Lymphangiomyomatosis in the Atlantic bottlenose dolphin (Tursiops truncatus).

The first case of lymphangiomyomatosis in a marine mammal is reported from a stranded male Atlantic bottlenose dolphin (Tursiops truncatus). This progressive proliferative disease involved the lungs and the mediastinal and probably mesenteric lymph nodes. An extraordinarily low level of testosterone may have been pathologically significant since all reported cases of this disease in humans occur in females.     

Struvite calculus in the vagina of a bottlenose dolphin (Tursiops truncatus)

On 27 January 2000, a struvite calculus was observed in the vagina during necropsy of a 138-cm-long female bottlenose dolphin (Tursiops truncatus) collected from the Stono River, South Carolina (USA). Vaginal calculi have been reported in other species of cetaceans but not in bottlenose dolphins. Urinary tract infection might have been an underlying cause of the calculus. While urinary tract inflammation was not detected by light microscopic evaluation of sections of the urinary tract, it is conceivable that sufficient time had lapsed following voiding of the calculus through the urethra for urinary tract infection to have resolved. To further define the prevalence and significance of urolithiasis, prosectors of dead stranded marine mammals are encouraged to closely observe their urinary and genital tracts for calculi and to submit them for quantitative analysis.     

Conflict and reconciliation behavior trends of the bottlenose dolphin (Tursiops truncatus)

Wild bottlenose dolphin (Tursiops truncatus) populations display societal structures characterized by numerous and frequent changes in group composition, complex social relationships, and high levels of cooperation, attributes also observed in human and nonhuman primate cultures. Maintaining social relationships under such elemental conditions can frequently create conflict—and the opportunity for reconciliation—among group members. The conflict and reconciliation behavior patterns of the chimpanzee (Pan troglodytes) have been studied extensively; trends are well‐documented in the wild and in captivity. Apparent cultural similarities have prompted several analogous studies on wild and captive bottlenose dolphins. This research attempted to corroborate previous efforts by analyzing the social behavior of seven captive bottlenose dolphins to determine the effects of sex and age on the frequency of conflict and reconciliation, and to investigate the incidence of consolatory behavior within the group. A total of 3,428 interactions involving focal animals, 414 of which were conflict episodes, were documented during 261 hr of videotaped observations. Although the sample size precluded meaningful statistical evaluation of the influence of sex on conflict and reconciliation, participant age was a significant determinant of conflict frequency. Conversely, age did not impact frequency of reconciliation, which only occurred after 18% of all conflict interactions. Little to no definitive evidence of consolation was apparent within the study group. While results partially support the findings of previous dolphin reconciliation research, extensive behavioral studies of wild populations should be conducted before generating broad comparisons between human terms and nonhuman behavioral interactions. Zoo Biol 29:567–585, 2010. © 2009 Wiley‐Liss, Inc.     

Orbital gland structure and secretions in the Atlantic bottlenose dolphin (Tursiops truncatus)

Orbital gland structure of the Atlantic bottlenose dolphin, Tursiops truncatus, was examined at the macroscopic, light microscopic, and electron microscopic levels. The gland completely encircles the ocular globe in a belt-like fashion near the conjunctival fornix but is considerably more developed medially. Duct openings are scattered throughout the fornix and over the surface of the palpebral conjunctiva. Microscopically, the gland has a tubuloalveolar arrangement; alveolar cells contain numerous secretory vesicles which can be interpreted as two structural types by light and electron microscopy. Histochemical staining demonstrates that both types contain glycosaminoglycans. Lipid analysis of the glandular secretion (dolphin tears) shows them to be non-oily and to contain only negligible amounts of cholesterol, triglycerides, phospholipids, and free fatty acids. The secretion is clear, slippery, and viscoelastic and well-adapted to protecting the eye and to reducing frictional forces between the eye surface and surrounding seawater.     

Harderian gland ultrastructure of the black sea bottlenose dolphin (Tursiops truncatus ponticus)

Examination of the Harderian gland structure of the Black Sea bottlenose dolphin, Tursiops truncatus ponticus, at macroscopic, microscopic, and electron microscopic levels shows significant sexual dimorphism. The epithelial cells of male and female glands are different cell types, capable of producing chemically different products. Secretory cells in both sexes contain secretion granules that produce a secretion consisting mainly of proteins and carbohydrates, but thought to be sex-specific in composition. The female glands also contain lipid secretion granules. It is suggested that in the bottlenose dolphin the Harderian gland functions to produce sexually distinct pheromones and may have other physiological activities, e.g., participating in local immunological or endocrine-related reactions. © 1994 Wiley-Liss, Inc.     

Vertebral osteomyelitis and suspected diskospondylitis in an Atlantic bottlenose dolphin (Tursiops truncatus)

A 21-yr-old male Atlantic bottlenose dolphin (Tursiops truncatus) was performing at an aquatic park when it developed a soft tissue swelling anterior to the flukes. Subsequent radiographic evaluation revealed the animal to have vertebral osteomyelitis and suspected diskospondylitis. The case was successfully managed with long-term antibiotic therapy.     

Behaviorally measured tactile sensitivity in the common bottlenose dolphin,Tursiops truncatus

Little research has been conducted on the somatosensory system of toothed whales and it remains uncertain how tactile sensitivity varies about their bodies. In this study, tactile sensitivity to high-frequency (250-Hz) displacement of the skin was quantified in three trained adult common bottlenose dolphins (Tursiops truncatus) using a vibratory device (tactor). The magnitude of skin displacement was controlled by varying the voltage to the tactor held against the skin surface with a constant force. Tactile thresholds were determined using an adaptive method of limits in which dolphins reported perception of the tactile stimulus by producing a whistle. Displacement thresholds ranged from 2.4 to 40 μm, with the greatest sensitivity found along the rostrum, melon, and blowhole. Sensitivity decreased caudally along the body, with the dorsal fin and tip of the fluke being the least sensitive locations tested. The results support hypotheses that the follicles on the dolphin rostrum are particularly important for perception. The reduction in tactile sensitivity at the appendages is consistent with their primary role in stabilization and locomotion compared to exploration or environmental sensing.     

Unique seasonal forage bases within a local population of bottlenose dolphin (Tursiops truncatus)

Using photo‐identification data, bottlenose dolphin (Tursiops truncatus) populations can be differentiated based on their use of particular estuaries or coastal habitats. Questions remain, however, about the validity of such fine‐scale population partitioning and whether the resulting assemblages utilize unique forage bases. To address the issue of forage base use, stable isotopes of carbon (δ¹³C), nitrogen (δ¹⁵N) and sulfur (δ³⁴S) were analyzed from skin tissues (n= 74) of bottlenose dolphins sampled seasonally along the coast and in three estuaries near Charleston, South Carolina. Autumn values of δ³⁴S, δ¹⁵N, and δ¹³C and summer values of δ³⁴S indicated that dolphins sampled from these four assemblages utilized unique forage bases, despite limited sample sizes. Likewise, autumn and spring differences in δ¹⁵N and δ¹³C values were evident in the North Edisto River, and in δ³⁴S from dolphins sampled from all three estuarine assemblages; no seasonal differences were identified in the coastal assemblage. Results demonstrate the importance of considering spatial and temporal variation in forage base when developing local management plans for bottlenose dolphin and highlight the discriminatory power of δ³⁴S for estuarine and coastal marine mammals. These results also suggest that stable isotopes could be developed as a complementary tool for photo‐identification based partitioning of bottlenose dolphin populations.     

Age structure of strandings and growth of Lahille's bottlenose dolphin (Tursiops truncatus gephyreus)

This study describes the age structure and sex-specific growth patterns of Lahille's bottlenose dolphins (Tursiops truncatus gephyreus), a subspecies endemic to the Southwest Atlantic Ocean (SWAO). The ages of 120 animals collected in southern Brazil between 1976 and 2017 were determined. We found high frequencies of young animals, mostly males, with no sex bias among adults. A temporal change in the age structure of strandings was observed, and we conclude it is a consequence of increased bycatch rates of young dolphins after 2000. The oldest male and female were 27 and 44 years old, respectively, suggesting that females live longer than males in southern Brazil. Growth curve analysis using Gompertz and Laird-Gompertz growth models estimated asymptotic lengths of 316.5 cm for females and 351.6 cm for males, (reached around 13 and 18 years old, respectively), supporting sexual size dimorphism for the subspecies. A second growth pulse was identified for males. Our work highlights the benefit of long-term studies and contributes valuable information toward understanding the life history of Lahille's bottlenose dolphin. It will serve as baseline for future studies that seek to understand mortality patterns of bottlenose dolphins elsewhere and the effects of anthropogenic actions on the survival of these animals.     

Effect of cryopreservation methods and precryopreservation storage on bottlenose dolphin (Tursiops truncatus) spermatozoa

Research was conducted to develop an effective method for cryopreserving bottlenose dolphin (Tursiops truncatus) semen processed immediately after collection or after 24-h liquid storage. In each of two experiments, four ejaculates were collected from three males. In experiment 1, three cryopreservation methods (CM1, CM2, and CM3), two straw sizes (0.25 and 0.5 ml), and three thawing rates (slow, medium, and fast) were evaluated. Evaluations were conducted at collection, prefreeze, and 0-, 3-, and 6-h postthaw. A sperm motility index (SMI; total motility [TM] x % progressive motility [PPM] x kinetic rating [KR, scale of 0-5]) was calculated and expressed as a percentage MI of the initial ejaculate. For all ejaculates, initial TM and PPM were greater than 85%, and KR was five. At 0-h postthaw, differences in SMI among cryopreservation methods and thaw rates were observed (P < 0.05), but no effect of straw size was observed. In experiment 2, ejaculates were divided into four aliquots for dilution (1:1) and storage at 4 degrees C with a skim milk- glucose or a N-tris(hydroxymethyl)methyl-2-aminoethane sulfonic acid (TES)-TRIS egg yolk solution and at 21 degrees C with a Hepes-Tyrode balanced salt solution (containing bovine albumin and HEPES) (TALP) medium or no dilution. After 24 h, samples were frozen and thawed (CM3, 0.5-ml straws, fast thawing rate) at 20 x 10(6) spermatozoa ml(-1) (low concentration) or at 100 x 10(6) spermatozoa ml(-1) (standard concentration). The SMI at 0-h postthaw was higher for samples stored at 4 degrees C than for samples stored at 21 degrees C (P < 0.001), and at 6-h postthaw, the SMI was higher for samples frozen at the standard concentration than for samples frozen at the low concentration (P < 0.05). For both experiments, acrosome integrity was similar across treatments. In summary, a semen cryopreservation protocol applied to fresh or liquid-stored semen maintained high levels of initial ejaculate sperm characteristics.     

Temperature regulation of the testes of the bottlenose dolphin (Tursiops truncatus): evidence from colonic temperatures

Dolphins possess a countercurrent heat exchanger that functions to cool their intra-abdominal testes. spermatic arteries in the posterior abdomen are juxtaposed to veins returning cooled blood from the surfaces of the dorsal fin and flukes. A rectal probe housing a linear array of five copper-constantan thermocouples was designed to measure colonic temperatures simultaneously at positions anterior to, within, and posterior to the region of the colon flanked by the countercurrent heat exchanger. Colonic temperatures adjacent to the countercurrent heat exchanger were maximally 1.3°C cooler than temperatures measured outside this region. Temporary heating and cooling of the dorsal fin and flukes affected temperatures at the countercurrent heat exchanger, but had little or no effect on temperatures posterior to its position. These measurements support the hypothesis that cooled blood is introduced into the deep abdominal cavity and functions specifically to regulate the temperature of arterial blood flow to the dolphin testes.     

Occurrence of a unique sialyl tetrasaccharide in colostrum of a bottlenose dolphin (Tursiops truncatus)

Crude oligosaccharides were recovered from bottlenose dolphin (Tursiops truncatus) colostrum after chloroform/methanol extraction of lipids and protein precipitation, and purified using gel filtration, anion exchange chromatography and high performance liquid chromatography (HPLC). Their chemical structures characterized by NMR spectroscopy were as follows: GalNAc(beta1-4)[Neu5Ac(alpha2-3)]Gal(beta1-4)Glc, Neu5Ac(alpha2-3)Gal(beta1-4)Glc, Neu5Ac(alpha2-6)Gal(beta1-4)Glc and Gal(alpha1-4)Gal(beta1-4)Glc. The monosialyltetrasaccharide and neutral trisaccharide have not previously been found as free forms in any natural sources including milk or colostrum, although these structures have been found in the carbohydrate units of glycosphingolipids GM2 and Gb3.     

Assessment of increased serum aminotransferases in a managed Atlantic bottlenose dolphin (Tursiops truncatus) population

Nonspecific chronic hepatitis and increased activities of serum aminotransferases have been reported in cetaceans (dolphins, porpoises, and whales). We identified bottlenose dolphins in our current population with episodic increases in serum aminotransferases, specifically alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and we hypothesized that hematologic and serum biochemical changes in these animals may provide clues as to potential causes of liver disease in cetaceans. A retrospective case-control study involving 1,288 blood samples collected during 1998-2006 from 18 dolphins (six cases and 12 age- and sex-matched healthy controls) was conducted to compare eosinophil and platelet counts; and serum proteins, albumin, globulins, bilirubin, gamma glutamyltransferase (GGT), cholesterol, triglycerides, glucose, iron, and erythrocyte sedimentation rates. Bottlenose dolphins with increased ALT and AST activities were more likely to have higher serum globulins, bilirubin, GGT, iron, glucose, triglycerides, and cholesterol levels, greater erythrocyte sedimentation rates, and lower platelet counts compared to healthy controls. Our findings suggest that dolphins with chronic increases in aminotransferases may have a chronic hepatitis involving iron overload with similar etiologies and pathophysiology compared to terrestrial mammals. Areas for future research include predisposing metabolic risk factors; associations between iron overload and a diabetes-like condition; and a potential overlap syndrome involving autoimmune responses that may or may not be associated with viral infection.     

Importance of spontaneous micronucleated erythrocytes in bottlenose dolphin (Tursiops truncatus) to marine toxicology studies

The objective of the work was to characterize the presence of spontaneous micronucleated erythrocytes (MNES) from peripheral blood of bottlenose dolphins (Tursiops truncatus) to evaluate the possibility to use this species as potential bioindicator of genotoxic compounds. Forty-eight blood samples from 12 bottlenose dolphins were obtain from three Mexican dolphinariums, and from 10 dolphins was possible to obtain more than one sample at different sampling times. Smears were processed and observed with an epifluorescence microscope. The average of MNES and polychromatic erythrocytes (PCE) from the 48 samples was 24.3 +/- 6.1 MNES/10,000 total erythrocytes (TE), and 9.1 +/- 5.5 PCE/1,000 TE. MNES and PCE number did not show differences between gender and age. No variations in the MNES values of the bottlenose dolphins that were sampled more than one occasion were found. Comparisons among dolphinariums revealed differences in MNES frequency, with the highest significant frequency observed in dolphins from dolphinarium "A" (26.0 +/- 5.9 MNES/10,000 TE) than dolphinarium "B" (19.5 +/- 3.1 MNES/10,000 TE) (p < 0.05) and dolphinarium "C" (18.6 +/- 3.5 MNES/10,000 TE) (p < 0.007). The presence of MNES and PCE in the bottlenose dolphin may provide a useful marine mammal model to detect DNA damage by means of micronuclei test in peripheral blood erythrocytes to evaluate genotoxicity and cytotoxicity expositions.     

Progress report: Results of a long-range captive breeding program for the bottlenose dolphin,Tursiops truncatus and Tursiops truncatus gilli

There have been 36 bottlenose dolphins born in breeding colonies at Sea World, California, and Sea World, Florida, from 1978–1985. Significant features of this successful reproductive program are construction of a compatible breeding colony, early hormonal detection of pregnancy, pre- and postnatal association of inexperienced mothers with experienced females and their calves, and minimized handling of the mothers and calves until the calves are over 1 year of age. Inclusion in the breeding colonies of males old enough to be effective breeders is stressed. Females in the colonies have successfully bred from 8–9 years of age to 23–24 years of age. Calving intervals in the colonies vary from 2 to over 3 years. Calves are born all year round, with some peaking in calving activity in the spring and fall months. Serum progesterone levels greater than 6,000 pg/ml, maintained over a 4–6-week period, are considered indicative of pregnancy. Progesterone levels vary from less than 10,000 to over 50,000 pg/ml during gestation, averaging 25,000 pg/ml. The need for further study of variation in the pattern of progesterone levels during pregnancy is emphasized. A gestation period for Tursiops of 11.5 to 12 months is consistent with our cumulative progesterone data.     

Blubber development in bottlenose dolphins (Tursiops truncatus)

Blubber, the lipid-rich hypodermis of cetaceans, functions in thermoregulation, buoyancy control, streamlining, metabolic energy storage, and locomotion. This study investigated the development of this specialized hypodermis in bottlenose dolphins (Tursiops truncatus) across an ontogenetic series, including fetuses, neonates, juveniles, subadults, and adults. Blubber samples were collected at the level of the mid-thorax, from robust specimens (n = 25) that stranded along the coasts of North Carolina and Virginia. Blubber was dissected from the carcass and its mass, and the depth and lipid content at the sample site, were measured. Samples were prepared using standard histological methods, viewed by light microscopy, and digital images of blubber captured. Images were analyzed through the depth of the blubber for morphological and structural features including adipocyte size, shape, and numbers, and extracellular, structural fiber densities. From fetus to adult, blubber mass and depth increased proportionally with body mass and length. Blubber lipid content increased dramatically with increasing fetal length. Adult and juvenile blubber had significantly higher blubber lipid content than fetuses, and this increase was reflected in mean adipocyte size, which increased significantly across all robust life history categories. In juvenile, subadult, and adult dolphins, this increase in cell size was not uniform across the depth of the blubber, with the largest increases observed in the middle and deep blubber regions. Through-depth counts of adipocytes were similar in all life history categories. These results suggest that blubber depth is increased during postnatal growth by increasing cell size rather than cell number. In emaciated adults (n = 2), lipid mobilization, as evidenced by a decrease in adipocyte size, was localized to the middle and deep blubber region. Thus, in terms of both lipid accumulation and depletion, the middle and deep blubber appear to be the most metabolically dynamic. The superficial blubber likely serves a structural role important in streamlining the animal. This study demonstrates that blubber is not a homogeneous tissue through its depth, and that it displays life history-dependent changes in its morphology and lipid content.