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.

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.