Top marine predators present high mercury concentrations in their tissues due to biomagnification in the marine food chain. This study reports mercury (Hg) and selenium (Se) status, and the Hg:Se ...molar ratio assessment in bottlenose (Tursiops truncatus), striped (Stenella coeruleoalba) and Risso's dolphins (Grampus griseus). Total Hg and Se concentrations were determined in muscle, liver, kidney, lung, spleen, adipose tissue and skin collected from 186 specimens stranded in the Croatian part of Adriatic Sea from 1995 to 2014. Total Hg concentrations in tissue samples ranged from 0.001 in the spleen to 2238 mg/kg wet weight in liver. Se concentrations in dolphin samples ranged from 0.010 to 2916 mg/kg ww. Minimum Se concentration was found in muscle and maximum Se concentration were found in liver of bottlenose dolphin. Hg and Se levels in Risso's dolphins showed higher concentrations in all tissues in comparison to bottlenose and striped dolphins. Significant and positive correlations were observed between age and Hg concentrations (P < 0.05). In 66.6 % of Risso's, 15.3 % of bottlenose dolphins and one stranded striped dolphin in this study, the hepatic concentration of Hg exceeded the higher toxic thresholds (400 mg/kg w.w.) previously defined as evidence of liver damage in marine mammals. The Hg:Se molar ratio in the liver of Risso's dolphin was 0.670. The liver of adult bottlenose dolphins showed expected values (0.870), while the liver of young dolphins had a high ratio (0.750), non-specific for the age group. The Hg:Se molar ratio in the liver of striped dolphins was 0.390, which is lower than the literature values.
Display omitted
•Hg and Se were determined in 186 specimens stranded in the Adriatic Sea.•64 individuals exceeded the lower critical level (Hg = 100 mg/kg) in liver.•The upper critical level in the liver (Hg = 400 mg/kg) exceeded 29 dolphins.•Bioaccumulation of Hg and Se was found in the liver of dolphins.
The major histocompatibility complex (MHC) includes highly polymorphic genes involved in antigen presentation, which is crucial for adaptive immune response. They represent fitness related genetic ...markers particularly informative for populations exposed to environmental challenges. Here we analyse the diversity and evolutionary traits of MHC class II DQA and DQB genes in the dolphins Stenella coeruleoalba and Grampus griseus from the Mediterranean Sea. We found substantial nucleotide and functional diversity, as well as strong evidence of balancing selection indicated by allele and supertype frequencies, Tajima's D statistics and dN/dS tests. The Risso's dolphin, considered the least abundant in the region, showed the effect of divergent allele advantage at the nucleotide and functional-peptide levels. An outstanding polymorphism was found in the striped dolphin, particularly intriguing in the DQA gene where the Ewens-Watterson test detected a selection sweep that occurred in recent history. We hypothesize that morbillivirus, which has recurrently invaded Mediterranean populations over the last decades, exerted the detected selective pressure.
•Five bottlenose dolphin carcasses in the Adriatic Sea were tested on brucellosis.•Brucella strains ST27 was isolated from multiple organs in one dolphin.•First evidence of brucellosis in bottlenose ...dolphin from the Adriatic Sea.•Zoonotic strain ST27 is for first time identified in Europe.
Marine mammal brucellosis has been known for more than 20 years, but recent work suggests it is more widespread than originally thought. Brucella (B.) pinnipedialis has been isolated from pinnipeds, while B. ceti strains have been associated with cetaceans. Here we report a Brucella strain isolated from multiple lymph nodes of one bottlenose dolphin (Tursiops truncatus) during routine examination of dolphin carcasses found in the Croatian part of the northern Adriatic Sea during the summer of 2015. Classical bacteriological biotyping, PCR-based techniques (single, multiplex, PCR-RFLP) and 16S rRNA DNA sequencing were used to identify Brucella spp. Multiple-locus variable number tandem repeat analysis of 16 loci and multilocus sequence typing of 9 loci were used for genotyping and species determination. The combination of bacteriological, molecular and genotyping techniques identified our strain as ST27, previously identified as a human pathogen. This report provides, to our knowledge, the first evidence of ST27 in the Adriatic Sea in particular and in European waters in general. The zoonotic nature of the strain and its presence in the Adriatic, which is inhabited by bottlenose dolphins, suggest that the strain may pose a significant threat to human health.
Morphological characteristics of bones have shaped as a result of adaptation to life in the aquatic environment and whale diving habits. This study deals with the postnatal bone development and ...microscopic characteristics of bones of bottlenose dolphins (
Tursiops truncatus
). Bone sections of the right humerus and the fifth right rib of 106 dolphins aged less than 1–21 years were used to determine the density of the primary, secondary and remodelling osteons, the magnitude of the area occupied by the osteons, and the number of osteon lamellae. Bone sections were analysed using a compound microscope with standard and polarized light. Our study showed the primary osteons of bones to occupy a smaller area than the secondary ones. The secondary osteon area in the humerus is significantly larger than that in the rib. All rib osteons are significantly denser than those of the humerus. In both bones, the number of osteon lamellae is higher in secondary than in primary osteons. The number of secondary and remodelling osteons and the areas occupied by them increase with age, as opposed to primary osteons in which a decrease was noted. The number of lamellae in primary osteons decreases with age, while in secondary osteons their number increases. Within the study frame, morphometric osteon values of the bottlenose dolphin were determined, to the best of our knowledge, for the first time ever as concerns the aquatic mammals.
Anatomical variations of the thoracic duct in the dog Korpes, Kim; Kolenc, Magdalena; Trbojević Vukičević, Tajana ...
Anatomia, histologia, embryologia,
November 2021, 2021-11-00, 20211101, Letnik:
50, Številka:
6
Journal Article
Recenzirano
Anatomical variations can be frequently found in the lymphatic system, which is also true for the shape and course of the thoracic duct (ductus thoracicus), the biggest lymph vessel in the body. From ...2012 to 2019, the thoracic duct was successfully dissected in 43 dog carcasses that were used in the anatomy course at the Faculty of Veterinary Medicine, University of Zagreb. The thoracic duct originated from the cranial border of the cisterna chyli as one lymph vessel in 36 dogs (83.7%), as two vessels in six dogs (14%) and as three vessels in one dog (2.3%). We divided the observed thoracic duct variations into six groups according to their anatomical similarities. Considering the specific embryonic development, we can conclude that all observed variations are the result of minor deviations from the standard ontogenesis. However, the importance of thoracic duct variations is significant in surgical procedures done in the thoracic cavity to prevent or cure the chylothorax. Since this research showed variations in 39 out of 43 dogs (90.7%) throughout the whole course of the thoracic duct, great care must be taken while performing the ligation or embolization of the thoracic duct.
Various anthropogenic threats negatively influence the survival of cetaceans in all world seas. Thanks to a long-running marine mammal surveillance program, we are able to report the results of a ...detailed analysis of the influence of cetacean-fisheries interactions and marine litter ingestion on cetacean mortality in the Croatian part of the Adriatic Sea over the last three decades. The total number of dead cetaceans was 459, and included 334 bottlenose dolphins (Tursiops truncatus), 40 striped dolphins (Stenella coeruleoalba), ten Risso’s dolphins (Grampus griseus), six Cuvier’s beaked whales (Ziphius cavirostris) and four fin whales (Balaenoptera physalus). Three hundred of them were examined postmortally. Cetacean-fisheries interaction occurred frequently in the Adriatic Sea, being detected in 96 (20.9%) of the recorded cases. Bycatch was the most abundant cetacean-fisheries interaction, with 66 (14.4%) cases recorded. Good nutritional condition and evidence of recent feeding were the most common findings recorded in bycatch cases, followed by persistent froth in the airways, edematous lungs, bruises and an amputated fluke or tail. Cetacean-fisheries interactions other than bycatch affected 30 animals and included larynx strangulations, long-term tail entanglement and fishing gear in the stomach. Ingestion of marine litter that was not related to fisheries was recorded in four animals. This study reveals the considerable negative anthropogenic influence on cetaceans in the Adriatic Sea, especially the bottlenose dolphin that is considered to be the most numerous cetacean species therein, and demonstrates the need for the urgent development of a cetacean bycatch reduction program. Finally, it also shows the importance of sustaining national surveillance programs to gain scientifically based knowledge important for cetacean protection and prospects for their long-term survival.
•Anisakis pegreffii is the most abundant anisakid (96.73%) in toothed whales.•Anisakis simplex s. s. and Anisakis physeteris are newly recorded in the Adriatic Sea.•The A. pegreffii population was ...not panmictic at a global level.•No distinctive pattern was noticed between host and parasite ecological traits.
Knowledge concerning cetacean ecology in the Mediterranean is limited but important for sustainable planning and enforcement of appropriate conservation measures. Any information that might help to elucidate their ecology is essential. We explored the population and genetic structures of Anisakis spp. nematodes isolated from four toothed whale species – bottlenose dolphins (Tursiops truncatus), striped dolphins (Stenella coeruleoalba), Risso’s dolphins (Grampus griseus) and Cuvier’s beaked whales (Ziphius cavirostris) – stranded along the eastern Adriatic Sea coast (1990–2012) to reveal more information on host ecological patterns. Lower parasite prevalence was observed in resident dolphin species compared with occasionally occurring species, as well as in young compared with adult dolphins, indicating different feeding habits related to age. No unequivocal relationship between the biological traits of a host (age, body length, body mass and blubber depth) and Anisakis population parameters was observed. Phylogenetic analysis revealed a new geographical record of Anisakis simplex sensu stricto (1.96%) and Anisakis physeteris (1.31%) in the Adriatic Sea in addition to resident Anisakis pegreffii (96.73%). In an assessment of the Adriatic Sea and oceans worldwide, the genetic structure of Anisakis revealed that A. pegreffii populations do not differ among various final host species but do differ with respect to geographical location in contrast to previously accepted Anisakis panmixia.
Vranić site is a sand quarry that is located on the southern foothills of Papuk Mountain. From bottom to top of the succession, three sedimentary units have been recognized as: Unit 1 containing ...massive sand with scattered gravel-sized clasts, marl cobbles and boulders, and abundant marine mammal and fish fossils; Unit 2 consisting of sand intercalated with silt, clay and gravel, which may be horizontally bedded; and Unit 3, which is an erosionally-based lenticular matrix to clast-supported structureless gravel. The basal part of Unit 1 shows numerous reworked skeletal remains of Miocene marine mammals. Cosmogenic radionuclides constrain the age of burial of Unit 1 to 895 ± 211 ka, while the source area of Unit 1 had a quick denudation.
The massive sands deposited on the slopes of Papuk Mountain were vulnerable to erosion due to the absence of clay. Heavy rainfall or water from snow melting created flash floods that infiltrated the sands, thereby causing slope destabilization and deformation. This process led to slumps that were transformed into a sandy debris flow. This sediment was probably deposited during the interglacial marine isotope age (MIS) 21 period when the scarce vegetation and a warmer climate favored the melting of permafrost ice and consequently triggered slope movements during MIS 22. The reworked skeletal material sampled at the Vranić site comprises fossilized fish along with mammal bones and teeth. Thus, the Vranić site represents an important site for cetacean fossil remains and serves as an important data source for marine life in the Central Paratethys.
Manganese concentrations were determined in muscle, kidney, liver, spleen, lung and fat tissues and skin of three cetacean species, the bottlenose (
Tursiops truncatus
), striped (
Stenella ...coeruleoalba
) and Risso’s (
Grampus griseus)
dolphins, stranded along the Croatian Adriatic coast between 1995 and 2013. Mean ranges determined in tissues were (mg/kg, ww): muscle 0.23–0.27, liver 2.87–4.00, kidney 0.66–1.26, spleen 0.37–0.79, lung 0.18–0.57, skin 0.11–0.97, fat 0.06–0.42. The highest Mn mean levels in tissues were measured in species (mg/kg, ww):
T. truncates
lung 0.41, skin 0.97, fat 0.42;
S. coeruleoalba
muscle 0.26;
G. griseus
kidney 1.26, liver 4.00, spleen 0.64. Significant differences of Mn concentrations in the liver (
p
= 0.034), spleen (
p
= 0.037) and skin (
p
= 0.013) were found among the three dolphin species. Significant differences in Mn levels were found between young and adult
T. truncates
in kidney (
p
= 0.042), lung (
p
= 0.0040) and skin (
p
= 0.0034).
The bottlenose dolphin (Tursiops truncatus) is the most common cetacean species worldwide and the only marine mammal species resident in the Croatian part of the Adriatic Sea. To gain insight into ...genetic diversity of bottlenose dolphins at adaptively important loci relevant to conservation, we analysed the polymorphism of major histocompatibility complex (MHC) genes, which play a key role in pathogen confrontation and clearance. Specifically, we examined the diversity of MHC class II DRA, DQA and DQB alleles in 50 bottlenose dolphins from the Adriatic Sea collected between 1997 and 2011 and in 12 animals from other Mediterranean locations. Notable variation in DQA, DQB and three-locus haplotypes was found, with all 10 DQA and 12 DQB alleles encoding unique protein products. Analysis of the ratio of non-synonymous to synonymous substitution rates suggests that positive selection acts at both highly variable loci. Phylogenetic analyses revealed trans-species polymorphism at the DQB locus, strongly indicating the influence of balancing selection in the long term. In fact, the balancing selection observed in bottlenose dolphins is higher than that reported for most other cetaceans and comparable to that seen in terrestrial mammals.
PDF
