Sang Wha Kim

Objective: Jellyfish are known to be difficult species to breed, yet little is known about the diseases that affect them. This study investigated the behavioral and histopathological changes caused by gas bubble disease (GBD) in upside-down jellyfish Cassiopea sp. Methods: Upside-down jellyfish were assigned to control and microbubble-exposed tanks (n = 7 each; 36 L size). Microbubbles were supplied to the experimental group tank by inducing an insufficient water level in the sump tank, which allowed air to be entrained into the return pump. Result: All upside-down jellyfish maintained in the microbubble-exposed tank exhibited signs of GBD. Gas bubbles were observed both grossly and histologically, along with chronic lesions, which progressed to bell ulceration. Behavioral changes, including loss of equilibrium and abnormal pulsation, were observed. These results demonstrate that excessive microbubbles induce GBD. Conclusion: This study demonstrates that excessive microbubble exposure can experimentally induce GBD in upside-down jellyfish and highlights the need to monitor gas supersaturation during jellyfish rearing.

Erysipelothrix rhusiopathiae causes sporadic, often fatal septicaemia in cetaceans; published cases rest almost entirely on cultured isolates, and none has included post-mortem imaging. We investigated a juvenile male short-beaked common dolphin (Delphinus delphis) stranded on Jeju Island, Republic of Korea, using post-mortem computed tomography (PMCT) of the frozen carcass, necropsy, histopathology and tiered molecular testing. Rhomboid skin lesions extended through the skin into the blubber. PMCT documented gravity-dependent pulmonary opacification, fluid in the trachea and bronchi, peritoneal effusion, no decomposition gas and a gastric fishing hook, confirmed at necropsy. Culture was not attempted because the carcass had been stored frozen. Erysipelothrix spp. DNA was detected by broad-range 16S rRNA sequencing in 11 of 12 tissues, and E. rhusiopathiae was identified by species-specific PCR and amplicon sequencing in all 12 tissues, yielding one identical 356-bp sequence. Histopathology showed epidermal coagulative necrosis with septal panniculitis and abundant Gram-positive bacteria throughout the lesion, pulmonary haemorrhage and oedema, interstitial nephritis and reactive lymphadenitis, consistent with fatal septicaemia. The case provides imaging correlates of erysipelas, a culture-independent diagnostic framework for frozen carcasses and a tissue-by-tissue molecular dataset; the relationship of the strain to other Korean cetacean isolates remains to be established genomically.

Introduction: Rays rarely develop neoplasia in nature, yet tumors have been repeatedly reported in captive individuals, suggesting environmental or species-specific factors. Methods: We surgically removed the nasal fibroma under general anesthesia, followed by transcriptomic and histopathological analyses in a captive Javanese cownose ray ( Rhinoptera javanica ). Results: Histopathology revealed a fibromatous lesion characterized by dense, mature collagen-rich fibrosis in the central core, accompanied by peripheral fibroinflammatory change, vascular congestion, hemorrhage, and inflammatory-cell infiltration. Exploratory transcriptomic profiling of the central fibrotic core provided complementary evidence of candidate remodeling-associated expression patterns, including increased mechanical-stimulus response and epithelial proliferation terms. Together, these findings support a plausible link between repeated surface contact and chronic injury-associated remodeling of the nasal tissue. Discussion and conclusion: These findings suggest that persistent mechanical stimulation in artificial environments may contribute to chronic fibrosis and fibroinflammatory tumor development. Together with the clinicopathological findings, the transcriptomic findings provide exploratory, hypothesis-generating support for a possible association between captivity-related mechanical stress and species-specific fibroma formation in the Javanese cownose ray.

An Indo-Pacific bottlenose dolphin (Tursiops aduncus) in the coastal waters of Jeju Island, Republic of Korea, exhibited an oral mass and mandibular deform

The spotted seal (Phoca largha) is a flagship species and natural monument inhabiting Korean coastal waters. Due to its conservation importance and the rarity of carcass discoveries, determining the cause of death of each individual is critical. A juvenile female spotted seal carcass was discovered on the eastern coast of Korea in May 2025. External examination revealed multiple parallel lacerations consistent with propeller strike injuries. Post-mortem computed tomography (PMCT) was performed prior to necropsy to provide a comprehensive forensic analysis. CT imaging revealed the longest wound measured 10.49 cm in length and 1.58 cm in depth, suggesting a minimum propeller diameter of approximately 19 cm. Skeletal injuries included a coccygeal vertebral fracture and subluxation of the left astragalus and calcaneus. CT images of the respiratory tract showed frothy fluid in the nasal cavity and trachea, as well as ground-glass opacity and consolidation in the lung parenchyma. Necropsy findings confirmed severe pulmonary edema, congestion, and abundant frothy foam throughout the respiratory tract. Histological analysis revealed pulmonary edema with eosinophilic fluid and erythrocytes in alveolar spaces, markedly distended blood vessels, and intra-alveolar hemorrhage. This comprehensive approach demonstrated that the cause of death was drowning, secondary to propeller strike by a small vessel (<4.5 m). To the authors’ knowledge, this is the first case report providing a detailed forensic analysis of a juvenile spotted seal found on the eastern coast of Korea. This case highlights the importance of integrating PMCT with conventional necropsy to improve cause-of-death determination in marine mammal conservation.

Background: Post-mortem imaging has become indispensable in marine mammal research, offering non-destructive alternatives to conventional necropsy. While micro-computed tomography (microCT) provides high resolution for small specimens, its utility in cetacean fetal studies is limited by long scanning time, accessibility, and high cost. Diffusible iodine-based contrast-enhanced CT (diceCT) using clinical-grade scanners presents a potential solution, particularly for endangered species like the narrow-ridged finless porpoise ( Neophocaena asiaeorientalis ) (NRFP), where fetal specimens are exceptionally rare. This study pioneers the application of clinical CT-based diceCT for NRFP fetal imaging, addressing the gap in developmental morphology research. Results: A 41 cm NRFP fetus was recovered from a stranded pregnant female and preserved for iodine-enhanced CT imaging. The specimen underwent 22 weeks of staining in 1% iodine-ethanol solution, with weekly solution replacement and biweekly clinical CT scans (100 kVp, 300 mAs, 0.3 mm slice thickness) to monitor progression. Complete staining was confirmed by clear radiographic differentiation between adjacent tissue, variance of Hounsfield unit (HU) values of the specimen, and a plateau in the signal-to-noise ratio (SNR) among all scans within the liver. High-resolution 3D reconstructions successfully visualized the gastrointestinal tract, urogenital structures, and cardiovascular network, with preserved spatial relationships. Conclusions: Clinical-grade diceCT provides a practical alternative to microCT for cetacean fetal imaging by achieving organ-scale resolution. The protocol enabled comprehensive 3D morphological analysis without tissue destruction. The archived dataset and destained specimen offer enduring value for conservation research, education, and method development.

Penguin molts occur annually after breeding, allowing effective waterproofing and temperature regulation. However, aberrant molts frequently occur in penguins, which can lead to health problems if prolonged. Although the exact mechanisms underlying molting in birds remain unclear, some studies have focused on the roles of thyroid and sex hormones in penguins. Previous studies on forced molting using hormonal treatments have shown both success and failure. In particular, the use of synthetic thyroxine (levothyroxine) has mostly not been successful. This study aimed to induce molting by administering commercial levothyroxine to one Humboldt penguin (Spheniscus humboldti) and four African penguins (Spheniscus demersus) with abnormal molting, housed in aquaria. The planned levothyroxine dosing protocol was to start with 25 μg/kg PO q24h for 7 d, then increase it gradually to 50 μg/kg PO q24h for the next 7 d and 75 μg/kg PO q24h for 7 d, followed by a gradual decrease to 50 μg/kg PO q24h for 7 d, and 25 μg/kg PO q24h for the final 7 d. Three penguins received treatment according to this scheduled protocol, two of which initiated molting during the dosing period, while the third began to molt approximately 3 months post-treatment. Another penguin was administered the maximum dose for an additional week, which led to molting in the final week of treatment. In the remaining penguin, the medication was deemed to be insufficiently absorbed because of inadequate drug delivery methods. Consequently, the drug delivery strategy was changed during the 5^th week of treatment, and the treatment was extended for an additional 3 weeks beyond the original plan, after which the penguin began to molt. Therefore, all five penguins in this study exhibited molting following oral levothyroxine treatment, suggesting that this is a potential option for inducing molting in banded penguins (Spheniscus sp.) experiencing aberrant molt.