Lagenorhynchus Obliquidens Research Articles

Lectin Binding Pattern of Gastric Mucosa of Pacific White-Sided Dolphin, Lagenorhynchus obliquidens

The stomach of the Pacific white-sided dolphin is divided into three parts: forestomach, proper gastric gland portion, and pyloric chamber. The histological features of the dolphin stomach are similar to those of terrestrial mammal stomachs, although the distribution of glycoconjugates in mucosal cells of the dolphin stomach is unknown. To learn about glycoconjugates in cetacean gastric mucosa, the glycoconjugate distribution in the mucous epithelium of the Pacific white-sided dolphin was studied using 21 lectins. Among the lectins tested, GSL-I and DBA specifically labelled the superficial layer of the forestomach epithelium. GSL-I, SBA, RCA-I, VVA, GSL-II, DSL, LEL, STL, s-WGA, WGA, PNA, and Jacalin labelled the luminal surface of the chief cells in the proper gastric gland. GSL-I, SBA, RCA-I, DSL, LEL, STL, s-WGA, PNA, and LCA labelled tubular structures in the cytoplasm of parietal cells. The surface portion of the pits in the pyloric chamber strongly reacted with RCA-I, GSL-II, WGA, PNA, LCA, PHA-L, and UEA-I, whereas the neck portion reacted weakly. Although lining one tubular portion, individual secretory cells in the pyloric gland displayed a heterogeneous reaction. This is the first report on the lectin histochemistry of a cetacean stomach and reveals GSL-I and DBA as specific marker lectins for the cornified stratified squamous epithelium cells of the Pacific white-sided dolphin. The stomachs of cetaceans and terrestrial mammals have similar histological features and mucous glycoconjugate content.

Changes in partial pressures of respiratory gases during submerged voluntary breath hold across odontocetes: is body mass important?

Odontocetes have an exceptional range in body mass spanning 10(3) kg across species. Because, size influences oxygen utilization and carbon dioxide production rates in mammals, this lineage likely displays an extraordinary variation in oxygen store management compared to other marine mammal groups. To examine this, we measured changes in the partial pressures of respiratory gases ([Formula: see text], [Formula: see text]), pH, and lactate in the blood during voluntary, quiescent, submerged breath holds in Pacific white-sided dolphins (Lagenorhynchus obliquidens), bottlenose dolphins (Tursiops truncatus), and a killer whale (Orcinus orca) representing a mass range of 96-3,850 kg. These measurements provided an empirical determination of the effect of body size on the variability in blood biochemistry during breath hold and experimentally determined aerobic dive limits (ADL) within one taxonomic group (odontocetes). For the species in this study, maximum voluntary breath-hold duration was positively correlated with body mass, ranging from 3.5 min in white-sided dolphins to 13.3 min for the killer whale. Variation in breath-hold duration was associated with differences in the rate of change for [Formula: see text] throughout breath hold; [Formula: see text] decreased twice as fast for the two smaller species (-0.6 mmHg O(2) min(-1)) compared to the largest species (-0.3 mmHg O(2) min(-1)). In contrast, the rate of increase in [Formula: see text] during breath hold was similar across species. These results demonstrate that large body size in odontocetes facilitates increased aerobic breath-hold capacity as mediated by decreased mass-specific metabolic rates (rates of change in [Formula: see text] served as a proxy for oxygen utilization). Indeed the experimentally determined 5 min ADL for bottlenose dolphins was surpassed by the 13.3 min maximum breath hold of the killer whale, which did not end in a rise in lactate. Rather, breath hold ended voluntarily as respiratory gases and pH fell within a narrow range for both large and small species, likely providing cues for ventilation.

Classification of behavior using vocalizations of Pacific white-sided dolphins (Lagenorhynchus obliquidens)

Surface behavior and concurrent underwater vocalizations were recorded for Pacific white-sided dolphins in the Southern California Bight (SCB) over multiple field seasons spanning 3 years. Clicks, click trains, and pulsed calls were counted and classified based on acoustic measurements, leading to the identification of 19 key call features used for analysis. Kruskal-Wallis tests indicated that call features differ significantly across behavioral categories. Previous work had discovered two distinctive click Types (A and B), which may correspond to known subpopulations of Pacific white-side dolphins in the Southern California Bight; this study revealed that animals producing these different click types also differ in both their behavior and vocalization patterns. Click Type A groups were predominantly observed slow traveling and milling, with little daytime foraging, while click Type B groups were observed traveling and foraging. These behavioral differences may be characteristic of niche partitioning by overlapping populations; coupled with differences in vocalization patterns, they may signify that these subpopulations are cryptic species. Finally, random forest decision trees were used to classify behavior based on vocalization data, with rates of correct classification up to 86%, demonstrating the potential for the use of vocalization patterns to predict behavior.

한국 근해에 서식하는 고래 피하지방의 층별 지방 함량 및 구성 변화

Blubber plays different biological roles in cetaceans, including structural support, physiological demands (thermoregulation, streamlining, buoyancy, etc.), and energy storage. As such, biochemical composition, especially lipid, in the blubber may be vertically stratified in order to effectively assist with these functions. We analysed lipid content, class and fatty acid composition in the blubber of by-catch minke whale (Balaenoptera acutorostrata; n = 11), long-beaked common dolphin (Delphinus capensis; n = 3) and Pacific white-sided dolphin (Lagenorhynchus obiquidens; n = 2) from Korean waters. Lipid content for all three species ranged from 55 to 96% of wet weight, with a dominance of triacylglycerols. Vertical stratification of blubber lipid content was different between species. For minke whale and longbeaked common dolphin, it increased from inner (near the muscle) to outer (near the skin) layer, whereas it decreased for Pacific white-sided dolphin. Thirty-one fatty acids were found in all blubber samples and vertical stratification of fatty acid composition was similar among all three species. Among grouped fatty acids, monounsaturates were the most abundant, gradually increasing from inner to outer blubber layer, whereas polyunsaturates and saturates decreased. Such vertical stratification of lipid content and composition suggests that the modification and accumulation of lipid occur in the blubber itself in order to help cetaceans with their specific physiological needs.

Risso’s and Pacific white-sided dolphin habitat modeling from passive acoustic monitoring

Habitat characterization allows prediction of dolphin distributions in response to oceanographic processes and can be used to understand and predict effects of anthropogenic disturbances. Many habitat models focus on contemporary dolphin occurrence and environmental predictor data, but time-lagged oceanographic data may increase a model's predictive power due to ecological successional processes. Using hourly occurrence of Risso's dolphin Grampus griseus clicks and 2 types of Pacific white-sided dolphin Lagenorhynchus obliquidens clicks in autonomous passive acoustic recordings, we investigate the importance of time-lagged predictor variables with general- ized additive models. These models relate dolphin acoustic activity from recordings at 6 sites in the Southern California Bight between August 2005 and December 2007 to oceanographic variables including sea surface temperature (SST), SST coefficient of variation (CV), sea surface chlorophyll concentration (chl), chl CV, upwelling indices, and solar and lunar temporal indices. The most consis- tently selected variables among the trial models evaluated during cross-validation were SST (100% of models) and SST CV (80%) for Risso's dolphin clicks; solar indices (100%) and SST and SST CV (60% each) for Pacific white-sided type A (PWS A) clicks; and SST CV (100%), solar indices (100%) and SST (80%) for Pacific white-sided type B (PWS B) clicks. Best predictive models for Risso's dolphins and PWS A clicks included time-lagged variables, suggesting the importance of ecological succession between abiotic variables and dolphin occurrence, while best models of PWS B clicks were for current conditions, suggesting association with prey-aggregating features such as fronts and eddies.

Maternal–Fetal Transmission ofCryptococcus gattiiin Harbor Porpoise

Maternal–Fetal Transmission of<i>Cryptococcus gattii</i>in Harbor Porpoise

Lectin Histochemistry of Respiratory Mucosa in the Pacific White-Sided Dolphin

Sugars in the glycocalyx play an important role in the attachment of infectious agents to the respiratory mucosa. We examined the histochemistry of 23 lectins to survey the sugar expression in the glycocalyx of the respiratory mucosa of the Pacific white-sided dolphin, Lagenorhynchus obliquidens. The ciliated and basal cells were positive for all of the lectins studied. SBA, WFA, GSL-II, STL, S-WGA, and PNA staining in the cytoplasm showed different intensities between basal cells and ciliated cells. These results suggest that multiple terminal glycosylation occurs on ciliated and basal cells, such as GalNAc, GlcNAc, NeuNAc, galactose, glucose/mannose, oligosaccharide, and fucose, and that sugar residue expression changes during cell differentiation. The Pacific white-sided dolphin respiratory mucosa might express multiple sugar residues in the glycocalyx, to prevent the attachment and colonisation of infectious agents.

Birney Creek

Spring 2011 - Volume 15 Number 2 “Pacific White-Sided Dolphins” photograph Stephen Henry, MD Pacific White-Sided Dolphins bow riding in the inside passage just north of Vancouver Island. Dr Henry is retired from The Permanente Medic

Classification of echolocation clicks from odontocetes in the Southern California Bight

This study presents a system for classifying echolocation clicks of six species of odontocetes in the Southern California Bight: Visually confirmed bottlenose dolphins, short- and long-beaked common dolphins, Pacific white-sided dolphins, Risso's dolphins, and presumed Cuvier's beaked whales. Echolocation clicks are represented by cepstral feature vectors that are classified by Gaussian mixture models. A randomized cross-validation experiment is designed to provide conditions similar to those found in a field-deployed system. To prevent matched conditions from inappropriately lowering the error rate, echolocation clicks associated with a single sighting are never split across the training and test data. Sightings are randomly permuted before assignment to folds in the experiment. This allows different combinations of the training and test data to be used while keeping data from each sighting entirely in the training or test set. The system achieves a mean error rate of 22% across 100 randomized three-fold cross-validation experiments. Four of the six species had mean error rates lower than the overall mean, with the presumed Cuvier's beaked whale clicks showing the best performance (<2% error rate). Long-beaked common and bottlenose dolphins proved the most difficult to classify, with mean error rates of 53% and 68%, respectively.

Characteristic Metabolism of Free Amino Acids in Cetacean Plasma: Cluster Analysis and Comparison with Mice

From an evolutionary perspective, the ancestors of cetaceans first lived in terrestrial environments prior to adapting to aquatic environments. Whereas anatomical and morphological adaptations to aquatic environments have been well studied, few studies have focused on physiological changes. We focused on plasma amino acid concentrations (aminograms) since they show distinct patterns under various physiological conditions. Plasma and urine aminograms were obtained from bottlenose dolphins, pacific white-sided dolphins, Risso's dolphins, false-killer whales and C57BL/6J and ICR mice. Hierarchical cluster analyses were employed to uncover a multitude of amino acid relationships among different species, which can help us understand the complex interrelations comprising metabolic adaptations. The cetacean aminograms formed a cluster that was markedly distinguishable from the mouse cluster, indicating that cetaceans and terrestrial mammals have quite different metabolic machinery for amino acids. Levels of carnosine and 3-methylhistidine, both of which are antioxidants, were substantially higher in cetaceans. Urea was markedly elevated in cetaceans, whereas the level of urea cycle-related amino acids was lower. Because diving mammals must cope with high rates of reactive oxygen species generation due to alterations in apnea/reoxygenation and ischemia-reperfusion processes, high concentrations of antioxidative amino acids are advantageous. Moreover, shifting the set point of urea cycle may be an adaption used for body water conservation in the hyperosmotic sea water environment, because urea functions as a major blood osmolyte. Furthermore, since dolphins are kept in many aquariums for observation, the evaluation of these aminograms may provide useful diagnostic indices for the assessment of cetacean health in artificial environments in the future.

Polychlorinated Biphenyls and Their Hydroxylated Metabolites (OH-PCBs) in the Blood of Toothed and Baleen Whales Stranded along Japanese Coastal Waters

In this study, we determined the residue levels and patterns of polychlorinated biphenyls (PCBs) and hydroxylated PCBs (OH-PCBs) in the blood from eight species of toothed whales and three species of baleen whales stranded along the Japanese coast during 1999-2007. Penta- through hepta-chlorinated PCB congeners were the dominant homologue groups in all cetaceans. In contrast, specific differences in the distribution of dominant OH-PCB isomers and homologues were found among the cetacean species. In five species of toothed whales (melon-headed whale, Stejneger's beaked whale, Pacific white-sided dolphin, Blainville's beaked whale, and killer whale), the predominant homologues were OH-penta-PCBs followed by OH-tetra-PCBs and OH-tri-PCBs. The predominant homologues of finless porpoise and beluga whale were OH-penta-PCBs followed by OH-hexa-PCBs and OH-tri-PCBs. The predominant OH-PCB isomers were para-OH-PCBs such as 4OH-CB26, 4'OH-CB25/4'OH-CB26/4OH-CB31, 4OH-CB70, 4'OH-CB72, 4'OH-CB97, 4'OH-CB101/4'OH-CB120, and 4OH-CB107/4'OH-CB108 in toothed whales. In three baleen whales (common minke whale, Bryde's whale, and humpback whale) and in sperm whale (which is a toothed whale), OH-octa-PCB (4OH-CB202) was the predominant homologue group accounting for 40-80% of the total OH-PCB concentrations. The differences in concentrations and profiles of OH-PCBs may suggest species-specific diets, metabolic capability, and the transthyretin (TTR) binding specificity. These results reveal that the accumulation profiles of OH-PCBs in cetacean blood are entirely different from the profiles found in pinnipeds, polar bear, and humans.

Phylogenetic analyses in cetacean species of the family Delphinidae using a short wavelength sensitive opsin gene sequence

The short wavelength sensitive (SWS) opsin gene is expected to contain informative sites for understanding the speciation of the family Delphinidae, because it is not functional in cetaceans. We determined partial SWS gene sequences from 15 delphinid species of 12 genera and from harbor porpoise for comparison. We found a 39-bp insertion that was shared by six species (the insertion group: Delphinus delphis, Delphinus capensis, Stenella longirostris, Stenella coeruleoalba, Lagenodelphis hosei, and Sousa chinensis) and common base substitutions shared by eight species (Stenella frontalis, Tursiops truncatus, and six species of the insertion group). As these insertions and substitutions are not found in the other seven delphinids or in the cloven-hoofed mammals (which are close to cetaceans), it is suggested that these eight species are more closely related to each other than to the other species. This hypothesis is supported by phylogenetic analyses. The eight species with the substitutions formed a clade containing two sister clades, one consisting of the insertion group and the other consisting of the two other species, in both neighbor-joining and Bayes analyses. Phylogenetic analyses also showed that Lissodelphis borealis and Lagenorhynchus obliquidens are closely related and that their common ancestor diverged from the others at an early stage of delphinid evolution.

Spatio-temporal comparison of Pacific white-sided dolphin echolocation click types

A comparison of temporal and geographical trends in different echolocation click types produced by Pacific white-sided dolphin Lagenorhynchus obliquidens can lead to insights into the significance of their usage by the dolphins. Using autonomous seafloor recording packages, the spa- tial, diel and seasonal patterns of Pacific white-sided dolphin echolocation click activity are described for 6 locations in the Southern California Bight. Click bouts of the 2 types of Pacific white-sided dol- phin echolocation clicks are identified based on their unique spectral characteristics in long-term spectral averages. Type A clicks were detected on 317 of 1959 recording days and were heard at all 6 sites, with the majority of detections occurring at San Clemente Island and Point Conception. Type B clicks were detected on 130 recording days and were only heard at the 2 southern inshore sites. Significant diel patterns were evident for both click types: Type A click bouts were detected during more hours and with higher click rates at night than during the day, while Type B click bouts exhib- ited the opposite behavior, with greater activity during the day. At the southern sites, both click types exhibited a fall-winter peak in seasonal occurrence. At Point Conception, where only Type A was detected, peak occurrence was during spring. The described spatial and seasonal patterns support the hypothesis that click types are population-specific, while diel patterns suggest differences in prey preferences.

Climate change and a poleward shift in the distribution of the Pacific white-sided dolphin in the northeastern Pacific

Increasing water temperatures due to global warming mean that specific isotherms are shifting polewards. This may cause the poleward shifts in the range limits of species that are only found in specific thermal habitats. Such range shifts have been recorded in a number of plant and animal species. In the last 3 decades, we observed a decline in the presence of Pacific white-sided dolphin Lagenorhynchus obliquidens in the southwest Gulf of California (GOC), which is considered the southern boundary of their distribution. Considering that the thermal environment is physiologi- cally important to animals, we believe that this poleward shift in the usual geographic range of the Pacific white-sided dolphin is due to long-term changes in the local climate. To obtain the conceptual framework needed to discuss such a hypothesis, we summarize and analyze current knowledge about Pacific white-sided dolphins in the southwest GOC, and sea surface temperature variability at a regional scale.

Effect of Breath-Hold on Blood Gas Analysis in Captive Pacific White-Sided Dolphins (Lagenorhynchus obliquidens)

The effect of a breath-hold on blood gas was evaluated in captive Pacific white-sided dolphins (Lagenorhynchus obliquidens). Serial blood collections were performed from a vessel on the ventral surface of the flukes during breath-hold. In total, 178 blood samples were taken from three dolphins for five trials in each animal. During a breath-hold, partial pressure of oxygen (Po₂) decreased from 152.5 to 21.8 mmHg and partial pressure of carbon dioxide (Po₂) conversely increased from 31.8 to 83.6 mmHg. The range of pH was 7.54 to 7.25, suggesting drastic change from alkalemia to acidemia. These wide ranges of blood gas imply a considerable change of oxygen affinity caused by the Bohr effect during breath-hold, which enable effective uptake and distribution of oxygen to metabolizing tissues.

Temporal change of school size on Pacific white-sided dolphin Lagenorhynchus obliquidens in the Tsugaru Strait, Japan

Temporal change of school size on Pacific white-sided dolphin Lagenorhynchus obliquidens in the Tsugaru Strait, Japan

The odontocete community and its environment in the southwestern Gulf of California

Community structure is a function of the number of species, their relative abundance and the characteristics of the dominant, common and rare species that are part of it. It also can be described by changes in its physical and biological environment. The aim of the present work is to describe the odontocete community, its temporal changes and the relationship with environmental variability and food availability in the southwestern Gulf of California (GC). Information was obtained from 21 sampling trips from September 2003 to March 2006 between La Paz Bay and Loreto, with a sampling effort of 8769.1km. We recorded the presence, location and other biological parameters of odontocete sightings. Data on environmental variability was obtained from satellite images of sea surface temperature and chlorophyll concentration, and food availability from published reports. A total of 30201 odontocete cetaceans were recorded from 353 sightings, belonging to 10 different species. We observed a temporal lag between the peaks in productivity and an increased presence of odontocete species. The community structure showed a seasonal change in the abundance of the dominant (Tursiops truncatus and Delphinus sp.) and common species (Globicephala macrorhynchus and Kogia sp.), as well as by the absence or presence of scarce (Physeter macrocephalus and Orcinus orca) and rare species (Pseudorca crassidens and Lagenorhynchus obliquidens). This seasonal community change is in agreement with the known seasonal movements of its main prey inside the GC, which, in turn, is related to seasonal environmental variation. We observed that the community structure was dominated by fish-eating species during the temperate season and responded to the increased presence and aggregation of sardines (Sardinops sagax caerulea) in the southern GC, whereas the warm season was dominated by squid-eating species and related to the increased presence and aggregation of the jumbo squid (Dosidicus gigas) in the GC's west coast.

Comparative feeding kinematics and performance of odontocetes: belugas, Pacific white-sided dolphins and long-finned pilot whales

Cetaceans are thought to display a diversity of feeding modes that are often described as convergent with other more basal aquatic vertebrates (i.e. actinopterygians). However, the biomechanics of feeding in cetaceans has been relatively ignored by functional biologists. This study investigated the feeding behavior, kinematics and pressure generation of three odontocetes with varying feeding modes (belugas, Delphinapterus leucas; Pacific white-sided dolphins, Lagenorhynchus obliquidens; and long-finned pilot whales, Globicephala melas). Four feeding phases were recognized in all odontocetes: (I) preparatory, (II) jaw opening, (III) gular depression, and (IV) jaw closing. Belugas relied on a feeding mode that was composed of discrete ram and suction components. Pacific white-sided dolphins fed using ram, with some suction for compensation or manipulation of prey. Pilot whales were kinematically similar to belugas but relied on a combination of ram and suction that was less discrete than belugas. Belugas were able to purse the anterior lips to occlude lateral gape and form a small, circular anterior aperture that is convergent with feeding behaviors observed in more basal vertebrates. Suction generation in odontocetes is a function of hyolingual displacement and rapid jaw opening, and is likely to be significantly enhanced by lip pursing behaviors. Some degree of subambient pressure was measured in all species, with belugas reaching 126 kPa. Functional variations of suction generation during feeding demonstrate a wider diversity of feeding behaviors in odontocetes than previously thought. However, odontocete suction generation is convergent with that of more basal aquatic vertebrates.

Seasonality, estrous cycle characterization, estrus synchronization, semen cryopreservation, and artificial insemination in the Pacific white-sided dolphin (Lagenorhynchus obliquidens)

The reproductive physiology of the Pacific white-sided dolphin, Lagenorhynchus obliquidens, was characterized to facilitate the development of artificial insemination (AI) using cryopreserved spermatozoa. Specific objectives were to: 1) describe reproductive seasonality of the Pacific white sided dolphins; 2) describe urinary LH and ovarian steroid metabolites during the estrous cycle; 3) correlate LH and ovarian steroidal metabolite patterns to ultrasound-monitored follicular growth and ovulation; and 4) assess the efficacy of synchronizing estrus, sperm collection/cryopreservation, and intrauterine insemination. Ovulations (64%, n=37) and conceptions (83%, n=18) occurred from August to October. Peak mean serum testosterone (24 ng/ml), cross-sectional testicular area (41.6 cm(2)), and sperm concentration (144.3 x 10(7) sperm/ml) occurred in July, August, and September respectively. Spermatozoa were only found in ejaculates from July to October. Estrous cycles (n=22) were 31 d long and were comprised of a 10 d follicular and 21 d luteal phase. Ovulation occurred 31.2 h after the onset of the LH surge and 19.3 h after the LH peak. Follicular diameter and circumference within 12 h of ovulation were 1.52 and 4.66 cm respectively. Estrus synchronization attempts with altrenogest resulted in 17 (22%) ovulatory cycles with ovulation occurring 21 d post-altrenogest. Ten AI attempts using cryopreserved semen resulted in five pregnancies (50%). The mean gestation length was 356 days (range 348-367). These data provide new information on the Pacific white-sided dolphin's reproductive physiology and collectively enabled the first application of AI in this species.

Dall’s porpoise (Phocoenoides dalli) echolocation click spectral structure.

Dall’s porpoise (Phocoenoides dalli) echolocation clicks have not been widely recorded. Concurrent with visual observations, acoustic recordings of free-ranging Dall’s porpoise were made offshore of southern California using a towed hydrophone array with two elements of 250 kHz bandwidth. We examined 6035 clicks from 12 sessions totaling more than two hours over the course of seven days. The Dall’s porpoise echolocations recorded were short (48–804 μs), narrow band (2–10 kHz [−3dB]) clicks with most peak frequencies between 117 and 141 kHz, but some as high as 198 kHz. Many clicks contained a multipulse temporal structure, resulting in stereotyped spectral peaks and notches. Two distinctive click types with different spectral banding patterns and peak frequencies (122.8 and 135.8 kHz) were observed. Spectral banding patterns have been used as a species identifier for Risso’s dolphins and Pacific white-sided dolphins. These two dolphins and Dall’s porpoise have similar head morphologies, which may play a role in producing clicks with spectral peaks and notches. This study shows that Dall’s porpoise produce multiple click types, which may provide a tool for population classification, and that their clicks contain spectral banding patterns, which may provide insight into the mechanism by which such clicks are produced.