Belugas (Delphinapterus leucas) create facial displays during social interactions by changing the shape of their melons.

Beluga whales are considered unique among odontocetes in their ability to visibly alter the appearance of their head by changing the shape of the melon, but only anecdotal observations are available to evaluate the use or potential function of these melon shapes. This study of belugas in professionally managed care aimed to establish an ethogram for the repertoire of categorizable melon shapes and then evaluate their potential function as intentional communication signals by determining if they were produced and elaborated during social interactions of varying behavioral contexts while in the line of sight of a recipient. Five different melon shapes were reliably identified in video observations of the primary study population (n = 4) and externally validated in a second aquarium population (n = 51). Among the 2570 melon shapes observed from the primary study subjects, melon shapes occurred 34 × more frequently during social interactions (1.72 per minute) than outside of social interactions (0.05 per minute). Melon shapes occurring during social interactions were performed within the line of sight of a recipient 93.6% of the time. The frequency of occurrence of the different melon shapes varied across behavioral contexts. Elaboration of melon shapes through extended duration and the occurrence of concurrent open mouth displays varied by shape type and across behavioral contexts. Melon shapes seem to function as visual displays, with some characteristics of intentional communication. This ability could yield adaptive benefits to belugas, given their complex social structure and hypothesized mating system that emphasizes pre-copulatory female mate choice.

Evaluating beluga (Delphinapterus leucas) blow samples as a potential diagnostic for immune function gene expression within the respiratory system.

Evaluating respiratory health is important in the management of cetaceans, which are vulnerable to respiratory diseases. Quantifying the expression of genes related to immune function within the respiratory tract could be a valuable tool for directly assessing respiratory health. Blow (exhale) samples allow DNA analysis, and we hypothesized that RNA could also be isolated from blow samples for gene expression studies of immune function. We evaluated the potential to extract RNA from beluga blow samples and tested whether transcripts associated with immune function could be detected with endpoint polymerase chain reaction. A total of 54 blow samples were collected from clinically healthy aquarium belugas (n = 3), and 15 were collected from wild belugas temporarily restrained for health assessment in Bristol Bay, Alaska (n = 9). Although RNA yield varied widely (range, 0-265.2 ng; mean = 85.8; SD = 71.3), measurable RNA was extracted from 97% of the samples. Extracted RNA was assessed in 1-6 PCR reactions targeting housekeeping genes (Rpl8, Gapdh or ActB) or genes associated with immune function (TNFα, IL-12p40 or Cox-2). Fifty of the aquarium samples (93%) amplified at least one transcript; overall PCR success for housekeeping genes (96/110, 87%) and genes associated with immune function (90/104, 87%) were similarly high. Both RNA yield and overall PCR success (27%) were lower for wild beluga samples, which is most likely due to the reduced forcefulness of the exhale when compared with trained or free-swimming belugas. Overall, the high detection rate with PCR suggests measuring gene expression in blow samples could provide diagnostic information about immune responses within the respiratory tract. While further study is required to determine if quantitative gene expression data from blow samples is associated with disease states, the non-invasive nature of this approach may prove valuable for belugas, which face increasing anthropogenic disturbances.

Testosterone and progesterone concentrations in blow samples are biologically relevant in belugas (Delphinapterus leucas).

Steroid hormone analysis in blow (respiratory vapor) may provide a minimally invasive way to assess the reproductive status of wild cetaceans. Biological validation of the method is needed to allow for the interpretation of hormone measurements in blow samples. Utilizing samples collected from trained belugas (Delphinapterus leucas, n=20), enzyme immunoassays for testosterone and progesterone were validated for use with beluga blow samples. Testosterone concentrations in 40 matched blood and blow samples collected from 4 male belugas demonstrated a positive correlation (R2=0.52, p<0.0001). Progesterone concentrations in 64 matching blood and blow samples from 11 females were also positively correlated (R2=0.60, p<0.0001). Testosterone concentrations (mean±SD) in blow samples collected from adult males (119.3±14.2pg/ml) were higher (p<0.01) than that of a juvenile male (<8years) (59.4±6.5pg/ml) or female belugas (54.1±25.7pg/ml). Among adult males, testosterone concentrations in blow demonstrated a seasonal pattern of secretion, with peak secretion occurring during the breeding season (February-April, 136.95±33.8pg/ml). Progesterone concentrations in blow varied by reproductive status; pregnant females (410.6±87.8pg/ml) and females in the luteal phase of the estrous cycle (339.5±51.0pg/ml) had higher (p<0.0001) blow progesterone concentrations than non-pregnant females without a corpus luteum (242.5±27.3pg/ml). Results indicate that blow sample analysis can be used to detect variation in reproductive states associated with large differences in circulating testosterone or progesterone in belugas.