bonds, reducing tensions, or restoring relationships. Common bottlenose dolphins (Tursiops truncatus) engage in several affiliative behaviors, including parallel swimming, contact swimming, and flipper rubbing. Dolphins affiliate with former opponents after aggression, suggesting that this is a function of tension reduction. This study investigated how affiliative behaviors occur after aggression. Parallel swimming occurred more frequently than expected after aggression, while contact swimming and flipper rubbing occurred less frequently than expected. Parallel swimming and contact swimming occurred immediately after aggression; in contrast, flipper rubbing tended to occur more than one minute after aggression. These results suggest that common bottlenose dolphins engage in parallel swimming and contact swimming when social tension increases. The function may differ among these affiliative behaviors, and dolphins may engage in specific affiliations after aggression. [ABSTRACT FROM AUTHOR]

Between 2019 and 2021, 21 bottlenose dolphins were found stranded dead along the Ligurian Pelagos Sanctuary coast (Italy). For 11 animals, out of a total of 14 recovered, the cause of death was classified as natural, anthropic, or not determined based on gross and histological pathology and ancillary testing. Hexachlorobenzene (HCB), dichlorodiphenyltrichloroethanes (DDTs), and polychlorinated biphenyls (PCBs) were examined in their blubber, and results were discussed according to their toxicological properties. All specimens showed the following trend: PCBs > DDTs >> HCB, and the levels of cancerogenic, mutagenic, and teratogenic organochlorine compounds (T-OCs) were >50% of total OCs. Immunosuppressant organochlorine compound (IS-OC) levels in 10 out of 11 animals were above 50% of the total OCs. PCB levels always exceeded the threshold of 17 mg/kg lipid weight for PCB-induced adverse health effects. The results suggest that bottlenose dolphins living in the Pelagos Sanctuary undergo a high level of exposure to pathogens and OCs, betraying the designation of the Cetacean Sanctuary and, consequently, of a region created for their conservation. Immune dysfunction and infectious disease susceptibility appear to be highly connected with high levels of OC xenobiotics. These data are useful to understand health and mortality trends in cetacean populations, as well as for developing policies for cetacean conservation and management in this important protected area of the Mediterranean. [ABSTRACT FROM AUTHOR]

Understanding the depredation process is pivotal to the management of conflicts between wildlife and human activities. Depredation by marine mammals on fisheries occurs when animals 'steal' fish from the fishing gear, causing catch loss and damage to gear and catches. The common bottlenose dolphin is a vulnerable species and is the main depredator of coastal static net fisheries in the Mediterranean Sea.The nature and extent of the phenomenon is still poorly understood since evidence is often incomplete or inconsistent mostly due to the different methods used to measure depredation.Here, passive acoustic monitoring devices were used to estimate the consistency between dolphin acoustic detection in proximity to the net and direct dolphin observations and catch measurements at different sites in Sardinia (north‐western Mediterranean Sea). Further, some factors influencing depredation (fishing duration and fishing net length) and changes in catch amount and composition were evaluated.The frequency of dolphin detection based on direct dolphin observations was significantly lower than that based on acoustic monitoring; the latter was related to the amount of catch. Thus, the measurement of catch was more realistically related to depredation than direct dolphin observations. Further, dolphin depredation was related to the duration of the fishing operation.The measure of depredation and catch loss provided here can be used to realistically estimate the damage suffered by fishers and provide preliminary insights to guide the development of an approach for sustainable coexistence between dolphins and fisheries. [ABSTRACT FROM AUTHOR]

This study aims to provide information on the site fidelity, residency patterns and the social structures of bottlenose dolphins occurring in the Gulf of Taranto in order to supply effective indications supporting the future management and conservation measures of the species. Out of 141 photo-identified individuals about 76% were re-sighted from 2 up to 31 times. The site fidelity analysis of photo-identified individuals highlighted the occurrence of 20 seasonal residents, 62 visitors and 59 transient individuals that were included in a local population in which emigration and reimmigration events occurred, as suggested by the residency-pattern analysis. The association pattern, performed using SOCPROG 2.9, highlighted a relatively low mean value of the overall half-weight association index (0.11 ± 0.04). However, the test for the null hypothesis of 'random association' was rejected and the temporal analysis made with SLAR suggested the presence of both extremely fluid and stable associations between individuals, describing a fission fusion social structure with a certain degree of social organization. Moreover, the cluster and social network analysis showed two geographically and socially segregated units. Thus, more investigations are needed and the development of a specific conservation plan for bottlenose dolphins in the whole area is required. [ABSTRACT FROM AUTHOR]

Common bottlenose dolphins (Tursiops truncatus) in estuarine systems are often subjected to natural and anthropogenic risks, which may impact their health and behaviors. Effective management for this species should incorporate continual, updated information on behavioral patterns of the individuals within populations. Currently, the Jacksonville Estuarine System stock assessment report, which includes dolphins in the St. Johns River (SJR) in northeast Florida, is based on data from the 1990s. Since then, dolphins' use of the SJR has shifted, and the community has been impacted by two unusual mortality events (UME). This study analyzed site fidelity, space use and overlap, and social mixing with respect to the epizootic 2013–2015 UME, whose infectious agent was cetacean morbillivirus (CeMV). Examination of residency status determined that most dolphins sighted in the river were year-round residents ( x ¯ =45%, SD = 3.20). Space use and overlap of core areas occurred among residency categories but varied between cold and warm seasons and across time periods. There were key, highly connected individuals in the social network, which may have influenced disease transmission during the UME. Individuals infected by CeMV that stranded during the UME shared overlapping core areas with each other and with individuals from different residency categories. Altogether, this information on site fidelity, spatial overlap, and social mixing will help improve management plans for SJR dolphins, lead to better response efforts to future unusual mortality events, and increase the understanding of disease transmission in social species. [ABSTRACT FROM AUTHOR]

Human interaction (HI) is known to disturb cetaceans. Regional wildlife interaction guidelines exist to mitigate harmful impacts, but the efficacy of these guidelines is understudied. HI with bottlenose dolphins was documented opportunistically in Tampa Bay from 2009 to 2018. Vessel compliance to the guidelines was low with 80% of encounters being non-compliant. HI was observed in 33% of days in the field and in 22% of dolphin sightings. Poisson regression identified vessel type as a strong key factor related to compliance, with faster more maneuverable boats more likely to be non-compliant. Additionally, HI involved recreational vessels much more frequently than tourism vessels. These results likely underestimate true HI rates because of sampling limitations. Researchers should opportunistically document HI including vessel characteristics and vessel behavior to help quantify compliance. When developing HI guidelines and their promotion, managers should carefully consider which stakeholders engage in HI to best direct resources to that audience. [ABSTRACT FROM AUTHOR]

Assessing the distribution of marine apex–predators is pivotal to understanding community interactions and defining management goals. However, several challenges arise in both estimates and predictions considering the distinctive and mutable biological/ecological requirements of these species and the influence of human activities. Thus, efforts to study apex–predators’ spatial distribution patterns must deal with inherent uncertainty. Relying on different data sources (research programs and social media reports), physiographic and environmental covariates (depth, slope, surface temperature and chlorophyll–a), and specific source–related detection functions, this study selected a Spatial Log–Gaussian Cox Process to model the distribution patterns of an opportunistic apex–predator, the common bottlenose dolphin (Tursiops truncatus), over 14 years (2008−2021) in the Mediterranean Sea (Italy) using a total of 955 encounters. Both depth and slope showed a significant (95% significance) reduction effect in the encounters when deeper and steeper, respectively. Temperature (parabolic) shows a positive effect (90% significance), while chlorophyll–a values did not seem to have a significant effect on encounter intensities within each season. The estimated posterior mean and the coefficient of variation surfaces for the intensity by season showed higher intensity in summer near the Tiber River estuary than other regions. Almost homogeneous predictions were observed in winter, with marginal greater intensities where lower temperatures and higher chlorophyll–a concentration were observed. The relatively low variance was predicted in the more coastal parts of the study area within each season, while higher uncertainty was instead revealed in the southernmost offshore area. This study highlighted the persistent presence of the common bottlenose dolphin in the investigated area both winter and summer, with a coherent distribution within each season, and rare transient occurrences in deeper waters (where uncertainty increases). Thanks to its versatile characteristics, the species seems to well adapt to different seasonal conditions and maintain its distributional range.

The Cetacean Migration Corridor is an important marine protected area for cetacean species in the Western Mediterranean, and part of its waters constitute the main fishing grounds for the Valencia region (East Spain) fishing fleet. Here we aim to assess the interactions between all active fisheries operating in the waters of the Valencia region and the cetacean species inhabiting this area. A total of 282 face-to-face interviews (51.37% of the total fleet) to fishers were held on 20 ports at the study area to gather information about cetacean by-catch and all types of interactions between fisheries and cetaceans. The interviewed bottom trawlers (n = 148 boats) reported a monthly by-catch rate (C) of 0.01 dolphins per vessel. Bottom trawling vessels operating at neritic zones only reported by-catch of common bottlenose dolphin (C = 0.009), while those fishing at oceanic zones by-caught striped dolphin (C = 0.006) and common bottlenose dolphin (C = 0.003). The interviewed artisanal fishers (n = 114 boats), the second most important fishery in the study area, only reported one dolphin by-catch event, but 90 of these boats communicated continued negative interactions with the common bottlenose dolphin, causing gear damage and catch take. The interviewed vessels gave an estimation of their annual economic loss produced by this interaction (mean ± SD: 2,998.10 ± 2095.02 € per boat). Other fisheries operating in the Valencia region were purse-seiners (n = 15 boats) and pelagic longlines, a fishery that has almost disappeared in the study area (n = 5 boats). The first one had the highest estimated dolphin by-catch rate (C= 0.04) and mainly interacted with common bottlenose dolphin, but also with striped dolphin. The information gathered from interviews was complimented with long-term stranding data (1990–2020). Despite the fact that only 7.80% of all recorded stranded cetaceans showed fisheries interaction signs, 26.72% of the common bottlenose dolphins recorded showed evidence of this interaction, thus confirming that it is the cetacean species most affected by fisheries in the area. Records of stranded striped dolphin (6.45%) also showed evidence of fisheries interaction. Based on both dolphin by-catch and gear damage, management plans are needed in the area to ensure cetacean conservation and also fisheries sustainability in waters inside and around marine protected areas at the Spain’s Mediterranean.

Between 2019 and 2021, 21 bottlenose dolphins were found stranded dead along the Ligurian Pelagos Sanctuary coast (Italy). For 11 animals, out of a total of 14 recovered, the cause of death was classified as natural, anthropic, or not determined based on gross and histological pathology and ancillary testing. Hexachlorobenzene (HCB), dichlorodiphenyltrichloroethanes (DDTs), and polychlorinated biphenyls (PCBs) were examined in their blubber, and results were discussed according to their toxicological properties. All specimens showed the following trend: PCBs > DDTs >> HCB, and the levels of cancerogenic, mutagenic, and teratogenic organochlorine compounds (T-OCs) were >50% of total OCs. Immunosuppressant organochlorine compound (IS-OC) levels in 10 out of 11 animals were above 50% of the total OCs. PCB levels always exceeded the threshold of 17 mg/kg lipid weight for PCB-induced adverse health effects. The results suggest that bottlenose dolphins living in the Pelagos Sanctuary undergo a high level of exposure to pathogens and OCs, betraying the designation of the Cetacean Sanctuary and, consequently, of a region created for their conservation. Immune dysfunction and infectious disease susceptibility appear to be highly connected with high levels of OC xenobiotics. These data are useful to understand health and mortality trends in cetacean populations, as well as for developing policies for cetacean conservation and management in this important protected area of the Mediterranean.

Depredation by cetaceans on fisheries is a major issue globally, both in terms of conservation and fisheries economics. The present study conducted in Cyprus, Eastern Mediterranean Sea, aimed to understand the extent, level, and type of cetacean depredation on the albacore tuna pelagic longline fishery, and in particular to quantify and evaluate the economic consequences of depredation and identify potential dolphin-longline conflict areas and mitigation practices for management. The data were obtained from fisher’s logbooks, interviews and onboard observations between June and August 2018. A novel and simple approach was applied to estimate the depredation rate and economic loss by using simple calculations including the number and weight of depredated fish, landings and fishing effort. The results revealed that there is an estimated economic loss per fishing trip of 313.07± 486.19 EUR and an estimated annual economic loss for the entire fleet of 259,272 EUR from depredation caused by cetaceans. The study also estimated that 16,639 albacore tunas were depredated in 2018 and the depredation rate ranged between 0% to 100% with a mean depredation rate of 17% per fishing trip. Depredation by the common bottlenose dolphin and striped dolphin was reported in more than 50% of their fishing trips. Other species that were found to be involved in depredation were the neon flying squid, the shortfin mako shark and the Risso’s dolphin. This is the first official record worldwide of depredation from the common bottlenose dolphin, the striped dolphin and the neon flying squid on the pelagic longline albacore tuna fishery. A total bycatch of 62 individuals of common bottlenose dolphins and one individual of stripped dolphin were reported in interviews as a result of depredation on bait and catch. The study also identified depredation hotspots and possible depredation mitigation measures. Such information could support the development of management action plans and measures to minimise interactions between cetaceans and pelagic longlines.

Simple Summary: In the acoustic repertoire of common bottlenose dolphins (Tursiops truncatus), Gulps, Grunts, and Squeaks are part of a group of vocalizations called "bray-call" for which little has been previously studied. The name comes from the alternating structure characteristic of a donkey's bray. Sounds can be of different types at low frequencies and audible to the human hear—of short duration, produced in sequence. The function of these sequences is not clarified yet, and it is not known if they are part of the vocal "catalog" of all the different populations of common bottlenose dolphin at global level. What is certain is that bray-calls are present in two geographical areas of the Mediterranean and that the "Capitoline" individuals (Rome, Tyrrhenian Sea, Italy) emit them with greater frequency and variety than the Sicilian ones (Mazara del Vallo, Sicilian Channel, Italy). A number of 13 different types of sequences have been identified, and only 2 of them are shared between the study areas. For the first time this study identifies variants of the main bray-call elements, highlights the structural complexity of these vocalizations, and suggests addressing future research on the context of emissions and the possible function(s) of such acoustic arrangements. Acoustic sequences are commonly observed in many animal taxa. The vast vocal repertoire of common bottlenose dolphins (Tursiops truncatus) also includes sequences of multi-unit rhythmic signals called bray-call which are still poorly documented, both functionally and geographically. This study aimed to (1) describe, classify, and characterize series of bray-call recorded in two sites of the Mediterranean basin (Rome—Tyrrhenian Sea and Mazara del Vallo—Strait of Sicily) and (2) investigate for the existence of possible geographic differences. The acoustic analysis identified 13 different sequence types, only two detected in both study areas. The Sørensen–Dice index revealed a low degree of similarity between the sequence repertoire of the two common bottlenose dolphin sub-populations, with the Tyrrhenian being more diversified and complex than the Sicilian one. The acoustic parameters also showed variability between the study area. Different variants of the main acoustic elements composing the bray-call sequences were detected in the Tyrrhenian Sea only. The Markov-chain model demonstrated that the transition probability between acoustic elements is not uniform, with specific combinations of elements having a higher probability of occurrence. These new findings on common bottlenose dolphin bray-call sequences highlight the structural complexity of these vocalizations and suggest addressing future research on the context of emissions and the possible function(s) of such acoustic arrangements. [ABSTRACT FROM AUTHOR]

Long-term trends in marine mammal stranding patterns can provide useful information on basic life history parameters, spatiotemporal distribution, natural and human-related mortality events, and potentially vulnerable populations. Between 1980 and 2019, a total of 5,303 marine mammal strandings were recorded in Texas, USA. In total, 23 species were identified, including 19 odontocete species (toothed whales and dolphins), 3 mysticete species (baleen whales), and 1 sirenian species (manatee). Common bottlenose dolphins (Tursiops truncatus) stranded most frequently (94%). Common bottlenose dolphin stranding events increased significantly from late winter to mid-spring, with an early onset in southern Texas, and had a consistent peak in March involving primarily calves and adults. Spatial analyses using kernel density estimation within seven coastal Texas stock management areas, delineated by the National Marine Fisheries Service, identified potential hotspots for common bottlenose dolphin strandings near higher human population density and deep water channels. Peak stranding density estimates in each stock area ranged from 0.32-4.6km-2 for presumed bay, sound and estuarine (BSE) stocks and 0.82km-2 for the presumed Western Gulf of Mexico Coastal Stock. Common bottlenose dolphin stranding events were positively male-biased, including a significantly higher number of stranded male fetuses and neonates, and sexual dimorphism was observed in total body length of adults, with significantly greater length in males. For all records where human interaction (HI) could be determined as 'yes' or 'no', 30% were positive for HI, with the highest proportion of HI events occurring in the central and southernmost BSE stock areas; however, it is unknown how many HI cases contributed to mortality. This longitudinal study provides a comprehensive overview of marine mammal stranding patterns in Texas and serves as a useful resource for stranding investigators and Gulf-wide natural resource managers. [ABSTRACT FROM AUTHOR]

The exchange of prosocial behaviors such as grooming may be affected by several factors, including the social structure and social relationships of the individuals. However, studies on the reciprocity of prosocial affiliative behaviors in non-primate animals are limited. Flipper rubbing is considered a prosocial affiliative behavior in dolphins. We investigated the reciprocity of flipper rubbing and tested the following hypotheses in common bottlenose dolphins: trade for tolerance, trade for a reduction in renewed aggressions, the value of flipper rubbing partner, and reciprocity over short and long time frames. There was no correlation between the frequency of flipper rubbing and aggression. Age difference did not affect reciprocal flipper rubbing. Flipper rubbing by former opponents did not increase after aggression. Dolphins did not provide flipper rubbing immediately after receiving flipper rubbing. The exchange of flipper rubbing was more reciprocal over long time frames than over short time frames. Dolphins preferentially rubbed the individuals who rubbed them the most. Pairs who performed flipper rubbing more frequently partook in more reciprocal flipper rubbing than pairs who performed flipper rubbing less frequently. Results suggest that bottlenose dolphins maintain flipper rubbing reciprocity over the long-term via partner choice based on an emotional bookkeeping system. [ABSTRACT FROM AUTHOR]

In this study, we examined the usefulness of a simpler and more feasible method for determining the optimal timing of artificial insemination and the conditions for its success in six female common bottlenose dolphins. Pregnancy was successfully achieved in five dolphins by performing intrauterine insemination, using chilled semen stored for less than 3 days or frozen semen within 24 hr of exhibiting a peak serum estradiol (E 2 ) level of 100 pg/mL or higher or on the day with a serum E 2 level of approximately 100 pg/mL, measured with a simple measuring device. We concluded that the determining the optimal timing of intrauterine insemination by measuring serum E 2 levels is a simpler and more useful method compared with the conventional approach.

Despite an increasing appreciation in the importance of host–microbe interactions in ecological and evolutionary processes, information on the gut microbial communities of some marine mammals is still lacking. Moreover, whether diet, environment, or host phylogeny has the greatest impact on microbial community structure is still unknown. To fill part of this knowledge gap, we exploited a natural experiment provided by an aquarium with belugas (Delphinapterus leucas) affiliated with family Monodontidae, Pacific white-sided dolphins (Lagenorhynchus obliquidens) and common bottlenose dolphin (Tursiops truncatus) affiliated with family Delphinidae, and Cape fur seals (Arctocephalus pusillus pusillus) affiliated with family Otariidae. Results show significant differences in microbial community composition of whales, dolphins, and fur seals and indicate that host phylogeny (family level) plays the most important role in shaping the microbial communities, rather than food and environment. In general, the gut microbial communities of dolphins had significantly lower diversity compared to that of whales and fur seals. Overall, the gut microbial communities were mainly composed of Firmicutes and Gammaproteobacteria, together with some from Bacteroidetes, Fusobacteria, and Epsilonbacteraeota. However, specific bacterial lineages were differentially distributed among the marine mammal groups. For instance, Lachnospiraceae , Ruminococcaceae , and Peptostreptococcaceae were the dominant bacterial lineages in the gut of belugas, while for Cape fur seals, Moraxellaceae and Bacteroidaceae were the main bacterial lineages. Moreover, gut microbial communities in both Pacific white-sided dolphins and common bottlenose dolphins were dominated by a number of pathogenic bacteria, including Clostridium perfringens , Vibrio fluvialis , and Morganella morganii , reflecting the poor health condition of these animals. Although there is a growing recognition of the role microorganisms play in the gut of marine mammals, current knowledge about these microbial communities is still severely lacking. Large-scale research studies should be undertaken to reveal the roles played by the gut microbiota of different marine mammal species. [ABSTRACT FROM AUTHOR]

Despite an increasing appreciation in the importance of host–microbe interactions in ecological and evolutionary processes, information on the gut microbial communities of some marine mammals is still lacking. Moreover, whether diet, environment, or host phylogeny has the greatest impact on microbial community structure is still unknown. To fill part of this knowledge gap, we exploited a natural experiment provided by an aquarium with belugas (Delphinapterus leucas) affiliated with family Monodontidae, Pacific white-sided dolphins (Lagenorhynchus obliquidens) and common bottlenose dolphin (Tursiops truncatus) affiliated with family Delphinidae, and Cape fur seals (Arctocephalus pusillus pusillus) affiliated with family Otariidae. Results show significant differences in microbial community composition of whales, dolphins, and fur seals and indicate that host phylogeny (family level) plays the most important role in shaping the microbial communities, rather than food and environment. In general, the gut microbial communities of dolphins had significantly lower diversity compared to that of whales and fur seals. Overall, the gut microbial communities were mainly composed of Firmicutes and Gammaproteobacteria, together with some from Bacteroidetes, Fusobacteria, and Epsilonbacteraeota. However, specific bacterial lineages were differentially distributed among the marine mammal groups. For instance, Lachnospiraceae, Ruminococcaceae, and Peptostreptococcaceae were the dominant bacterial lineages in the gut of belugas, while for Cape fur seals, Moraxellaceae and Bacteroidaceae were the main bacterial lineages. Moreover, gut microbial communities in both Pacific white-sided dolphins and common bottlenose dolphins were dominated by a number of pathogenic bacteria, including Clostridium perfringens, Vibrio fluvialis, and Morganella morganii, reflecting the poor health condition of these animals. Although there is a growing recognition of the role microorganisms play in the gut of marine mammals, current knowledge about these microbial communities is still severely lacking. Large-scale research studies should be undertaken to reveal the roles played by the gut microbiota of different marine mammal species.

This study aims to provide information on the site fidelity, residency patterns and the social structures of bottlenose dolphins occurring in the Gulf of Taranto in order to supply effective indications supporting the future management and conservation measures of the species. Out of 141 photo-identified individuals about 76% were re-sighted from 2 up to 31 times. The site fidelity analysis of photo-identified individuals highlighted the occurrence of 20 seasonal residents, 62 visitors and 59 transient individuals that were included in a local population in which emigration and reimmigration events occurred, as suggested by the residency-pattern analysis. The association pattern, performed using SOCPROG 2.9, highlighted a relatively low mean value of the overall half-weight association index (0.11 ± 0.04). However, the test for the null hypothesis of ‘random association’ was rejected and the temporal analysis made with SLAR suggested the presence of both extremely fluid and stable associations between individuals, describing a fission fusion social structure with a certain degree of social organization. Moreover, the cluster and social network analysis showed two geographically and socially segregated units. Thus, more investigations are needed and the development of a specific conservation plan for bottlenose dolphins in the whole area is required.

Many marine mammal species exhibit complex patterns of population structure. Specifically, common bottlenose dolphin (Tursiops truncatus) populations in the southeastern United States display varying degrees of spatial overlap and residency, including some that have year-round site fidelity to localized bays, sounds, and estuaries. Evidence of resident estuarine animals along the U.S. Atlantic and Gulf of Mexico coastlines is supported through photo-identification and genetic studies, although, currently, few studies have integrated both methods. The purpose of this project was to couple long-term photo-identification data with spatial and genetic analyses to examine population structure of common bottlenose dolphins in northern Georgia. Genomic DNA was extracted from skin samples (n = 69) collected in the Northern Georgia/Southern South Carolina Estuarine System Stock, and a portion of the mitochondrial DNA control region was sequenced. To determine potential fine-scale geographic delineations within this stock, the study area was split into three regions: (1) north, (2) buffer, and (3) south. No significant genetic differentiation was found when regions were compared by only sample collection location. The sighting locations of sampled dolphins that had been seen ≥ 10 times between 2009 and 2017 (n = 45) were mapped in ArcMap, Version 10.2. In an analysis of dolphins with ≥ 10 sightings only, a significant difference in FST was found between the north vs buffer area (p = 0.0147). When dolphins with ≥ 10 sightings (n = 45) were assigned to the region where ≥ 50% of their sightings were located, a significant difference in FST was found between the north vs buffer and north vs south regions (p = 0.0018 and p = 0.0164, respectively). The addition of spatial data revealed genetic division among the three regions. Thus, the combination of photo-identification and genetic analyses used in this study may be useful in determining population structure in the future. [ABSTRACT FROM AUTHOR]

We examined bone mineral density (BMD) in the pectoral flipper of the common bottlenose dolphin, Tursiops truncatus. These data addressed the need to define a comprehensive target site for osteodensitometric assessment and to provide a descriptive bone density data set for this species. We analyzed 388 radii from 279 bottlenose dolphins using dual energy X‐ray absorptiometry (DXA), the accepted standard in human medical studies. Radii were examined for differences based on sex, age, total body length, handedness, geographical affinity, and nutritional status at death. BMD increased with age and body length (R2 = 0.58, p <.05). No statistically significant differences were observed in BMD measurements for male and female dolphins (t = −1.60, p >.05) or right and left flippers (t = −1.76, p >.05). Additionally, no statistically significant differences were observed based on geographical region (t = −0.190, p >.05) or nutritional status (F = 0.83, p >.05). These results support the use of these findings as a preliminary descriptive data set for BMD in bottlenose dolphins and detail a primary skeletal site for clinical assessment of bone density for the species. As this study relies on archived museum specimens collected from dolphins at time of death, further studies regarding bone density may be better addressed using live dolphins with known health status. [ABSTRACT FROM AUTHOR]

Acoustic sequences are commonly observed in many animal taxa. The vast vocal repertoire of common bottlenose dolphins (Tursiops truncatus) also includes sequences of multi-unit rhythmic signals called bray-call which are still poorly documented, both functionally and geographically. This study aimed to (1) describe, classify, and characterize series of bray-call recorded in two sites of the Mediterranean basin (Rome—Tyrrhenian Sea and Mazara del Vallo—Strait of Sicily) and (2) investigate for the existence of possible geographic differences. The acoustic analysis identified 13 different sequence types, only two detected in both study areas. The Sørensen–Dice index revealed a low degree of similarity between the sequence repertoire of the two common bottlenose dolphin sub-populations, with the Tyrrhenian being more diversified and complex than the Sicilian one. The acoustic parameters also showed variability between the study area. Different variants of the main acoustic elements composing the bray-call sequences were detected in the Tyrrhenian Sea only. The Markov-chain model demonstrated that the transition probability between acoustic elements is not uniform, with specific combinations of elements having a higher probability of occurrence. These new findings on common bottlenose dolphin bray-call sequences highlight the structural complexity of these vocalizations and suggest addressing future research on the context of emissions and the possible function(s) of such acoustic arrangements.

Cetacean physical maturity is defined by growth cessation and complete fusion of epiphyses to vertebral bodies indicated by invisible sutures. Many studies have shown epiphyseal fusion is highly variable among individuals. In‐depth examinations into fusion variability are lacking. We analyzed vertebrae of 37 (n = 21 female, n = 16 male) stranded common bottlenose dolphins (Tursiops truncatus) from the well‐studied Gulf of Mexico, Sarasota Bay community. For each specimen, vertebrae were examined by vertebral region for degree of fusion anteriorly and posteriorly of each centrum and categorized from unfused to fused in five degrees. An ordinal logistic regression was used to estimate degree of fusion probability for each epiphysis. The model had fixed effects for age, number of offspring, sex, sexual maturity, and a random effect for epiphysis. Results show that age/reproductive status significantly explains an individual's degree of fusion. Adult females with fewer calves had more fusion than those with more reproductive experience across multiple ages. Access to long‐term observational and sample data on the dolphins residing in the area served by Mote Marine Laboratory's Stranding Investigations Program offers a unique opportunity to examine the relationship between energetic demands of reproduction (calcium production/reproductive output) versus preconceived definitions of physical maturity (skeletal fusion) more closely. [ABSTRACT FROM AUTHOR]

In animal societies with fission‐fusion dynamics, demographic disturbances can influence the social and spatial structure of the population. Within the Indian River Lagoon (IRL), Florida, common bottlenose dolphins (Tursiops truncatus) have experienced recurrent unusual mortality events (UMEs) providing an opportunity to examine postdisturbance population and social cluster restructuring. This study investigates the impact of the potentially nonepizootic 2008 UME on the IRL dolphin population. Photo‐identification surveys conducted from August 2006 to May 2010 were stratified into pre‐ (August 2006–April 2008) and post‐UME (September 2008–May 2010) time periods. Social network and spatial (univariate kernel density) analyses were limited to individuals sighted 5+ times per period (pre‐UME = 183, post‐UME = 134), and indicated a change from 11 to ten social clusters, although individuals did not always reassociate with pre‐UME cluster associates. Despite the social and spatial disconnect between IRL proper and Mosquito Lagoon clusters, both network density and core area spatial overlap increased post‐UME allowing for increased intercluster interactions. However, intracluster associations increased as well, allowing the population to maintain multiple social clusters within a loosely connected network. This study shows the important role sociality may play in the adaptability of cetaceans to environmental and demographic changes. [ABSTRACT FROM AUTHOR]

Common bottlenose dolphins (Tursiops truncatus truncatus) (hereafter referred to as "dolphins") are distributed along the east coast of Florida in a longitudinal continuum within inland waterways and federally managed via assignment into stocks. Seven regional studies have identified local estuarine populations with resident and seasonally transient dolphins. However, study area boundaries limit understanding of distribution and movement patterns between these geographically separated regions. To reveal the bigger picture of spatiotemporal movements, a multi-organizational consortium conducted semiannual photo-identification surveys from the Florida-Georgia border to Titusville, Florida (331 km). The study area incorporated dolphins occurring in the Jacksonville Estuarine System (JES) stock in the north, the Mosquito Lagoon within the Indian River Lagoon Estuarine System (IRLES-ML) stock in the south, and the connecting 156-km inland waterway currently managed under the Western North Atlantic Northern Florida and Central Florida coastal stocks. The area was divided into segments, and simultaneous surveys were conducted from 2011 to 2016 during two primary sampling seasons within each year: five summers and five winters (primary period), with two to three surveys (secondary sessions) within each primary period separated by oneweek intervals to allow mixing of the population. A total of 6,896 dolphins, including 196 neonates, were observed, and 649 individuals were identified. Spatial autocorrelation analyses of 222 marked dolphins sighted in ≥ 5 primary surveys revealed that 78% exhibited significant regional and seasonal fidelity to one or more segments, which no single study could elucidate. Additionally, JES-North dolphins demonstrated strong regional site fidelity and were consistently sighted during both seasons, similar to studies in the 1990s, and continued to be partitioned from dolphins to the south. JES-South and IRLES-ML dolphin home ranges extended beyond previously known boundaries. Based on spatiotemporal movement patterns between the segments, recommendations are made to revise boundaries of the JES and IRLES stocks. [ABSTRACT FROM AUTHOR]

Under the US Marine Mammal Protection Act, common bottlenose dolphins along the United States Atlantic coast are managed as a series of 17 distinct stocks. To determine the status of each stock, the Potential Biological Removal (PBR) is compared with anthropogenic removals, primarily as a result of fisheries bycatch. Estimates of abundance, with associated measures of variance, are required to generate the PBR for each stock. The objectives of the current study were to estimate abundance for the Southern North Carolina Estuarine System Stock (SNCESS) of common bottlenose dolphins and to better define the southern boundary of this stock. To meet these objectives, photo-identification surveys were conducted during the summer and winter of 2014 in estuarine and nearshore coastal waters in southern North Carolina. The surveys extended 25km South of the defined southern stock boundary, along the northern South Carolina coast. One mark and one recapture survey were conducted for each season. Each survey was completed in four or five days and covered over 300km of survey tracklines. Dorsal fin images were processed and managed using FinBase, and only images of suitable quality and distinctiveness were used for estimates of abundance. A three-step decision tree was used to assign each dolphin group to either the SNCESS or an adjacent coastal stock, based on sighting location, ranging patterns derived from matches to photo-identification catalogues and statistical modelling. Only sightings classified as SNCESS were used to estimate stock abundance. Abundance estimates were calculated using three approaches: the Chapman modification to the Lincoln-Petersen method, package Rcapture in program R and program MARK 6.2. The most parsimonious approach was the Chapman LP method yielding an estimate of 272 dolphins (95% CI 189--390, CV = 0.32) in the summer of 2014. The distribution of SNCESS dolphins shifted South in the winter and several individuals were observed up to 70km southwest of the currently recognised southern boundary. The results of this study support the current definition of the SNCESS but suggest revisions to the southern boundary. The SNCESS is the smallest bottlenose dolphin stock off the East coast of the USA and is at risk of population decline as a result of fisheries-related mortality. [ABSTRACT FROM AUTHOR]

The physiological demands of pregnancy inevitably result in changes of both biochemical and hematological parameters as the fetus develops. Alterations in blood parameters have been observed to shift according to both trimester and species, to support fetal physiological needs and maternal basal requirements. Establishing normal reference ranges for each stage in gestation is important to facilitate diagnosis of underlying health concerns and prevent over-diagnosing abnormalities. Despite bottlenose dolphins (Tursiops truncatus) being one of the most highly studied cetaceans, the blood profile changes occurring as a result of pregnancy have not been previously described. A retrospective analysis was performed from blood samples obtained from 42 successful pregnancies from 20 bottlenose dolphins in a managed population over 30 years. Samples were compared to non-pregnant states and among trimesters of pregnancy. Blood profile fluctuations occurred throughout gestation, however significant alterations predominantly occurred between the 2nd and 3rd trimester. Hematological changes from the 2nd to the 3rd trimester included a decrease in lymphocytes, decrease in platelet count, and hemoconcentration with increased hematocrit and hemoglobin. Biochemical changes in the 3rd trimester included significant reductions in ALKP (alkaline phosphatase), ALT (alanine aminotransferase) and AST (aspartate aminotransferase) with significant increases observed in albumin, globulins, total protein, cholesterol, triglycerides and CO 2. It's important to note that despite significant shifts occurring between the 2nd and 3rd trimester, there was no significant change in platelets, hematocrit, hemoglobin, lymphocytes or CO 2 between non-pregnant and 3rd trimester blood samples. The normal reference ranges for each trimester established herein, will enable future identification of abnormalities occurring during pregnancy and help improve our understanding of factors potentially influencing a failed or successful pregnancy outcome. • HCT, HGB, RBC normally increase significantly during 3rd trimester. • Total WBC should remain consistent throughout all three trimesters. • Inflammatory hemogram of ALKP decreasing significantly in 3rd trimester is expected. • Total protein, albumin and globulins increase consistently throughout gestation. [ABSTRACT FROM AUTHOR]

Aims: This study was conducted to assess the presence and extent of differences in the gut microbiota of common bottlenose dolphins depending on rearing facilities. Methods and Results: Faecal samples were collected from 16 common bottlenose dolphins at three aquaria in Japan. After extracting DNA from the faeces, the V3–V4 region of bacterial 16S rRNA was amplified and sequenced using Illumina MiSeq platform. The constituent phyla of the gut microbiota were similar among aquaria; however, the most dominant phylum differed depending on the facility, and the compositions of microbiota were remarkably varied at the family level among aquaria. The alpha diversity indices tended to differ among aquaria. Some bacterial families observed in terrestrial mammalian carnivores or carnivorous fish were detected, as well as several bacterial species suspected of being pathogenic in dolphins. Conclusion: Our findings indicate that captive environmental conditions including prey and housing types may contribute to differences in the gut microbiota of the dolphins. Significance and Impact of the Study: This is the first study revealing the differences in gut microbiota of captive dolphins among facilities. Our findings will provide valuable information for improving the health management of dolphins. [ABSTRACT FROM AUTHOR]

Nesfatin-1 (Nesf-1) is an anorexigenic peptide involved in the regulation of homeostatic feeding. Nesf-1 is expressed in the central nervous system and other organs, including pancreas, where it promotes the release of insulin from β-cells. This raises the possibility that Nesf-1 dysfunction could be involved in metabolic disorders, particularly in type 2 diabetes mellitus (T2D). Recently, it has been discovered that dolphins can be a natural animal model that fully replicates human T2D, due to its prolonged glucose tolerance curve and maintenance of a state of hyperglycemia similar to human T2D during fasting. This correspondence suggests that dolphins may be a suitable model for investigating physiological and pathological metabolic disorders. Here, we have characterized Nesf-1 distribution in the pancreas of the common bottlenose dolphin (Tursiops truncatus) and measured plasmatic levels of Nesf-1 and glucose during fasting and post-prandial states. The Mediterranean Marine Mammal Tissue Bank (MMMTB) of the University of Padova provided us with pancreas samples, derived from four animals, and plasma samples, collected before and after the main meal. Interestingly, our results showed that Nesf-1-immunoreactive cells were distributed in Langerhans islets, co-localized with glucagon in α-cells. Similar to humans, dolphin plasma Nesf-1 concentration doesn’t show a statistically significant difference when comparing fasting and post-prandial states. On the other hand, blood glucose levels were significantly higher before than after the main meal. Our data provide a comparative analysis for further studies on the involvement of Nesf-1 in mammalian metabolic disorders.

The secondary adaptation of Cetacea to a fully marine lifestyle raises the question of their ability to maintain their water balance in a hyperosmotic environment. Cetacea have access to four potential sources of water: surrounding salt oceanic water, dietary free water, metabolic water and inhaled water vapour to a lesser degree. Here, we measured the 18O/16O oxygen isotope ratio of blood plasma from 13 specimens belonging to two species of Cetacea raised under human care (four killer whales Orcinus orca, nine common bottlenose dolphins Tursiops truncatus) to investigate and quantify the contribution of preformed water (dietary free water, surrounding salt oceanic water) and metabolic water to Cetacea body water using a box-modelling approach. The oxygen isotope composition of Cetacea blood plasma indicates that dietary free water and metabolic water contribute to more than 90% of the total water input in weight for cetaceans, with the remaining 10% consisting of inhaled water vapour and surrounding water accidentally ingested or absorbed through the skin. Moreover, the contribution of metabolic water appears to be more important in organisms with a more lipid-rich diet. Beyond these physiological and conservation biology implications, this study opens up questions that need to be addressed, such as the applicability of the oxygen isotope composition of cetacean body fluids and skeletal elements as an environmental proxy of the oxygen isotope composition of present and past marine waters., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Nesfatin-1 (Nesf-1) is an anorexigenic peptide involved in the regulation of homeostatic feeding. Nesf-1 is expressed in the central nervous system and other organs, including pancreas, where it promotes the release of insulin from β-cells. This raises the possibility that Nesf-1 dysfunction could be involved in metabolic disorders, particularly in type 2 diabetes mellitus (T2D). Recently, it has been discovered that dolphins can be a natural animal model that fully replicates human T2D, due to its prolonged glucose tolerance curve and maintenance of a state of hyperglycemia similar to human T2D during fasting. This correspondence suggests that dolphins may be a suitable model for investigating physiological and pathological metabolic disorders. Here, we have characterized Nesf-1 distribution in the pancreas of the common bottlenose dolphin (Tursiops truncatus) and measured plasmatic levels of Nesf-1 and glucose during fasting and post-prandial states. The Mediterranean Marine Mammal Tissue Bank (MMMTB) of the University of Padova provided us with pancreas samples, derived from four animals, and plasma samples, collected before and after the main meal. Interestingly, our results showed that Nesf-1-immunoreactive cells were distributed in Langerhans islets, co-localized with glucagon in α-cells. Similar to humans, dolphin plasma Nesf-1 concentration doesn't show a statistically significant difference when comparing fasting and post-prandial states. On the other hand, blood glucose levels were significantly higher before than after the main meal. Our data provide a comparative analysis for further studies on the involvement of Nesf-1 in mammalian metabolic disorders. [ABSTRACT FROM AUTHOR]

Clinical and epidemiological features of tattoo skin disease (TSD) are reported for 257 common bottlenose dolphins held in 31 facilities in the Northern Hemisphere. Photographs and biological data of 146 females and 111 males were analyzed. Dolphins were classified into three age classes: 0-3 years, 4-8 years, and older than 9 years. From 2012 to 2014, 20.6% of the 257 dolphins showed clinical TSD. The youngest dolphins with tattoo lesions were 14 and 15 months old. TSD persisted from 4 to 65 months in 30 dolphins. Prevalence varied between facilities from 5.6% to 60%, possibly reflecting variation in environmental factors. Unlike in free-ranging Delphinidae, TSD prevalence was significantly higher in males (31.5%) than in females (12.3%). Infection was age-dependent only in females. Prevalence of very large tattoos was also higher in males (28.6%) than in females (11.1%). These data suggest that male T. truncatus are more vulnerable to TSD than females, possibly because of differences in immune response and susceptibility to captivity-related stress. [ABSTRACT FROM AUTHOR]

The bottlenose dolphin (Tursiops truncatus M.) local population off west Istria in the North-eastern Adriatic has received no prior study of abundance and distribution despite the habitat's relevance for the preservation of this key species in the marine ecosystem. The research area comprises part of the NATURA 2000 network which was predominantly established here for these dolphins. Official data regarding the local population's status in the region are currently marked as deficient. Thus, the aim of the present study was to provide the first population data for the area. Boat-based survey work was carried out from April to September 2012–2015 using a mark–recapture photo-identification method. Prior to this period a random data collection was used to study distribution, since 2001, to cover the area of 927 km2 lying between Umag to lighthouse Albanež in the south. 143 bottlenose dolphins were photo-identified to date with the average group size of 9.27 ± 6.53 animals. Several abundance models were used, from which the Markovian robust model proved the best fit and predicted between 47–142 dolphins along the west Istria coast. A few individuals were also identified in Slovenia, indicating a bigger home range along the 98 km length of the studied area. There is an indication of a regular year round presence of dolphins. The west Istria coast constitutes an important feeding and breeding ground. The region should develop a sustainable plan to manage those human activities negatively impacting the dolphins. Therefore the present study is of relevance for the implementation of management directives for their conservation. [ABSTRACT FROM AUTHOR]

In this study photo-identification data were used to better understand movements, population structure and abundance of common bottlenose dolphin (Tursiops truncatus) in south-west England and surrounding waters, to inform conservation efforts. A catalogue of 485 photographic sightings of 113 individuals was compiled from ~150 common bottlenose dolphin encounters made on 87 dates between March 2007 and January 2014. From these and other data, three likely sub-populations were identified in the western English Channel, demarcated by bathymetry and distance to land: (1) south-west England – inshore Cornwall to Devon, (2) offshore English/French waters and (3) inshore France from Brittany to Normandy. Maximum abundance estimates for south-west England coastal waters, using two methods, ranged between 102 and 113 (range 87–142, 95% CL) over the period 2008–2013, likely qualifying the region as nationally important, whilst the yearly maximum was 58 in 2013. The population was centred on Cornwall, where 19 well-marked animals were considered ‘probable’ residents. There were no ‘probable’ resident well-marked individuals found to be restricted to either Devon or Dorset, with animals moving freely within coastal areas across the three counties. Movements were also detected within offshore English waters and French waters (from other studies) of the western English Channel, but no interchange has as yet been detected between the three regions, highlighting the possible separation of the populations, though sample sizes are insufficient to confirm this. Given the findings, south-west England waters should be considered as a separate management unit requiring targeted conservation efforts. [ABSTRACT FROM AUTHOR]

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

Cetacean morbillivirus (CeMV) has caused several epizootics in multiple species of cetaceans globally and is an emerging disease among cetaceans in Australia. We detected CeMV in 2 stranded coastal Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Western Australia. Preliminary phylogenetic data suggest that this virus variant is divergent from known strains.